1638 October Special Issue 2011 radiographics.rsna.org Figures 1, 2. (1) Normal findings after limited scapholunate arthrodesis. Posteroanterior (a) a

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1 Note: This copy is for your personal non-commercial use only. To order presentation-ready copies for distribution to your colleagues or clients, contact us at MUSCULOSKELETAL IMAGING 1637 Imaging Assessment of the Postoperative Arthritic Wrist1 CME FEATURE See /rg_cme.html LEARNING OBJECTIVES FOR TEST 4 After completing this journal-based CME activity, participants will be able to: Discuss the indications for arthrodesis and the advantages it offers compared with arthroplasty and carpectomy. Describe the normal postoperative imaging findings after wrist arthroplasty, arthrodesis, and carpectomy. List the most common complications of each type of wrist surgery. Jonelle M. Petscavage, MD, MPH Alice S. Ha, MD Felix S. Chew, MD Wrist arthritis is a common disease entity that can result in severe pain, swelling, and decreased wrist motion, leading to the impairment of daily activities and vocational functions. Nonsurgical treatment for wrist arthritis can improve function and provide pain relief in some cases. With disease progression, however, conservative therapy may become ineffective, and surgical treatment may be required. The three main surgical options for wrist arthritis are arthrodesis, carpectomy, and arthroplasty. Because of the high prevalence of wrist arthritis, radiologists will commonly encounter images that were obtained in patients who have undergone one or more of these surgical options. All three options are common in contemporary orthopedic practice and have evolved in recent years, making it imperative that radiologists understand current procedures and stay abreast of advances in techniques and hardware. In addition, familiarity with both normal and abnormal postoperative imaging findings can aid in the assessment of complications and early failure. Introduction Wrist arthritis affects approximately 13.6% of the U.S. population (1). It can result in severe pain, swelling, and decreased wrist motion, which may impair daily activities and vocational functions. Osteoarthritis (also known as degenerative arthritis) of the wrist is most commonly secondary to trauma resulting from (a) fractures of the distal radius, scaphoid, or carpal bones; (b) scapholunate ligament injury; or (c) Kienböck disease (1). Rheumatoid arthritis is a complex inflammatory process that often starts in the small joints of the hand and wrist. The wrist is involved in 75% of patients with rheumatoid arthritis, or 2.5 million people in the United States (2). Other sources of wrist arthritis include juvenile inflammatory arthritis, calcium pyrophosphate deposition disease, gout, and spastic or congenital disorders such as Madelung deformity. Nonsurgical treatment options for wrist arthritis include splint or cast immobilization, disease-modifying agents (for rheumatoid arthritis), and nonsteroidal anti-inflammatory drugs (for degenerative arthritis) (3). Intraarticular injections of corticosteroids can also improve function and provide pain relief in selected patients. However, as disease progresses, conservative management options may lose their efficacy. Several surgical options are available when conservative management fails. In this article, we discuss the three main surgical options for wrist arthritis wrist arthrodesis, carpectomy, and arthroplasty along with the latest surgical techniques and Abbreviation: DRUJ = distal radial ulnar joint RadioGraphics 2011; 31: Published online /rg Content Code: From the Department of Radiology, Penn State Hershey Medical Center, 500 University Dr, Hershey, PA (J.M.P.); and Department of Radiology, University of Washington Medical Center, Seattle, Wash (A.S.H., F.S.C.). Recipient of a Cum Laude award for an education exhibit at the 2010 RSNA Annual Meeting. Received February 2, 2011; revision requested February 22 and received May 25; accepted June 9. For this journal-based CME activity, the authors, editor, and reviewers have no relevant relationships to disclose. Address correspondence to J.M.P. ( jopa905@gmail.com). 1 RSNA, 2011 radiographics.rsna.org

