WRIST TERMINOLOGY AS DEFINED BY THE INTERNATIONAL WRIST INVESTIGATORS WORKSHOP (IWIW)

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1 1 WRIST TERMINOLOGY AS DEFINED BY THE INTERNATIONAL WRIST INVESTIGATORS WORKSHOP (IWIW) GILULA LA, MANN FA, DOBYNS JH, YIN Y, AND IWIW TERMINOLOGY COMMITTEE* the shape or size of the carpal bones even if all of its ligaments are intact. Although these alterations of the osseous elements may disrupt the ligament anchorage, may be accompanied by ligament damage, or may secondarily develop ligament attenuation, they often begin as a normal carpus. 2) The carpus may be malaligned between the two rows or remain aligned within itself, while translating at the radiocarpal level to a new position (usually dorsal, sometimes volar, even ulnar or radial). 3) This definition refers to an extracarpal, not an intracarpal, problem. If the malalignment is due to an intracarpal problem, then the case falls into a CID, CIND, or CIC category and would not fit into the category of an adaptive carpus as described here. Any adaptive carpus, by definition, can be solved by an extracarpal intervention that does not require surgery on the carpus. However, with time an adaptive carpus may degenerate to a point that the intrinsic ligaments fail and a secondary CID pattern (an intracarpal problem) is established. CODE: Clinical Conditions: Residuals of Injuries (IIIC)** Fig. 1 ADAPTIVE CARPUS-ADAPTIVE DISI: the distal articular surface of the radius is inclined 30 dorsally from an old impacted distal radius fracture. The lunate is tilted dorsally to account for dorsal inclination of the distal radius, while the capitate is in neutral position following the position of the metacarpals with the hand. Changes in the carpal alignment creates a capitolunate angle of approximately 30 and a scapholunate angle of 85. The increased scapholunate angle creates a DISI (dorsal intercalated segmental instability) configuration. ADAPTIVE CARPUS (FIGURE 1) SYNONYM: none CLINICAL: NA RADIOLOGIC: a carpal malalignment usually identified by a dorsal or volar tilt of the lunate caused by an extracarpal osseous abnormality, usually a distal radial malunion without ligament tears COMMENTS: 1) every carpus must adjust in some way to alterations of the radius articular surface, the ulnar head position, and *See Appendix C. **See Appendix B. 1. Dobyns JH, Linscheid RL. Complications of treatment of fractures and dislocations of the wrist. In: Epps CH Jr, editor. Complications in orthopaedic surgery. Vol 2. Philadelphia: JB Lippincott; p Cooney WP 3rd, Dobyns JH, Linscheid RL. Complications of Colles fractures. JBone Joint Surg Am. 1980;62: Brahin B, Allieu Y. [Compensatory carpal malalignments]. Ann Chir Main. 1984;3: French. 4. Allieu Y. [Carpal instability. General therapeutic principles]. Ann Chir Main. 1984;3: French. 5. Taleisnik J, Watson HK. Midcarpal instability caused by malunited fractures of the distal radius. J Hand Surg [Am]. 1984;9: Saffar P. Carpal injuries: anatomy, radiology, current treatment. Paris: Springer; Dobyns JH, Berger RA. Dislocations of the carpus. In: Chapman MW, Madison M, editors. Operative orthopedics. 2nd ed, vol 2. Philadelphia: JB Lippincott; p ANATOMIC NEUTRAL (FIGURE 2) SYNONYM: zero-position CLINICAL: the wrist placed in neutral (zero) position of extensionflexion, radial-ulnar deviation, and forearm pronation-supination. The third metacarpal is positioned collinear with the radius. RADIOLOGIC: NA COMMENTS: 1) PA radiographs of this position are facilitated by flexing the elbow to 90 and abducting the shoulder to 90. 2) See LATERAL VIEW and POSTEROANTERIOR VIEW. CODE: Radiologic: Positions (IA) 1. Palmer AK. The distal radioulnar joint. Orthop Clin North Am. 1984;15: Bowers WH. Problems of the distal radioulnar joint. Advances in Orthopedic Surgery. 1984;7:289.

2 2 Fig. 2a Fig. 3a Fig. 2b ANATOMIC NEUTRAL (ZERO POSITION): a) posteroanterior (PA) position and b) lateral position. The wrist is placed so that there is no flexion, extension, or radial or ulnar deviation. The third metacarpal is positioned collinear with the radius. In the PA position (see also Fig 4B) the elbow is elevated to the shoulder height, and in the lateral position the elbow is adducted to the patient s side. (Reprinted with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 226. Fig 9-1, A and B.) ANCHOR see TETHER ANTERIOR see PALMAR or VOLAR ANTEROPOSTERIOR (AP) VIEW OR PROJECTION (FIGURE 3) SYNONYMS: coronal, frontal, palm-to-dorsum, volar-to-dorsal, AP projection, AP position CLINICAL: NA; see RADIOLOGIC Fig. 3b ANTEROPOSTERIOR (AP) VIEW OR PROJECTION: a) clinical view for an AP view of the hand and wrist combined: the x-ray beam enters the anterior (palmar) surface of the hand/wrist at the level of the third metacarpal head and exits the posterior (dorsal) surface of the hand/ wrist to expose the x-ray film, which is posterior to the hand/wrist. For a wrist view, the central ray would be centered in the middle of the wrist at the level of the capitate head. b) On the AP radiographic view of the hand and wrist, the ulnar styloid (barely included on this figure) is typically more radial in position than with the PA view and commonly overlies the central portion of the distal ulna. Also, the scapholunate and lunotriquetral joints are commonly better profiled on the AP than on the PA view. (Reprinted with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 98. Fig 5-5, A and B.)

3 3 RADIOLOGIC: radiologic beam enters the anterior and exits the posterior surface of a body part; the radiographic film is on the posterior surface of the radiographed body part. COMMENTS: none CODE: Radiologic: Views (ID) 1. Radiology textbooks 2. Yin Y, Mann FA, Gilula LA. Positions and techniques. In: Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p ARCS see CARPAL ARCS AXIAL CARPAL DISLOCATION see LONGITUDINAL CARPAL DISLOCATION AXIAL CARPAL FRACTURE-DISLOCATION see LONGITUDINAL CARPAL FRACTURE-DISLOCATION AXIAL CARPAL INSTABILITY see LONGITUDINAL CARPAL INSTABILITY AXIAL CARPAL SUBLUXATION see LONGITUDINAL CARPAL SUBLUXATION AXIAL PLANE see TRANSVERSE PLANE BACK see POSTERIOR BALL CATCHER S VIEW OR PROJECTION (FIGURE 4) SYNONYM: Norgaard view CLINICAL: NA RADIOLOGIC: the hand or hands are placed palm up, with thumbs elevated approximately off the film cassette, and the dorsal aspect of the hypothenar eminences flush on the radiographic cassette. The central ray enters the midportion of the hand if one hand is radiographed or the space between both hands if both hands are radiographed simultaneously. COMMENTS: a position of the wrist and hand to project the palmar ulnar aspect of hand and wrist bones in more detail. This projection has been used to look for erosions seen in arthritis but could be used whenever the ventral ulnar aspects of these bones must be profiled or when a different oblique projection of the bones of the hands and wrists is desired. CODE: Radiologic: Views (ID) 1. Norgaard F. Earliest roentgenological changes in polyarthritis of the rheumatoid type: rheumatoid arthritis. Radiology. 1965;85: Norgaard F. Earliest roentgen changes in polyarthritis of the rheumatoid type. Continued investigations. Radiology. 1969;92: BONDED see NONDISSOCIATION BREWERTON VIEW OR PROJECTION (FIGURE 5) SYNONYM: none CLINICAL: NA RADIOLOGIC: the dorsum of the fingers are positioned flat on the radiographic cassette with the metacarpophalangeal joints flexed and the central beam angled from the ulnar to the radial side of the hand. COMMENTS: this view is designed to display the metacarpophalangeal areas of the fingers. In contrast to standard frontal and oblique radiographs, these views demonstrate the grooved area between the collateral ligaments and the articular cartilage of the metacarpal Fig. 4a Fig. 4b BALL CATCHER S VIEW OR PROJECTION: a) clinical view: the hands are placed with the ulnar side of the hands on the cassette or table top with the radial sides of the hands elevated off the cassette in a position as to catch a ball. b) This view demonstrates the ventroulnar sides of the hand and wrist bones in better profile than on other views. (Reprinted with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 152. Fig 5-56, A and B.)

4 4 Fig. 5a Fig. 5b BREWERTON VIEW OR PROJECTION: a) the dorsa of the fingers are placed flat on the table or film cassette, with the hand flexed at the metacarpophalangeal (MCP) joints. The pointer designates the centering place for the central x-ray beam, which is entering the MCP joints at an angle of ulnar to radial. b) Good detail of the metacarpal heads with better demonstration of the ventral surfaces of the metacarpal heads is provided with this view as compared to the routine PA or AP views of the metacarpals. (Reprinted with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 104. Fig 5-11, A and B.) heads and, when the carpus is included, the metacarpal bases and angled oblique view of carpal bones. CODE: Radiologic: Views (ID) 1. Brewerton DA. A tangential radiographic projection for demonstrating involvement of metacarpal heads in rheumatoid arthritis. Br J Radiol. 1967;40: CAPITATE RADIUS DISTANCE, INDEX, RATIO see CARPAL HEIGHT CAPITOLUNATE INSTABILITY PATTERN (CLIP) (FIGURE 6) SYNONYMS: dorsal midcarpal instability (see comment #2), midcarpal instability CLINICAL: a form of carpal instability manifested most obviously at the capitolunate joint in which the clinical presentation is one of painful discomfort of presenting symptomatology produced by a stress maneuver (by the patient or by the examiner), which may or may not be accompanied by a clicking or snapping in the midcarpal region. The stress maneuver, as performed by the examiner, is similar to that used for radiologic demonstration. See RADIOLOGIC for description of stress maneuvers. See COMMENTS for controversy with CLIP. RADIOLOGIC: dorsal displacement of the hand and distal part of the carpus is produced while fixing the distal part of the forearm. Longitudinal traction can be useful. Slight wrist flexion is the test position, although ulnar deviation may assist or radial deviation may hinder the ease of testing. This displacement is produced by pressing on the scaphoid tubercle or volar aspect of the midportion of the carpus in a dorsal direction. Typically, slight capitolunate subluxation will occur with the dorsal displacing force. These radiographic views are obtained in the lateral position with the patient having relaxed musculature. This test stresses both RC (radiocarpal) and MC (midcarpal) joints and could show loss of congruity at either the radiocarpal or the capitolunate joint. The stress can be limited to the midcarpal level by including the proximal carpal row in the distal forearm fixation grip. When the test is positive, there is dorsal displacement of the capitate and hamate from the distal articular surface of the proximal carpal row (recognized by the lunate on radiographs) and occasionally a dorsal displacement of the lunate and proximal carpal row from the fossae of the radius. However, a positive radiologic finding must be matched by the clinical re-creation of the patient s presenting symptomatology. The opposite wrist should be examined in the same way for comparison to see if the displacement is the same or more on the symptomatic side. COMMENTS: 1) wide practice variation suggests the need for improved standardization of the performance and interpretation of the provocative maneuver used to identify this condition. 2) CLIP is said by some to be a combination of dorsal radiocarpal and midcarpal instability. However, the exact pattern of ligament tears or insufficiency associated with this instability remains unclear. 3) With clinical testing, it is important to distinguish CLIP from a positive Scaphoid Shift Test (Watson Test). 4) Some people also check midcarpal laxity by performing this same test with palmardirected force applied over the dorsum of the second through the fourth carpometacarpal joints (see reference #5). With the ventral displacing force, the lunate will typically change its orientation to face volarly with the capitate head still remaining within the distal lunate concavity. More rarely, the capitate could sublux out of the distal lunate concavity. A positive test would occur when presenting symptomatology is associated with this maneuver. Again, as for the dorsal-directed maneuver, the opposite wrist should be included for comparison.

5 5 CODE: Clinical Conditions: Sprains-Instabilities-Subluxations (IIIB) 1. Louis DS, Hankin FM, Greene TL, Braunstein EM, White SJ. Central carpal instability--capitate lunate instability pattern. Diagnosis by dynamic placement. Orthopaedics. 1984;7: White SJ, Louis DS, Braunstein EM, Hankin FM, Greene TL. Capitate-lunate instability: recognition by manipulation under fluoroscopy. AJR Am J Roentgenol. 1984;143: Dobyns JH, Linscheid RL, Chao EYS, Weber ER, Swanson GE. Traumatic instability of the wrist. AAOS Instr Course Lect. 1975;24: Johnson RP, Carrera GF. Chronic capitolunate instability. J Bone Joint Surg Am. 1986;68: Truong NP, Mann FA, Gilula LA. II. Indications for wrist instability series and its cost-effectiveness. In: Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p CARPAL ANGLE (FIGURE 7) Fig. 6a SYNONYM: frontal carpal condyle angle CLINICAL: the angle subtended by the proximal surfaces of the proximal carpal row as seen on the PA radiograph RADIOLOGIC: The carpal angle is defined by the intersection of two tangents, one touching the proximal contour of the scaphoid and lunate bones and the second touching the triquetrum and lunate bones. Between 4 and 83 years of age for males and females, Caucasians and blacks, the angle is (See reference #1) COMMENTS: none CODE: Radiologic: Measurements (IE) Fig. 6b CAPITOLUNATE INSTABILITY PATTERN (CLIP): a) lateral wrist view with dorsally directed stress (arrow with S ) pushes the capitate partially out of the lunate fossa. See Text. The wrist is still in satisfactory lateral position as noted by the scaphopisocapitate (SPC) relationship (see LATERAL VIEW). b) With stress released, a normal capitolunate relationship is restored. (Reprinted with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 215. Fig 8-15, A and B.) Fig. 7 CARPAL ANGLE: the angle created between the two lines X and Y. X is a line drawn tangential to the proximal cortical surfaces of the scaphoid and lunate, and Y is the line tangent to the proximal cortices of the triquetrum and lunate. (Reprinted with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 233. Fig 9-8.)

6 6 1. Harper HA, Poznanski AK, Garn SM. The carpal angle in American populations. Invest Radiol. 1974;9: Kosowicz J. The carpal sign in gonadal dysgenesis. J Clin Endocrinol Metab. 1962;22: Kosowicz J. The roentgen appearance of the hand and wrist in gonadal dysgenesis. AJR Am J Roentgenol. 1965;99:354. CARPAL ARCS (FIGURE 8) SYNONYMS: Gilula s arcs, radiologic carpal arcs I-III, Gilula s lines CLINICAL: NA RADIOLOGIC: three smooth arcs with changing radii normally can be drawn along surfaces of carpal bones seen on radiographs when the hand is supinated or pronated and is in neutral position (see COM- MENTS). 1) Arc I represents the smooth curvature or arc that normally defines the proximal convex cortical surfaces of the scaphoid, lunate, and triquetrum; 2) Arc II represents the smooth arc that defines the distal cortical concavities of the scaphoid, lunate, and triquetrum; and 3) Arc III refers to the smooth arc that outlines the proximal cortical convexities of the capitate and hamate. (See COMMENTS.) COMMENTS: 1) the arcs can be evaluated only in the neutral PA or AP position, which is defined as the situation when the long axis of the third metacarpal is coaxial with the long axis of the distal radius. 2) Any break in one of the arcs implies an abnormality at the broken site. Exceptions are: (a) at each joint, the edge of the adjacent bones have a more acute curvature; therefore, only the major curvatures of bones should be used; (b) a carpal arc is not applicable when one carpal bone is congenitally smaller than the adjacent carpal bone; e.g., the triquetrum may be smaller in its proximal-distal dimension than the adjacent lunate, resulting in a normal break in Arc I and a normal Arc II at the lunotriquetral joint; and (c) with a prominent hamate facet (distal ulnar concavity) of the lunate described by Viegas as the type II lunate, Arc II may not be smooth at the lunotriquetral joint and Arc III may also have an offset at the capitohamate articulation. 3) Arcs I and II commonly will be broken normally at the scapholunate and lunotriquetral joints with radial and ulnar deviation. (See reference #4.) CODE: Radiologic: Measurements (IE); Anatomic: Carpal (IID) 1. Dobyns JH, Linscheid RL, Chao EYS, Weber ER, Swanson GE. Traumatic instability of the wrist. AAOS Instr Course Lect. 1975;24: Gilula LA. Carpal injuries: analytic approach and case exercises. AJR Am J Roentgenol. 1979;133: Viegas SF, Wagner K, Patterson R, Peterson P. Medial (hamate) facet of the lunate. J Hand Surg [Am]. 1990;15: Peh WC, Gilula LA. Normal disruption of carpal arcs. J Hand Surg [Am]. 1996;21: CARPAL BOSS (FIGURE 9) SYNONYMS: os styloideum, carpe bossu, dorsal boss CLINICAL: an osseous prominence at the second and/or third carpometacarpal joints RADIOLOGIC: the carpal boss may be produced by one of four entities: a separate bone [1) os styloideum or 2) ununited fracture], 3) osteophyte (osteoarthritis), or 4) osseous prominence (exostosis) at the second and/or third CMC. COMMENTS: 1) strictly speaking, the os styloideum is not identical to the term carpal boss. A carpal boss may exist because of a variety of conditions as described under radiologic and is not necessarily Fig. 8a Fig. 8b CARPAL ARCS: a) on this PA neutral view (no radial or ulnar deviation of the carpus), Arc 1 is a smooth arc outlining the proximal surfaces of the scaphoid, lunate, and triquetrum. Arc 2 is a smooth arc that outlines the distal surfaces of these same three carpal bones, and Arc 3 outlines the proximal surfaces of the capitate and hamate. b) When the proximal-distal dimension of the triquetrum is less than the adjacent surface of the lunate (see arrows), Arc 1 can normally be broken at the lunotriquetral joint. With a type II lunate (with a large hamate articulating facet of the lunate), Arcs 2 and 3 can also be broken normally at the lunotriquetral and capitohamate joints. (Reprinted with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 296. Fig 11-3, A and C.) due only to the os styloideum. 2) Usually fluoroscopically obtained spot views can serve best with plain radiography to determine which of the above causes exists for the carpal boss (see CARPAL BOSS VIEW). 3) CT scans or complex motion tomography may be necessary to fully clarify the anatomic cause of the dorsal boss. CODE: Anatomic: Radial (IIA) 1. see CARPAL BOSS VIEW

7 7 CARPAL COLLAPSE see COLLAPSE DEFORMITY Fig. 9 CARPAL BOSS: large bone prominences (arrowheads) project dorsally off the junction of the second and third carpometacarpal joints. (Reprinted with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 527. Fig 20-8A.) CARPAL HEIGHT, INDEX, AND RATIO (FIGURE 11) SYNONYM: none CLINICAL: see RADIOLOGIC RADIOLOGIC: carpal height is a radiologic concept to aid in the quantification of carpal collapse. (1) CARPAL HEIGHT (see references #4 and #5) is defined as the distance from the base of the third Fig. 10a CARPAL BOSS VIEW OR PROJECTION (FIGURE 10) SYNONYM: carpal boss projection CLINICAL: NA RADIOLOGIC: two different tangential projections have been described: lateral or slightly supinated off-lateral, and the carpal bridge view. 1) With the off-lateral projection, the wrist is positioned in flexion and slight supination (off lateral), so that the dorsal boss projects off the underlying carpometacarpal joints. The central ray of the x-ray beam is passed through the carpal boss perpendicular to the cassette. Twenty to thirty degrees of angulation toward the fingers or similar ulnar deviation of the wrist may aid in demonstration of the boss or separate ossicle. 2) The carpal bridge view is obtained by passing an x-ray beam tangent to the dorsum of the carpus with the wrist palmar flexed approximately 90 or maximally flexed. The dorsum of the hand is placed directly on the cassette. The central beam passes tangent to the carpal boss at approximately 45 to the cassette. COMMENTS: the off-lateral projection is the more reliable means to demonstrate the carpal boss and its anatomic structure (see CARPAL BOSS: COMMENTS). CODE: Radiologic: Views (ID) 1. Conway WF, Destouet JM, Gilula LA, Bellinghausen HW, Weeks PM. The carpal boss: an overview of radiographic evaluation. Radiology. 1985;156: Kaulesar-Sukul DM, Steinberg PJ, Lichtveld PL. The carpal boss. Neth J Surg. 1986;38: Cuono CB, Watson HK. The carpal boss: surgical treatment and etiological considerations. Plast Reconstr Surg. 1979;63: Hultgren T, Lugnegard H. Carpal boss. Acta Orthop Scand. 1986;57: Fig. 10b CARPAL BOSS VIEW OR PROJECTION: a) this is accomplished with the ulnar side of the wrist on the cassette or table, with ulnar deviation of the wrist and enough supination to make the dorsal boss project dorsal to the adjacent metacarpal bases. Positioning for the central x-ray beam is indicated with the pointer. b) A separate ossicle, the os styloideum (arrow), is the cause for the dorsal boss in this case. (Reprinted with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 147. Fig 5-51, A and B.)

8 8 Fig. 11b CARPAL HEIGHT AND CARPAL HEIGHT RATIO: a) carpal height is measured by the line L b, which is the distance from the base of the third Fig. 11a metacarpal to the distal radius articular surface, measured along the central axis of the third metacarpal. L a (from the head to the base of the third metacarpal) is the length of the third metacarpal. L b /L a is 0.54 ± 0.03 for the carpal height ratio. b) An alternate carpal height ratio can be determined by dividing the carpal height (L2) by the length of the capitate (L1) for a ratio of 1.57 ± L1 is determined by the longest length of the capitate starting at a point on the distal cortex of the capitate at the junction between the bases of the second and third metacarpal bones. (Reprinted with permission from Mann FA, Wilson AJ, Gilula LA. Radiographic evaluation of the wrist: what does the hand surgeon want to know? Radiology. 1992;184: Fig 1, A and B.) metacarpal to the subchondral sclerotic line of the distal radial articular surface as measured along the axis extended from the third metacarpal. The mean has been measured as 33.8 mm ( mm) by Schuind et al. Another way to measure carpal height, which is believed to be more precise and reliable by some experts than that mentioned in references #4 and #5, is to measure the shortest distance between the proximal pole of the capitate and the radius, the CAPITATE RADIUS DISTANCE (CRD) or index (see reference #6). This is determined by comparing this distance between both wrists of the same individual or the same wrist on subsequent follow-up examinations. Normally, comparing this distance between wrists produces a ratio of 0.99 with a standard deviation of and a range of The authors (see reference #6) state that a ratio of the new and old CR distances of the same hand which is lower than 0.95 (lower rounding error limit) should be considered to be significant. (2) The CARPAL HEIGHT RATIO (see references #1, #3, and #4) is obtained by dividing the carpal height (L b ), measured as the distance from the third metacarpal base to the subchondral sclerotic line of the distal radial articular surface, by the length of the third metacarpal (L a ): L b /L a = 0.54 ± An ALTERNATE CARPAL HEIGHT RATIO (see reference #2) is obtained by dividing carpal height (L2) by the capitate length (L1), measured as the distance between the intersection point of the capitate articular facets for the second and third metacarpals and the proximal subchondral osseous cortex of the capitate along the line that passes through the center of the capitate head: L2/L1 = 1.57 ± (3) The CARPAL HEIGHT INDEX (see reference #1), which corrects for differences in body habitus, is obtained by dividing the carpal height ratio of the diseased hand by that of the normal hand (1.00 ± 0.015). COMMENTS: 1) when making important surgical decisions based on carpal height, the carpal height index can become valuable to see what could be normal variant by seeing what is actually present in the asymptomatic opposite wrist of the same individual. 2) Reliance upon structures within the field of collapse is inherently less reliable than using structures outside the problem area; however, the frequent lack of inclusion of metacarpals on radiographs of the wrist make the alternate system for determining the alternate carpal height ratio quite useful. CODE: Radiologic: Measurements (IE) 1. Stahelin A, Pfeiffer K, Sennwald G, Segmuller G. Determining carpal collapse: an improved method. J Bone Joint Surg Am. 1989;71; Nattrass GR, King GJ, McMurtry RY, Brant RF. An alternative method for determination of the carpal height ratio. J Bone Joint Surg Am. 1994;76: Schuind FA, Linscheid RL, An K-N, Chao EY. A normal database of posteroanterior roentgenographic measurements of the wrist. J Bone Joint Surg Am. 1992;74: Youm Y, McMurtry RY, Flatt AE, Gillespie TE. Kinematics of the wrist. I. An experimental study of radial-ulnar deviation and flexion-extension. J Bone Joint Surg Am. 1978;60: McMurtry RY, Youm Y, Flatt AE, Gillespie TE. Kinematics of the wrist. II. Clinical applications. J Bone Joint Surg Am. 1978;60: Zdravkovic V, Sennwald GR. A new radiographic method of measuring carpal collapse. J Bone Joint Surg Br. 1997;79:167-9.

9 9 CARPAL INSTABILITY COMBINED OR COMPLEX (CIC) (FIGURE 12) SYNONYM: none CLINICAL: a carpal instability characterized by derangement both within and between carpal rows RADIOLOGIC: see CLINICAL COMMENTS: 1) the specific malalignments, dissociations, subluxations, dislocations, and fractures that compose the abnormality should be named. 2) Perilunate instabilities as SLD (scapholunate dissociation) or TLD (triquetrolunate or lunotriquetral dissociation) alone are CIDs and are not CICs unless they have an additional component of another category, e.g., ulnar translation, which is a radiocarpal instability deformity or perilunate dislocation. Longitudinal (axial) carpal instabilities are seldom seen as subluxations only, which would qualify as CID; they usually demonstrate a dislocation component, indicating rupture of both extrinsic and intrinsic ligaments, which make them CICs, e.g., dorsal CMC dislocation, dorsal dislocation of the capitate, or ulnar translation of the carpus. 3) CIC represents a combination of two or more well-defined patterns as a combination of scapholunate and lunotriquetral instabilities (2 CIDs) or SLD plus ulnar translocation (a CID plus a CIND). Interestingly, many CIDs become CICs as gradual attenuation or additional injury involves the extrinsic support systems surrounding the CID lesion. 4) It is common for both dissociative and nondissociative types of injury to be present in the same wrist, which fits the description of CIC. It is now recognized that most CIDs and many CINDs either become CICs or have elements of CIC from the beginning. Knowing how many elements of instability are present is fundamental in selecting a surgical method for control of the instability. 5) LT dissociation is seldom evident as widening at this joint. Indeed this pathology is usually shown by an abnormal translation between the triquetrum and lunate, but not by a gap. 6) The term instability has been frequently understood as a synonym of malalignment. According to this view, a wrist is categorized as unstable when there is a sporadic or permanent alteration of the sagittal and/or frontal alignment of the carpal bones beyond the limits of what is considered normal. From this perspective, instability would be a radiographic diagnosis. Such a concept of instability has been criticized by different authors who claim that an alteration of the carpal alignment should not always be considered pathologic (see reference #7). CODE: Clinical Conditions: Mixed Bag (IIID) 1. Cooney WP III, Garcia-Elias M, Dobyns JH, et al. Anatomy and mechanics of carpal instability. Surg Rounds Orthop. 1989;9: Fig. 12a Fig. 12b CARPAL INSTABILITY COMBINED OR COMPLEX (CIC): a) this PA view shows scapholunate dissociation, ventral tilting of the scaphoid (foreshortened shape) and lunate (triangular shape), and offset of Arc 1 at the lunotriquetral joint. The scaphoid fossa is deepened from erosive change, and osteoarthritis involves the radial styloid and scaphoid (the scaphoid tubercle with its osteophyte is not shown here). The proximal end of the capitate is flattened and the capitolunate joint is narrowed. b) On the lateral view, a satisfactory SPC relationship is maintained (see LATERAL VIEW). The scaphoid, lunate, and triquetrum are tilted toward the palm, but these are tilted in a dissociated pattern as emphasized on the PA view. The lunate is displaced dorsally, riding on the dorsal rim of the radius, and the scaphoid is riding on the ventral rim of the radius. A slight concavity in the dorsal rim of the radius proximal to the lunate indicates that this portion of the distal radius has reformed from longstanding articulation between the radius and the dorsally displaced lunate. Osteophytes involve the distal dorsal radius indicative of radiocarpal osteoarthritis. All these findings demonstrate radiocarpal, scapholunate, and lunotriquetral dissociation with VISI configuration (capitolunate angle of approximately 55 and scapholunate angle of about 20 ). Therefore, abnormalities exist at the radiocarpal and midcarpal levels as well as within the proximal carpal row.

10 10 2. Cooney WP, Dobyns JH, Linscheid RL. Arthroscopy of the wrist: anatomy and classification of carpal instability. Arthroscopy. 1990;6: Linscheid RL, Dobyns JH. Carpal instability. Curr Orthop. 1989;3: Wilson AJ, Mann FA, Gilula LA. Imaging the hand and wrist. J Hand Surg [Br]. 1990;15: Dobyns JH. Carpal instability: a review. In: Nakamura R, Linscheid RL, Miura T, editors. Wrist disorders. New York: Springer; p Dobyns JH, Berger RA. Dislocations of the carpus. In: Chapman MW, Madison M, editors. Operative Orthopedics. 2nd ed, vol 2. Philadelphia: JB Lippincott; p Garcia-Elias M, Berger RA, Horii E, Kauer JMG, Lanz U, Rongières M, Ryu J, Sennwald GR, Viegas SF. Definition of carpal instability. Anatomy and Biomechanics Committee of the International Federation of Societies for Surgery of the Hand. 2nd ed. Barcelona, Spain: Institut Kaplan; Feb CARPAL INSTABILITY COMBINED-PERILUNAR (CIC-PLD) see PERILUNATE DISLOCATION (PLD) CARPAL INSTABILITY COMPLEX-PERILUNATE TYPE (CIC-PLI) see PERILUNATE INSTABILITY (PLI) CARPAL INSTABILITY DISSOCIATIVE (CID) (FIGURE 13) SYNONYM: none CLINICAL: transosseous and/or transarticular dissociation within the proximal or distal carpal rows (PCR or DCR) RADIOLOGIC: when radiologic findings are present, they will demonstrate asynchronous movement or alignment between or through bones within the proximal or distal carpal rows. COMMENTS: 1) intercarpal communications shown on arthrography or seen at arthroscopy or at operation may have no appreciable mechanical or kinematic effect. 2) CID is rare in the DCR without associated metacarpal instability, in which case the preferred term is longitudinal or axial instability of some type. 3) See comment #6 and reference #7 in CARPAL INSTABILITY COMBINED OR COM- PLEX (CIC). CODE: Clinical Conditions: Mixed Bag (IIID) 1. see CARPAL INSTABILITY COMBINED (CIC) CARPAL INSTABILITY DISSOCIATIVE DORSAL INTERCALATED SEGMENT INSTABILITY (CID-DISI) (FIGURE 14) SYNONYM: none CLINICAL: transosseous and/or transarticular dissociation(s) within the proximal or distal carpal rows associated with a carpal malalignment characterized by pathologic extension of the lunate with respect to the radius and/or flexion of the capitate with respect to the lunate RADIOLOGIC: in the presence of a recognized DISI, radiographic evidence of dissociation between any two contiguous carpal bones within the same carpal row, either the proximal carpal row or the distal carpal row COMMENTS: 1) CID-DISI is the combination of clinical and radiologic findings necessary to support both diagnoses of DISI and CID. 2) A common CID-DISI is seen with scapholunate dissociation (SLD), but it also is seen with a fractured scaphoid when there is associated carpal collapse. To date, CID-VISI has been seen almost exclusively in the proximal carpal row (PCR). 3) The specific malalignments, dissociations, subluxations, and fractures within the proximal or distal carpal row that compose the abnormality should be named. 4) CID-DISI includes, but is not synonymous with SLD and Fig. 13a Fig. 13b CARPAL INSTABILITY DISSOCIATIVE (CID): a) the PA view demonstrates foreshortening of the scaphoid and tilting of the lunate (triangularshaped lunate) consistent with palmar tilting of these two bones. Dissociation at the lunotriquetral joint is indicated by a break in Arc 1 at the lunotriquetral joint (arrows). Because of palmar tilting of the scaphoid and lunate, the ventral portion of the scapholunate (SL) joint is the proximal portion (between large arrowheads) of this joint. The ventral and dorsal portions of the SL joint can normally be wider than its midportion (between small arrowheads). b) On the lateral view, the scaphoid and lunate are both tilted palmarly with a normal scapholunate angle of 40 but with an increased capitolunate angle of 55. These are findings of VISI with dissociation at the lunotriquetral joint, or CID-VISI. (Reprinted with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 219. Fig 8-19, A and B.)

11 11 Fig. 14a CARPAL INSTABILITY DISSOCIATIVE DORSAL INTERCALATED SEGMENT INSTABILITY (CID-DISI): a) on this PA view, the scapholunate joint space is widened (between arrows) more than twice the width of the capitolunate joint. b) The lateral view shows dorsal tilting of the lunate and ventral tilting of the scaphoid with resultant scapholunate angle of 80 consistent with DISI configuration. An osseous projection on the dorsal rim of the lunate (arrowhead) makes the distal articular surface of the lunate project to be less dorsally tilted than is probably present. Such DISI configuration with the scapholunate dissociation makes this a CID-DISI. The two white densities ventral to the lunate are artifacts. (Modified and reprinted with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 218. Fig 8-18, A and B.) Fig. 14b scaphoid fracture with DISI collapse deformity of the proximal carpal row. 5) See comment #6 and reference #7 in CARPAL INSTABIL- ITY COMBINED OR COMPLEX (CIC). CODE: Clinical Conditions: Mixed Bag (IIID) 1. see CARPAL INSTABILITY COMBINED (CIC) CARPAL INSTABILITY DISSOCIATIVE VOLAR INTERCALATED SEGMENT INSTABILITY (CID-VISI) (SEE FIGURE 13) SYNONYM: none CLINICAL: transosseous and/or transarticular dissociation(s) within the proximal or distal carpal rows associated with a carpal malalignment characterized by pathologic flexion of the lunate, usually in association with the scaphoid, with respect to the radius and/or extension of the capitate with respect to the lunate RADIOLOGIC: in the presence of a recognized VISI, radiographic evidence of dissociation between any two contiguous carpal bones within the same carpal row, either proximal or distal COMMENTS: 1) CID-VISI is the combination of clinical and radiologic findings necessary to support both diagnoses of VISI and CID. 2) The most common CID-VISI is seen with lunotriquetral dissociation (LTD). 3) To date, CID-VISI has been seen almost exclusively in the proximal carpal row (PCR). 4) The specific malalignments, dissociations, subluxations, and fractures within the proximal or distal carpal row that compose the abnormality should be named. 5) See comment #6 and reference #7 in CARPAL INSTABILITY COM- BINED OR COMPLEX (CIC). CODE: Clinical Conditions: Mixed Bag (IIID) 1. see CARPAL INSTABILITY COMBINED (CIC) CARPAL INSTABILITY NONDISSOCIATIVE (CIND) (FIGURE 15) SYNONYM: none CLINICAL: a general class of carpal instability existing either at the radiocarpal or the midcarpal joint levels with intact proximal and distal carpal rows RADIOLOGIC: a malposition or abnormal movement of the entire proximal carpal row as a unit (common) or the entire distal carpal row (exceedingly rare). The site of abnormality can be at the radiocarpal level, midcarpal level, or both, but each row itself is intact. The abnormal motion may be associated with a clunk. COMMENTS: 1) this is midcarpal instability (dissociation between the proximal and distal carpal rows) or proximal instability (dissociation between the distal radius and the first carpal row). 2) Ligamentous de-

12 12 CARPAL INSTABILITY NONDISSOCIATIVE DORSAL INTERCALATED SEGMENT INSTABILITY (CIND-DISI) (SEE FIGURE 15) Fig. 15a CARPAL INSTABILITY NONDISSOCIATIVE (CIND): a) PA view: the scaphoid is elongated from dorsal tilting of the scaphoid, with marked osteoarthritis involving the scaphotrapezial, scaphotrapezoidal, and the first carpometacarpal joints. Degenerative ossicles are present radial to the trapezium and between the first and second metacarpal bases. The trapezium has lost some of its volume, and the first metacarpal is subluxed radially. Arcs 1 and 2 are intact, indicative that the entire proximal carpal row is moving as a unit without dissociation at the lunotriquetral or scapholunate joints. b) The lateral view shows dorsal tilting of the scaphoid and lunate maintaining a scapholunate angle of about 65, while the capitolunate angle is increased to about 40. These features are that of a DISI configuration with the entire proximal carpal row moving as a unit or DISI-CIND. SYNONYM: none CLINICAL: a carpal instability existing either at the radiocarpal or the midcarpal joint levels with intact proximal and distal carpal rows associated with pathologic extension of the lunate (along with the scaphoid and the triquetrum) with respect to the capitate and radius RADIOLOGIC: in the presence of a recognized DISI, no radiographic evidence of dissociation (static or dynamic) exists between any two contiguous carpal bones within either carpal row. The CIND aspect of the instability must be proven by demonstrating competence at the two ligamentous connections of the proximal carpal row, i.e., in the scapholunate interosseous ligament and the lunotriquetral ligament. COMMENTS: 1) since there is by definition (of CIND) no significant scapholunate or lunotriquetral ligament abnormality, the scapholunate and lunotriquetral angles are normal. 2) CIND-DISI is the combination of clinical and radiologic findings necessary to support both diagnoses of DISI and CIND. The CIND part of the diagnosis may be confirmed by demonstrating no abnormal motion between adjacent carpal bones at radiographic examination, arthroscopy, or surgical inspection. 3) Some experts believe that: (a) this condition must be due to a combined lesion located at both the midcarpal and radiocarpal levels (references #2 and #3 in CIC); (b) as a rule, ligament tears are present at both midcarpal and radiocarpal levels; (c) it is mechanically impossible to have malposition of the proximal carpal row without combined pathology; and (d) these comments are supported by the fact that cutting a specific ligament does not change the position of the carpal bones, even if pathologic movement can be observed kinemati- fects seen at arthrography, arthroscopy, or surgery between radiocarpal and midcarpal joints without abnormal kinematics do not imply carpal instability dissociative (CID). 3) The posture of the collapsed row may be either extension or flexion. 4) See comment #6 and reference #7 in CARPAL INSTABILITY COMBINED OR COMPLEX (CIC). CODE: Clinical Conditions: Mixed Bag (IIID) 1. see CARPAL INSTABILITY COMBINED (CIC) 2. Ambrose L, Posner MA. Lunate-triquetral and midcarpal joint instability. Hand Clin. 1992;8: Lichtman DM, Schneider JR, Swafford AR, Mack GR. Ulnar midcarpal instability clinical and laboratory analysis. J Hand Surg [Am]. 1981;6: Wright TW, Dobyns JH, Linscheid RL, Macksoud W, Siegert J. Carpal instability non-dissociative. J Hand Surg [Br]. 1994;19: Fig. 15b

13 13 Fig. 16a CARPAL INSTABILITY NON-DISSOCIATIVE VOLAR INTERCALATED SEG- MENT INSTABILITY (CIND-VISI): a) PA view: slight foreshortening of the scaphoid and triangular shape (tilting) of the lunate is present. These changes of the scaphoid and lunate are actually more prominent than shown here, since the wrist is in some dorsiflexion as evidenced by the fact that the second and third CMC joints are not in profile, and the hook of the hamate is elongated. No radial deviation is present since the third metacarpal shaft is grossly coaxial with the axis of the radius. Parallel articular surfaces between the lunate and triquetrum and suggestion of similar parallelism between the scaphoid and lunate on the PA view combined with presence of intact carpal arcs I and II on the PA view support the fact that the entire proximal carpal row has moved as a unit. b) Lateral view: both the scaphoid and lunate are tilted palmarly with a normal scapholunate angle of about 50. The capitolunate angle is abnormally increased to about 45. This configuration of CIND-VISI may commonly be a normal variant and should be compared to the opposite side to see if the opposite side has the same configuration without symptoms. An extra ossicle projects dorsal to the lunate and proximal to the triquetrum (arrow). associated with pathologic flexion of the lunate with respect to the capitate and radius RADIOLOGIC: in the presence of a recognized VISI, no radiographic evidence of dissociation (static or dynamic) exists between any two contiguous carpal bones within either carpal row. The CIND aspect of the instability must be proven by demonstrating competence at the two ligamentous connections of the proximal carpal row, i.e., in the scapholunate interosseous ligament and the lunotriquetral ligament. COMMENTS: 1) since there is by definition (of CIND) no significant scapholunate or lunotriquetral ligament abnormality, the scapholunate and lunotriquetral angles are normal. 2) CIND-VISI is the combination of clinical and radiologic findings necessary to support both diagnoses of VISI and CIND. The CIND part of the diagnosis may be confirmed by demonstrating no abnormal motion between adjacent carpal bones at radiographic examination, arthroscopy, or surgical inspection. 3) Some experts believe that: (a) this condition must be due to a combined lesion located at both the midcarpal and radiocarpal levels (references #2 and #3 in CIC); (b) as a rule, ligament tears are present at both midcarpal and radiocarpal levels; (c) it is mechanically impossible to have malposition of the proximal carpal row without combined pathology; and (d) these comments are supported by the fact that cutting a specific ligament does not change the position of the carpal bones, even if pathologic movement can be observed kinematically (references #2 and #3 in CIC). 4) See comment #6 and reference #7 in CARPAL INSTABIL- ITY COMBINED OR COMPLEX (CIC). CODE: Clinical Conditions: Mixed Bag (IIID) 1. see CARPAL INSTABILITY COMBINED (CIC) 2. Sennwald GR, Zdravkovic V. Wrist arthroscopy: a prospective analysis of 53 post-traumatic carpal injuries. Scand J Plast Reconstr Surg Hand Surg. 1997;31: North ER, Meyer S. Wrist injuries: correlation of clinical and arthroscopic findings. J Hand Surg [Am]. 1990;15: cally (references #2 and #3 in CIC). 4) See comment #6 and reference #7 in CARPAL INSTABILITY COMBINED OR COMPLEX (CIC). CODE: Clinical Conditions: Mixed Bag (IIID) 1. see CARPAL INSTABILITY COMBINED (CIC) 2. Sennwald GR, Zdravkovic V. Wrist arthroscopy: a prospective analysis of 53 post-traumatic carpal injuries. Scand J Plast Reconstr Surg Hand Surg. 1997;31: North ER, Meyer S. Wrist injuries: correlation of clinical and arthroscopic findings. J Hand Surg [Am]. 1990;15: CARPAL INSTABILITY NONDISSOCIATIVE VOLAR INTERCALATED SEGMENT INSTABILITY (CIND-VISI) (FIGURE 16) SYNONYM: none CLINICAL: a carpal instability existing either at the radiocarpal or the midcarpal joint levels with intact proximal and distal carpal rows Fig. 16b

14 14 CARPAL TUNNEL VIEW (FIGURE 17) Fig. 17a SYNONYMS: carpal tunnel projection, carpal pillars projection CLINICAL: NA RADIOLOGIC: a radiographic view showing the arch of the carpal tunnel. Two common methods can be used for its exposure: 1) having the patient hold his or her fingers and wrist in the maximum extended position, the central x-ray beam is passed from distal to proximal across the hand and wrist at centered at and parallel to the third metacarpal shaft with the wrist held over or lying on the radiographic screen; and 2) having the patient place the palm of his or her hand flat on a radiographic screen, the wrist is hyperextended as much as possible and the central beam of the x-ray is centered at the midportion of the carpal tunnel and projected from proximal to distal at 40 to the radiographic cassette. COMMENT: variation in positioning affects which portion (proximal, distal, radial, or ulnar aspects) of the carpal tunnel area will be shown. CODE: Radiologic: Views (ID) 1. Hart VL, Gaynor V. Roentgenographic study of the carpal canal. J Bone Joint Surg. 1941;23: Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p CARPE BOSSU see CARPAL BOSS CARPOMETACARPAL (CMC) DISLOCATION (FIGURE 18) Fig. 17b CARPAL TUNNEL VIEW: a) a small sponge is placed under the wrist. The wrist is extended as much as possible by the patient s other hand, and the central beam (indicated by the pointer) is aimed to pass through the palmar aspect of the carpal tunnel, angled to the third metacarpal shaft. b) Another way to obtain this view is to place the hand flat on the cassette or tabletop and extend the wrist as much as possible. The central beam (indicated by the pointer) is directed tangent to the palmar aspect of the wrist parallel to the long axis of the carpal tunnel. c) The carpal tunnel view is depicted here with P = pisiform, H = hook of hamate, S = scaphoid (arrow points to scaphoid), Td = trapezoid, and Tm = trapezium. (Modified and reprinted with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p Figs 5-52, A and B; and 5-53A.) SYNONYM: hand-wrist dislocation CLINICAL: a general term reserved for complete loss of articular congruence without fractures at one or more individual carpometacarpal joint(s) RADIOLOGIC: suspect with loss of normal parallelism between adjacent articular cortices of one or more metacarpal bases and adjacent carpal bones most easily seen on the neutral supine (AP) or prone (PA) views of the wrist and confirmed for complete displacement on additional views COMMENTS: 1) this is one of the CMC instability categories; the other two are CMC subluxation and CMC fracture-dislocation/sub- CARPAL PILLARS PROJECTION see CARPAL TUNNEL VIEW CARPAL REVOLUTE see SLIDER-CRANK MECHANISM Fig. 17c

15 15 3. Cain JE Jr, Shepler TR, Wilson MR. Hamatometacarpal fracture-dislocation: classification and treatment. J Hand Surg [Am]. 1987;12: Dobyns JH. Fractures and dislocations at the base of the metacarpals. In: Barton NJ, editor. Fractures of the hand and wrist. Edinburgh: Churchill Livingstone; p CARPOMETACARPAL INSTABILITY Fig. 18 CARPOMETACARPAL (CMC) DISLOCATION: on this PA slightly obliqued view of the wrist, the thumb metacarpal is profiled in a lateral position. Radial dislocation of the base of the first metacarpal is evidenced by complete lack of articulation between the first metacarpal and the trapezium and some overlapping of the wellprofiled base of the first metacarpal and the adjacent trapezium. SYNONYM: none CLINICAL: an abnormal condition occurring between the metacarpal(s) and the distal carpal row, which results in the inability to maintain normal anatomic relationship(s) under physiologic loads RADIOLOGIC: a radiographic diagnosis of carpometacarpal instability is suspected if there is any evidence of subluxation of a carpometacarpal joint as seen either on a static or dynamic (i.e., stress) radiograph (see comment #1). COMMENTS: 1) some authorities believe that a fixed instability is a contradiction in terminology, i.e., that such a condition is no longer deserving of being called unstable. However, the definition of instability includes any situation where anatomic alignment cannot be maintained. In such a situation, the abnormal alignment, although it luxation. 2) Pure CMC dislocation without fracture is extremely rare of the second through fifth CMCs. CODE: Clinical Conditions: Fractures-Dislocations-Diastases (IIIA) 1. Lawlis JF 3rd, Gunther SF. Carpometacarpal dislocations. Long-term follow-up. J Bone Joint Surg Am. 1991;73:52-9. CARPOMETACARPAL (CMC) FRACTURE-DISLOCATION (FIGURE 19) SYNONYM: hand-wrist fracture dislocation CLINICAL: a general term reserved for any carpometacarpal dislocation that is accompanied by a fracture of one or more of the opposing articular surfaces (see CARPOMETACARPAL DISLOCATION) RADIOLOGIC: loss of any congruence (loss of normal parallelism between adjacent cortices) between the two articular components of any CMC joint associated with a fracture of some portion of that joint COMMENTS: 1) all finger CMCs may be involved together or some may be involved with fractures, subluxations, or dislocations of the adjacent carpal bones. 2) The dislocations are more often dorsal, but can be volar, radial, or ulnar. 3) When combined with adjacent carpal instabilities, this condition will fall into the longitudinal (axial) instability group. CODE: Clinical Conditions: Fractures-Dislocations-Diastases (IIIA) 1. see CARPOMETACARPAL (CMC) DISLOCATION 2. Garcia-Elias M, Bishop AT, Dobyns JH, Cooney WP, Linscheid RL. Transcarpal carpometacarpal dislocations, excluding the thumb. J Hand Surg [Am]. 1990;15: Fig. 19a CARPOMETACARPAL (CMC) FRACTURE-DISLOCATION: a) on this PA view, the bases of the second through fifth metacarpals are overlapping their adjacent carpal bones, indicative of CMC dislocations at the second through fifth CMC joints. A bone density (arrow) has some parallelism (between arrowheads) to the capitate, suggesting a fracture fragment of the base of the third metacarpal that has remained articulating with the capitate. A density ulnar to the hamate (curved arrow) and adjacent to the fifth metacarpal base is a chip fracture off the ulnar edge of the hamate. b) The lateral view confirms dislocation of the second through fifth metacarpals at their CMC joints and shows that the dislocation is dorsal and proximal. A fragment of bone distal to the capitate (arrow) represents the piece of the third metacarpal base as seen on the PA view (Fig 19A). The final diagnosis of this abnormality is trans-third metacarpal, transhamate, dorsal second through fifth carpometacarpal fracture-dislocation.

16 16 1. see CARPOMETACARPAL (CMC) DISLOCATION and FRACTURE-DISLOCATION CATCH-UP CLUNK SYNONYMS: catch-up phenomenon, homing-in phenomenon CLINICAL: a carpal malalignment present with motion or other provocative maneuver during which the usual pattern of carpal motion is not maintained. Near the end of the maneuver, the bone(s), which are not following the usual motion pattern, suddenly move toward the normal position, often producing a palpable, perceptible (to the patient) and audible, sudden alteration of position. Although similar clunks can occur with the sudden repositioning of one bone (e.g., Fig. 19b may be fixed (or stable in the abnormal state), progressed from normal to abnormal alignment and may further deteriorate. 2) Since CMC dislocations and fracture-dislocations may also be unstable (old, healed ones may be stable), this term may be used as a major category with three subcategories, i.e., CMC subluxation, CMC dislocation, and CMC fracture-dislocation. CODE: Clinical Conditions: Sprains-Instabilities-Subluxations (IIIB) 1. see CARPOMETACARPAL (CMC) DISLOCATION and FRACTURE-DISLOCATION CARPOMETACARPAL SUBLUXATION (FIGURE 20) SYNONYM: none CLINICAL: any degree of displacement in any direction short of complete loss of contact between the distal articular surface of the distal carpal bone(s) and its (their) respective metacarpal articulation(s) RADIOLOGIC: subluxation of the carpometacarpal joint exists when there is anything less than 100% contact between opposing articular surfaces. COMMENTS: 1) the direction of subluxation is defined by the direction of displacement of the distal segment. 2) The amount of subluxation can be given as a percentage determined by the measured displacement divided by the normal articular dimension in that same plane. 3) A CMC subluxation may or may not be unstable, therefore carpometacarpal subluxation and carpometacarpal instability are not synonymous. This is considered by some experts to be a subcategory of CMC instability (see COMMENTS under CMC INSTABILITY). CODE: Clinical Conditions: Sprains-Instabilities-Subluxations (IIIB) Fig. 20a CARPOMETACARPAL (CMC) SUBLUXATION: a) PA view: some extension of the wrist is evident by loss of clear profile of the second and third carpometacarpal joints and elongation of the hook of the hamate. Good parallelism is present at the fifth and the ulnar aspect of the third CMC joint. The intervening fourth CMC joint has lost profile of its parallel articular cortices. More specifically, the cortex of the base of the fourth metacarpal is not visible, whereas the adjacent cortex of the hamate (arrowheads) is clearly visible. A defect involves the radial cortex of the base of the fourth metacarpal (arrow). These findings support some type of fracture subluxation/dislocation at the fourth CMC joint. The fifth metacarpal shaft is fractured at its distal fourth. b) The lateral view shows the base of one metacarpal (arrow) projecting dorsal to the carpus, supporting dorsal subluxation of a metacarpal. c) A sagittal CT section through the junction of the fourth and fifth CMC joints shows dorsal subluxation of the fourth metacarpal at its base. The arrow on the reader s right points to the dorsal cortex of the fourth metacarpal. The arrow to the reader s left indicates part of the fifth metacarpal base, which is articulating proximally (toward the bottom of the figure) to the hamate. This example shows subluxation, but it actually is a case of a fracture subluxation of the fourth CMC joint since there is also a fracture of the fourth metacarpal base. (Fig 20C is modified and reprinted with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 433. Fig )

17 17 Fig. 20b and circumduction along with the deviation are sometimes more provocative. This may occur with midcarpal instability. (See COMMENTS.) RADIOLOGIC: a common type of this clunk can be recognized by displacing the carpus palmarly while the wrist is in radial deviation. Maintaining this palmar-displacing stress while moving the wrist into ulnar deviation, the proximal carpal row as identified by the scaphoid and lunate will remain palmarly tilted until near the end of ulnar deviation. At this point, the proximal carpal row abruptly tilts dorsally, sometimes with an audible noise, but often with a palpable jerk (see comment #6). Videotape examination (or cineradiography) can demonstrate this jumping or jerky motion best in the lateral position, but also in the PA position. COMMENTS: 1) many authorities do not like this term and feel that this term should be discarded, as it is used differently by different people. 2) This term can be used to describe any bone that moves back into anatomic relationship with an audible or palpable noise including also the scaphoid test with rotary subluxation of the scaphoid. 3) Sometimes the lunate lags behind the scaphoid on radial translation, then suddenly extends and catches up to the scaphoid. This motion is associated with an audible and palpable clunk. 4) It is common that the maneuver described above under RADIOLOGIC occurs in lax-jointed individuals and it may occur bilaterally symmetrically or asymmetrically, but typically presents with pain only in one wrist. 5) Some experts believe that this audible sound occurs because of lack of stability due to failure of damaged ligament(s) to maintain normal carpal relationships during motion. 6) To produce this clunk, loading of the wrist is usually necessary. This can be done as the pronated wrist is moved from radial to ulnar deviation with compression applied (forcing the wrist toward the elbow). CODE: Tests (IV) 1. Dobyns JH, Linscheid RL, Chao EYS, Weber ER, Swanson GE. Traumatic instability of the wrist. AAOS Inst Course Lect. 1975;24: Lichtman DM, Schneider JR, Swafford AR, Mack GR. Ulnar midcarpal instability clinical and laboratory analysis. J Hand Surg [Am]. 1981;6: Schernberg F. [Mediocarpal instability]. Ann Chir Main. 1984;3: French. Fig. 20c the subluxed scaphoid), the classic catch-up-clunk describes the sudden positioning of the entire proximal carpal row, which commonly occurs during movement from one deviation position to another (usually from radial deviation to ulnar deviation) although gripping CENTRAL COLUMN (FIGURE 21) SYNONYM: none CLINICAL: the capitate and lunate and their proximal and distal articulations RADIOLOGIC: from proximal to distal, this is composed of the radiolunate joint, lunate, capitolunate (lunocapitate) joint, capitate, and capitate third metacarpal joint. COMMENTS: 1) column here is used in the anatomic sense, as some authorities do not believe in the functional columnar theory of the wrist. 2) Others believe that this central column is important for transmission of loads from the hand to the forearm. 3) Some experts believe that this term is of only historical interest. The capitate functionally shifts from the scaphoid and lunate, and a rupture of the scapholunate ligament permits the capitate head to protrude between these two bones. CODE: Anatomic: Central (IIB) 1. Navarro A. La fisiologia del carpo. An Inst Clin Quirurg Chirurgia Exp. 1937; 6: Taleisnik J. The wrist. New York: Churchill Livingstone; 1985.

18 18 there is a decrease in the carpal height index (see carpal height) without evidence of destruction of carpal bones. COMMENTS: 1) this is often recognized by a lunate tilted abnormally in the dorsal or palmar direction with the wrist in a neutral position. 2) Some experts believe that the zigzag and the concertina collapse deformities are not true synonyms, but are special cases of collapse deformity. 3) The term collapse deformity is used here with respect to the wrist but could apply to other parts of the body. CODE: Clinical Conditions: Residuals of Injuries (IIIC) Fig. 21 COLUMNAR CARPUS: this diagram demonstrates the columnar concept of the carpus with the central (C) column being the flexion-extension column composed of the lunate with the distal carpal row. The lateral column (L) is the mobile column and consists of the scaphoid. The medial or rotation column (M) is composed of the triquetrum. (Reprinted with permission from Taleisnik J. The wrist. New York: Churchill Livingstone; p 41. Fig 3-2.) 1. Gilford WW, Bolton RH, Lambrinudi C. The mechanism of the wrist joint with special reference to fractures of scaphoid. Guy s Hosp Rep. 1943;92: Fisk GR. Carpal instability and the fractured scaphoid. Ann R Coll Surg Engl. 1970;46: Linscheid RL, Dobyns JH, Beabout JW, Bryan RS. Traumatic instability of the wrist. Diagnosis, classification, and pathomechanics. J Bone Joint Surg Am. 1972;54: Sebald JR, Dobyns JH, Linscheid RL. The natural history of collapse deformities of the wrist. Clin Orthop. 1974;104: COLUMNAR AXIS see LONGITUDINAL AXIS CEPHALAD see PROXIMAL CHAMAY MEASUREMENT FOR ULNAR TRANSLATION (FIGURE 22) see ULNAR TRANSLATION CLUNK SYNONYM: thud CLINICAL: a low-pitched dull sound (as opposed to the sharp, ringing sound of clank or clink ) and palpable phenomenon produced by a sudden and significant shift in alignment of articular surfaces RADIOLOGIC: NA COMMENTS: 1) this is not restricted to one observable phenomenon, but it is usually best seen during videotape or cineradiographic examination of the moving wrist and is usually marked by a sudden shift of the entire proximal carpal row or a part of the proximal carpal row from a dorsiflexed to a palmar-flexed position or vice versa (see CATCH-UP CLUNK). 2) Some authorities prefer not to define sounds and feelings. CODE: General Terms (V) 1. see MIDCARPAL INSTABILITY COLLAPSE DEFORMITY (SEE FIGURES 12B, 13B, 14B, 15B, 16B) see CONCERTINA DEFORMITY SYNONYMS: carpal collapse, zigzag deformity/collapse, concertina deformity/collapse CLINICAL: loss of carpal stability with independent proximal and distal row motion RADIOLOGIC: 1) any abnormal angular relationship between the long axis of the capitate and the mid dorsal-palmar lunate axis as seen on the neutral lateral. 2) Any carpal malalignment in which Fig. 22 CHAMAY MEASUREMENT FOR ULNAR TRANSLATION: ulnar translation is evaluated by determining L4/L1 when L1 is the length of the third metacarpal, L4 is the capitate-radial styloid distance, and L2 is the carpal height line passing through the center of the capitate head (C). L4/L1 = ; ARS = axis of the radial styloid. (Reprinted with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; 1996, p 208, Fig 8-6C.)

19 19 COMBINATION ARC INJURY see GREATER ARC INJURY; LESSER ARC INJURY COMPETENT (AS RELATES TO LIGAMENTS) SYNONYMS: physiologic integrity, intact, functionally adequate/sufficient, physiologically intact CLINICAL: 1) a competent ligament is one that prevents abnormal displacement, angulation, or rotation between adjacent bones. 2) A structure, not necessarily a ligament although most often used in that context among wrist investigators, which may be normal or injured but is adequate for unrestricted functional use. RADIOLOGIC: lack of evidence for incompetence, i.e., no evidence for dislocation, subluxation, or loss of congruence COMMENTS: 1) some authorities prefer dropping this term. In Europe, competent has more to do with entitled or skillful than with anatomically intact. 2) The word is used in one of its standard meanings, i.e., adequate for a purpose, and would not require listing except that it is not familiar in this context to some investigators. 3) Competency must be shown both on a static examination and dynamically. 4) Maybe this is not the best word, but a term is needed to describe anatomic structures that are not adequate for whatever reason (injury, congenital, disease, infection, etc.) to maintain normal stability of a musculoskeletal part during function and even at rest. Structures that are inadequate for these purposes are incompetent. CODE: General Terms (V) CONSTRAINT see TETHER CORONAL PLANE/POSITION (FIGURE 23) see ANTEROPOSTERIOR VIEW OR PROJECTION SYNONYMS: frontal plane/position, radial to ulnar or ulnar to radial plane, PA or AP view of wrist on radiographs CLINICAL: any plane passing longitudinally through the wrist from side to side equivalent to the radioulnar plane, at right angles to the median plane. The coronal plane is obtained when the arm is alongside the body with the palm facing anteriorly or posteriorly without wrist flexion or extension and divides the body into front and back (dorsal and ventral [volar or palmar]) parts. This plane is so called because such a plane roughly parallels the frontal (coronal) suture of the skull. RADIOLOGIC: see CLINICAL. The radiographic views that represent the coronal plane are the AP or PA views or cuts ( cuts refers to sections obtained at different levels with tomography, either conventional or computed in type). COMMENTS: 1) with the hand or wrist in the true coronal position, 1. Dobyns JH, Berger RA. Dislocations of the carpus. In: Chapman MW, Madison M, editors. Operative orthopedics. 2nd ed, vol 2. Philadelphia: JB Lippincott; p The New Lexicon Webster s Dictionary of the English Language edition. p 200. CONCERTINA COLLAPSE see CONCERTINA DEFORMITY and COL- LAPSE DEFORMITY CONCERTINA DEFORMITY (SEE FIGURES 12B, 13B, 14B, 15B, 16B) see COLLAPSE DEFORMITY SYNONYMS: zigzag deformity/collapse, carpal collapse CLINICAL: 1) a zigzag collapse deformity of the capitate-lunateradius axis as seen on the lateral radiograph in association with disruption of the structural support (ligamentous or osseous) of the carpus. 2) A zigzag collapse deformity of the capitate-lunate-radius axis, either VISI or DISI in configuration, more notable in lateral than in PA projection, associated with diminished carpal height index (CHI) and due to damage to ligament, bone, or both. RADIOLOGIC: pathologic malalignment, particularly on the lateral projection, as described in VISI and DISI. Suggestive abnormalities are also evident on PA radiographs as for the current usage of VISI and DISI. COMMENTS: 1) see CARPAL COLLAPSE. 2) This is mainly of historical interest. 3) Fisk defined concertina STRICTLY as it applied to fractures of the scaphoid. CODE: Clinical Conditions: Residuals of Injury (IIIC) 1. see COLLAPSE DEFORMITY Fig. 23 CORONAL PLANE: an anatomic section through the wrist in a plane that passes from radial to ulnar. This resulting section provides a view that looks like a PA or AP view of the wrist on radiography. (Case donated by Dr. Rudi Richli, Radiologist, MD Anderson Hospital, Houston, Texas.)

20 20 DESTABILIZATION see INSTABILITY DIASTASIS (FIGURE 24; SEE ALSO FIGURES 12A, 14A) Fig. 24 DIASTASIS: on this PA view, the scapholunate space is widened (diastatic) more than twice the width of the capitolunate space. Radioscaphoid joint space narrowing is present with subcortical sclerosis of the radius and scaphoid. Spurs (osteophytes) involve the radial styloid and radial aspect of the scaphoid waist, indicative of osteoarthritis. As the CMC joints are not in profile and the hamate hook is elongated, this wrist is extended (the palm is not flat on the cassette). An osseous mass off the radial aspect of the lunate is consistent with either an avulsion deformity or a developing osteophyte. The radiolunate joint is preserved. The features of scapholunate widening, radioscaphoid osteoarthritis, and preserved radiolunate joint width are diagnostic of SLAC wrist, before capitolunate osteoarthritis has developed. with the palm facing forward, an AP radiograph results. With the hand in a similar position, but rotated 180 from the anatomic position so the palm faces the back side of the patient, a PA radiograph results. Current standard procedure for obtaining either one of the views requires that the forearm-wrist-hand unit be in the 0 or midposition when either PA or AP radiographs are to be made. 2) In radiology, this plane corresponds to the AP or PA views; however, strictly speaking, a frontal view would only be the AP or frontal view of the hand or wrist. 3) When the palm is facing forward in this plane (supinated), the hand is considered to be in the anatomic position. 4) Practically speaking, however, many x-rays are still made with the forearm-wrist-hand unit in either full supination or full pronation, and it is wise for the image interpreter to check some guideline, such as the position of the ulnar styloid, to confirm whether the prone or supine position was used. 5) The resultant parts after a coronal section has been passed may be equal (true coronal or frontal) or unequal (paracoronal or parafrontal). 6) Particularly in European articles, the AP and PA views may be referred to in terms of anatomic planes. CODE: Radiologic: Planes (IB) 1. anatomy or radiology textbooks DE QUERVAIN S FRACTURE-DISLOCATION see comment #5 under PERILUNATE FRACTURE-DISLOCATION SYNONYMS: gap, distraction (fracture-diastasis) CLINICAL: abnormal separation of two anatomic structures but used only with reference to osseous gaps in the present context RADIOLOGIC: 1) there is a measurable increase of the normal distance between two bones (e.g., scapholunate diastasis). 2) Fracturediastasis, e.g., distraction consequent to excessive traction of fracture fragments, may also be seen with increased gap between opposing parts of the fracture. COMMENTS: 1) although used in reference to pathology, an apparent diastasis may be a normal variant, as when appropriate amounts of bone are present but are not yet ossified (as incomplete ossification of the immature scaphoid) or may be associated with normal laxity of supporting structures. 2) Diastasis is not always synonymous with dissociation, as dissociation can be present in the absence of joint gapping (see DISSOCIATION). CODE: Clinical Conditions: Fractures-Dislocations-Diastases (IIIA) 1. Linscheid RL, Dobyns JH, Beabout JW, Bryan RS. Traumatic instability of the wrist. Diagnosis, classification, and pathomechanics. J Bone Joint Surg Am. 1972;54: DISLOCATION (SEE FIGURE 18) SYNONYM: luxation CLINICAL: complete loss of articular surface contact of a given joint RADIOLOGIC: same as CLINICAL COMMENTS: NA CODE: Clinical Conditions: Fractures-Dislocations-Diastases (IIIA) 1. standard dictionary; radiology, traumatology, and orthopedic textbooks DISLOCATION OF... see part dislocated, e.g., DISTAL RADIOULNAR DISLOCATION DISPLACEMENT SYNONYM: none CLINICAL: a shift from anatomic position during rest, motion, or force application, which may be angular, axial, rotational, or translational displacement. This may be normal or abnormal, i.e., physiologic or pathologic. RADIOLOGIC: loss of anatomic relations with abnormal movement between two or more adjacent parts COMMENTS: none CODE: General Terms (V) 1. standard dictionary DISSOCIATION (SEE FIGURES 12A, 13A, 14A, 24) SYNONYMS: un- or not linked, un- or not bonded CLINICAL: a carpal malalignment in which there is a loss of the normal association of the skeletal elements within either the proximal carpal row (PCR) or the distal carpal row (DCR) or both

21 21 RADIOLOGIC: 1) the term dissociation may be applied to a malalignment pattern in which there is a demonstrated loss of integrity of one or more intercarpal ligaments within either the PCR or the DCR or both as evidenced by abnormal widening of an interosseous distance or abnormal displacement or offset of one of the three carpal arcs (see CARPAL ARCS). 2) This term may also be applied to similar loss of functional integrity from fracture destabilization. COMMENTS: 1) usually an arthrogram will demonstrate abnormal flow of contrast between carpal bones, or arthroscopy will show a ligament defect at the dissociated site; however, failure to demonstrate or see such a defect may still occur with dissociated carpal bones or through a fracture site if scar tissue or ligament elongation has developed at the site of dissociation. Importantly, the presence of a perforation through a ligament or triangular fibrocartilage does not necessarily mean that there is functional dissociation at that site, as asymptomatic perforations commonly occur in the wrist. 2) This is contrasted to a nondissociated malalignment (CIND), in which the intercarpal (intrinsic) ligaments are intact but the extracapsular (extrinsic) ligaments are stretched or disrupted. 3) The dissociation may occur because of injury or secondary changes in ligaments (intrinsic, extrinsic, or both) or in bone (fractures; ligament tears or insertion avulsions; infectious, rheumatoid, or crystalline arthropathies; ischemic, cyst, or tumor deformities; etc.). 4) Pathologic dissociation can be found at open surgery or arthroscopy in the absence of abnormal radiographic or arthrographic findings. 5) Originally, this term was used for loss of ligament functional integrity. It is now commonly used for loss of intra-row integrity, whether due to ligament problems, bone problems, or both. It still retains the original distinction of referring to intra-row loss of functional integrity (CID), whereas the term nondissociative still refers to inter-row problems (CIND). Using this slightly altered concept, it is now appropriate to call an unstable scaphoid fracture with DISI deformity a dissociative deformity, since there is a dissociative separation and deformity between two components of the proximal carpal row, i.e., the two fragments of the scaphoid (see CIND and CID). CODE: Clinical Conditions: Fractures-Dislocations-Diastases (IIIA) 1. Linscheid RL, Dobyns JH, Beabout JW, Bryan RS. Traumatic instability of the wrist. Diagnosis, classification, and pathomechanics. J Bone Joint Surg Am. 1972;54: DISTAL CARPAL ROW (DCR) (SEE FIGURE 8A) SYNONYM: os distale CLINICAL: the trapezium, trapezoid, capitate, and hamate and the ligaments binding them together form the distal carpal row. RADIOLOGIC: see CLINICAL COMMENTS: none CODE: Anatomic: Carpal (IID) 1. see DIASTASIS 2. anatomy textbooks DISTAL RADIAL INSTABILITY see DISTAL RADIOULNAR INSTABILITY DISTAL RADIOULNAR DISLOCATION (FIGURE 25) SYNONYM: dislocation of the distal radioulnar joint CLINICAL: a complete loss of joint congruity between the distal end Fig. 25a Fig. 25b DISTAL RADIOULNAR DISLOCATION: a) on a transaxial computed tomographic (CT) section through the distal radioulnar joint (DRUJ) with the wrist in supination, the ulna (U) is dislocated ventrally out of the sigmoid fossa (arrows) of the distal radius. (Ventral is to the top of the figure.) b) On another transaxial CT image of the DRUJ with the wrist in pronation (ventral is to the bottom of the figure), the ulna (U) is normally positioned in the sigmoid fossa of the distal radius. of the ulna and the sigmoid notch of the radius RADIOLOGIC: same as CLINICAL COMMENTS: this is actually a dislocation of the distal radius and hand around the distal ulna, since the ulna is the bone that is fixed in place (fixed at the elbow). CODE: Clinical Conditions: Fractures-Dislocations-Diastases (IIIA) 1. see DISTAL RADIOULNAR INSTABILITY DISTAL RADIOULNAR FRACTURE-DISLOCATION (FIGURE 26) SYNONYM: fracture-dislocation of the distal radioulnar joint CLINICAL: a complete loss of joint congruity between the distal end of the ulna and the corresponding aspect of the radius (at the

22 22 RADIOLOGIC: same as CLINICAL COMMENTS: this would not include Madelung s and other epiphyseal dysplasias; however, a fracture deformity of childhood with early closure of the ulnar side of the distal radius epiphyseal plate simulating Madelung s could be included. CODE: Clinical Conditions: Fractures-Dislocations-Diastases (IIIA) 1. see DISTAL RADIOULNAR INSTABILITY DISTAL RADIOULNAR IMPACTION see IMPINGEMENT, RADIOULNAR (DISTAL) DISTAL RADIOULNAR INSTABILITY (SEE FIGURES 25, 26, 27) Fig. 26a SYNONYMS: distal ulnar instability, distal radial instability CLINICAL: an abnormal condition between the distal radius and ulna that results in loss of the normal distal radioulnar joint (DRUJ) relationship(s) RADIOLOGIC: NA COMMENTS: 1) the status of joint congruency (subluxation or dislocation) can be radiologically assessed, especially with computed tomography or magnetic resonance imaging; however, instability is a clinical inference. 2) There is often a palpable subluxation, usually dorsal and rarely volar. With this, there may also be a concomitant supination of the carpus. This results in the loss of normal joint relationships under some conditions (i.e., resisted rotation, manipulation by the examiner). 3) Instability may be a subjective determination by the patient of his/her ability to function. 4) This is a generic term covering three subcategories, i.e., DRUJ subluxation, DRUJ dislocation, and DRUJ fracture-dislocation. CODE: Clinical Conditions: Sprains-Instabilities-Subluxations (IIIB) 1. Dobyns JH, Linscheid RL. Fractures and dislocations of the wrist. In: Rockwood CA Jr, Green DP, editors. Fractures. Vol 1. Philadelphia: JB Lippincott; p Bowers WH. The distal radioulnar joint. In: Green DP, editor. Operative hand surgery. 2nd ed, vol 2. New York: Churchill Livingstone; p Mino DE, Palmer AK, Levinsohn EM. The role of radiography and computerized tomography in the diagnosis of subluxation and dislocation of the distal radioulnar joint. J Hand Surg [Am]. 1983;8: DISTAL RADIOULNAR SUBLUXATION (FIGURE 27) Fig. 26b DISTAL RADIOULNAR FRACTURE-DISLOCATION: a) this PA view demonstrates a fracture of the base of the ulnar styloid with the rest of the ulna displaced radially, overlapping the radius. b) On the lateral view, which shows an acceptable SPC relationship (see NEUTRAL LAT- ERAL VIEW), the ulnar shaft is displaced ventrally. This case shows transulnar styloid, ventral radial fracture-dislocation of the ulna. sigmoid notch) as a result of fracture of the distal radius or distal ulna or both SYNONYM: none CLINICAL: incomplete loss of normal articular contact between the distal radius and ulna at the distal radioulnar joint (see comment #2) RADIOLOGIC: best defined by comparing symptomatic to asymptomatic wrists imaged by transaxial views of the distal radioulnar joint on CT scan or MRI in at least two positions of forearm rotation (full pronation and full supination). Midrotation and supplemental positions that recreate a patient symptom complex may be necessary to demonstrate loss of distal radioulnar joint congruence not evident on the two standard positions (see comment #3). COMMENTS: 1) this common clinical entity is often asymptomatic. 2) As mentioned elsewhere, a subluxation or malalignment may or may not be unstable. Therefore, this subluxation is not necessarily an instability. 3) Analysis of congruency of the distal radioulnar joint depends on exact symmetric pronation/supination positioning of the wrist during cross-sectional imaging.

23 23 DORSAL CARPAL SPRAIN-FRACTURE SYNDROME see DORSAL CARPAL SYNDROME DORSAL CARPAL SUBLUXATION see DORSAL CARPAL TRANSLATION DORSAL CARPAL SYNDROME Fig. 27a Fig. 27b DISTAL RADIOULNAR (DRUJ) SUBLUXATION: a) axial CT images of both overpronated wrists in two different patients show a normal DRUJ joint relationship, and b) widening of the left (L) DRUJ (between black arrows) with associated soft tissue swelling (white arrows). (Reprinted with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 433. Fig 16-22, A and B.) CODE: Clinical Conditions: Sprains-Instabilities-Subluxations (IIIB) 1. see DISTAL RADIOULNAR INSTABILITY DISTAL ULNAR INSTABILITY see DISTAL RADIOULNAR INSTABILITY DORSAL see POSTERIOR DORSAL BOSS see CARPAL BOSS DORSAL CARPAL IMPINGEMENT SYNDROME see DORSAL CARPAL SYNDROME DORSAL CARPAL SPRAIN SYNDROME see DORSAL CARPAL SYNDROME SYNONYMS: dorsal carpal impingement syndrome, dorsal carpal sprain syndrome, dorsal carpal sprain-fracture syndrome CLINICAL: this syndrome covers a wide variety of damage to the dorsal carpus from avulsion or tension fractures of ligament insertions, with their frequent residua of ununited chips, exostotic spurs, and thickened impinging scars, to contact damage at capsular-cartilagebone interfaces subjected to repetitive shear or compression stresses. Stripping of capsular and Sharpey fibers, ridging of osseous margins, chondromalacic changes of cartilage any or all of these may occur and in some special instances, e.g., gymnast s wrist, a ganglion response may also be present. Although probably more common at the radiocarpal junction, particularly between radius and scaphoid or radius and lunate, these reactions also occur between components of the proximal and distal carpal rows and, between components of the carpus and the metacarpus. RADIOLOGIC: a standard motion series of PA views (neutral, radial deviation, and ulnar deviation) and lateral views (neutral, extension, and flexion) will usually show osseous deformity, but tomography, bone scintigraphy, and MRI may be needed to confirm clinical suspicion. OTHER DIAGNOSTIC MODALITIES: Arthroscopy may show intra-articular and even margin lesions, but some of these dorsal carpal syndromes are so devoid of dramatic findings that surgery may be indicated only by symptom degree, localized tenderness, or palpable abnormality and provocative maneuver, with the pathology only finally revealed by the surgical examination itself. COMMENTS: 1) variants of this syndrome, such as carpe bossu, in which the principal tension is provided by the ECRB (extensor carpi radialis brevis) insertion, and boxer s boss, in which the principal force vector is provided by repetitive compression stress, are sufficiently unique to have acquired a specific name. 2) Although viewed by some as invalid or self-healing conditions (and many, such as the common dorsal triquetral avulsion fracture, are self-healing), this group of injuries overall is one of the most common diagnoses seen in the post-traumatic carpus. Only its propensity for self-healing or at least healing to a low level of symptoms has kept this diagnosis from the notoriety that it deserves. 3) This entity includes DORSAL RADIOCARPAL IMPACTION SYNDROME, where the abnormality is at the radiocarpal level. CODE: Clinical Conditions: Compression-Impaction (IIIE) 1. Dobyns JH, Sim FH, Linscheid RL. Sports stress syndromes of the hand and wrist. Am J Sports Med. 1978;6: Dobyns JH, Linscheid RL. Complications of treatment of fractures and dislocations of the wrist. In: Epps CH Jr, editor. Complications in orthopedic surgery. Philadelphia: Lippincott; p Weinzweig J, Watson HK. Wrist sprain to SLAC wrist: a spectrum of carpal instability. In: Vastamaki M, Vilkki S, Raatikainen T, Viljakka T, editors. Current trends in hand surgery. Proceedings of the 6th Congress of the International Federation of Societies for Surgery of the Hand (IFSSH), Helsinki, 1995 July 3-7. New York: Elsevier; p DORSAL CARPAL TRANSLATION (DCT) (FIGURE 28) SYNONYMS: dorsal carpal translocation, dorsal carpal subluxation, dorsal radiocarpal translocation or subluxation

24 24 DORSAL CARPAL TRANSLOCATION see DORSAL CARPAL TRANSLATION DORSAL COLLAPSE see DORSAL INTERCALATED SEGMENTAL INSTABILITY (DISI) DORSAL INTERCALATED SEGMENTAL INSTABILITY (DISI) (FIGURE 29; SEE ALSO FIGURES 14, 15) SYNONYMS: concertina collapse deformity (Fisk), zigzag collapse deformity, dorsal intercalary segmental instability, dorsal collapse CLINICAL: a carpal instability characterized by proximal and dorsal migration of the bones of the distal carpal row, associated with extension and often palmar translation of the lunate with the metacarpals in line with the distal radius Fig. 28 DORSAL CARPAL TRANSLATION (DCT): the proximal articular surface of the carpus as recognized by the proximal convexity of the lunate is located dorsal to the midportion of the distal radius with the hand and wrist in the neutral position. The SPC relationship is excellent (see NEUTRAL LATERAL VIEW). Old fracture deformity with dorsal inclination of the distal articular surface involves the radius. (Reprinted with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 212. Fig 8-11.) CLINICAL: abnormal dorsal shift of the entire carpus in relationship to the long axis of the radius RADIOLOGIC: on lateral radiographs of the wrist, the lunate and the rest of the carpus is translated dorsally with respect to the long axis of the radius, and there is loss of parallelism between the opposing articular surfaces of the radius and lunate. COMMENTS: 1) this may be pathologic from acute ligament disruption or may develop chronically as an adaptive response to an altered tilt (increased extension) of the distal radius articular surface, postfracture. 2) When secondary to the adaptive carpus (see ADAPTIVE CARPUS) following a dorsally impacted distal radius fracture, the lunate will usually tip dorsally before translating dorsally, but both may occur. 3) Like the other carpal malalignments, DCT may present as a static deformity or may present only dynamically with some provocative stress. CODE: Clinical Conditions: Sprains-Instabilities-Subluxations (IIIB) 1. see DORSAL INTERCALATED SEGMENTAL INSTABILITY (DISI) Fig. 29a DORSAL INTERCALATED SEGMENTAL INSTABILITY (DISI): a) lateral view: the lunate is tilted dorsally and lies along the ventral surface of the distal radius. The scapholunate angle is increased to more than 80 and the capitolunate angle is more than 30. The ventral rim of the distal radius is fractured (arrow). b) Posteroanterior view: the lunate has a triangular shape indicative of lunate tilting. A transverse fracture of the radial styloid is present. c) This three-part drawing demonstrates on the left drawing that with DISI, as the lunate tilts dorsally (left curved arrow), the lunate may move ventrally (short straight arrow pointing to the right), the capitate tends to move dorsally (straight arrow passing to the left), and the scaphoid tilts palmarly (curved arrow to the right). As a result there is an increased scapholunate angle of more than 80 (middle drawing) and/or an increased capitolunate angle of more than 30 (drawing to the right). S = scaphoid axis, L = lunate axis, and C = capitate axis. (Reprinted and modified with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 216. Fig 8-16B.)

25 25 RADIOLOGIC: on a lateral radiograph centered on the wrist, with the wrist in neutral flexion/extension and pronosupination, the lunate is dorsiflexed with regard to the long axis of the radius, by 15 or more. The diagnosis of DISI is made with the wrist in neutral position identifying a capitolunate angle of more than +30, usually accompanied by an equivalent 15 angle at the radiolunate joint. The scapholunate angle, which may be abnormal in some DISI situations, is considered abnormal when >80, and is of questionable significance when between Also, DISI should have abnormal intercarpal motion. On lateral views of the wrist, the failure of the mid axis of the capitate to flex and extend with respect to the mid axis of the lunate, and the mid axis of the lunate to flex and extend with respect to the mid axis of the radius with flexion and extension of the wrist respectively, may be used as an indicator of abnormal intercarpal motion (see reference #3). COMMENTS: 1) see CID-DISI and CIND-DISI. 2) Comparison with the unaffected side is always important in that 10 or more difference is usually clinically meaningful. 3) Dorsal shift of the distal carpal row can be quantified by the RCA (radius-carpal axis)-tocapitate distance. 4) In compression, the proximal carpal row acts as an intercalated segment between two relatively fixed structures (the metacarpals/distal carpal row and the radius) and moves palmarly or dorsally, unless controlled by an intact musculoligamentous system. When the proximal row displaces palmarly and tilts dorsally, as visualized by the lunate on lateral roentgenograms, the displacement is called DISI. 5) In the DISI with SLD (scapholunate dissociation) the scaphoid is palmar flexed, but in CIND-DISI the entire proximal carpal row is dorsiflexed. 6) To separate DISI from rotary subluxation of the scaphoid, the lunate motion should be evaluated. With typical DISI having an increased scapholunate angle, the lunate will have abnormal motion on flexion/extension lateral views and radial and ulnar deviation lateral views. Using these same views, the lunate motion will be normal with isolated rotary subluxation of the scaphoid. 7) Some DISI deformities may not seem unstable or pathologic, since the position may be relatively fixed, although there may still be progression at a slower pace. 8) Within the proximal carpal row, the lunate may be abnormally aligned alone (rare), bonded with one of the other of its proximal carpal row neighbors (most commonly, the scaphoid), or bonded and extended with both of its PCR neighbors as in CIND-DISI. CODE: Clinical Conditions: Residuals of Injuries (IIIC) 1. Linscheid RL, Dobyns JH, Beabout JW, Bryan RS. Traumatic instability of the wrist. Diagnosis, classification, and pathomechanics. J Bone Joint Surg Am. 1972;54: Dobyns JH, Berger RA. Dislocations of the carpus. In: Chapman MW, Madison M, editors. Operative orthopedics. 2nd ed, vol 2. Philadelphia: JB Lippincott; p Gilula LA, Weeks PM. Post-traumatic ligamentous instabilities of the wrist. Radiology. 1978;129: Fisk GR. Carpal instability and the fractured scaphoid. Ann R Coll Surg Engl. 1970;46: DORSAL MIDCARPAL INSTABILITY see CAPITOLUNATE INSTABILITY PATTERN DORSAL RADIOCARPAL IMPACTION SYNDROME see DORSAL CARPAL SYNDROME DORSAL RADIOCARPAL TRANSLOCATION/SUBLUXATION see DORSAL CARPAL TRANSLATION Fig. 29b DORSOPALMAR PROJECTION/POSITION see POSTEROANTERIOR VIEW DORSOVOLAR PROJECTION/POSITION see POSTEROANTERIOR VIEW DORSOVOLAR TRIQUETROLUNATE TRANSLATION/ DISPLACEMENT TEST see TRIQUETROLUNATE BALLOTTEMENT Fig. 29c DYNAMIC INSTABILITY (SEE FIGURE 6) SYNONYMS: stress instability, intermittent instability CLINICAL: this is a malalignment shown only on radiographs made during or after stress provocation of the wrist. RADIOLOGIC: a situation in which nonstressed neutrally positioned posteroanterior and lateral views (i.e., no flexion or extension, no radial or ulnar deviation, no pronosupination) are normal, while some other hand position or provocative maneuver (PM) may demonstrate malalignment

26 26 COMMENTS: 1) some people divide dynamic instability into two subgroups: Dynamic 1 = no radiologic changes at all, and Dynamic 2 = the definition described here under RADIOLOGIC. Other people do not accept this subgroup classification of Dynamic 1 and 2. Some use dynamic and static instability as classifications in themselves; most use the terms only as stages of a major classification, i.e., SLD may be subclassified for treatment purposes between several stages, three of which might be dynamic, static reducible, and static irreducible. 2) The effective provocative maneuver may be as simple as performing some element of wrist motion or making a fist. 3) Some experts have difficulty with the terms static and dynamic. As one expert states: An instability is always dynamic. A static instability is a contradiction, if we analyze the words correctly. 4) Some experts believe very strongly that the term instability should be used only in patients who have abnormal alignment that is associated with abnormal carpal motion (see reference #4). CODE: Clinical Conditions: Sprains-Instabilities-Subluxations (IIIB) Fig. 30a 1. Dobyns JH, Linscheid RL. Fractures and dislocations of the wrist. In: Rockwood CA Jr, Green DP, editors. Fractures. Vol 1. Philadelphia: JB Lippincott; p Taleisnik J. The wrist. New York: Churchill Livingstone; Taleisnik J. Classification of carpal instability. Bull Hosp Dis Orthop Inst. 1984;44: Garcia-Elias M, Berger RA, Horii E, Kauer JMG, Lanz U, Rongières M, Ryu J, Sennwald GR, Viegas SF. Definition of carpal instability. Anatomy and Biomechanics Committee of the International Federation of Societies for Surgery of the Hand. 2nd ed. Barcelona, Spain: Institut Kaplan; Feb FIXED CARPAL INSTABILITY see STATIC CARPAL INSTABILITY FLEXION INSTABILITY see VOLAR INTERCALATED SEGMENT INSTABILITY (VISI) FRACTURE-DISLOCATION (FIGURE 30) Fig. 30b FRACTURE-DISLOCATION: a) PA view: the scaphoid and lunate (proximal arrowheads) with a bone fragment (arrows) related to the lunate overlap the radius (distal arrowheads). The lunate and triquetrum overlap the distal radius and ulna. All the carpal bones are normally related to each other. These features indicate a fracture, probably from the radius, which is associated with a dislocated carpus. b) The lateral view demonstrates palmar and proximal dislocation of the carpus with a fragment from the palmar rim of the distal radius, most likely from the lunate fossa, as the fragment moves with the lunate. This case can be called transradial palmar carpal fracturedislocation. (Reprinted with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 211. Fig 8-10, A and B.) SYNONYM: fracture-luxation CLINICAL: a condition represented by a break in one or more bones with an accompanying complete disruption of one or more joints in the wrist such that usually congruent articular surfaces no longer contact one another RADIOLOGIC: see CLINICAL COMMENTS: along with its sibling, fracture-subluxation, i.e., a partial dislocation with associated fractures, this is considered by some wrist experts as the third category of carpal instability. CODE: Clinical Conditions: Fractures-Dislocations-Diastases (IIIA) 1. see DYNAMIC INSTABILITY FRACTURE-LUXATION see FRACTURE-DISLOCATION FRACTURE-SUBLUXATION (FIGURE 31, SEE ALSO FIGURE 20) SYNONYM: fracture with partial dislocation (see comment #2) CLINICAL: a condition represented by a break in one or more bones with an accompanying partial joint disruption, so the normally contiguous joint surfaces are now only partially in contact with one another RADIOLOGIC: see CLINICAL COMMENTS: 1) along with its sibling, fracture-dislocation, this is

27 27 FRACTURE-DISLOCATION; LESSER ARC INJURY; COMBINATION ARC INJURY Fig. 31 FRACTURE-SUBLUXATION: a sagittal plane CT section through the fourth metacarpal (4), hamate (H), and ulna (U) shows a fracture (black arrowheads) through the base of the fourth metacarpal. The fracture fragments are separated above the distal articular surface of the hamate, and the dorsal surface of the fourth metacarpal (arrows) is subluxed dorsally with respect to the dorsal surface of the hamate (white arrowhead). SYNONYMS: transscaphoid, transcapitate, transtriquetral perilunate injuries (see COMMENTS) CLINICAL: 1) a summary term to describe the radial to ulnar disruption patterns through the scaphoid and capitate bones and ligament(s) at some distance from the lunate. 2) This is an injury along the greater arc of the carpus. As originally described, this injury arc is projected across the mid scaphoid, capitate head or neck, and lunate articulation of the triquetrum with or without fracture of the proximal pole of the hamate (per input from Dr. Roger Johnson). (See REFERENCES and see comment #1). RADIOLOGIC: see CLINICAL COMMENTS: 1) this classification of injuries is described only as a carpal injury pattern and as originally described does not include fractures of the radius (radial styloid) or ulna (ulnar styloid). Fractures of the radial and ulnar styloid processes may be associated with greater or lesser arc injuries, but as originally described are not part of the classification of greater and lesser arc injuries. 2) COMBINATION ARC INJURIES include any injury of the carpus that are between a LESSER ARC INJURY and a full GREATER ARC INJURY. 3) Examples of this injury are transscaphoid transcapitate fracture dislocation; transscaphoid, transcapitate, transtriquetral fracture dislocation; and transscaphoid, transcapitate, transhamate, transtriquetral fracture dislocation. 4) Some experts believe that the only value of recognizing the pattern of the greater (and lesser) carpal arc(s) is to realize the underlying mechanism of injuries, and that the exact description of the anatomic abnormalities is more important when describing the abnormality present. 5) These include transosseous perilunate injuries, as opposed to ligament-only perilunate injuries. See above comment #2 as regards separation of the greater arc injury from the combination arc injury. 6) See COMMENTS in LESSER ARC INJURY. considered by some wrist experts as the third category of carpal instability (see comment #4 under MIDCARPAL SUBLUXATION). 2) The terms dislocation and subluxation refer to the condition present at the joint and not at the bone fracture site. CODE: Clinical Conditions: Fractures-Dislocations-Diastases (IIIA) 1. see DYNAMIC INSTABILITY FRACTURE WITH PARTIAL DISLOCATION see FRACTURE-SUBLUXATION FRONTAL see ANTEROPOSTERIOR VIEW see POSTEROANTERIOR VIEW FRONTAL CARPAL CONDYLE ANGLE see CARPAL ANGLE GAP see DIASTASIS GILULA S ARCS see CARPAL ARCS GREATER ARC INJURY (FIGURE 32) see PERILUNATE Fig. 32 GREATER AND LESSER ARC INJURIES: A refers to the greater arc, B refers to the lesser arc, and C refers to the radiolunate joint through which injury also takes place with a lunate dislocation. The vulnerable zone of the carpus is represented by the shaded area. Irregular lines in the carpal bones represent sites of potential fractures. See text. (Reprinted with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 306. Fig )

28 28 Fig. 33 IMPACTION, ULNOCARPAL: on this PA view, flattening (distal arrowheads) and subchondral sclerosis of the proximal ulnar surface of the lunate with similar flattening (proximal arrowheads) and subchondral sclerosis of the distal end of the ulna represent impaction between the ulna and the opposing surface of the lunate. Loss of normal cortical medullary junction of the proximal radial corner of the triquetrum supports reaction from ulnocarpal impaction at this site also. (Reprinted with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 525. Fig 20-4) CODE: Clinical Conditions: Fractures-Dislocations-Diastases (IIIA) 1. Johnson RP. The acutely injured wrist and its residuals. Clin Orthop. 1980; 149: Mayfield JK. Mechanism of carpal injuries. Clin Orthop. 1980;149: Mayfield JK, Johnson RP, Kilcoyne RK. Carpal dislocations: pathomechanics and progressive perilunar instability. J Hand Surg [Am]. 1980;5: HAMATE FACET OF THE LUNATE see LUNATE, TYPES I AND II HAND-WRIST FRACTURE DISLOCATION see CARPOMETACARPAL FRACTURE-DISLOCATION HOMING-IN PHENOMENON see CATCH-UP CLUNK HOOK OF HAMATE VIEW see SEMISUPINATED OBLIQUE VIEW HYPOTHENAR see ULNAR IMPACTION, DORSAL RADIOCARPAL see DORSAL CARPAL SYNDROME IMPACTION SYNDROME, DORSAL RADIOCARPAL see DORSAL CARPAL SYNDROME IMPACTION SYNDROME, ULNOCARPAL (FIGURE 33) SYNONYMS: ulnocarpal abutment, ulnar impaction syndrome, ulnar impingement (not preferable see COMMENTS) CLINICAL: a syndrome characterized by ulnar-sided wrist pain produced by the grip-loaded movements of ulnar deviation and rotation of the forearm/wrist unit (often with supination). It is thought to occur when there is abnormal load borne by the ulnar axis, and it may vary from mild to severe. It is associated with degenerative changes in the contact surfaces of the lunate, ulnar dome (distal end of the ulna), the intervening TFC (triangular fibrocartilage), and occasionally the triquetrum (see comment #1). RADIOLOGIC: on conventional posteroanterior radiographs, neutral or positive ulnar variance is usually seen. There may be associated arthritic or lucent ( cyst-like ) changes in the osseous structure of the ulnar side of the lunate, radial side of the ulnar dome (distal end of the ulna), and the triquetrum. On arthrography (including tomography cuts ), MRI, or arthroscopy, chondromalacia of these articular surfaces is often associated with LT (lunotriquetral) and central TFC perforations. COMMENTS: 1) ulnocarpal impaction can occur with only pathologic cartilage changes (chondromalacia) and no osseous changes. 2) Occasionally this may be seen with ulnar negative variance with forces transmitted through the TFC. 3) This may be related to chronic physiologic distal migration of the radius as the radius moves from a more proximal position during pronation to a more distal position during supination. 4) Radiographic changes of ulnocarpal arthrosis may occur without pain, especially in some elderly persons. Without pain, this shouldn t be considered as the ulnar impaction syndrome and may be due to aging or senescent changes. 5) The terms ulnar impingement or ulnocarpal impingement are sometimes used for this condition, but ulnar impingement is preferentially used for the ulnar stump-adjacent radius syndrome, possibly more clearly called distal radioulnar impaction. The use of the words ulnocarpal impaction also eliminates any question about the site of distal ulnar impaction or impingement. 6) It is the opinion of at least one expert that currently it is unknown what part a TFC tear or defect plays in producing the pain of ulnocarpal impaction syndrome. If pain were related only to a TFC tear, it could be questioned if the condition should be called ulnocarpal impaction syndrome. CODE: Clinical Conditions: Compression-Impaction (IIIE) 1. Dobyns JH, Linscheid RL. Fractures and dislocations of the wrist. In: Rockwood CA Jr, Green DP, editors. Fractures. Vol 1. Philadelphia: JB Lippincott; p Friedman SL, Palmer AK. The ulnar impaction syndrome. Hand Clin. 1991; 7: IMPINGEMENT, RADIOULNAR (DISTAL) (FIGURE 34) SYNONYMS: radioulnar compression or abutment syndrome, distal radioulnar impaction CLINICAL: NA RADIOLOGIC: a condition leading to distal radioulnar arthrosis in which the ulnar head converges to, articulates with, and impinges on the radius, typically proximal to a horizontally inclined distal radius sigmoid fossa COMMENTS: 1) some physicians use impingement and impaction interchangeably. However, impingement refers more generally to the ulna abutting the side of the radius, and impaction refers to the ulna abutting the carpus. Probably the safest way to clearly define the impaction or impingement is to specify the site of the impaction, impingement, or abutment, e.g., ulnocarpal or distal radioulnar. 2) Impingement may occur between the distal ulnar stump and the adja-

29 29 Fig. 34 IMPINGEMENT, RADIOULNAR (DISTAL): the ulna articulates with the side of the distal end of the radius (arrowheads). The ulnar aspect of the distal end of the radius curves ulnarly to cover the distal end of the radius. Subcortical sclerosis in the radius and ulna at the distal radioulnar articulation supports reactive bone formation from radioulnar impingement. This type of articulation is a congenital variation that may not have associated symptoms. (Reprinted with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 526. Fig 20-6.) cent radius post distal ulnar resection or Sauvé-Kapandji procedure. CODE: Clinical Conditions: Compression-Impaction (IIIE) 1. Cooney WP 3rd, Linscheid RL, Dobyns JH. Fractures and dislocations of the wrist. In: Rockwood CA Jr, Green DP, Bucholz RW, Heckman JD, editors. Fractures in adults. 4th ed, vol 1. Philadelphia: Lippincott-Raven; p Watson HK, Brown RE. Ulnar impingement syndrome after Darrach procedure: treatment by advancement lengthening osteotomy of the ulna. J Hand Surg [Am]. 1989;14: INSTABILITY (SEE FIGURES 13, 14, 15, 16, 29) SYNONYMS: destabilization, loss of stability CLINICAL: 1) the opposite of stability. 2) A condition represented by the inability to maintain, or an actual loss of normal alignment of carpal bones under physiologic loads (see comments #3 and #4). It is a corollary that instability alters normal carpal kinematics (see STATIC CARPAL INSTABILITY). 3) A condition in which normal anatomic relationships are present, but through some provocative maneuver, such as external stress, muscle contracture, or positioning, an abnormal relationship can be demonstrated. Once this stress positioning or contracturing stops, the parts (usually bones) can be returned to their normal anatomic positions (see DYNAMIC IN- STABILITY). Such abnormal positions are called subluxation if they are not extreme enough to fit the definition for a dislocation or a fracture-dislocation. RADIOLOGIC: the abnormal carpal position or arc of motion can be documented using non-stress and stress (provocative) maneuvers with various imaging techniques to confirm the diagnosis. The abnormal alignment may be between adjacent carpal bones, between carpal bones and the radius, between the distal radius and ulna, or between the carpus and the metacarpus. COMMENTS: 1) Major controversy exists among experts about the use of this term. Some strongly believe that malalignment does not necessarily mean instability is present and that malalignment is not a synonym for instability (see reference #3). 2) Static instability is malalignment present on neutral PA and lateral radiographs without provocative stress. For clinical purposes, static instability is sometimes further divided into reducible and irreducible malalignment. Dynamic malalignment ( instability ) is a malalignment present only on stress radiographs or with other provocative examinations. 3) Some malalignments that fit the criteria for a static instability with abnormal kinematics may actually be constantly in a fixed or relatively stable position. Even so, they have progressed from the normal and may progress further. 4) A provocative maneuver may show physiologic laxity, a condition that has nothing to do with a wrist instability. 5) Some experts do not like this term to be used when the malalignment is fixed and not reducible. However, this may be considered a spectrum of conditions starting from a symptomatic condition not shown by imaging tests or clinical findings to one shown by imaging tests and clinical findings and finally to a fixed deformity. Some of these experts feel very strongly that the term instability should be used only in the patients who have abnormal alignment that is associated with abnormal carpal motion (see reference #3). 6) Currently, this is a term in evolution. With continual growth in knowledge, this term will continue to be modified. CODE: Clinical Conditions: Sprains-Instabilities-Subluxations (IIIB) 1. Linscheid RL, Dobyns JH, Beabout JW, Bryan RS. Traumatic instability of the wrist. Diagnosis, classification, and pathomechanics. J Bone Joint Surg Am. 1972;54: Dobyns JH, Linscheid RL, Chao EYS, Weber ER, Swanson GE. Traumatic instability of the wrist. AAOS Instr Course Lect. 1975;24: Garcia-Elias M, Berger RA, Horii E, Kauer JMG, Lanz U, Rongières M, Ryu J, Sennwald GR, Viegas SF. Definition of carpal instability. Anatomy and Biomechanics Committee of the International Federation of Societies for Surgery of the Hand. 2nd ed. Barcelona, Spain: Institut Kaplan; Feb INTACT see COMPETENT INTERCALATED CARPAL ROW see PROXIMAL CARPAL ROW INTERMITTENT INSTABILITY see DYNAMIC INSTABILITY LATERAL (FIGURE 35) see RADIAL, THENAR SYNONYMS: varies for direction, as radial or thumbward; and plane, as sideview, sagittal, or dorsovolar for anatomic or radiographic plane CLINICAL: 1) further from the midline of the body with the hand in the anatomic position of supination. 2) Views made from the radial or ulnar side of the hand, wrist, or forearm displaying the osseous structures in the sagittal or dorsovolar plane. 3) Displacement of a distal segment in a direction away from the midline of the body. RADIOLOGIC: NA (see LATERAL VIEW)

30 30 COMMENTS: lateral, the direction, is often confused with the radiologic term, LATERAL VIEW (see discussion of this term). CODE: Radiologic: Sides (IC) 1. anatomy or radiology textbooks LATERAL CARPAL COLUMN see RADIAL COLUMN OF THE CARPUS LATERAL PLANE see SAGITTAL PLANE LATERAL VIEW (FIGURE 35; SEE ALSO FIGURE 2B) Fig. 35a SYNONYMS: lateral projection/position, sagittal view, side view CLINICAL: NA (see LATERAL) RADIOLOGIC: a view of the wrist from either the radial to the ulnar or ulnar to radial side with the metacarpals aligning in the same plane. The radiographic view should be made with the ulnar (or radial) border of the wrist on the film cassette, and the roentgenographic tube placed directly opposite on the radial (or ulnar) aspect, respectively, of the wrist. An adequate lateral view of the carpus can be identified with recognition of the SPC relationship: the ventral (volar) surface of the pisiform ( P ) lies between the ventral (volar) cortex of the distal pole of the scaphoid ( S ) and the ventral (volar) cortex of the proximal convexity of the capitate ( C ) to create the SPC relationship (see reference #2). COMMENTS: 1) a lateral view gives a sagittal plane view of the structures. If incremental lateral views across the wrist are made, they are often called parasagittal views. 2) A lateral plane view in contradistinction to a lateral view gives a frontal or AP/PA view of the structures. 3) The SPC relationship identifies the carpus and not the distal forearm alignment. CODE: Radiologic: Views (ID) 1. radiology textbooks 2. Yang Z, Mann FA, Gilula LA, Haerr C, Larsen CF. Scaphopisocapitate alignment: criterion to establish a neutral lateral view of the wrist. Radiology. 1997;205: LESSER ARC DISRUPTION/DISLOCATION see PERILUNATE DISLOCATION (PLD) LESSER ARC INJURY (SEE FIGURE 32) Fig. 35b LATERAL VIEW (see also Figure 2B): a) standard positioning for lateral view is performed with the elbow flexed 90 and the elbow adducted against the patient s side. b) An adequate lateral view of the carpus can be detected when the ventral cortex of the pisiform (arrow) is projected between the ventral surfaces of the head of the capitate (right arrowhead of the double-headed arrow) and the distal pole of the scaphoid (left arrowhead of the double-headed arrow). This is the SPC (scaphopisocapitate) lateral as described in the text. The doubleheaded arrow shows the distance between the ventral surfaces of the capitate head and the distal pole of the scaphoid. (Reprinted with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p Fig 5-30, A and B.) SYNONYM: perilunate injury CLINICAL: a conceptual summary term describing the radial to ulnar ligamentous disruption pattern found with perilunate and lunate subluxation or dislocations. This is any dislocation or dissociation through ligaments around the lunate with or without radialsided avulsions of the triquetrum (per personal discussion with Roger Johnson, M.D., original descriptor of this concept) and is therefore more proximal than the GREATER ARC INJURY. RADIOLOGIC: same as description for perilunate dislocation and lesser stages of perilunate dislocation, such as scapholunate dissociation, lunotriquetral (triquetrolunate) dissociation, etc. COMMENTS: 1) ligamentous failure occurs at the periphery of the lunate, in other words, at the radiocarpal level radially, perilunate (radial, distal, and ulnar) centrally, and at the radioulnocarpal level ulnar to the lunate. This definition describes the site rather than the specific injury. 2) Clinically, it is preferable that a specific description

31 31 LINKED see NONDISSOCIATION LONGITUDINAL AXIS (FIGURE 36) see SAGITTAL PLANE SYNONYM: columnar axis; see comment #2 regarding sagittal axis CLINICAL: see COMMENTS RADIOLOGIC: see COMMENTS COMMENTS: 1) every anatomic structure or group of structures in this area may have a longitudinal axis. It is a general term that needs to be specifically designated to something each time it is used, i.e., the longitudinal axis of the scaphoid. 2) Sagittal axis is not a true synonym of longitudinal axis, as sagittal axis is a specific type of longitudinal axis, one that is in the same plane as the sagittal suture. CODE: Radiologic: Planes (IB) 1. anatomy or radiology textbooks LONGITUDINAL CARPAL DISLOCATION (FIGURE 37) Fig. 36 LONGITUDINAL AXIS: this anatomic section is taken in the sagittal plane (in the plane of the sagittal suture) when the hand is placed in anatomic position, that is, with the palm facing forward. The plane passes between dorsal and ventral surfaces of the wrist. (Case donated by Dr. Rudi Richli, Radiologist, MD Anderson Hospital, Houston, Texas.) of fracture/dislocation is provided, as this term does not provide a specific description of the abnormality present. 3) The term includes the various levels of perilunate subluxation/dislocation; lunate subluxation/dislocation; and may include carpal instability combined radiocarpal and perilunate type. 4) Many experts prefer not to use the terms greater and lesser arc or combination arc injuries. However, the terms provide shorthand terminology for the most common dislocations of the carpus, the perilunate, and the transosseous perilunate types. These terms have been accepted and are frequently used. 5) At least one expert questions if the greater, lesser, and combination arc injuries as described by Mayfield and Johnson are clearly defined entities, since their work was performed without loading the muscles. 6) Strictly speaking (per input from Dr. Roger Johnson), this lesser arc injury is any dislocation or dissociation around the lunate with or without radial-sided avulsion of the triquetrum (see references in GREATER ARC INJURY). 7) COMBI- NATION ARC INJURIES include any injury of the carpal arcs that are between a LESSER ARC INJURY and a GREATER ARC INJURY. CODE: Clinical Conditions: Fractures-Dislocations-Diastases (IIIA) 1. see GREATER ARC INJURY SYNONYM: axial carpal dislocation CLINICAL: traumatic injury to the wrist consisting of a longitudinal transarticular disruption of the metacarpal and carpal transverse arches with complete loss of the normal relationship between the parts into which the carpus has been divided. No fractures are present. RADIOLOGIC: complete loss of articular apposition through any distal row intercarpal joint and the attached metacarpals. There may be transarticular extension into the proximal carpal row. No fractures are present. COMMENTS: 1) see LONGITUDINAL CARPAL INSTABILITY. 2) Axial is used in the anatomic sense (parallel to the long axis of the forearm) rather than the biomechanic sense. CODE: Clinical Conditions: Fractures-Dislocations-Diastases (IIIA) 1. Norbeck DH Jr, Larson B, Blair SJ, Demos TC. Traumatic longitudinal disruption of the carpus. J Hand Surgery [Am]. 1987;12: Garcia-Elias M, Dobyns JH, Cooney WP 3rd, Linscheid RL. Traumatic axial dislocations of the carpus. J Hand Surg [Am]. 1989;14: LONGITUDINAL CARPAL FRACTURE-DISLOCATION/ SUBLUXATION (FIGURE 38) SYNONYM: axial carpal fracture-dislocation CLINICAL: traumatic injury to the wrist consisting of a combined transarticular and transosseous longitudinal disruption of the metacarpal and carpal transverse arches of the hand with loss of the normal relationships between the parts into which the carpus has been divided. RADIOLOGIC: complete loss (dislocation) or partial loss (subluxation) of articular apposition through any distal row intercarpal joint and the attached metacarpals associated with fractures. There may be transosseous and/or transarticular extension into the proximal carpal row. COMMENTS: see LONGITUDINAL CARPAL INSTABILITY. Axial is used in the anatomic sense (parallel to the long axis of the forearm) rather than the biomechanic sense. CODE: Clinical Conditions: Fractures-Dislocations-Diastases (IIIA) 1. see LONGITUDINAL CARPAL DISLOCATION

32 32 Fig. 37 LONGITUDINAL CARPAL DISLOCATION: axial radial dislocation includes peri-trapezoid and peri-trapezium types. Peri-hamate, peri-pisiform is an axial-ulnar dislocation. (Reprinted and modified with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 221. Fig 8-21.) LONGITUDINAL CARPAL INSTABILITY (SEE FIGURES 37 AND 38) SYNONYM: axial carpal instability CLINICAL: traumatic injury to the wrist consisting of transarticular and/or transosseous longitudinal disruption of the metacarpal and carpal transverse arches with partial or complete loss of the normal relationships between the parts into which the carpus has been divided. There may be transosseous and/or transarticular extension into the proximal carpal row. The malalignment is unstable. RADIOLOGIC: partial or complete loss of articular apposition through any distal row intercarpal joint and the attached metacarpals with or without associated fractures. There may be transosseous and/ or transarticular extension into the proximal carpal row. Abnormal widening between two adjacent bones of the distal carpal row that in- Fig. 38 LONGITUDINAL CARPAL FRACTURE DISLOCATION/SUBLUXATION: trans-trapezium is an axial-radial fracture dislocation. Trans-hamate, peri-pisiform and peri-hamate, trans-triquetrum are types of axial-ulnar fracture dislocations. (Reprinted and modified with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 221. Fig 8-21.)

33 33 Fig. 39a LUNATE DISLOCATION: a) the lunate is triangular, indicating that it is tilted. There is no parallelism between the margins of the lunate and its adjacent carpal bones (scaphoid, capitate, hamate, and triquetrum). The lunate overlaps the capitate, hamate, and triquetrum. Parallelism Fig. 39b of cortices between the scaphoid, capitate, trapezium, hamate, and triquetrum and at the fifth carpometacarpal (CMC) joint indicates that these bones have stayed (moved) together. Parallelism at the third and fourth CMC joints is not well seen because the palm is not flat in this view. All these findings demonstrate dislocation between the lunate and the rest of the carpal bones. b) On lateral view, the lunate has dislocated ventrally and the capitate head (arrowheads) is centered over the distal radius, resulting in the diagnosis of ventral lunate dislocation. This case is part of the perilunate spectrum of abnormality as described in the text. (Reprinted and modified with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 310. Fig 11-25, A and B.) creases or closes under manipulation in conjunction with abnormal widening between the bases of the two contiguous metacarpals may be demonstrated either in standard radiographs or stress views (e.g., traction or compression views). COMMENTS: 1) to be strictly correct, disruption of the transverse carpal arch requires involvement of the palmar surface of the carpus. 2) To be truly unstable, the malalignment should not be in a fixed state and should be truly mobile. CODE: Clinical Conditions: Sprains-Instabilities-Subluxations (IIIB) 1. see LONGITUDINAL CARPAL DISLOCATION LONGITUDINAL CARPAL SUBLUXATION (SEE FIGURES 37 AND 38) SYNONYM: axial carpal subluxation CLINICAL: traumatic injury to the wrist consisting of a longitudinal subluxation of the metacarpal and carpal transverse arches with partial loss of the normal relationship between the parts into which the carpus has been divided RADIOLOGIC: loss of congruence without dislocation between two or more carpal bones and their attached metacarpals COMMENTS: 1) see LONGITUDINAL CARPAL INSTABILITY and LONGITUDINAL CARPAL FRACTURE-DISLOCATION/SUBLUX- ATION. 2) It is the mildest type of longitudinal carpal malalignment. 3) Such a subluxation could be stable in the displaced position or grossly unstable. If grossly unstable, then that would be a true instability. CODE: Clinical Conditions: Sprains-Instabilities-Subluxations (IIIB) 1. see LONGITUDINAL CARPAL DISLOCATION LONGITUDINAL (COLUMNAR) INSTABILITY PATTERN (SEE FIGURE 21) SYNONYM: axial carpal instability CLINICAL: a concept introduced originally by Navarro that provides a different viewpoint in understanding carpal instability problems. It is based on three columns: (1) the radial or support column; (2) the central or flexion-extension column; and (3) the ulnar or rotational column. This concept emphasizes the longitudinal interactions of the carpus with the forearm and hand. RADIOLOGIC: see CLINICAL COMMENTS: 1) two types of this pattern would be scapholunate instability and lunotriquetral (triquetrolunate) instability. 2) This is principally of historical interest. Many reviewers of this work believed that this term should be dropped. 3) Some experts believe that this may now be considered synonymous with axial carpal instability. 4) There is some disagreement among experts about which bones belong to which column. This concept emphasizes the longitudinal in-

34 34 teractions of the carpus with the forearm and hand. CODE: Clinical Conditions: Sprains-Instabilities-Subluxations (IIIB) 1. Navarro A. La fisiologia del carpo. An Inst Clin Quirurg Chirurgia Exp. 1937; 6: Taleisnik J. The wrist. New York: Churchill Livingstone; LUNATE DISLOCATION (FIGURE 39) SYNONYM: radiolunate dislocation CLINICAL: complete loss of articulation of the lunate with the distal radius and its carpal articulations RADIOLOGIC: same as CLINICAL. The carpal bones normally surrounding the lunate may be in relatively normal relationship with the radius, or they too may be subluxed/dislocated with reference to the radius. COMMENTS: 1) this is considered by many experts as the last stage of perilunate dislocation. 2) In most instances, perilunate disruption precedes lunate dislocation. 3) There may be two types of lunate dislocation. The common type is simply the end stage of perilunate dislocation and both radial and ulnar columns are also unstable with loss of articulation between these columns and the radius. Theoretically, there may be another type with the lunate dislocated from the radius without significant damage to the support ligaments of the radial and ulnar columns. However, this has not yet been shown in the literature. For surgical reconstruction purposes, the differences between the two could be significant. 4) Lunate position in dislocation is usually volar (palmar), but may be dorsal, radial, ulnar, or completely displaced outside the wrist boundaries. 5) A lunate dislocation is a LESSER ARC INJURY. CODE: Clinical Conditions: Fractures-Dislocations-Diastases (IIIA) 1. Dobyns JH, Linscheid RL. Fracture and dislocations of the wrist. In: Rockwood CA Jr, Green DP, editors. Fractures. Vol 1. Philadelphia: JB Lippincott; p Fig. 40a LUNATE, TYPES I AND II (FIGURE 40) SYNONYM: lunates with or without hamate facets CLINICAL: NA RADIOLOGIC: a congenital variation in the shape of the distal ulnar aspect of the lunate related to presence of a distal ulnar articular surface to articulate with the hamate. The Type I lunate is a lunate without a radiologically visible hamate articular surface (facet) of the lunate. The Type II lunate is a lunate with a radiologically visible hamate facet of the lunate. Often the Type II lunate has a broken carpal arc II at this hamate facet of the lunate (see reference #1). COMMENTS: 1) chondromalacia may occur in the proximal pole of the hamate and the hamate facet of the lunate, and by arthroscopy this appears to be a common area of early midcarpal arthritis. 2) Antuna- Zapico as well as Stanley and Trail have described various configurations of the lunate, which may be of importance relative to other problems, i.e., Kienböck s disease and proximal carpal row stability, respectively. CODE: Anatomic: Carpal (IID) 1. Viegas SF, Wagner K, Patterson R, Peterson P. Medial (hamate) facet of the lunate. J Hand Surg [Am]. 1990;15: Fig. 40b LUNATE, TYPES I AND II: a) type I lunate shows no evident hamate facet of the lunate. b) Type II lunate shows an articulation for the proximal end of the hamate in the distal ulnar aspect of the lunate (arrowheads). 2. Antuna-Zapico JM. Malacia del semilunar (tesis doctoral). Valladolid: Universidad de Valladolid; Stanley JK, Trail IA. Carpal instability. J Bone Joint Surg Br. 1994;76: LUNOTRIQUETRAL BALLOTTEMENT see TRIQUETROLUNATE BALLOTTEMENT LUNOTRIQUETRAL DISSOCIATION (LTD) (SEE FIGURE 13) SYNONYMS: lunatotriquetral dissociation, triquetrolunate dissociation (see COMMENTS) CLINICAL: incompetence of the intrinsic and extrinsic ligament(s) supporting the lunotriquetral articulation causing an abnormal relationship between the lunate and triquetrum

35 35 RADIOLOGIC: the spectrum of symptomatic LTD is such that there may be no radiographic abnormality on standard radiographs or such may be demonstrated only with a provocative maneuver. Whether demonstrated dynamically or statically, the direct findings include abnormal disruption of carpal arcs I and/or II on a neutral PA or AP radiograph (see CARPAL ARCS) and an abnormal rotary positioning between the lunate and triquetrum on lateral radiographs. The arthrographic demonstration of a communicating LT ligamentous defect is a common associated finding; however, communicating defects of the lunotriquetral ligament may be present without abnormal alignment or kinematics at this joint; conversely, the intracarpal lunotriquetral ligament (membrane) may be incompetent without an overt tear. COMMENTS: 1) a part of the spectrum of CID-VISI. 2) Malalignment of the lunate and triquetrum may be perceptible only during the stress of movement, compression, etc. 3) It may be due to or aggravated by direct trauma, inflammation, or congenital looseness of the ligaments supporting the articulation found between the two carpal bones. 4) A more advanced stage of LTD will show a static CID-VISI with both scaphoid and lunate flexed, and the triquetrum neutral or extended. With further progression by involvement of the extrinsic or capsular ligaments, the deformity becomes severe and eventually fixed. It becomes a CIC (carpal instability combined) type lesion at this stage. 5) With lunotriquetral sprain, there may not be sufficient disruption of these ligaments to show characteristic radiologic findings. Some people believe that sprain is due to or associated with ulnar impaction syndrome; however, objective criteria to diagnose a sprain have not been established for general acceptance. 6) This is a spectrum of injury (just as is scapholunate dissociation) that includes lunotriquetral ligament disruptions without overt instability but painful instabilities both by the patient s and the physician s evaluations. Early, this may occur without VISI, and finally the static VISI deformity may be present. 7) Lunotriquetral dissociation is one stage of LESSER ARC INJURY. CODE: Clinical Conditions: Fractures-Dislocations-Diastases (IIIA) 1. Reagan DS, Linscheid RL, Dobyns JH. Lunotriquetral sprains. J Hand Surg [Am]. 1984;9: Taleisnik J. Classification of carpal instability. Bull Hosp Jt Dis Orthop Inst. 1984;44: Horii E, Garcia-Elias M, An KN, Bishop AT, Cooney WP, Linscheid RL, Chao EY. A kinematic study of luno-triquetral dissociations. J Hand Surg [Am]. 1991; 16: LUNOTRIQUETRAL (TRIQUETROLUNATE) INSTABILITY see LONGITUDINAL (COLUMNAR) INSTABILITY PATTERN; LUNOTRIQUETRAL DISSOCIATION LUXATION see DISLOCATION McMURTRY S CARPAL ULNAR DISTANCE RATIO see McMURTRY S INDEX McMURTRY S INDEX (FIGURE 41) SYNONYM: McMurtry s carpal ulnar distance ratio CLINICAL: a measurement to detect ulnar carpal translation or translocation (see ULNAR TRANSLATION) RADIOLOGIC: on the PA radiograph of the wrist, a line is drawn down the mid axis of the ulna (UA-ulnar axis). The length of the third metacarpal (L1) is measured. The distance between the center of the head of the capitate and AU (central axis of the ulna) is called L3. L3 divided by L1 = This measurement is McMurtry s Index. COMMENTS: 1) McMurtry s name is also associated with carpal height, carpal height ratio, and carpal height index (see CARPAL HEIGHT). 2) See ULNAR TRANSLOCATION/TRANSLATION OF THE CARPUS. CODE: Radiologic: Measurements (IE) 1. McMurtry RY, Youm Y, Flatt AE, Gillespie TE. Kinematics of the wrist. II. Clinical applications. J Bone Joint Surg Am. 1978;60: MEDIAL SYNONYMS: ulnar, ulnarward, mesial CLINICAL: 1) closer to the midline of the body with the hand and wrist in the anatomic position (supination); 2) displacement or angulation of the distal segment toward the midline of the body with the hand-wrist-forearm in supination. RADIOLOGIC: see CLINICAL COMMENTS: 1) ulnar or medial is an adjective, not a noun. 2) It is recommended that the term medial be avoided whenever the meaning of ulnar is being used, in order to minimize the chance of misusing the word medial. However, ulnar is used not only to indicate direction but also that something, i.e., a styloid, is a part of the ulna. So deceptive is this usage that at least one expert uses the term, ulna styloid rather than ulnar styloid. 3) See COMMENTS under RADIAL. CODE: Radiologic: Sides (IC) 1. Hollinshead WH. Textbook of anatomy. 3rd ed. New York: Harper and Row; Fig. 41 McMURTRY S INDEX (see text): L1 is the length of the third metacarpal; L2 is carpal height, and L3 is the distance between the center of the head of the capitate and AU (central axis of the ulna). L3/L1 = (Reprinted with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 208. Fig 8-6B.)

36 36 MEDIAL ANTERIOR MIDCARPAL INSTABILITY (MAMI) see TRIQUETROHAMATE INSTABILITY MEDIAL COLUMN see ROTARY COLUMN MEDIOCARPAL JOINT see MIDCARPAL JOINT MESIAL see MEDIAL MIDCARPAL DISLOCATION (FIGURE 42) Fig. 42a SYNONYM: midcarpal instability II CLINICAL: dislocation between the proximal and distal carpal rows or any two bones (involving both rows) which normally form congruent joint surfaces RADIOLOGIC: the loss of normal articular contact: a) between the articular surfaces of the proximal and distal carpal rows (complete midcarpal dislocation); b) between scaphoid and trapeziotrapezoidal articular surfaces (radial midcarpal dislocation); c) between capitolunate articular surfaces (central midcarpal dislocation); d) between triquetrohamate articular surfaces (ulnar midcarpal dislocation); or e) any combination of a, b, c, or d. Arthrography will show no or inconsequential leaks between radiocarpal and midcarpal joints through the scapholunate or lunotriquetral ligaments. COMMENTS: 1) a true midcarpal dislocation that occurs with one or more of the bones in the proximal carpal row dislocating from one or more of the bones in the distal carpal row is very unusual. It is much more common to see other dislocations between bones of both carpal rows as a perilunate or a lunate dislocation or such a dislocation associated with fracture of the scaphoid and/or triquetrum. Other names are available for these conditions, such as perilunate dislocation, lunate dislocation, transscaphoid perilunate dislocation, etc. 2) Although not strictly correct, the term midcarpal dislocation has been used occasionally in past literature to refer to the condition of lunate or perilunate dislocation where neither the lunate nor the capitate is centered over the distal radius in the lateral neutral view of the wrist (see Figure 42). CODE: Clinical Conditions: Fractures-Dislocations-Diastases (IIIA) 1. see MIDCARPAL SUBLUXATION MIDCARPAL FRACTURE-DISLOCATION (SEE FIGURE 42) SYNONYM: midcarpal instability III CLINICAL: dislocation between the proximal and distal carpal rows or any portion of those rows, associated with fracture(s) of the involved carpal bones (see MIDCARPAL DISLOCATION) Fig. 42b MIDCARPAL DISLOCATION (see text): a) PA radiograph shows that there is a dislocation between the lunate, capitate, and triquetrum, and the other carpal bones have moved with the capitate in a perilunate type of pattern. b) The lateral radiograph shows that, in this case, neither the capitate nor the lunate is centered over the distal radius (dashed line through the center of the radius). (Reprinted with permission from Gilula LA. Carpal injuries: analytic approach and case exercises. AJR Am J Roentgenol. 1979;133:510. Fig 17.) RADIOLOGIC: the loss of contact between the articular surfaces of the proximal and distal carpal rows: (a) between scaphoid and trapeziotrapezoidal articular surfaces, (b) between capitolunate and triquetrohamate articular surfaces, or (c) a plus b associated with one or more carpal fractures. The capitolunate dislocation can be most easily seen by observing the relationships of the radius, lunate, and capitate on the lateral radiographic projection. COMMENTS: 1) while this may not be an ideal term, it describes situations in the perilunate-lunate fracture-dislocation spectrum in which the resting position of the carpus is transitional between the recognized lunate and perilunate dislocation classifications, and neither the capitate nor lunate may be centered over the radius on lateral radiographic projection. 2) The strict definition of this term should

37 37 represent dislocation between all or most of the bones in the distal carpal row from all or most of the bones in the proximal carpal rows with additional carpal bone fractures; therefore, this would involve dislocation of the scaphotrapeziotrapezoidal (STT), capitolunate (CL), and triquetrohamate (TH) joints (see MIDCARPAL DISLO- CATION). This entity is very uncommon. The situation in comment #1 is much more common. 3) There is no perilunate type disruption between the scaphoid and lunate, or lunate and triquetrum; there is instability (in this instance a fracture-dislocation instability) between the two carpal rows, with the distal carpal row malpositioned either dorsal, palmar, radial, or ulnar to the proximal carpal row. 4) Some experts believe that the only midcarpal joint is the capitolunate joint, while others believe that the STT and TH joints are also part of the midcarpal joint. 5) Involvement of the capitolunate, STT, triquetrohamate joints or any combination of these can be fracturedislocations. 6) If there is an associated perilunate type disruption of the proximal carpal row (PCR), the condition becomes a carpal instability complex or combined (CIC), i.e., CIC with components of the injury being midcarpal instability (MCI) (either subluxation, dislocation, or fracture-dislocation). These components may be scapholunate dissociation (SLD) or lunotriquetral dissociation (LTD), or perilunate dissociation (PLD), if both SLD and triquetrolunate (lunotriquetral) dissociation (TLD) are present. 7) The opinions of experts who reviewed this term were divided equally as to whether it should be discarded or retained. Fig. 43 MIDCARPAL INSTABILITY (MCI): with dorsal displacing force, as with a CLIP (capitolunate instability pattern) wrist maneuver, the capitate subluxes out of the lunate fossa. This amount of displacement may be seen in normal individuals with lax wrists or may be abnormal in patients with associated symptoms. CODE: Clinical Conditions: Fractures-Dislocations-Diastases (IIIA) 1. see MIDCARPAL SUBLUXATION MIDCARPAL INSTABILITY (MCI) (FIGURE 43; SEE ALSO FIGURE 6) SYNONYM: see comment #1; see MIDCARPAL SUBLUXATION; see MIDCARPAL INSTABILITY TYPES I, II, and III CLINICAL: midcarpal instability is a loss of normal alignment or relationship between bones in the proximal and distal carpal rows under physiologic loads, or under pathologic loads (trauma and other mechanical stress) due to ligamentous disruption or attenuation. RADIOLOGIC: abnormal alignment between the proximal and distal carpal rows as characterized by: 1) a capitolunate angle less than 30 or greater than +30 when the dorsal surfaces of the metacarpals and radius are parallel; or 2) abnormal displacement between the proximal and distal carpal rows with applied stress producing the patient s presenting symptoms. COMMENTS: 1) examples of MCI include ulnar midcarpal instability, capitolunate instability pattern (CLIP wrist), carpal instability nondissociative (CIND), palmar and/or dorsal midcarpal instability, scaphotrapeziotrapezoidal (STT) instability (radial midcarpal), triquetrohamate instability, and midcarpal anteromedial instability (MAMI). 2) There is no general agreement if dissociation within the proximal and/or distal carpal rows can be present with MCI. 3) Defining MCI points out the potential for instability at both the midcarpal (MC) and radiocarpal (RC) levels. 4) This term should not include proximal carpal row malalignment due to distal radial malunion, or the adaptive carpus. 5) Although a variety of lesions can cause this instability, a common link in MCI is a loss of normal contact joint forces at the midcarpal articulation, which ultimately leads to an abnormal clunk. Ultimately, it is the flexion deformity of the proximal carpal row that unlinks the midcarpal joint and permits the sudden clunk as the proximal row extends when the wrist moves into ulnar deviation. Definitive radiographic diagnosis of the clunk with dynamic examination can be made with video fluoroscopy or cineradiography. In other words, the normal smooth translation of proximal row flexion to extension between radial and ulnar deviation occurs only at the very last moment of ulnar deviation as the midcarpal subluxation is reduced. Wrist arthrograms are commonly normal. 6) Some persons believe that the underlying anatomy of MCI is an induced instability between the two carpal rows identified by the capitate and the lunate due to palmar ligamentous stretching or disruption (incomplete perilunate disruption). If it becomes fixed dorsally, it is dorsal collapse; if fixed volarly, it is volar collapse. 7) MCI may be interpreted as the major category of abnormality, which includes midcarpal subluxation, midcarpal dislocation, and midcarpal fracture/dislocation. However, usual text reference to MCI refers to the subluxation variety, which is reasonable, since dislocations and fracture-dislocations at this level can be designated specifically as a midcarpal dislocation or fracture-dislocation. Nevertheless, the term midcarpal instability is more inclusive than the term midcarpal subluxation. CODE: Clinical Conditions: Sprains-Instabilities-Subluxations (IIIB) 1. see MIDCARPAL SUBLUXATION 2. Lichtman DM, Schneider JR, Swafford AR, Mack GR. Ulnar midcarpal instability: clinical and laboratory analysis. J Hand Surg [Am]. 1981;6:

38 38 Mediocarpal is not used by some experts, as this term can be interpreted to mean the ulnar (medial) aspect of the wrist. 3) Some believe that the scapholunate and lunotriquetral joints are part of the midcarpal joint system, as are the carpometacarpal and intermetacarpal joints of digits two through five. CODE: Anatomic: Central (IIB) 1. Zancolli EA, Cozzi EP. Atlas of surgical anatomy of the hand. New York: Churchill Livingstone; p Fig. 44a MIDCARPAL JOINT (MCJ): on all the following views, the white density is the contrast ( dye ) that was injected under fluoroscopic control. The thin space between the white contrast and each adjacent carpal bone is the cartilage on that carpal bone. The contrast outlines the midcarpal joint, which is the space between all the carpal bones except for the pisotriquetral joint. This compartment commonly communicates (fills) with the second through fifth carpometacarpal (CMC) joints. The first CMC joint normally does not communicate with the midcarpal joint. a) PA view: contrast material in the midcarpal joint fills the second through fifth CMC joints, and some of this contrast extends distally between metacarpal bases. Contrast outlines the distal surfaces of the scapholunate (arrow) and the lunotriquetral (small arrowhead) ligaments. b) Oblique view: this view presents a different view of the midcarpal joint and is the best survey view to profile contrast in the trapeziotrapezoidal joint (arrowheads). c) Lateral view: the dorsal and ventral surfaces of the midcarpal compartment are outlined. Some extravasation of contrast out the needle track presents dorsal to the head of the capitate. Fig. 44b 3. Lichtman DM, Bruckner JD, Culp RW, Alexander CE. Palmar midcarpal instability: results of surgical reconstruction. J Hand Surg [Am]. 1993;18: MIDCARPAL INSTABILITY (MCI) II see MIDCARPAL DISLOCATION MIDCARPAL INSTABILITY (MCI) III see MIDCARPAL FRACTURE-DISLOCATION MIDCARPAL JOINT (MCJ) (FIGURE 44) SYNONYMS: mediocarpal joint; any of the midcarpal joint segments, e.g., the capitolunate joint, the scaphotrapeziotrapezoidal joint, the triquetrohamate joint, and in some instances, the lunohamate joint CLINICAL: the midcarpal or mediocarpal joint is the articulation between all or any of the bones of the proximal and distal carpal rows. RADIOLOGIC: see CLINICAL COMMENTS: 1) some (erroneously) consider the capitolunate joint as the only joint in the middle of the carpus. This joint s importance is that it is the observational key to most radiologic decisions about the presence or absence of subluxation or dislocation at this level. 2) Fig. 44c

39 39 MIDCARPAL SUBLUXATION (MCS) (SEE FIGURE 6) SYNONYM: midcarpal instability I (MC-I); see comment #4 CLINICAL: midcarpal subluxation is an abnormal condition in which the proximal and distal carpal rows are malaligned (incongruent) in relation to each other, but there is partial joint contact between these carpal rows. RADIOLOGIC: lateral view shows loss of parallelism or congruency between the articulating cortices of the capitate and lunate, but the capitate head is not fully displaced out of the lunate fossa. For CIND- VISI or CIND-DISI collapse, a capitolunate angle in excess of 30 is usually considered abnormal and warrants further evaluation. See COMMENTS. PA view: with carpometacarpal joints in profile (palm flat), capitolunate subluxation (or dislocation) is suspected when the proximal articular cortex of the head of the capitate overlies the corresponding distal articular surface of the lunate. Scaphocapitate subluxation is suspected when this scaphocapitate joint is wider than other intercarpal joints or when normally parallel surfaces of these two carpal bones are overlapping. COMMENTS: 1) Accurate radiologic descriptions of subluxations at the scaphocapitate, scaphotrapeziotrapezoidal, and triquetrohamate joints have not been clearly established in the lateral position. 2) Criteria for the radiologic diagnoses of midcarpal subluxations other than that described above are not generally known. 3) Midcarpal subluxation may be dorsal, volar, radial, or ulnar. 4) Some people believe that this is the mildest and stage 1 of midcarpal instability with stage 2 being dislocation and stage 3 being fracture-dislocation. 5) There are some midcarpal subluxations that do not have any appreciable DISI or VISI deformity, but simply present as translational deformities (as CLIP wrist). 6) Some people consider midcarpal subluxation synonymous with midcarpal instability. Others disagree, feeling that subluxation can be very stable, whereas instabilities should be unstable. However, if the above radiologic definition is strictly applied, midcarpal subluxation would apply only to the cases where the capitate is subluxed with respect to the lunate fossa. Midcarpal instability would apply to the other cases with abnormal alignment between carpal rows without capitolunate subluxation. Examples of this would include CID-VISI, CIND-VISI, CID-DISI, and CIND-DISI, etc. Midcarpal instability of the CIND-VISI or CIND-DISI type often produces a catch-up clunk as the proximal carpal row first delays then suddenly adjusts from flexion to extension or vice versa on clinical or radiologic motion studies. 7) Dorsal midcarpal instability, also known as CLIP wrist or capitolunate instability pattern, is one form of midcarpal subluxation, but so are CIND-VISI and CIND-DISI subluxations, which constitute the better known subluxations commonly referred to as midcarpal instabilities. 8) As is true with other carpal instabilities, these collapse deformities may be either static (present constantly) or dynamic (present only with provocative stress). 9) CLIP as well as the DISI and VISI deformities may have a radiocarpal translational deformity in association with the midcarpal level destabilization. Some experts believe that it may be worthwhile to consider a proximal row instability and remember that the proximal row instability can come from damage on either or both sides of the proximal carpal row. 10) As in other definitions with the term instability, some experts feel strongly that malalignments are not the same as instabilities because malalignments can be stable (see reference #8). CODE: Clinical Conditions: Sprains-Instabilities-Subluxations (IIIB) 1. see TRIQUETROHAMATE INSTABILITY 2. Gilula LA. Carpal injuries: analytic approach and case exercises. AJR Am J Roentgenol. 1979;133: Louis DS, Hankin FM, Greene TL, Braunstein EM, White SJ. Central carpal instability: capitate-lunate instability pattern. Diagnosis by dynamic placement. Orthopedics. 1984;7: White SJ, Louis DS, Braunstein EM, Hankin FM, Greene TL. Capitate-lunate instability: recognition by manipulation under fluoroscopy. AJR Am J Roentgenol. 1984;143: Johnson RP, Carrera GF. Chronic capitolunate instability. J Bone Joint Surg Am. 1986;68: Cooney WP, Garcia-Elias M, Dobyns JH, Linscheid RL. Anatomy and mechanics of carpal instability. Surg Rounds Orthop. 1989;3: Cooney WP, Dobyns JH, Linscheid RL. Arthroscopy of the wrist: anatomy and classification of carpal instability. Arthroscopy. 1990;6: Garcia-Elias M, Berger RA, Horii E, Kauer JMG, Lanz U, Rongières M, Ryu J, Sennwald GR, Viegas SF. Definition of carpal instability. Anatomy and Biomechanics Committee of the International Federation of Societies for Surgery of the Hand. 2nd ed. Barcelona, Spain: Institut Kaplan; Feb NAVICULAR VIEW see SCAPHOID VIEW NEUTRAL LATERAL VIEW (SEE FIGURE 35) SYNONYMS: zero lateral position or view, neutral lateral position CLINICAL: see RADIOLOGIC RADIOLOGIC: a standard and reproducible radiographic view achieved when the shoulder is abducted 90 such that the elbow is at the level of the shoulder or the elbow is adducted against the trunk. In either of these positions, the elbow is flexed 90, the forearm is in 0 pronation-supination, and the third metacarpal is parallel to the long axis of the radius. With the elbow adducted against the trunk, a vertical x-ray beam enters radially and exits ulnarly. When the elbow is abducted to the level of the shoulder, a horizontal x-ray beam enters radially and exits ulnarly. The x-ray cassette is against the ulnar side of the hand so that the x-ray beam enters the cassette at right angles. COMMENTS: 1) an acceptable lateral position of the carpus can be recognized when the ventral surface of the pisiform projects midway between the ventral surfaces of the capitate head and the distal pole of the scaphoid. This is called the SPC (scaphopisocapitate) alignment criteria. See LATERAL VIEW (see Figure 35B). 2) Although it is commonly described to have the elbow flexed 90 for this view, failure to have 90 elbow flexion should not change the anatomic relationship at the wrist, contrary to the situation with the NEUTRAL POSTEROANTERIOR VIEW of the wrist. CODE: Radiologic: Positions (IA) 1. Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p Yang Z, Mann FA, Gilula LA, Haerr C, Larsen CF. Scaphopisocapitate alignment: criterion to establish a neutral lateral view of the wrist. Radiology. 1997;205: NEUTRAL POSTEROANTERIOR (PA) VIEW (FIGURE 45) SYNONYMS: zero posteroanterior position or view, neutral PA position, preferred PA position or view CLINICAL: see RADIOLOGIC RADIOLOGIC: a standard and reproducible radiographic view achieved when the shoulder is abducted 90 such that the elbow is at the level of the shoulder or the elbow is adducted against the trunk, the elbow is at 90 flexion, the forearm is in 0 pronation-supination with the palm flat on the radiographic cassette, and the third metacarpal is parallel to the long axis of the radius. The x-ray beam passes

40 40 Fig. 45b Fig. 45a NEUTRAL POSTEROANTERIOR (PA) VIEW (see also Figure 2A): a) the palm of the wrist and hand is placed flat on the film cassette or x-ray table without flexion, extension, or radial or ulnar deviation of the wrist. The third metacarpal is coaxial with the radius, the elbow is flexed 90, and the elbow is abducted to the shoulder height. b) The PA radiograph can be recognized to have been made in adequate position (elbow at shoulder height) when the extensor carpi ulnaris groove (arrowheads) projects radial to the base (arrow) or the midportion of the ulnar styloid. The third metacarpal and radius are coaxial. (Reprinted and modified with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p Fig 5-29, A and B.) through the back of the carpus and exits the palm with the central beam centered at the head of the capitate. If the elbow is adducted against the trunk, the x-ray beam passes horizontally. COMMENTS: 1) reproducible positioning promotes improved precision for repeated assessments (measurements) and comparisons. 2) The terms PA (posteroanterior) and AP (anteroposterior) are NOT synonymous. 3) Correct positioning as described here (see also POSTEROANTERIOR VIEW) is necessary for accurate ulnar variance measurements (see ULNAR VARIANCE). A practical point to remember is that the ulnar head moves distally in pronation, proximally in supination. CODE: Radiologic: Positions (IA) 1. radiology textbooks 2. Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p NONDISSOCIATION (SEE FIGURES 15 AND 16) SYNONYMS: linked, bonded, anatomically connected CLINICAL: 1) opposite of dissociation; with respect to the wrist, normal or near-normal linkage between the bones within the proximal carpal row or between the bones within the distal carpal row. 2) Used with the term carpal instability, as in Carpal Instability Nondissociative (CIND), to designate a malalignment in which there is normal association of the skeletal elements within both the proximal and distal carpal rows, but a malalignment (incongruency) between the two carpal rows. 3) Absence of dissociation (asynchronous movement) of the bones within a carpal row. RADIOLOGIC: normal or near-normal motion patterns of the bones of a carpal row, linked by interosseous ligaments, as observed by fluoroscopy, videotape, cineradiography, or other imaging techniques COMMENTS: 1) this term is usually used in conjunction with the term carpal instability. 2) A small degree of ligament tearing or fracturing evidenced by arthrography, arthroscopy, or surgery does not negate this condition; only evidence of significant dissociative movement between any two carpal bones within a carpal row will change the diagnosis from nondissociation to dissociation. 3) Both dissociative and nondissociative injuries may be present in the same wrist, and the term carpal instability complex (combined) (CIC) is designed to cover that situation. (See CIC.) CODE: Clinical Conditions: Sprains-Instabilities-Subluxations (IIIB)

41 41 1. see TRIQUETROHAMATE INSTABILITY and MIDCARPAL SUBLUXATION 2. Amadio PC. Carpal kinematics and instability: a clinical and anatomic primer. Clin Anat. 1991;4:1-12. NORGAARD VIEW see BALL CATCHER S VIEW OS DISTALE see DISTAL CARPAL ROW OS STYLOIDEUM see CARPAL BOSS PALMAR see VOLAR SYNONYMS: anterior, volar, ventral CLINICAL: a term used in reference to certain portions (those near the palm of the hand) of the ventral or belly surface of the body, the wrist and hand RADIOLOGIC: see CLINICAL COMMENTS: 1) volar is used consistently as a synonym or even as the preferred term in the hand literature. Both words are used interchangeably in the hand literature, often in the same article. This is unlikely to change. 2) The reason volar remains a controversial anatomic descriptor for the hand and wrist to some experts is because some people believed that the base word for this term, vole, refers to a short-tailed ratlike or mouselike rodent of the genus Microtus. Actually, the field mouse or vole is named from the Norwegian woll or field, not from the Latin vol, which refers to the palm or sole (James Dobyns). 3) Even though volar may not be the term preferred by some anatomists, it is not likely that this term will be removed from hand and wrist literature. CODE: Anatomic: Carpal (IID); Radiologic: Sides (IC) 1. Webster s Encyclopedic Unabridged Dictionary of the English Language. New York: Portland House/Crown Publishers; Warwick R, Williams PL, editors. Gray s anatomy, 35th ed. Philadelphia: WB Saunders; PALMAR CARPAL SUBLUXATION see PALMAR RADIOCARPAL SUBLUXATION PALMAR CARPAL TRANSLATION see PALMAR RADIOCARPAL SUBLUXATION PALMAR INTERCALATED SEGMENT INSTABILITY (PISI) see VOLAR INTERCALATED SEGMENT INSTABILITY PALMAR RADIOCARPAL SUBLUXATION (FIGURE 46) SYNONYMS: volar carpal translation, palmar carpal subluxation, palmar carpal translation, palmar (or volar) radiocarpal translation CLINICAL: this deformity has a reversed silver-fork deformity due to the volar (palmar) displacement of the proximal carpal row, and may be associated with CID or CIND, DISI or VISI, or ulnar translation. RADIOLOGIC: the PA view shows an overlap of the subchondral sclerotic line of the distal radius and the normally apposed articular surfaces of the proximal carpal row. On the lateral view, the proximal carpal row, as reflected by the lunate, demonstrates a loss of parallelism at the radiocarpal joint due to palmar displacement of the carpus. COMMENTS: 1) this can be quantitated by using the RCA-capitate distance (reference #1), which is the distance between the sagittal axis of the radius prolonged across the carpal space (radiocarpal axis or Fig. 46 PALMAR RADIOCARPAL SUBLUXATION: the carpus, as identified by the proximal convexity of the lunate, is centered along the ventral portion of the distal radius. The wrist has slight extension. A small chip fracture (arrowhead) is off the ventral edge of the distal radius. Dorsal tilting of the lunate is also present. (Reprinted with permission from Gilula LA, editor. The Traumatized hand and wrist: radiographic and anatomic correlation. Philadelphia: WB Saunders; p 324. Fig 13-7B.) RCA) and the sagittal axis of the capitate (RCA-capitate distance), or more simply by noting the lunate to be at or volar to the volar third of the lunate sulcus of the radius. 2) Palmar radiocarpal subluxation is probably most common in association with a fracture of the volar lip of the radius (the reverse Barton s fracture-subluxation). However, a fracture of the radius in association with the subluxation would not be a true radiocarpal subluxation, but a radiocarpal fracture subluxation. 3) This is a very unstable condition (therefore could be called an instability ), often associated with global disruption of the radiocarpal support system and prone to redisplacement either palmarward or ulnarward or both. The volar Barton variant is actually more stable if reduced and healed, since the volar support ligaments are usually on the distal radius fragment. CODE: Clinical Conditions: Sprains-Instabilities-Subluxations (IIIB) 1. Wright TW, Dobyns JH, Linscheid RL, Macksoud W, Siegert J. Carpal instability non-dissociative. J Hand Surg [Br]. 1994;19: see SCAPHOLUNATE DISSOCIATION (SLD) PARTIAL/INCOMPLETE DISLOCATION see SUBLUXATION PARTIAL/INCOMPLETE LUXATION see SUBLUXATION

42 42 PERILUNATE DISLOCATION (PLD): a) on this PA view, the lunate is triangular in shape, indicating some tilting of the lunate, but the lunate remains grossly parallel to the radius. The distal articular surface of the lunate overlaps the triquetrum and capitate, indicating dislocation between the lunate and these two adjacent bones. The proximal pole of the scaphoid overlaps the radial styloid, indicating dislocation between these two structures. Parallel articular surfaces between the scaphoid, trapezium, trapezoid, capitate, hamate, triquetrum, and metacarpals 1-5 indicate that these bones are staying together as a unit. b) Fig. 47a On the lateral view, the lunate is articulating with the radius but is palmarly tilted. Dorsal dislocation of the capitate and the remainder of the carpal bones is present, indicating a dorsal perilunate dislocation. (Reprinted and modified with permission from Gilula LA, editor. The traumatized hand and wrist: radiographic and anatomic correlation. Philadelphia: WB Saunders; p 290. Fig 12-2, A and B.) Fig. 47b PARTIAL LIGAMENT TEAR see SPRAIN PARTIAL PERILUNATE DISLOCATION see PERILUNATE SUBLUXATION PERILUNAR DISLOCATION see PERILUNATE DISLOCATION PERILUNATE DISLOCATION (PLD) (FIGURE 47) SYNONYMS: perilunar dislocation, lesser arc disruption or dislocation, carpal instability combined-perilunar (CIC-PLD) CLINICAL: a dislocation without fracture, in any direction, of some or all carpal bones around the lunate. This is commonly recognized by dislocation between the capitate and lunate. The basic pattern may be varied by retained connections between the lunate and other carpal bones or by partial/total realignment of the other carpal bones with the radius, forcing the lunate into varying degrees of subluxation. RADIOLOGIC: see CLINICAL. The fundamental criterion for a perilunate dislocation is description of a capitolunate dislocation with the lunate maintaining all or much of its relationship with the radius. Historically, to be classified as a perilunate dislocation rather than a lunate dislocation, the lunate should be more anatomically aligned with the distal radius than the carpal bones surrounding the lunate. (See COMMENTS.) COMMENTS: 1) perilunate and lunate injuries fit into the same category and mechanism. In both, the surrounding carpal bones are dislocated from the lunate; therefore, both could be called perilunate dislocations. A basic assumption for the above definition is that in most cases, lunate dislocation is merely the final stage of a perilunate dislocation (see LUNATE DISLOCATION). 2) Since motion or stress can often change the relationships between a lunate and perilunate type of displacement and since these patterns can easily merge into one another, it is not critical to do other than describe the relationships between the forearm, lunate, and other carpal bones as they lie, including the occasionally seen displacement of the lunate into the carpal canal, the palm, the forearm, or external to the skin. 3) All or part of the radial or the ulnar columns may retain some connection with the lunate; in fact, the radial or ulnar columns may not be truly dislocated in all instances in perilunate fracture dislocation or perilunate instability spectrum. 4) Some believe there are several stages of perilunate instability, with the first being perilunate subluxation; second, perilunate dislocation; and third, perilunate fracturedislocation. Lunate dislocation may be considered the fourth stage. 5) The perilunate spectrum classically begins with radial disruption of the various fascicles of the radioscaphocapitate ligament, then around or through the scaphoid itself, and then across the carpus by a variety of possible pathways. That there is a similar perilunate-type disruption that begins ulnarly and propagates radially has long been known clinically, and investigative work to clarify this mechanism is ongoing. CODE: Clinical Conditions: Fractures-Dislocations-Diastases (IIIA) 1. Dobyns JH, Linscheid RL. Fractures and dislocations of the wrist. In: Rockwood CA Jr, Green DP, editors. Fractures. Vol 1. Philadelphia: JB Lippincott; p Mayfield JK, Johnson RP, Kilcoyne RK. Carpal dislocations: pathomechanics and progressive perilunar instability. J Hand Surg [Am]. 1980;5: Viegas SF, Patterson RM, Peterson PD, Pogue DJ, Jenkins DK, Sweo TD, Hokanson JA. Ulnar-sided perilunate instability: an anatomic and biomechanic study. J Hand Surg [Am]. 1990;15:

43 43 PERILUNATE FRACTURE-DISLOCATION (FIGURE 48) SYNONYM: perilunar fracture-dislocation; see comment #6 CLINICAL: 1) dislocation of the carpal bones surrounding the lunate including single or multiple fractures of the carpal bones. 2) Loss of articular contact between the lunate and capitate with accompanying but variable degrees of subluxation or dislocation of the other carpal and radiocarpal articulations. (See PERILUNATE DISLOCATION). RADIOLOGIC: 1) dislocation in any direction of the carpal bones surrounding the lunate as evidenced by loss of articular contact between the lunate and capitate accompanied by single or multiple fractures of the involved carpal bones. 2) Same as CLINICAL, with the finding that the lunate maintains a more normal relationship to the long axis of the radius than the remainder of the carpus, as indicated by the position of the capitate. 3) See PERILUNATE DISLOCATION for various stages of the perilunate displacement spectrum. COMMENTS: 1) if the capitolunate joint is dislocated and the lunate is in anatomic or near-anatomic relationship to the distal radius, a perilunate dislocation is diagnosed regardless of the position of the other carpal bones. 2) In the later phases of perilunate instability, the relationship of the lunate and capitate changes with respect to the radius, so that neither the lunate nor capitate are normally aligned with the radius (see MIDCARPAL DISLOCATION; COMMENTS), and then finally the capitate may be more normally aligned with the radius than the lunate. This latter condition would be lunate dislocation. 3) See PERILUNATE DISLOCATION. 4) Associated fractures are within the zone of vulnerability that constitutes the Greater Arc of transosseous fractures with their associated dislocations, e.g., transscaphoid, transcapitate dorsal perilunate fracture-dislocation. 5) de Quervain s fracture-dislocation is an older term and a synonym for the most common type of carpal fracture dislocation, the transscaphoid perilunate fracture dislocation. 6) Perilunar injury with fracture represents a combination arc injury, unless fractures of the scaphoid, capitate head or waist, with or without an avulsion of the radial side of the triquetrum are also present (see GREATER ARC INJURY). CODE: Clinical Conditions: Fractures-Dislocations-Diastases (IIIA) 1. see PERILUNATE DISLOCATION PERILUNATE FRACTURE-DISLOCATION: a) on this PA view, the lunate is triangular in shape, indicative of tilting. Articulation between the radius and lunate is present, but parallelism consistent with normal articulation is absent at the lunotriquetral and scapholunate joints. The proximal cortices of the capitate and hamate overlap the lunate. The scaphoid is fractured through its waist, and the proximal scaphoid fracture fragment is rotated about 90 with the fractured surface of the proximal fracture fragment projecting into the scaphoid fossa. The distal portion of the scaphoid, trapezium, capitate, hamate, triquetrum, and first through fifth metacarpals are articulating with each other normally, indicating that they are staying together as a unit. b) Lateral view: the lunate is tilting ventrally while it is still centered over the palmar portion of the radius. The capitate and other carpal bones have moved dorsally. The density with a convex surface distally (arrowheads), which is overlapping the lunate, represents the rotated proximal scaphoid fracture fragment. These features are those of transscaphoid, dorsal perilunate fracture-dislocation with about 90 rotation of the proximal scaphoid fracture fragment. Fig. 48a Fig. 48b

44 44 PERILUNATE INJURY see COMBINATION ARC INJURY; GREATER ARC INJURY; LESSER ARC INJURY PERILUNATE INSTABILITY (PLI) SYNONYMS: perilunar instability, carpal instability complex-perilunate type (CIC-PLI), the de Quervain wrist injury spectrum CLINICAL: 1) a generic term describing instability of the boneligament-bone complexes surrounding the lunate (i.e., scaphoid, capitate, triquetrum, and, occasionally, the hamate). The ultimate degree of this instability spectrum involves increasing instability of the lunate itself. 2) A general term for the perilunate instability spectrum of perilunate subluxation, perilunate dislocation, and perilunate fracture-dislocation. RADIOLOGIC: see specifics for perilunate subluxation, dislocation, and fracture-dislocation COMMENTS: 1) there is strong expert opinion that this term is an unprecise overview term that is not related to a specific problem, but a global feeling. Use of such a global term or overview can be misleading and can allow authors to use such a term for convenience rather than provide a precise anatomic understanding of a problem. 2) Several entities, as scapholunate and lunotriquetral dissociations, perilunate subluxations and dislocations, dissociative instabilities, and others, seem to fit into this category. 3) The major value of this phrase may be in terms of injury patterns and pathogenesis. 4) Many people favor dropping this term; however, others believe that it is very descriptive of the residua of the most common dislocations and gives a more immediate visualization of the potential disruptions that may be present than any of the other terms, either alone or in combination. 5) This is considered by some to be the generic term for perilunate instabilities with subclassifications of subluxation, dislocation, and fracture-dislocation. 6) Perilunate instability has the same generic coverage as do the terms radiocarpal and midcarpal instability. As with those entities, the usual reference is to the specific injury, which will be one of the subcategories of subluxation, dislocation, or fracture dislocation, and often the diagnostic term used will be specific of the subcategory, such as scapholunate dissociation (SLD). The recognized abnormality can be either a specific discrete injury without other elements of the perilunate spectrum or may be a residua of a perilunate injury with the additional ligament injury that the name implies. An example of the difference this indicates is that SLD is a type of carpal instability dissociative (SLD-CID), while SLD as part of a perilunate instability will be SLD-complex (SLD-CIC). Thus the overall instability of the carpus will be greater for the SLD-CIC type of SLD, and this information is a factor in choosing treatment. CODE: Clinical Conditions: Sprains-Instabilities-Subluxations (IIIB) 1. see PERILUNATE SUBLUXATION, DISLOCATION, and FRACTURE-DISLOCATION PERILUNATE SUBLUXATION (SEE FIGURES 6 AND 43) SYNONYMS: perilunar subluxation, partial perilunate dislocation CLINICAL: 1) a condition of the wrist that shows partial articular contact between the lunate, the forearm bones, and the adjacent carpal bones, usually recognized best by the radiologic alignment of the radiolunocapitate axis. 2) A condition in which joints in the lesser perilunate arc are in partial contact. RADIOLOGIC: see CLINICAL. Partial contact remains between the articular surfaces of the capitate head and the distal lunate concavity, especially as seen on the lateral wrist view. The alignment of the lunate and the radius may also be incongruent but will not be dislocated. COMMENTS: 1) this may be seen with one of the incomplete perilunate dislocations, e.g., as when the scaphoid is dislocated, the capitolunate joint is subluxed, and the lunotriquetral and triquetrohamate joints appear normal or nearly normal. 2) It is quite common for a perilunate dislocation to be incomplete or to spontaneously reduce to the appearance of a DISI or VISI of the dissociative type. 3) The term is not used much because its component conditions, i.e., scapholunate dissociation (SLD) and lunotriquetral dissociation (LTD) are so well known under their specific names. However, when both are present together, as is often the case following reduction of a perilunate dislocation, the term perilunate subluxation describes the condition very nicely. 4) May also apply to a residual midcarpal instability with either or both of SLD and TLD. 5) Any subluxation may be the residua of a complete dislocation with the additional instability that this greater degree of initial injury implies. 6) Some experts are of the opinion that it is impossible to define a true perilunar subluxation. CODE: Clinical Conditions: Sprains-Instabilities-Subluxations (IIIB) 1. see LUNATE DISLOCATION. Same as for the other perilunate instabilities. PERMANENT CARPAL INSTABILITY see STATIC CARPAL INSTABILITY PISIFORM VIEW see SEMISUPINATED OBLIQUE VIEW PISOTRIQUETRAL VIEW see SEMISUPINATED OBLIQUE VIEW POSTERIOR (SEE FIGURE 45) SYNONYMS: dorsal, back CLINICAL: 1) closer to the back of the body or limb. 2) Displacement of a distal segment in that direction (see ULNAR: COMMENTS). 3) That portion of the wrist skeleton adjacent to the extensor tendons and covered by the dorsal skin of the hand, wrist, and distal forearm. RADIOLOGIC: see CLINICAL COMMENTS: frequently used in combinations, as posterolateral or posteroanterior, particularly to describe a specific pathway CODE: Radiologic: Sides (IC) 1. anatomy or radiology textbooks or dictionary POSTEROANTERIOR (PA) RADIAL DEVIATION VIEW (FIGURE 49) SYNONYM: PA radial deviation projection CLINICAL: NA RADIOLOGIC: a radiographic view made from posterior (dorsal) to anterior (palmar) with the wrist in radial deviation and without flexion or extension. This view is usually performed as one of the films of a motion study to determine carpal synchronicity, the amount of carpal motion, and other intercarpal relationships in radial deviation. COMMENTS: 1) this view can be readily compared to the same view of the opposite wrist to help determine normal variations, such as the presence and degree of ulnar translation, carpal impingement with the radial styloid, distal ulnar instability, etc. 2) This is probably the most valuable view when combined with the PA ULNAR DEVIA-

45 45 POSTEROANTERIOR (PA) ULNAR DEVIATION VIEW (FIGURE 50) SYNONYM: PA ulnar deviation projection CLINICAL: NA RADIOLOGIC: a radiographic view obtained with the pronated hand and wrist in maximal ulnar deviation without extension at the carpometacarpal joints and with the palm flat on the x-ray cassette. Fig. 49a Fig. 50a Fig. 49b POSTEROANTERIOR (PA) RADIAL DEVIATION VIEW: a) the palm is placed flat on the tabletop or x-ray cassette with the wrist radially deviated as much as possible without wrist extension. b) On this PA radiograph with radial deviation, motion between the carpal rows and between the radius and proximal carpal row can be seen when compared to the neutral PA wrist view. (Reprinted with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 131. Fig 5-36, A and B.) Fig. 50b TION VIEW, to recognize radial and ulnar motions at the midcarpal and radiocarpal levels. Such recognition of motion is readily accomplished by looking at the edges of the capitate and lunate for midcarpal motion and at the edges of the lunate and ulnar aspect of the lunate fossa of the radius for radiocarpal motion. CODE: Radiologic: Views (ID) 1. Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p radiologic technology textbooks POSTEROANTERIOR (PA) ULNAR DEVIATION VIEW: a) the palm is placed flat on the tabletop or x-ray cassette with the wrist ulnarly deviated as much as possible without wrist extension. b) On this PA radiograph with ulnar deviation, motion between the carpal rows and between the radius and proximal carpal row can be seen when compared to the neutral PA wrist view. This view also elongates the scaphoid so the waist of the scaphoid can be seen more easily than on the routine PA neutral view. (Reprinted with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 126. Fig 5-31, A and B.)

46 46 The x-ray beam, centered at the capitate head, enters dorsally and exits palmarly. COMMENTS: 1) this view may be positioned with elbow flexed 90 and held at shoulder height when ulnar variance positioning is of interest, and with the desire to standardize PA wrist techniques by radiologic technologists. However, the elbow can be positioned at any height if this view is only to survey the carpal bones, especially the scaphoid and its adjacent osseous relationships. 2) This view does elongate the scaphoid, but the scaphoid is still foreshortened (see SCAPHOID VIEW). 3) As for the PA RADIAL DEVIATION VIEW, this view displays intercarpal relationships in this ulnar-deviated PA position and can be best compared to the opposite wrist for normal variations. 4) This is probably the most valuable view when combined with the PA RADIAL DEVIATION VIEW, to recognize radial and ulnar motions at the midcarpal and radiocarpal levels. Such recognition of motion is readily accomplished by looking at the edges of the capitate and lunate for midcarpal motion and at the edges of the lunate and ulnar aspect of the lunate fossa of the radius for radiocarpal motion. CODE: Radiologic: Views (ID) 1. Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p radiologic technology textbooks POSTEROANTERIOR (PA) VIEW (SEE FIGURE 45) SYNONYMS: posteroanterior projection/position, back-to-front projection/position, dorsopalmar or dorsovolar projection/position CLINICAL: see RADIOLOGIC RADIOLOGIC: the x-ray beam enters the dorsum and exits the palmar aspect of the hand and wrist (see COMMENTS). COMMENTS: 1) the recommended zero or neutral PA view should be performed in 0 pronation, 0 supination with the palm of the hand flat on the cassette, with elbow flexed 90 and elbow at shoulder height to achieve standardization of technique. 2) Pronated view is not a true synonym of PA projection, since it is possible to obtain a PA view when the hand and wrist are not pronated, as when the hand is supinated and the beam enters the dorsum of the wrist. 3) The PA view is still commonly performed when criteria in comment #1 are not fulfilled. CODE: Radiologic: Views (ID) 1. Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p PROVOCATIVE MANEUVER (PM) (SEE FIGURE 6) SYNONYM: stress test (active or passive) CLINICAL: the application of passive, active, or combinations of force to the wrist to elicit abnormal displacements, clunks, clicks, symptomatic catches, or pain that can be detected clinically and/or radiographically. The displacements may cause no symptoms, may cause symptoms unlike those of the complaint, or may reproduce the symptoms of the complaint, with the last being most diagnostic of a positive test. Examples range from direct pressure to fist compression to various scaphoid instability tests. RADIOLOGIC: see CLINICAL COMMENTS: 1) the resting stance of the carpal structures may be suggestive or diagnostic of a certain problem, but further confirmation may come only with performing a provocative maneuver while the carpus is visualized radiographically. 2) Clinical and radiographic provocative maneuvers (PMs) may be identical, but not always; for instance, traction or fist compression may demonstrate very little clinically but may be very instructive in showing specific bone displacements radiographically. 3) Passive force is mostly a passive range of motion, but it can include traction, compression, translation, circumduction, and combinations of these. 4) Since there are numerous provocative maneuvers, it is not possible to describe one or more of these in any more detail here. 5) Some experts believe that provocative maneuvers test for abnormal movement, but a positive test does not necessarily identify a specific instability. CODE: Tests (IV) 1. Berger RA, Dobyns JH. Physical examination and provocative maneuvers of the wrist. In: Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p PROXIMAL SYNONYMS: cephalad, shoulderward CLINICAL: 1) closer to or toward the root or base of the limb. 2) Further from the distal end of the limb. RADIOLOGIC: see CLINICAL COMMENTS: none CODE: Radiologic: Sides (IC) 1. anatomy or radiology textbooks PROXIMAL CARPAL INSTABILITY see RADIOCARPAL INSTABILITY PROXIMAL CARPAL ROW (PCR) SYNONYM: the intercalated carpal row CLINICAL: the scaphoid, lunate and triquetrum constitute the proximal carpal row (see comment #1 with respect to the pisiform). RADIOLOGIC: NA COMMENTS: 1) the true function of the pisiform is controversial. 2) Some authorities commonly include the pisiform in the description of the proximal carpal row (PCR), while others disagree. The pisiform may also be considered as a palmar component of the PCR. Phylogenetic arguments include the pisiform in the first carpal row. 3) The pisiform is a bone that transfers forces indirectly from the flexor carpi ulnaris tendon. Some people believe that since it has attachments to the triquetrum, the pisiform is anatomically and functionally part of the proximal carpal row and could potentially (unproved) lend some stability to the proximal carpal row. 4) Rarely, a bipartite scaphoid occurs. In that situation, the proximal pole of the scaphoid may function as part of the PCR, and the distal pole, as part of the distal row; however, there is often a synchondrosis or synfibrosis between the fragments such that the bipartite scaphoid may act as a single bone. 5) The proximal carpal row, as defined, has a range of motion between itself and the forearm structures proximally, the distal carpal structures distally, and also internally between the components of the PCR. CODE: Anatomic: Carpal (IID) 1. Taleisnik J. The wrist. New York: Churchill Livingstone; May O. [The pisiform bone: sesamoid or carpal bone]. Ann Chir Main Memb Super. 1996;15: French.

47 47 PROXIMAL WRIST JOINT see RADIOCARPAL JOINT RADIAL SYNONYMS: lateral; thenar; thumbside; thumbward; outer, of the radius; radiolateral CLINICAL: 1) toward the radius or the radial column of the osseous structures (radial styloid, scaphoid, trapezium, first metacarpal) of the wrist. 2) See LATERAL. RADIOLOGIC: see CLINICAL COMMENTS: 1) unfortunately, this word is used both as a direction (toward the radius or the portion of the forearm occupied by the radius) AND as possessive or descriptive, i.e., radial styloid, radial tuberosity, radial osteotomy, etc. As a direction, it is used along with the words in the synonym to mean away from the ulna or medial aspect of the forearm. Used as a possessive or descriptive term, it can (and in some experts opinion should) be replaced by the phrase of the radius. 2) Although radial is always an adjective and is never a noun, it is often used in place of radius s or of the radius. 3) The term lateral should be avoided whenever the meaning of radial is being used to minimize the chance of misusing the word lateral. 4) Radial is not only used as toward the radius but also as toward the radial column of the osseous structures (radial styloid, scaphoid, trapezium, first metacarpal) of the wrist. CODE: Anatomic: Radial (IIA); Radiologic: Sides (IC) RADIOLOGIC: the long axis of the radius is obtained by bisecting its canal on the neutral PA view at 2-3 cm and 4-5 cm (or 4 and 8 cm) proximal to the distal articular surface of the radius and joining the points with a line that extends distally into the carpus. The distal tip of the radial styloid and the ulnar aspect of the distal radial articular surface are joined by a second line. A perpendicular from the long axis of the radius is placed to intersect the second line. The angle between these two lines is radial inclination. The mean as in reference #2 below is 22 ± 3 ; however, various authors (reference #1) show a range from COMMENTS: 1) there may be two angles of inclination, depending on whether the tracing is performed along the dorsal or the ventral (volar) rims of the radius. Although unproven, it is believed that generally the ulnar aspect of the lunate fossa (usually projecting as the ventral rim) is used as the ulnar point for measurement. 2) Some experts prefer many of the above synonyms combined with the phrase of the distal radius for clarity, as slope and inclination of the distal radius can be evaluated on the lateral radiograph or view of the distal radius. 3) The distal rim of the radius forms an angle of about 23 to the long axis of the forearm. In manual prehension, the wrist deviates ulnarly about the same extent, i.e., 20-25, to accommodate objects between the thumb and fingers. This results in the 1. anatomy or radiology textbooks RADIAL COLUMN OF THE CARPUS (SEE FIGURE 21) SYNONYM: lateral carpal column CLINICAL: the combination of the scaphoid fossa of the radius, radial styloid, scaphoid, trapezium, and trapezoid, and all the intervening articulations RADIOLOGIC: see CLINICAL COMMENTS: 1) some experts disagree with the column concept. Others would accept this as a descriptive, historic term that does not imply a kinematic function. 2) This term refers only to the carpus. CODE: Anatomic: Radial (IIA) 1. Ruby LK. Fractures and dislocations of the carpus. In: Browner BD, Jupiter JB, Levine AM, Trafton PG, editors. Skeletal trauma. Philadelphia: WB Saunders; p RADIAL INCLINATION ANGLE see RADIAL INCLINATION OF DISTAL RADIUS RADIAL INCLINATION OF DISTAL RADIUS (FIGURE 51) SYNONYMS: ulnar inclination of the distal radius, radioulnar inclination, radial-ulnar inclination, slope, lateromedial inclination, radial inclination angle CLINICAL: radial inclination of the distal radius is an angle measured on a PA radiograph formed by the intersection of a line from the distal ulnar aspect of the radius to the tip of the radial styloid with a line perpendicular to the long axis of the radius. Fig. 51 RADIAL INCLINATION OF DISTAL RADIUS: a) method of DiBenedetto et al.: A and B are two points bisecting the distal radius 4 and 8 cm proximal to the radiocarpal joint to make the line X. The line Y is drawn through point C, which is the distal sigmoid notch, and D, which is the tip of the radial styloid. Z is a line drawn perpendicular to line X through point C. Radial inclination angle is the angle between lines Z and Y. E is a point on line Z to allow radial height to be measured between D and E. Radial inclination angle is b) Method of Matashita, Firrel, and Tsai. This method is a modification of that of DiBenedetto et al., in which the central axis (X) of the ulna is drawn through midpoints A and B at 2 cm and 4-5 cm proximal to the distal end of the ulna. (Reprinted with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 231. Fig 9-5, A and B.)

48 48 carpus transmitting loads at approximately 90 to the inclination of the distal radius. CODE: Anatomic: Measurements (IE) 1. Baratz ME, Larsen CF. Wrist and hand measurements and classification schemes. In: Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p DiBenedetto MR, Lubbers LM, Ruff ME, Nappi JF, Coleman CR. Quantification of error in measurement of radial inclination angle and radial-carpal distance. J Hand Surg [Am]. 1991;16: Matsushita K, Firrell JC, Tsai T-M. X-ray evaluation of radial shortening for Kienböck s disease. J Hand Surg [Am]. 1992;17: RADIAL MIDCARPAL JOINT see TRISCAPHE JOINT RADIAL OBLIQUE SCAPHOID VIEW see SEMIPRONATED OBLIQUE VIEW SYNONYM: proximal carpal instability CLINICAL: dyssynchronous motion or malalignment between the radius and part of or all of the proximal carpal row. This includes all actual instabilities at the radiocarpal level other than adaptive positionings, as the carpus adapting to distal radius deformity from an impacted distal radius fracture. (See COMMENT.) RADIOLOGIC: dynamic instabilities are best shown on fluoroscopy, which includes standard and stressed range of motion views of both wrists. For static radiocarpal malalignment, ulnar (infrequently radial) translation is best appreciated on the PA view, and dorsal and ventral translation are best shown on the lateral or sagittal views. (See CLINICAL.) COMMENTS: 1) radiocarpal instability may present as a CIND instability (Ulnar Translation, Type I) or may include a CID instability (Ulnar Translation, Type II). In the latter case, there will be both extrinsic and intrinsic ligament damage, qualifying the lesion as a CIC (Carpal Instability Complex/Combined) lesion. 2) RCI is due to ligament damage to the support structures between the forearm and the proximal carpal row and can apply to any of the usual triad of subluxation, dislocation, or fracture-dislocation, the more common members of the latter group being the Barton s, the reverse Barton s, and the Chauffer s injuries. For subluxations, the proximal carpal row is displaced, ulnar > dorsal > volar > radial. The same order of frequency is true of dislocations except that the displacement is greater. Subluxations may present only dynamically as dyssynchronous motion or loss of normal alignment or may be statically malaligned, a common presentation for ulnar translation. 3) With ulnar displacement, a dimple may appear on the radial side of the wrist. The carpus may be subluxed palmarly as well as ulnarly. 4) The term instability is again brought into question here by some experts. Ulnar translocation, a type of radiocarpal instability, is really an ulnar shift (slide) of the proximal carpal row seen commonly in rheumatoid arthritis, and most of these deformities are fixed. Instability implies to some experts that the carpus can be put back into its normal anatomic position. Since most in these cases cannot be placed back to anatomic position, these experts believe that the instability part of the term is not strictly correct, unless this malalignment occurs only with stress and reduces when stress is released (see PRO- VOCATIVE MANEUVER). 5) Another clinical entity not yet well described is believed to exist by some experts; that is the so-called rotational instability at the radiocarpal joint level. This is a supination deformity. It is not yet clear what mechanism causes this deformity (see reference #2). 6) Radiocarpal instability may be best related to radiocarpal translation mainly without any lunate tilting. CODE: Clinical Conditions: Sprains-Instabilities-Subluxations (IIIB) 1. see CARPAL INSTABILITY COMBINED (CIC) 2. Ritt MJ, Stuart PR, Berglund LJ, Linscheid RL, Cooney WP 3rd, An KN. Rotational stability of the carpus relative to the forearm. J Hand Surg [Am]. 1995;20: RADIOCARPAL JOINT (FIGURE 52) SYNONYMS: proximal joint of the wrist or of the carpus, proximal wrist joint, radioulnocarpal joint CLINICAL: a joint between the radius and the proximal carpal bones RADIOCARPAL INSTABILITY (RCI) (SEE FIGURE 64) Fig. 52a RADIOCARPAL JOINT: on all the following views, the white density is the contrast ( dye ) that was injected under fluoroscopic control. The thin space between the white contrast and the underlying radius is the cartilage on the surface of the radius, and the thin darker space between the contrast and the adjacent carpal bone is the cartilage on that carpal bone. Contrast outlines the radiocarpal space, the space between the radius, carpal bones of the proximal carpal row, and the triangular fibrocartilage. Commonly, the pisotriquetral joint communicates to the radiocarpal joint. a) PA view: contrast material in the radiocarpal joint fills the pisotriquetral joint (large arrowhead), which extends into the prestyloid recess (white straight arrow). Portions of the radioscaphocapitate ligament (small arrowheads) and the long radiolunate or radiolunotriquetral ligament (black arrows) are outlined. A small preradial recess (curved arrow) is present. b) Oblique view: the prestyloid recess (white arrow) projects separately from the proximal recess of the pisotriquetral joint (large arrowheads). Portions of the radioscaphocapitate (small arrowheads) and the radiolunotriquetral or long radiolunate ligament (black arrows) are evident. c) Lateral view: ventrally is a small preradial recess (curved arrow) and a larger dorsal scaphoid recess (arrowheads). Some extravasation of contrast out the needle track is present dorsally (arrow).

49 49 possible to subdivide the joint into its various constituents as the radioscaphoid joint, the radiolunate joint, the TFC-lunate joint, and the TFC-triquetral joint, although the last two are often called the ulnocarpal joint. 3) This joint system accounts for roughly half of carpal area motion and is commonly involved in both trauma and disease. Many treatments for carpal problems involve this joint and its osseous boundaries. CODE: Anatomic: Radial (IIA) 1. see CARPAL INSTABILITY COMBINED (CIC) 2. anatomy or radiology textbooks RADIOLUNATE DISLOCATION see LUNATE DISLOCATION RADIOSCAPHOID SUBLUXATION see SCAPHOID SUBLUXATION; ROTARY SUBLUXATION OF THE SCAPHOID Fig. 52b RADIOULNAR ABUTMENT SYNDROME see IMPINGEMENT, RADIOULNAR RADIOULNAR COMPRESSION SYNDROME see IMPINGEMENT, RADIOULNAR (DISTAL) RADIOULNAR INCLINATION see RADIAL INCLINATION OF THE DISTAL RADIUS RADIOULNOCARPAL JOINT see RADIOCARPAL JOINT RADIUS PORTION OF THE DISTAL RADIOULNAR JOINT see SIGMOID SULCUS OF THE DISTAL RADIUS REAGAN-LINSCHEID TEST see TRIQUETROLUNATE (or LUNOTRIQUETRAL) BALLOTTEMENT Fig. 52c being composed of the radioscaphoid and radiolunate joints (see COMMENTS) RADIOLOGIC: arthrographically, the entire space between the forearm and the proximal carpal row with extensions into the pisotriquetral joint and the recessus sacciformis is usually found to be one anatomic space (see CLINICAL and COMMENTS). COMMENTS: 1) although the term refers to the entire joint system between the forearm and the proximal carpal row, it is sometimes used to refer only to the portion of the joint that involves the radius and the adjacent carpals (scaphoid and one-half the lunate). In this latter instance, the other portion of the proximal wrist joint is referred to as the ulnocarpal joint, although it is more accurately the TFC (triangular fibrocartilage) carpal joint. 2) Anatomically, the radiocarpal joint is actually the radioulnocarpal joint, usually with extension to the pisotriquetral joint and to the recessus sacciformis. It is REVERSE PA OBLIQUE VIEW (FIGURE 53) SYNONYMS: ulnar oblique scaphoid view/position, reverse PA oblique position, ulnar-deviated overpronated scaphoid view CLINICAL: NA (see COMMENTS) RADIOLOGIC: the wrist is rotated 45, so that the thumb side is closest to the film cassette and the ulnar side of the wrist is off the cassette. The fingers may be flexed sufficiently to support the hand as long as the metacarpals remain collinear with the distal radius. The central ray is directed perpendicular to the cassette through the midportion of the scaphoid. Ulnar deviation of the wrist may be used to elongate the scaphoid more, or the wrist may be positioned straight without ulnar deviation. COMMENTS: 1) this view is designed to look at the dorsoradial part of the scaphoid waist especially to detect avulsion fractures off the dorsoradial aspect of the waist of the scaphoid as well as to project the pisiform off the triquetrum. 2) Supplemental projections with various degrees of ulnar deviation of the wrist or various degrees of this reverse oblique position can also be performed. 3) Alternate views of the scaphoid and other portions of the proximal carpal row are sometimes needed to diagnose or evaluate injury. CODE: Radiologic: Views (ID) 1. Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 142.

50 50 Fig. 53a REVERSE PA OBLIQUE VIEW: a) the wrist is placed in ulnar deviation to align the radial side of the thumb with the radial side of the forearm. Flexing the fingers into a fist or placing the ulnar side of the hand on a 45 sponge will serve to overpronate the wrist. b) A PA radiograph with the wrist in this position profiles the dorsoradial surface of the scaphoid and the ventroulnar surface of the triquetrum. This also profiles the pisiform off the carpus and provides a different surface view of the remainder of the carpus. (Reprinted with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 142. Fig 5-46, A and B.) Fig. 53b RING DISRUPTION see TRANSVERSE INSTABILITY PATTERN ROTARY COLUMN (SEE FIGURE 21) SYNONYMS: medial column, triquetrum, ulnar column CLINICAL: 1) the hamate, triquetrum, and triangular fibrocartilage and their articulations. 2) See ULNAR COLUMN. 3) The triquetrum is considered the rotary or medial column (in Navarro s and Taleisnik s longitudinal columnar concept of the wrist) because of its rotation from volar flexion to dorsiflexion as the wrist is moved from radial to ulnar deviation. RADIOLOGIC: see CLINICAL COMMENTS: 1) the cause of this rotation of the triquetrum is the reaction force created by movement at the helicoid articulating surfaces of the triquetrohamate joint. Some people believe that rotary column (medial column) instability is therefore synonymous with lunotriquetral instability. However, in recent years it has become apparent that instability patterns are not longitudinal, and the columnar theory has given way in some degree to the concept of transverse carpal instabilities. 2) Most experts do not use the term rotary column. This term is more of historical than current value. 3) This term simply indicates the ulnar side of the wrist. Some experts refer to an ulnar carpal column and keep that limited to the triquetrum, while others refer to the ulnar aspect of the wrist, which may include the distal ulna, the triangular fibrocartilage, the ulnar side of the carpus, and the fourth and fifth metacarpal bases. 4) Although disruption patterns are seldom longitudinal (columnar) except for the axial patterns of fracture and fracture-dislocations, force transmission is commonly longitudinal. 5) This is the column containing the axis of pronosupination. CODE: Anatomic: Carpal (IID) 1. see LONGITUDINAL (COLUMNAR) INSTABILITY PATTERN ROTARY (ROTATORY) SUBLUXATION OF THE SCAPHOID (RSS) (FIGURE 54) see SCAPHOID SUBLUXATION/DISLOCATION SYNONYM: scaphoid subluxation, scaphoid instability, see comment #1 CLINICAL: a pathologic displacement (usually a hyperflexion deformity with pronation and/or palmar rotation) of the scaphoid with or without obvious scapholunate disruption secondary to disruption of some or all of the ligamentous attachments of the scaphoid (see RADIOLOGIC) RADIOLOGIC: 1) radiographic features include: (a) scapholunate (SL) widening in the midportion of the SL joint greater than twice the width of a normal capitolunate joint; (b) foreshortening of the scaphoid (signet ring sign on the PA projection) when the wrist is in neutral position (the long axis of the third metacarpal shaft is parallel to the long axis of the radius); (c) increased radioscaphoid angle (>60 ) on lateral projection (this assumes that a 45 radioscaphoid angle is normal, and a 90 radioscaphoid angle is when the scaphoid is at right angles to the radius); (d) subluxation of the scaphoid onto the dorsal rim of the radius on lateral projection; (e) increased scapholunate angle of more than with the radiolunate angle normal on the lateral view; and (f) decreased cortical ring distance (distance from the ring in the waist of the scaphoid to the proximal scaphoid cortex with the hand in the neutral PA position) to less than 7 mm or 4 mm shorter than the normal (contralateral) wrist (see reference #5). 2) As in other carpal instabilities, static and dynamic

51 51 Fig. 54a ROTARY (ROTATORY) SUBLUXATION OF THE SCAPHOID (RSS): a) on this PA view, the scaphoid is foreshortened, that is, the scaphoid is shorter in its proximal-distal length, creating a signet ring (arrowheads) appearance due to the distal scaphoid pole being projected end-on overlapping the waist of the scaphoid. The cortical ring distance between the edge of this ring and the proximal edge of the scaphoid is decreased (see text). The scapholunate joint is widened when compared to the width of the normal-appearing capitolunate joint. b) The lateral view shows the scaphoid to be tilted palmarly, with the lunate in neutral position (not tilted) to produce a scapholunate angle of about 80. These findings are supportive of rotary subluxation of the scaphoid. (Reprinted with permission from Gilula LA, editor. The traumatized hand and wrist: radiographic and anatomic correlation. Philadelphia: WB Saunders; p 317. Fig 13-1, A and B.) support the concept of predynamic rotary subluxation of the scaphoid, when rotary subluxation is not demonstrable by any study, but the clinical diagnosis is unequivocal. This predynamic concept is very controversial among experts. 5) SLD is usually part of the scapholunate advanced collapse (SLAC) wrist. 6) There may or may not be associated instability of the rest of the carpus. 7) See SCAPHOLUNATE DISSOCIATION (SLD) for further discussion of the relationship between RSS and SLD (scapholunate dissociation). CODE: Clinical Conditions: Fractures-Dislocations-Diastases (IIIA) 1. Watson HK, Hempton RF. Limited wrist arthrodeses. I. The triscaphoid joint. J Hand Surg. 1980;5: Watson HK, Ashmead D 4th, Makhlouf MV. Examination of the scaphoid. J Hand Surg [Am]. 1988;13: Watson HK, Ryu J, Akelman E. Limited triscaphoid intercarpal arthrodesis for rotatory subluxation of the scaphoid. J Bone Joint Surg Am. 1986;68: Watson HK, Ottani L, Pitts EC, Handal AG. Rotary subluxation of the scaphoid: a spectrum of instability. J Hand Surg [Br]. 1993;18: Armstrong GW. Rotational subluxation of the scaphoid. Can J Surg. 1968; 11: see SCAPHOLUNATE DISSOCIATION (SLD) for references to other management methods ROW INSTABILITY see TRANSVERSE INSTABILITY PATTERN SAGITTAL PLANE (SEE FIGURE 36) SYNONYMS: lateral plane, longitudinal axis or plane (see comment #2 in LONGITUDINAL AXIS), sagittal axis CLINICAL: with the hand(s) in anatomic position (parallel to the trunk with the forearm and hand in supination), this is a plane parallel to the sagittal suture of the skull. In cross-sectional imaging, sagittal plane is subgroups are recognized: (a) static, when visible on a PA or lateral radiograph of the wrist; and (b) dynamic, when rotary subluxation can be demonstrated by any other radiographic views, stress loading, cineradiography, fluoroscopy, arthrography, or other ancillary studies (tomography, MRI, etc.). COMMENTS: 1) controversy exists concerning SLD (scapholunate dissociation) and RSS. At least one expert states that SLD may or may not be present with rotary subluxation of the scaphoid; therefore, RSS and scapholunate dissociation are not truly synonyms. When true scapholunate diastasis is present, RSS should also be present. However, other experts believe that at this time it is not clear if scapholunate diastasis (SLD) and RSS are synonymous, or if one is a subset of the other. However, many experts believe that RSS and SLD refer to the same condition. 2) Commonly, the proximal pole of the scaphoid moves dorsally and rotates onto the dorsum of the radius and capitate to produce rotary subluxation of the scaphoid. However, the scaphoid can displace in many ways as yet poorly defined, secondary to various forms of periscaphoid ligamentous rupture, some resulting in overload and degenerative arthritis of the scaphotrapeziotrapezoidal joint instead of the radioscaphoid joint. 3) Some experts believe that rotary displacement of the scaphoid refers only to its increased flexion in the sagittal plane and that angulation in the radioulnar plane or pronation/supination rotation in the axial plane is not considered. Other experts disagree and believe RSS exists when the scaphoid moves abnormally in any direction. 4) Some experts Fig. 54b

52 52 used as a synonym for a section made along the anteroposterior plane producing a lateral cross-sectional view of the hand. RADIOLOGIC: used as a synonym for a section made along the anteroposterior plane parallel to the sagittal suture and producing a view called a lateral COMMENTS: none CODE: Radiologic: Planes (IB) 1. anatomy or radiology textbooks SAGITTAL VIEW see LATERAL VIEW SCAPHOID INSTABILITY see ROTARY SUBLUXATION OF THE SCAPHOID SCAPHOID NONUNION ADVANCED COLLAPSE (SNAC) see comment #9 in SCAPHOLUNATE ADVANCED COLLAPSE (SLAC) SCAPHOID PROJECTION see SCAPHOID VIEW SCAPHOID PROVOCATIVE MANEUVER see SCAPHOID STRESS TEST SCAPHOID SHIFT TEST see SCAPHOID STRESS TEST SCAPHOID SLIDER-CRANK MECHANISM see SLIDER-CRANK MECHANISM SCAPHOID STRESS TEST (WATSON) (FIGURE 55) SYNONYMS: scaphoid provocative maneuver, Watson maneuver, Watson test, scaphoid subluxation test, scaphoid shift test CLINICAL: a provocative clinical maneuver of the scaphoid performed by an examiner to determine the degree and type of mobility and symptom level during displacement of the scaphoid. The test is performed by stabilizing the distal radius with one hand and placing pressure on the palmar aspect of the distal scaphoid tuberosity with the other hand while the wrist is brought from a position of ulnar to radial deviation to prevent the excessive flexion of the unstable scaphoid. A positive test elicits pain of presenting type (see comment #6), abnormal mobility, and a palpable or audible clunk prior to displacement of the scaphoid from the scaphoid fossa of the radius. RADIOLOGIC: when this maneuver is performed under fluoroscopic control, abnormal displacement of the proximal pole of the scaphoid out of the scaphoid fossa of the distal radius can be observed, especially in the lateral or slightly supinated lateral position. Such motion when accompanied with pain of the presenting type constitutes a positive test. Increased motion can be recognized by comparing the amount of scaphoid displacement with the asymptomatic wrist. COMMENTS: 1) this movement of the proximal scaphoid pole may take place without fluoroscopically obvious scapholunate diastasis. 2) Without fluoroscopic or cineradiographic control, sometimes it may be impossible to tell if pain or popping signifies abnormal motion at the radiocarpal or midcarpal joint level, scaphocapitate instability, or instability at the proximal or distal poles of the scaphoid. 3) The test may be positive bilaterally and may be positive in an asymptomatic wrist, since mild to moderate scaphoid instability can be a variant of normal (hypermobile scaphoid) or abnormal but functionally competent. 4) Several similar tests give similar findings. These tests include direct pressure dorsally over the proximal end of the scaphoid or ventrally under the distal tuberosity of the scaphoid, or both, and exerting pressure for ballottment of the unstable scaphoid up and down. When unstable enough, the scaphoid will do its own snapping, creaking, and hurting with active deviation motion or circumduction motion. When pressure is applied in the areas described, evoked tenderness is also a significant positive finding. 5) One study evaluating this test found a low sensitivity and specificity for this test (see reference #2). 6) This test might be positive in the presence of pathologic cartilage at the proximal pole of the scaphoid without any evidence of ligament rupture. Conclusions given by this test must be cautious, since pain just defines pain, nothing else. CODE: Tests (IV) Fig. 55a Fig. 55b SCAPHOID STRESS TEST (WATSON): constant pressure is placed against the distal pole of the scaphoid as the patient s wrist is brought from ulnar deviation (a) to radial deviation (b), attempting to sublux the proximal pole of the scaphoid out of the scaphoid fossa of the radius. (Reprinted with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 197. Fig 7-26, A and B.)

53 53 1. Watson HK, Ashmead D 4th, Makhlouf MV. Examination of the scaphoid. J Hand Surg [Am]. 1988;13: LaStayo P, Howell J. Clinical provocative tests used in evaluating wrist pain: a descriptive study. Hand Ther. 1995;8:10-7. SCAPHOID SUBLUXATION/DISLOCATION (SEE FIGURE 54) SYNONYMS: radioscaphoid subluxation/dislocation, rotary (rotatory) subluxation of the scaphoid (see COMMENTS) CLINICAL: subluxation is an abnormal condition in which the scaphoid is malaligned with one or more of its adjacent bones, but partial joint contact is maintained. Dislocation at a scaphoid joint exists when all joint contact is lost between the scaphoid and an articulating bone(s) at that joint. RADIOLOGIC: in the neutral PA projection, subluxation of the scaphoid at the radioscaphoid joint is inferred by the presence of scapholunate diastasis (scapholunate joint width at its midportion is at least twice as wide as the normal capitolunate joint) without evidence of Type II ulnar translocation. Alternatively, when the wrist is in a neutral position (third metacarpal and radius in a straight line) there may be an associated cortical ring sign (with palmar flexion of the scaphoid, the cortices of the distal scaphoid pole are projected as a circle over the mid body of the foreshortened scaphoid). The foreshortened scaphoid is evidenced by a decrease in the minimal distance between the ring and the proximal pole of the scaphoid to less than 7 mm, or 4 mm shorter than the normal contralateral wrist (reference #1). Either or both of these findings may be present. In the neutral lateral projection the radioscaphoid congruence may be lost, typically with dorsal displacement of the proximal scaphoid pole. The radioscaphoid angle as measured between the long axis of the radius and the tangential long axis of the scaphoid is greater than 75 (see reference #2). Loss of parallelism between the tangential long axis of the scaphoid and the volar flare of the distal radius (lines converge to an acute angle) may be a useful clinical sign. COMMENTS: 1) the prior description refers to subluxation/dislocation changes at the proximal pole of the scaphoid. Subluxation parameters for the distal scaphoid and its relationships to the capitate, trapezium, and trapezoid are not as well defined but in general are a reciprocal of the proximal pole malalignment. Full dislocation at either or both poles does occur, sometimes with considerable displacement of the scaphoid or of its fragments. 2) At the distal end of the scaphoid, dorsal subluxation of the trapezium is considered scaphotrapezial subluxation. 3) Unusually, scaphoid subluxation may occur without rotation. 4) Except for dynamic and provocative types, there is no difference between scaphoid subluxation and rotary subluxation of the scaphoid or scapholunate dissociation. Therefore, in some situations, all three of these may be synonymous. 5) Although dorsal subluxation is most common, it is also possible to have ulnar, radial, or volar subluxation of the scaphoid. 6) This is distinct from but is frequently associated with DISI. 7) Complete dislocations of the scaphoid are rarities. CODE: Clinical Conditions: Fractures-Dislocations-Diastases (IIIA) 1. Armstrong GW. Rotational subluxation of the scaphoid. Can J Surg. 1968; 11: Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p Destot EAJ. Injuries of the wrist: a radiological study (translated by FRB Atkinson). London: Ernest Benn; Thompson TC, Campbell RD, Arnold WD. Primary and secondary dislocation of the scaphoid bone. J Bone Joint Surg Br. 1964;46: Dobyns JH, Linscheid RL. Fractures and dislocations of the wrist. In: Rockwood CA Jr, Green DP, editors. Fractures. Vol 1. Philadelphia: JB Lippincott; 1975, p Nigst H. [Luxations and subluxations of the scaphoid bone]. Ann Chir. 1973; 27:519. French. SCAPHOID SUBLUXATION TEST see SCAPHOID STRESS TEST SCAPHOID VIEW (FIGURE 56; see also FIGURE 60) see SEMIPRONATED OBLIQUE VIEW SYNONYMS: navicular view or projection, scaphoid projection Fig. 56a Fig. 56b SCAPHOID VIEW: a) the ulnar side of the wrist rests on the cassette or table and the radial side of the wrist is elevated about 20 off the table. The central x-ray beam is angled at the waist of the scaphoid, 35 toward the elbow. b) This view elongates the waist of the scaphoid to produce an elongated oblique view of the scaphoid. This represents one of several scaphoid views. (Reprinted with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 145. Fig 5-49, A and B.)

54 54 CLINICAL: a radiographic projection designed to show the long axis of the scaphoid (see RADIOLOGIC) RADIOLOGIC: several radiographic PA projections have been described that more accurately portray the long axis of the pronated scaphoid and provide a nonforeshortened (en face) or even elongated view of the scaphoid waist. Two more commonly used projections are: 1) PA positioning, in which the hand is placed in a loose fist and ulnar deviation, and the radiographic beam is directed perpendicular (dorsopalmar) to the imaging cassette through the scaphoid waist; and 2) PA positioning, in which the hand is ulnar deviated while maintaining the palm flat on the imaging cassette, and the radiographic beam is angled proximally (dorsopalmarly), from the fingers toward the elbow. COMMENTS: 1) such projections displaying the scaphoid waist can be obtained with any position of the elbow, but standard positioning with elbow flexed 90 and held at shoulder height may be preferable in attempts to standardize PA views of the wrist by each radiologic technologist. 2) Other techniques have been described, including use of a box to hold a radiographic screen at an angle to the wrist. Many other views are available to evaluate the scaphoid, and those can be seen in a variety of textbooks for radiographic positioning. 3) Because of different potential planes of a fracture line, it is possible that a fracture may show better with different angles of the radiographic beam. CODE: Radiologic: Views (ID) 1. Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p radiologic technology textbooks CLINICAL: 1) progressive degenerative joint disease beginning with the radioscaphoid articulation and progressing to involve the capitolunate articulation, usually with sparing of the radiolunate joint. 2) A special pattern of progressive, posttraumatic degenerative arthritis of the carpus, secondary to altered stress patterns that occur around an unstable scaphoid. This usually begins at the radial styloid and scaphoid contact areas, progresses to the scaphoid sulcus and scaphoid articulation, then to the capitolunate joint, often the scaphotrapeziotrapezoidal joints, and eventually to other carpal joints, but usually sparing the radiolunate joint. It is similar to the pattern of osteoarthritis that develops around an unstable fracture or nonunion of the scaphoid, but not identical. 3) A form of progressive degenerative arthritis following a dissociative lesion of the scapholunate joint or through the scaphoid, which classically begins with the radioscaphoid articulation and progresses to involve the capitolunate joint (and often the scaphotrapeziotrapezoidal joint), while sparing the radiolunate articulation until very late. RADIOLOGIC: the earliest changes occur as sharp spurring at the articular-nonarticular junction on the radial side of the scaphoid and at the radial styloid tip with loss of the normal rounded curvature of the radial styloid. This progresses to narrowing of the radioscaphoid joint, followed by narrowing of the capitolunate joint. In a similar fashion, narrowing of the joint between the hamate and lunate may occur. Scapholunate dissociation or malunion or nonunion of the scaphoid is commonly present (see COMMENTS). COMMENTS: 1) SLAC most commonly occurs because of scapholunate disruption, but it can also occur because of some other condition, such as scaphotrapeziotrapezoidal disease. 2) This pattern of changes could also be called something else such as degenerative joint disease of the radiocarpal joint secondary to scapholunate ligament disruption. 3) Rarely, capitolunate joint narrowing may begin before radioscaphoid degenerative joint disease. 4) Late, one may see endochondral new bone formation on the palmar surface of the lunate that effectively changes lunate contour and blocks lunate flexion. 5) SLAC is the usual pattern of posttraumatic arthritis following scapholunate dissociation. 6) Dorsal translation of the capitate with extension of the lunate (DISI) is commonly found on the lateral radiograph. 7) Although the problem appears to start at the scapholunate (SL) joint (with SL disruption), the primary clinical consequence is radioscaphoid degenerative joint disease. 8) Because the radiolunate joint is one of the last to become significantly involved, it is often available for stress loading, and the popular SLAC Wrist Procedure (Watson) of excising the scaphoid, aligning the lunate properly between the radius and capitate, and then fusing the midcarpal joint is often done to salvage many SLAC wrists. 9) The pattern of arthritis progression is very similar in patients with scaphoid non or malunion, and the same salvage procedures are often used for the SNAC (scaphoid nonunion advanced collapse) as for the SLAC wrist. SCAPHOLUNATE ADVANCED COLLAPSE (SLAC) (FIGURE 57) SYNONYM: scapholunar advanced collapse Fig. 57a SCAPHOLUNATE ADVANCED COLLAPSE (SLAC): a) PA view: scapholunate diastasis, degenerative joint disease at the radiocarpal and capitolunate joints, and preserved radiolunate joint width is present. b) Lateral view: dorsal tilting of the lunate and palmar tilting of the scaphoid result in a scapholunate angle of 70. See text. L = lunate axis, R = radius axis, S = scaphoid axis, and C = capitate axis. Radiolunate angle is 20 and capitolunate angle is 5. c) In a different patient, the same pattern of scapholunate widening associated with degenerative joint disease at the radioscaphoid and capitolunate joints is present; however, in this case there is also extensive volume loss of the proximal pole of the scaphoid and erosive change in the scaphoid fossa. This pattern is more consistent with CPDD (calcium pyrophosphate deposition disease), whereas the pattern in Fig. 57A is seen most commonly without CPDD. (Reprinted with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p Fig 20-24, A and B; and 25.)

55 55 Fig. 57c Fig. 57b The major difference between the SNAC and SLAC wrists is that the proximal scaphoid fracture fragment in the SNAC wrist acts as a small lunate, and the articulation of this proximal fracture fragment with the radius is usually normal. Also, the scapholunate ligament and joint are usually preserved in the SNAC wrist. CODE: Clinical Conditions: Residuals of Injuries (IIIC) 1. Sebald JR, Dobyns JH, Linscheid RL. The natural history of collapse deformities of the wrist. Clin Orthop. 1974;104: Watson HK, Ballet FL. The SLAC wrist: scapholunate advanced collapse pattern of degenerative arthritis. J Hand Surg [Am]. 1984;9: Taleisnik J. The wrist. New York: Churchill Livingstone; SCAPHOLUNATE DISSOCIATION (SLD) (FIGURE 58; SEE ALSO FIGURES 54A AND 57A) SYNONYMS: see comment #1 CLINICAL: loss of synchronous motion or normal alignment between the scaphoid and the lunate RADIOLOGIC: measured at the midpoint of the scapholunate joint on the PA view, a scapholunate gap greater than 4 mm or double the width of other intercarpal spaces, especially twice as wide as a normal capitolunate joint. The radioscaphoid joint may be abnormally decreased (see ROTARY SUBLUXATION OF THE SCAPHOID). COMMENTS: 1) several words are used as synonyms for SLD, but they are not true synonyms. Scapholunate diastasis (Terry Thomas Sign), or widening of the SL joint, may not always be present with SLD. When SL diastasis is definitely present, scapholunate dissociation should be present. See ROTARY SUBLUXATION OF THE SCAPHOID for commentary that RSS and SLD may not be synonymous. 2) Some people have an abnormally wide scapholunate space but a normal scapholunate ligament. One example of this is in a patient with lunotriquetral coalition. 3) Typically this should not be associated with the DISI pattern with abnormal dorsal lunate tilting. If DISI is present, then more anatomic structures should be abnormal than as seen with only RSS. 4) In the past, scapholunate joint space widening was termed Terry Thomas Sign for the space between the front teeth of that English actor. More recently, some people have called this the Leon Spinks Sign (a boxer), and the David Letterman Sign (a television talk-show host) for the space these people have between their front teeth (see comment #1). 5) Eventually, SLD leads to similar malalignment at the other scaphoid joints. 6) In the immature carpus, this space may appear wider because unossified cartilaginous portions of the scaphoid and lunate are present adjacent to the joint space. 7) Although there is a subtle difference in use of the terms rotary subluxation of the scaphoid vs. scapholunate dissociation (RSS focuses attention to the scaphoid; SLD emphasizes that both scaphoid and other carpal elements are disturbed), they are used as equivalent terms by many wrist investigators. The discussion for RSS then can be closely applied to SLD. Each includes the entire spectrum of extremely subtle scaphoid instability to a certain pattern of fixed deformity with associated arthritis with many intermediate stages between. Whatever one calls this common carpal instability, both diagnosis and treatment have suffered from not recognizing that there are several stages to the condition and that some recommended treatments are appropriate at one stage but not at the others. CODE: Clinical Conditions: Fractures-Dislocations-Diastases (IIIA) 1. Dobyns JH, Perkins JC. Instability of the carpal navicular. Proceedings of the American Academy of Orthopaedic Surgeons. J Bone Joint Surg Am. 1967; 49: Linscheid RL, Dobyns JH, Beabout JW, Bryan RS. Traumatic instability of the wrist. Diagnosis, classification, and pathomechanics. J Bone Joint Surg Am. 1972;54: Mayfield JK, Johnson RP, Kilcoyne RK. Carpal dislocations: pathomechanics and progressive perilunar instability. J Hand Surg. 1980;5: Taleisnik J. Scapholunate dissociation. In: Strickland JW, Steichen JB, editors. Difficult problems in hand surgery. St. Louis: CV Mosby; p Taleisnik J. The wrist. New York: Churchill Livingstone; 1985.

56 56 RADIOLOGIC: an excellent lateral position of the carpus can be recognized on a radiograph when the ventral cortex of the pisiform projects midway between the ventral surfaces of the capitate head and the distal pole of the scaphoid. Acceptable position is when the ventral cortex of the pisiform may not be in the midpoint but still lies dorsal to the ventral cortex of the distal pole of the scaphoid and ventral to the ventral cortex of the head of the capitate. When the ventral cortex of the pisiform projects ventral to the ventral cortex of the distal pole of the scaphoid or dorsal to the ventral cortex of the capitate, the SPC alignment is considered inadequate, especially for evaluation of carpal relationships. These are the SPC (scaphopisocapitate) alignment criteria. COMMENTS: 1) the SPC relationship was designed to identify carpal position. A long-used technique, checking alignment between the ulnar styloid and the dorsal rim of the radius is actually checking the alignment of the forearm. In any individual case, both may be adequate; however, in some patients with a prominent distal ulna and other congenital variations of the wrist, the radius and ulnar overlap method may not prove reliable. 2) When the carpus is not adequately aligned, as when the SPC relationship is inadequate, carpal alignment may be misinterpreted and the slope of the distal radius may be erroneously evaluated. Such inadequate assessment of the distal radius slope is especially common when evaluating the position of the distal radius articular surface after reduction of a distal radius fracture. CODE: Radiologic: Positions (IA) 1. Yang Z, Mann FA, Gilula LA, Haerr C, Larsen CF. Scaphopisocapitate alignment: criterion to establish a neutral lateral view of the wrist. Radiology. 1997;205: SCAPHOTRAPEZIOTRAPEZOIDAL (STT) JOINT (FIGURE 59; SEE ALSO FIGURE 60B) Fig. 58 SCAPHOLUNATE DISSOCIATION (SLD): scapholunate widening (diastasis) is pronounced and is much wider than the capitolunate joint. Foreshortening of the scaphoid and decreased scaphoid cortical ring distance are present (see ROTARY SUBLUXATION OF THE SCAPHOID). 6. Schernberg F. Roentgenographic examination of the wrist: a systematic study of the normal, lax, and injured wrist. Part 2: stress views. J Hand Surg [Br]. 1990;15; Saffar P. Carpal injuries: anatomy, radiology, current treatment. France: Springer; Cooney WP 3rd, Linscheid RL, Dobyns JH. Carpal instability: treatment of ligament injuries of the wrist. AAOS Instr Course Lect. 1992;41: Lavernia CJ, Cohen MS, Taleisnik J. Treatment of scapholunate dislocations by ligamentous repair and capsulodesis. J Hand Surg [Am]. 1992;17: SYNONYMS: triscaphe joint, radial midcarpal joint CLINICAL: joint formed by the articulation of the proximal surface of the trapezium and trapezoid with the distal surface of the scaphoid. Some authors believe this joint also includes the joint between the trapezium and trapezoid. RADIOLOGIC: see CLINICAL. This joint area can usually be seen best with some degree of semipronated oblique. Fluoroscopic spots or properly positioned computed tomographic or routine (especially complex-motion thin-section) tomographic sections can be utilized to profile each portion of these articulating surfaces. SCAPHOLUNATE INSTABILITY see LONGITUDINAL (COLUMNAR) INSTABILITY PATTERN SCAPHOPISOCAPITATE (SPC) LATERAL (SEE FIGURE 35B) SYNONYMS: scaphopisotriquetral relationship, scaphopisotriquetral alignment CLINICAL: this is a method utilizing points of the scaphoid (S), pisiform (P), and capitate (C) to determine adequacy of a lateral radiograph of the wrist, relying on the carpal and not the forearm bones. Fig. 59a SCAPHOTRAPEZIOTRAPEZOIDAL (STT) JOINT: a) this view is made with the radial side of the hand elevated 45 off the x-ray cassette or x-ray table and with the wrist in ulnar deviation. The central ray (indicated by the pointer) is passed through the trapezium perpendicular to the cassette. The wrist can be supported with a wedge sponge. b) On this PA axial oblique view, the joints between the scaphoid and trapezium (scaphotrapezial), the scaphoid and trapezoid (scaphotrapezoidal), and the trapezium and trapezoid (trapeziotrapezoidal) are seen. All of these together are referred to as the STT joint. Some people call this group of joints the triscaphe joint. (Reprinted with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 151. Fig 5-55, A and B.)

57 57 SEMISUPINATED OBLIQUE VIEW (FIGURE 61) SYNONYMS: pisiform view, pisotriquetral view, ulnovolar carpal projection, a hook of the hamate view, semisupinated oblique projection/position CLINICAL: a radiographic view designed to demonstrate the pisi- Fig. 59b Fig. 60a COMMENTS: 1) some experts do not support the use of the term triscaphe joint. 2) It is intriguing that the deformity in progressive arthritis of this joint is the opposite of the SLD/RSS position, i.e., with disease of the STT joint, the scaphoid becomes more extended with a smaller scapholunate angle. The joint is probably more of a factor in the dynamics of the radial column than is currently acknowledged. CODE: Anatomic: Radial (IIA) 1. Crosby EB, Linscheid RL, Dobyns JH. Scaphotrapezial trapezoidal arthrosis. JHand Surg. 1978;3: see ROTARY SUBLUXATION OF THE SCAPHOID SEMIPRONATED OBLIQUE VIEW (FIGURE 60) SYNONYMS: radial oblique navicular view, radial oblique scaphoid view, scaphoid view, semipronated oblique projection/position CLINICAL: provides an oblique nonforeshortened view of the scaphoid and shows the trapeziotrapezoidal and the scaphotrapeziotrapezoidal articulations RADIOLOGIC: the wrist is positioned so that the radial side of the wrist is elevated 45 off the film cassette. The central ray of the x-ray beam is centered to pass through the radial aspect of the head of the capitate from dorsal to palmar. COMMENTS: this is the best view to examine the STT joint and is valuable to examine the scaphoid. CODE: Radiologic: Views (ID) 1. radiologic technology textbooks 2. Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 127. Fig. 60b SEMIPRONATED OBLIQUE VIEW: a) the radial side of the wrist is elevated 45 off the cassette or table top. A 45 sponge can be used to support the wrist. The central ray (indicated by the pointer) is aimed to the waist of the scaphoid at its junction with the capitate. b) The produced radiograph shows the scaphotrapeziotrapezoidal joint, the waist of the scaphoid, and the other carpal bones in an oblique position displaying ventral radial and dorsoulnar surfaces of all the carpal bones. The first carpometacarpal joint may also be well profiled, and the trapezium can be seen more in a posteroanterior projection. (Reprinted with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 127. Fig 5-32, A and B.)

58 58 form, the pisotriquetral joint, and the palmar aspects of the hamate and triquetrum RADIOLOGIC: the ulnar aspect of the hand and wrist are placed on the cassette with the radial side of the wrist supinated from the neutral lateral position. This results in the palm facing upward. The central beam passes palmar to dorsal at the head of the capitate midway between the radial and ulnar borders of the wrist. COMMENTS: 1) this is the best or one of the best radiographic views to profile the pisotriquetral joint, and the volar ulnar column to display the hook of the hamate and the important ligament origininsertion area at the volar aspect of the triquetrum. 2) Profile of this joint can be optimized with fluoroscopic control. CODE: Radiologic: Views (ID) Fig. 61a 1. radiologic technology textbooks 2. Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 136. SIDE VIEW see LATERAL VIEW SIGMOID NOTCH OF DISTAL RADIUS see SIGMOID SULCUS OF DISTAL RADIUS SIGMOID SULCUS OF DISTAL RADIUS (SEE FIGURE 27) SYNONYMS: sigmoid notch of the distal radius, radius portion of the distal radioulnar joint CLINICAL: the concave articular groove on the ulnar side of the distal radius constituting the radial part of the distal radioulnar joint (DRUJ) and into which the distal ulna articulates RADIOLOGIC: see CLINICAL COMMENTS: 1) the anatomy of this structure and its relationship to the distal ulna can be readily and most accurately displayed by computed tomography or MRI, especially in the axial plane. 2). Abnormalities may be more obvious clinically than by standard x-ray techniques. CODE: Anatomic: Ulnar (IIC) 1. Forstner H. [Morphology of the distal radio-ulnar joint. Surgical orthopedic consequences]. Handchir Mikrochir Plast Chir. 1990;22: German. Fig. 61b SEMISUPINATED OBLIQUE VIEW: a) the wrist is positioned with its ulnar side on the cassette or x-ray tabletop and the radial side of the wrist supinated from true lateral, or elevated off the cassette or tabletop. The central ray (indicated by the pointer) is aimed toward the capitate head. b) This view demonstrates the pisotriquetral joint (between arrowheads), the dorsoradial surface of the waist of the scaphoid (white arrow), the hamate hook (black arrow), and the ventroulnar surfaces of the triquetrum, lunate, hamate, and capitate. (Reprinted with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 136. Fig 5-41, A and B.) SLIDER-CRANK MECHANISM (FIGURE 62) SYNONYMS: carpal revolute or scaphoid slider-crank mechanism CLINICAL: a specialized version of a mechanical engineering concept of a four-bar linkage in which one of the three revolute linkages is substituted by a prismatic linkage. The best example is the drive mechanism on a steam locomotive where the prismatic linkage is equivalent to the piston in the steam chamber, and the revolute linkages are those on the drive wheels of the locomotive. The clinical analogy is the scaphoid bone, which may be thought of as having a prismatic linkage at the scaphotrapeziotrapezoidal joint and one revolute linkage at the dorsal aspect of the scapholunate and a second revolute linkage at the capitolunate and radiolunate joints. The analogy is an attempt to show the stabilizing effect of the scaphoid in the sagittal plane as it passes at a 45 angle between the centers of rotation of the distal and the proximal carpal rows, with the centers of ro-

59 59 Fig. 62 SLIDER-CRANK MECHANISM: this figure shows a slider-crank in which the scaphoid acts as a bridge between the proximal and distal carpal rows controlling intercarpal motion much as the piston and crank shaft do in a compressor. C = capitate, L = lunate, S = scaphoid, R = radius. See text. (Reprinted with permission from Ritt MJPF. Biomechanical studies on ulnar-sided ligaments of the wrist. Akademisch Proefschrift [PhD Thesis]. Nederland: Universiteit van Amsterdam; p 12. Fig 1.2.) tation assumed to be in the mid neck of the capitate and on the distal articular surface of the lunate. RADIOLOGIC: see CLINICAL COMMENTS: 1) this simple analogy is now principally of historical interest, too simple to actually explain carpal mechanics. 2) This is a simple analogy in which mechanical does not seem to fit with motility. 3) Although seldom needed except to illustrate the definition, either multiple static or the dynamic sequence of lateral views between full extension and full flexion of the carpus will illustrate the concept. CODE: General Terms (V) 1. Gilford WW, Bolton RH, Lambrinudi C. The mechanism of the wrist joint with special reference to fractures of the scaphoid. Guy s Hosp Rep. 1943;92: Landsmeer JMF. Studies in the anatomy of articulation. I. The equilibrium of the intercalated bone. Acta Morphol Neerl Scand. 1961;3: Fisk GR. Carpal instability and the fractured scaphoid. Ann R Coll Surg Engl. 1970;46: Linscheid RL, Dobyns JH, Beabout JW, Bryan RS. Traumatic instability of the wrist. Diagnosis, classification, and pathomechanics. J Bone Joint Surg Am. 1972;54: Ritt MJPF. Biomechanical studies on ulnar-sided ligaments of the wrist. Akademisch Proefschrift (PhD thesis). Nederland: Universiteit van Amsterdam; ISBN# SPC LATERAL see SCAPHOPISOCAPITATE LATERAL SPRAIN SYNONYM: partial ligament tear CLINICAL: 1) a sprain is a ligamentous injury characterized by pain and sometimes a change in the dimensions of the affected ligaments with or without a loss of the structural integrity of the ligaments. Pathophysiologically, a sprain represents micro-tears within the substance of the ligament and thus is a partial disruption of the ligament on a microscopic level. 2) A spectrum of ligament injury ranging from a micro-tear with no perceptible loss of integrity to a variety of partial tears with varying degrees of structural loss to a complete tear with total loss of functional competence. 3) A stretching, twisting, or bending injury of a ligament compromising its structural integrity but leaving it in continuity. RADIOLOGIC: radiographically, a sprained ligament may appear normal on a routine radiograph. A sprain may also appear as a slight widening of the interosseous distance between two bones of a magnitude less than one would expect with a loss of integrity of the ligament. A sprained ligament will always appear normal on an arthrogram because it is intact. COMMENTS: 1) currently, we know of no reliable means to make an imaging diagnosis of a sprain with certainty. In the future, MRI or ultrasound with ultra-high spatial resolution may become diagnostically useful. 2) A sprained ligament may or may not be associated with functional stability. 3) For diagnosis and management, the degree of a sprain should be known or at least estimated. This plus the health status and the functional requirements of the damaged individual guide treatment selection. In the wrist, as in other joints of the body, attritional damage occurs, often with minimal loss of functional competence and few or no symptoms. 4) Clinical estimates aided by the standard x-ray findings of normality or swelling or osseous involvement or stressed displacement have served reasonably well to document sprain in its various stages. 5) It is obvious from the prior comments that a better and more complete imaging analysis of sprains is needed, and such differentiation is even now being attempted in the management of high-profile athletes. CODE: Clinical Conditions: Sprains-Instabilities-Subluxations (IIIB) 1. radiology or sports medicine textbooks STATIC CARPAL INSTABILITY (SEE FIGURES 12-16, 29, 54, 57, 58) SYNONYMS: fixed carpal instability, static deformity, permanent carpal instability CLINICAL: a malalignment of the carpal bones associated with carpal ligament or bone damage evident in the neutral PA and/or lateral radiographs in the absence of malunion of the distal radius and without stress or other provocative maneuvers (see COMMENTS) RADIOLOGIC: see CLINICAL COMMENTS: 1) fixed is suggested by some as a synonym for static carpal instability. However, a static deformity is not necessarily fixed. For instance, chronic rotatory subluxations of the scaphoid (by definition static) are not necessarily fixed, since they may be reduced by pushing the scaphoid with the thumb. Some experts believe that a condition, as with some cases of VISI and DISI that cannot be manipulated back and forth from a nonanatomic to an anatomic position, cannot be a true instability because no real instability is present. 2) In another interpretation, the static instabilities should not be considered to be permanently fixed, since they have progressed to the current degree of deformity but may progress further with time and stress. 3) When a malalignment is solidly fixed, it is a contracture, a collapse, or a persistent deformity, but it is not instability. For this reason, some experts challenge the accepted convention of the use of the word instability in these cases. Some of these experts believe that the word malalignment would be a better descriptive term than instability. One expert states: In this context, the term instability is not correct. It is confusing to those who adhere to its definition in physics, and in medicine in other joints than

60 60 the wrist. Furthermore, its current use blocks the term and abolishes its use in the correct meaning of the word. I would certainly prefer terms such as tilt, shift, subluxation, malalignment, etc. 4) Static instability is in contrast to a dynamic instability in which the standard radiographs are normal and the instability is only evident on cine or video fluoroscopic studies combined with provocative maneuvers of the wrist. 5) An adaptive carpus may be considered a static deformity pattern (not instability). 6) Some experts have difficulty with the terms static and dynamic. As one expert states: An instability is always dynamic. A static instability is a contradiction, if we analyze the words correctly. CODE: General Terms (V) 1. Vaughan-Jackson OJ. A case of recurrent subluxation of the carpal scaphoid. J Bone Joint Surg Br. 1949;31: Linscheid RL, Dobyns JH, Beabout JW, Bryan RS. Traumatic instability of the wrist. Diagnosis, classification, and pathomechanics. J Bone Joint Surg Am. 1972;54: Taleisnik J. The wrist. New York: Churchill Livingstone; STATIC DEFORMITY see STATIC CARPAL INSTABILITY STRESS INSTABILITY see DYNAMIC INSTABILITY STRESS TEST see PROVOCATIVE MANEUVER SUBLUXATION (SEE FIGURES 6, 20) SYNONYMS: partial or incomplete dislocation, partial or incomplete luxation CLINICAL: an abnormal and incongruent but partial contact between the articular surfaces of a joint, as opposed to a dislocation in which there is no contact between articular surfaces of a joint RADIOLOGIC: see CLINICAL COMMENT: use of the term subluxation of joint is seldom heard when carpal instabilities are being discussed, and the term is only needed to indicate that many of the common instabilities show less deformity and less instability than a dislocation. CODE: Clinical Conditions: Sprains-Instabilities-Subluxations (IIIB) 1. see STATIC CARPAL INSTABILITY 2. see SCAPHOID SUBLUXATION/DISLOCATION TETHER SYNONYMS: limiting band, restricting structure or attachment, attach, anchor, constraint, tie CLINICAL: a structure of anatomic or implant tissues that restricts the mobility of a bone or tendon or any moving structure RADIOLOGIC: see COMMENTS COMMENTS: 1) such a structure itself may be visible by imaging techniques, but more likely its effects will be noticeable. 2) Some people believe that the term is similar enough to its dictionary definition ( a rope or chain that restricts the motion of an animal ) that it is almost immediately recognizable and does not need to be defined separately for the wrist and hand. 3) Techniques of tethering a carpal bone or bones are quite commonly used in the carpus, although they are seldom given much mention. The tether method most commonly used is probably the Blatt technique of constructing a dorsal capsular tether to restrain the scaphoid against excessive flexion. CODE: General Terms (V) 1. Blatt G. Capsulodesis in reconstructive hand surgery: dorsal capsulodesis for the unstable scaphoid and volar capsulodesis following excision of the distal ulna. Hand Clin. 1987;3: THENAR see RADIAL TRANSAXIAL PLANE see TRANSVERSE PLANE TRANSOSSEOUS PERILUNATE INJURIES see GREATER ARC INJURIES TRANSVERSE INSTABILITY PATTERN SYNONYMS: row instability, ring disruption CLINICAL: a classification system that recognizes that carpal instabilities usually occur in the transverse plane secondary to forces directed transversely across the wrist. For instance, scapholunate instability, lunotriquetral (lunatotriquetral, triquetrolunate) instability, and perilunate dislocations occur because of a perilunate force that can create these injuries in sequence. (See COMMENTS.) RADIOLOGIC: NA COMMENTS: 1) although many experts do not support this concept, others still do. 2) It is believed by some that this pattern has been demonstrated and confirmed in studies by Mayfield and Johnson. Some of these same people believe that transverse instability patterns also include midcarpal instabilities (see MIDCARPAL INSTABILITY) as well as radiocarpal instabilities (dorsal radiocarpal instability, palmar radiocarpal instability, and ulnar proximal carpal instability). Ulnar carpal instabilities can be subdivided into (a) rheumatoid (synovial based), (b) iatrogenic, and (c) traumatic causes. 3) Axial instabilities fall outside this general etiologic term. 4) The term lunotriquetral is preferred to triquetrolunate by many to follow the general rule to name ligaments from radial to ulnar. CODE: Clinical conditions: Sprains-Instabilities-Subluxations (IIIB) 1. MacConaill MA. The mechanical anatomy of the carpus and its bearing on some surgical problems. J Anat. 1941;75: Lichtman DM, Martin RA. Introduction to the carpal instabilities. In: Lichtman DM, editor. The wrist and its disorders. Philadelphia: WB Saunders; p Cooney WP 3rd, Linscheid RL, Dobyns JH. Fractures and dislocations of the wrist. In: Rockwood CA JR, Green DP, Bucholz RW, Heckman JD, editors. Fractures in adults. 4th ed. Philadelphia: Lippincott-Raven; p Mayfield JK, Johnson RP, Kilcoyne RK. Carpal dislocations: pathomechanics and progressive perilunar instability. J Hand Surg [Am]. 1980;5: TRANSVERSE PLANE (SEE FIGURE 27) SYNONYMS: cross section, dorsal-to-volar plane, axial plane, transaxial plane CLINICAL: 1) dorsopalmar plane at right angles to the longitudinal axis of the hand. 2) Dorsopalmar plane at right angles to the longitudinal axis of the body, including the upper limb. RADIOLOGIC: see CLINICAL COMMENT: views in this plane are much more common now that computed tomography and MRI imaging are frequently used.

61 61 CODE: Radiologic: Planes (IB) 1. anatomy or radiology textbooks TRIQUETROHAMATE INSTABILITY (SEE FIGURE 16) SYNONYMS: ulnar midcarpal instability (UMI) (see comment #3), medial anterior midcarpal instability (MAMI) CLINICAL: 1) loss of the ability to keep a normal anatomic and/or kinematic relationship between the triquetrum and the hamate under physiologic loads. Usually due to rupture of the palmar triquetrohamatocapitate ligament. 2) Usually associated with lack of integrity in or around the space of Poirier, which is usually associated with CIND-VISI, contrasted to the CID-VISI, which is associated with lunotriquetral dissociation. RADIOLOGIC: not yet defined COMMENTS: 1) although the key ligament disruption is often in the ulnar volar arcuate (triquetro-hamate-capitate ligament) system, additional weakness around the space of Poirier contributes, and the proximal carpal row collapses as a unit unless there is also a lunotriquetral injury. For this reason, this condition is usually referred to as a midcarpal instability, but this also is problematic since some CIND-VISI collapse of the proximal carpal row occurs from radiocarpal ligament injury or from combinations of radiocarpal and midcarpal injury. 2) This is a condition accepted by some experts and not recognized by others. Therefore, with time, this may become more accepted or may be dropped as a true clinical condition. 3) There is some question if triquetrohamate instability and ulnar midcarpal instability are true synonyms. CODE: Clinical Conditions: Sprains-Instabilities-Subluxations (IIIB) 1. Lichtman DM, Schneider JR, Swafford AR, Mack GR. Ulnar midcarpal instability clinical and laboratory analysis. J Hand Surg [Am]. 1981;6; Taleisnik J. Triquetrohamate and triquetrolunate instabilities (medial carpal instability). Ann Chir Main. 1984;3: Schernberg F. Roentgenographic examination of the wrist: a systematic study of the normal, lax and injured wrist. Part 1: The standard and positional views. J Hand Surg [Br]. 1990;15: Schernberg F. Roentgenographic examination of the wrist: a systematic study of the normal, lax, and injured wrist. Part 2: stress views. J Hand Surg [Br]. 1990;15: Saffar P. Midcarpal instability. In: Saffar P, editor. Carpal injuries: anatomy, radiology, current treatment. Paris: Springer; p Wright TW, Dobyns JH, Linscheid RL, Macksoud W, Siegert J. Carpal instability non-dissociative. J Hand Surg [Br]. 1994;19: Dobyns JH. Carpal instability a review. In: Nakamura R, Linscheid RL, Miura T, editors. Wrist disorders current concepts and challenges. Tokyo: Springer; p TRIQUETROLUNATE BALLOTTEMENT (FIGURE 63) SYNONYMS: dorsovolar triquetrolunate translation or displacement test, triquetrolunate (lunotriquetral) shear test, Reagan-Linscheid test, lunotriquetral ballottement (see comment #2) CLINICAL: a clinical test in which the triquetrum and pisiform are held between the thumb and index finger of one examining hand, and the lunate is held similarly by the other hand. The examiner then attempts to translate the triquetrum dorsally and palmarly with regard to the lunate. The test is positive if there is excess mobility and/or crepitance between the triquetrum and lunate, especially if different from the opposite side. The test should reproduce the patient s pain. RADIOLOGIC: NA Fig. 63 TRIQUETROLUNATE BALLOTTEMENT: pressure is placed over the lunate and triquetral bones to cause translation between these bones and to see if pain of the presenting type is produced with this maneuver. Such produced pain supports ligamentous disruption at this site. (Reprinted with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 17. Fig 2-20.) COMMENTS: 1) this test does not always define stability between just the lunate and triquetrum but may also test the integrity of the ligaments between the triquetrum and/or scaphoid and/or capitate and hamate. 2) Many patients have prominent mobility at the lunotriquetral [triquetrolunate (TL)] level. Such mobility alone is not a problem when not accompanied by reproducible pain. CODE: Tests (IV) 1. Reagan DS, Linscheid RL, Dobyns JH. Lunotriquetral sprains. J Hand Surg [Am]. 1984;9: LaStayo P, Howell J. Clinical provocative tests used in evaluating wrist pain: a descriptive study. J Hand Ther. 1995;8: Berger RA, Dobyns JH. Physical examination and provocative maneuvers of the wrist. In: Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p

62 62 TRIQUETROLUNATE DISSOCIATION see LUNOTRIQUETRAL DISSOCIATION TRIQUETROLUNATE (LUNOTRIQUETRAL) INSTABILITY see LONGITUDINAL (COLUMNAR) INSTABILITY PATTERN TRIQUETROLUNATE SHEAR TEST see TRIQUETROLUNATE (LUNOTRIQUETRAL) BALLOTTEMENT TRISCAPHE JOINT (SEE FIGURE 59) see SCAPHOTRAPEZIOTRAPEZOIDAL (STT) JOINT SYNONYMS: scaphotrapeziotrapezoidal (STT) joint, distal scaphoid articulation, radial midcarpal joint CLINICAL: see STT joint RADIOLOGIC: see CLINICAL COMMENTS: 1) not a term unless used with the word joint. 2) The term was coined by Dr. Kirk Watson. 3) It is a contemporary and controversial term without descriptive meaning or Latin root origin; however, it has been widely publicized in and out of the literature and may survive. 4) Some experts consider this term slang, and consider STT a better contraction. Other experts do not accept this term. CODE: Anatomic: Radial (IIA) 1. see SCAPHOTRAPEZIOTRAPEZOIDAL (STT) JOINT and ROTARY SUBLUXATION OF THE SCAPHOID (RSS) ULNAR see MEDIAL SYNONYMS: medial, ulnolateral, hypothenar, little-finger side, ulnarward CLINICAL: the side of the wrist occupied normally by the ulnar head, triangular fibrocartilage (TFC), triquetrum, hamate, and fourth and fifth metacarpal bases and the soft tissues enveloping them (see MEDIAL) RADIOLOGIC: see CLINICAL COMMENTS: 1) ulnar is only an adjective, never a noun. 2) Ulnar occasionally means of ulna besides medial, as in ulnar collateral ligament of the elbow joint. 3) The use of ulnar is more descriptive and is less likely to be misused than the term medial when dealing with the wrist. CODE: Radiologic: Sides (IC) 1. anatomy textbooks ULNAR COLUMN (SEE FIGURE 21) see ROTARY COLUMN SYNONYMS: medial column, rotary column CLINICAL: the hamate, triquetrum, and triangular fibrocartilage and their articulations RADIOLOGIC: see CLINICAL COMMENTS: 1) see ROTARY COLUMN. 2) Some experts do not use this term. 3) Some experts believe this is a more useful term than rotary column, but ulnar wrist and specific terminology for the exact location should suffice. CODE: Anatomic: Ulnar (IIC) 1. see ROTARY COLUMN ULNAR IMPINGEMENT see IMPACTION SYNDROME, ULNOCARPAL ULNAR INCLINATION OF DISTAL RADIUS see RADIAL INCLINATION OF DISTAL RADIUS ULNAR MIDCARPAL INSTABILITY (UMI) see TRIQUETROHAMATE INSTABILITY ULNAR OBLIQUE SCAPHOID VIEW/POSITION see REVERSE PA OBLIQUE VIEW ULNAR RADIOCARPAL SUBLUXATION see ULNAR TRANSLATION ULNAR TRANSLATION (UT) OF THE CARPUS (FIGURE 64; FIGURE 22) SYNONYMS: ulnar translocation, ulnar radiocarpal subluxation CLINICAL: ulnar displacement of the hand at the radiocarpal joint relative to the forearm. RADIOLOGIC: 1) assessment is made on the zero (neutral) PA view (see COMMENTS). Qualitative and quantitative criteria exist. Qualitatively, UT is diagnosed when >50% of the lunate projects ulnar to the ulnarmost extent of the radiolunate fossa and the lunocapitate alignment remains normal (see reference #1). Also, when there is increased width of the radioscaphoid joint space compared to the radiolunate joint space, UT may be present. Quantitatively, UT is present when McMurtry s index ( carpal-ulnar distance) is <0.27 (see Mc- MURTRY S INDEX). 2) Chamay measurement for ulnar translation (Figure 22) is a measurement calculating a ratio between the length of the third metacarpal and the distance between the radial styloid and the central portion of the capitate head to determine ulnar translation of the carpus. A perpendicular line (L4) is measured between a line drawn proximal-distal (ARS) through the radial styloid process and the center of the head of the capitate through the carpal height line (L2) and the length of the third metacarpal (L1). Normally the ratio of ulnar translation (L4) to the length of the third metacarpal (L1) is defined as 0.28 ± 0.03 (see reference #2). 3) Two types of ulnar translations are recognized (Taleisnik) from the radiographic standpoint: Type I, in which the entire carpus is displaced ulnarward, with widening of the space between the radial styloid and the scaphoid; and Type II, in which the scaphoid retains an essentially normal relationship to the radius, while the remainder of the carpus migrates ulnarly, creating an abnormal scapholunate gap. COMMENTS: 1) the neutral PA position must be present as identified by the central axis of the third metacarpal being parallel to the midplane of the radius. Radial deviation of the wrist normally moves the lunate ulnar to the radius. 2) The Chamay method ( carpalradial styloid distance) of measuring UT using the radial styloid may be better when the ulnar head is absent. Some people prefer this method to measure UT routinely. 3) Palmar carpal subluxation commonly occurs simultaneously with ulnar carpal translation. 4) Ulnar translation, Type II, differs from the usual SLD (scapholunate dissociation) in that with UT Type II, there is an element of extrinsic (capsular) ligament damage as well as the intrinsic (interosseous) ligament damage. 5) This is a true subluxation, which is not spontaneously reducible.

63 63 Fig. 64a Fig. 64b ULNAR TRANSLATION (UT): a) ulnar translation Type I (the entire carpus is moved ulnarly) is recognized here with the radioscaphoid joint wider than all the other intercarpal and the radiolunate joints. Also, more than one half the width of the lunate projects ulnar to the edge of the radius with the wrist in neutral position (third metacarpal is coaxial with the midaxis of the radius). b) Type II ulnar translation is recognized when the radioscaphoid joint is normal, but the remainder of the carpus, identified by the position of the lunate with respect to the radius, is displaced ulnarly (as described in part a of this caption). The wrist is in slight radial deviation, which demonstrates the scapholunate dissociation and the ulnar lunate displacement. However, this illustration emphasizes the concept of the Type II ulnar translation. (Reprinted and modified with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 209. Fig 8-7B.) CODES: Clinical Conditions: Sprain-Instabilities-Subluxations (IIIB); Radiologic: Measurements (IE) 1. Gilula LA, Weeks PM. Post-traumatic ligamentous instabilities of the wrist. Radiology. 1978;129: Chamay A, Della Santa D, Vilaseca A. [Radiolunate arthrodesis. Factor of stability for the rheumatoid wrist]. Ann Chir Main. 1983;2:5-17. French. 3. Rayhack JM, Linscheid RL, Dobyns JH, Smith JH. Posttraumatic ulnar translation of the carpus. J Hand Surg [Am]. 1987;12: Dibenedetto MR, Lubbers LM, Coleman CR. Relationship between radial inclination angle and ulnar deviation of the fingers. J Hand Surg [Am]. 1991; 16: Pirela-Cruz MA, Firoozbakhsh K, Moneim MS. Ulnar translation of the carpus in rheumatoid arthritis: an analysis of five determination methods. J Hand Surg [Am]. 1993;18: Viegas SF, Patterson RM, Ward K. Extrinsic wrist ligaments in the pathomechanics of ulnar translation instability. J Hand Surg [Am]. 1995;20: McMurtry RY, Youm Y, Flatt AE, Gillespie TE. Kinematics of the wrist. II. Clinical applications. J Bone Joint Surg Am. 1978;60: Taleisnik J. Classification of carpal instability. Bull Hosp Jt Dis Orthop Inst. 1984;44: Taleisnik J. Current concept review. Carpal instability. J Bone Joint Surg Am. 1988;70: ULNAR TRANSLOCATION see ULNAR TRANSLATION ULNAR/ULNA VARIANCE (FIGURE 65) SYNONYMS: ulnar variant, ulna variant CLINICAL: relative level of the ulna (center of distal subchondral surface) to that of the radius at the subchondral surface of the distal radioulnar joint (DRUJ). This level is classified as minus when ulnar length is shorter than the radius, plus (positive) when the ulna is longer, and neutral or zero when both are approximately equal. RADIOLOGIC: the zero (neutral) PA view is used for determination (see NEUTRAL POSTEROANTERIOR VIEW for exact positioning). Two reproducible methods of measurement can be used: 1) extend a line perpendicular to the long axis of the distal radius from the midportion of the ulnar aspect of the subchondral surface of the distal radius toward the ulna and measure the shortest distance between this line and the distalmost subchondral carpal surface of the ulna, excluding the ulnar styloid (reference #1); and 2) with use of a template of concentric circles placed to best fit the contour of the articular margin of the distal radius, the concentric circle that best approximates the distal radial surface is selected as a reference and compared in millimeters to the carpal surface of the ulna (reference #2). COMMENTS: 1) since the ulnar length varies between individuals and ethnic groups, there are no real abnormal values. However, it is not common to find a variance of more than 3 mm either way. 2) Precise positioning (elbow should be flexed 90 and abducted to shoulder height) is necessary for reproducible measurement of ulnar variance. Recognizing that the groove of the extensor carpi ulnaris tendon is radial to the midpoint of the ulnar styloid, or preferably radial to the base of the ulnar styloid, can help validate correct posi-

64 64 Fig. 65a Fig. 65b ULNAR VARIANCE: all these are PA views made with the elbow at the shoulder height, the acceptable position to measure ulnar variance, which is the relative length of the ulna compared to the radius. Recognition of this position at radiography is supported by the fact that the extensor carpi ulnaris (ECU) groove (arrows) is radial to the midportion of the ulnar styloid. These views show a) ulnar neutral variance, b) ulnar negative variance, and c) ulnar positive variance. See text. Fig. 65c tioning (reference #6). 3) The ulnar head moves distally in pronation and proximally in supination. CODE: Radiologic: Measurements (IE) 1. Gelberman RH, Salamon PB, Jurist JM, Posch JL. Ulnar variance in Kienböck s disease. J Bone Joint Surg Am. 1975;57: Palmer AK, Glisson RR, Werner FW. Ulnar variance determination. J Hand Surg [Am]. 1982;7: Kristensen SS, Thomassen E, Christensen F. Ulnar variance determination. J Hand Surg [Br]. 1986;11: Czitrom AA, Dobyns JH, Linscheid RL. Ulnar variance in carpal instability. J Hand Surg [Am]. 12;1987: Schuind FA, Linscheid RL, An KN, Chao EY. A normal data base of posteroanterior roentgenographic measurements of the wrist. J Bone Joint Surg Am. 1992;74: Jedlinski A, Kauer JM, Jonsson K. X-ray evaluation of the true neutral position of the wrist: the groove for extensor carpi ulnaris as a landmark. J Hand Surg [Am]. 1995;20: ULNAR/ULNA VARIANT see ULNAR VARIANCE ULNOCARPAL ABUTMENT see

65 65 VOLAR SYNONYMS: anterior, palmar, ventral CLINICAL: the opposite side of the wrist from the dorsum; the portion of the wrist structures covered by the skin of the proximal palm and the distal, palmar skin of the forearm RADIOLOGIC: the portion of the wrist including the skeletal pillars (tuberosity of the scaphoid and trapezium, pisiform, hook of hamate) and the soft tissue structures adjacent to them COMMENTS: 1) volar is an adjective and at the wrist is used to indicate the underside of the wrist or any of its structures. 2) Although the term preferred by anatomists is said to be palmar, the term in most common usage among wrist investigators and surgeons is volar. 3) Some wrist experts in the past have not liked this word because they believed the root of the word vole refers to a small mouse-like rodent. However another wrist expert (James Dobyns) points out that the field mouse or vole is named from the Norwegian woll or field, not from the Latin vol, which refers to the palm or sole. CODE: Radiologic: Sides (IC) 1. anatomy or radiology textbooks Fig. 66a VOLAR INTERCALATED SEGMENT INSTABILITY (VISI): a) lateral view: the lunate is tilted palmarly as is the scaphoid to provide a decreased scapholunate angle of <30 and a capitolunate angle to be abnormally increased to >30. The capitate is also slightly subluxed ventrally. b) Diagrams of the wrist with VISI configuration in the lateral position from left to right show that, with VISI, both the scaphoid and lunate tilt (both curved arrows pointing toward the palm) toward the palm. As that happens, with time, the proximal end of the capitate tends to sublux ventrally (small arrow). Such change in alignment produces the typical decreased scapholunate angle of <30, and/or an increased capitolunate angle of >30. S = scaphoid, C = capitate, and L = lunate axes. (Reprinted with permission from Gilula LA, Yin Y, editors. Imaging of the wrist and hand. Philadelphia: WB Saunders; p 217. Fig 8-17, A and B.) IMPACTION SYNDROME, ULNOCARPAL ULNOCARPAL IMPACTION SYNDROME see IMPACTION SYNDROME, ULNOCARPAL ULNOCARPAL IMPINGEMENT see IMPACTION SYNDROME, ULNO CARPAL ULNOVOLAR CARPAL PROJECTION see SEMISUPINATED OBLIQUE VIEW VOLAR CARPAL TRANSLATION see PALMAR RADIOCARPAL SUBLUXATION VOLAR INTERCALATED SEGMENT INSTABILITY (VISI) (FIGURE 66) SYNONYMS: ventral ISI (VISI), palmar ISI (PISI), volar intercalated segmental instability (VISI), flexion instability CLINICAL: a general class of symptomatic carpal instability characterized by pathologic volar flexion of the lunate, with or without a similar posture of the other proximal carpal row bones, and asynchronous movement of the proximal and distal carpal rows. Also, see CIND-VISI and CID-VISI and comments #1 and #6. RADIOLOGIC: on a neutral (zero) lateral radiograph, the radiolunate angle is >20, and/or the capitolunate angle is >30, and/or the scapholunate angle is <30. To recognize abnormal motion within the proximal carpal row, fluoroscopic evaluation in the lateral position with flexion and extension and in the PA position with radial and ulnar deviation allows recognition if the lunate moves smoothly (synchronously) with the scaphoid and triquetrum or if one or more of these three bones move(s) in a nonsmooth (asynchronous) manner. COMMENTS: 1) occasional patients with ligamentous laxity have a configuration of VISI (CIND-VISI) that is asymptomatic, com- Fig. 66b UNBONDED see DISSOCIATION UNLINKED see DISSOCIATION VENTRAL see VOLAR, PALMAR VENTRAL INTERCALATED SEGMENT(AL) INSTABILITY (VISI) see VOLAR INTERCALATED SEGMENT INSTABILITY