2 1638 October Special Issue 2011 radiographics.rsna.org Figures 1, 2. (1) Normal findings after limited scapholunate arthrodesis. Posteroanterior (a) and lateral (b) radiographs of the wrist obtained 1 month after surgery for a ligament tear show a single Herbert screw (arrow in a) across the scapholunate joint. Suture anchors are also present in the scaphoid, lunate, and capitate bones. (2) Normal findings after limited triscaphe arthrodesis. Posteroanterior (a) and lateral (b) radiographs of the wrist obtained 3 months after surgery show two Herbert screws across the scaphoid, trapezium, and trapezoid bones (black arrow in a). Radial styloidectomy (white arrow in a) is routinely performed to prevent styloid impaction on the scaphoid bone. The round radiolucent defect in the distal radius (arrowhead in a) represents the bone graft donor site. hardware used around the wrist joint, indications for and alternatives to each surgical option, and the normal postoperative imaging findings as well as the complications associated with each option. Surgical Options Wrist Arthrodesis Wrist arthrodesis is surgical fusion between at least two bones in an attempt to decrease pain and slow or eliminate disease progression at the involved joint or joints. The first wrist arthrodesis was performed in 1910 in a patient with tuberculous arthritis of the wrist (4). Numerous technical advances have been made since that time. Currently, three main types of wrist arthrodesis are performed: limited, four-corner, and total wrist arthrodesis. Limited Wrist Arthrodesis. Limited wrist arthrodesis involves fusion between two or three bones, such as across the scapholunate joint (Fig 1) or triscaphe joint (Fig 2). Limited wrist arthrodesis is designed to treat isolated pain and instability related to ligament tears, osteoarthritis, or scapholunate advanced collapse while preserving motion at other normal joints (5). Radioscapholunate arthrodesis is most commonly performed for rheumatoid arthritis or posttraumatic arthritis from intraarticular distal radius fractures. At surgery, bone spurs, denuded cartilage, and irregular bone surfaces are removed and smoothed, and cancellous bone graft material from the distal radius or the iliac crest is placed across the joint (6). On radiographs and computed tomographic (CT) scans, the bone graft donor site is initially seen as a radiolucent defect in the distal radius, which scleroses over time as the graft site heals with the formation of new osteoid. Radial styloidectomy (Fig 2) is routinely performed to prevent secondary impingement and radial-sided wrist pain, which have been reported in up to 33% of patients who have not undergone styloidectomy (7).

3 RG Volume 31 Number 6 Petscavage et al 1639 Figure 3. Unsuccessful limited triscaphe arthrodesis in a 51-year-old patient. Coronal CT scans (bone window) obtained 18 months after surgery show lack of osseous bridging (arrow) across the trapezium-trapezoid (a) and scaphoid-trapezium (b) articulations, findings that represent nonunion. The round radiolucent defect in the distal radius (arrowhead in a) represents the bone graft donor site. Figure 4. Normal findings after four-corner arthrodesis. In both cases, the sclerotic area in the distal radius (arrowhead) represents a healed bone graft donor site, and the scaphoid bone has been excised. (a) Posteroanterior radiograph obtained 4 months after surgery shows the expected degree of four-corner fusion, which was achieved with K wires (white arrow) and screws (black arrow). (b) Posteroanterior radiograph obtained in a different patient 3 months after surgery shows four-corner fusion between the hamate, lunate, capitate, and triquetral bones that was achieved with staples (arrow). Hardware fixation can be achieved with staples, percutaneous K (Kirshner) wires, volar radioscapholunate plates, or screws. The benefits of K wires include low cost, ease of use, and reliable fixation. However, these wires require cast immobilization and eventual removal. In addition, K wires may protrude, resulting in soft-tissue infection or sensory nerve irritation (8). Staples are stable for fixation but may impinge against the distal radius during wrist extension. Screws (particularly if headless) provide stable compression with little impingement but may be more difficult to orient optimally (8). Hardware should remain in stable position with no perihardware radiolucent areas, impingement with extension, or fracture. Progressive fusion across the surgical site should be seen on subsequent radiographs, and fusion should be complete within 6 months on average. Nonunion rates are 0% 29% for the triscaphe joint (Fig 3), 5% 27% for the radioscapholunate joint, and over 50% for the scapholunate joint (9,10). Rates of nonunion for limited arthrodesis are higher than for fourcorner or total wrist arthrodesis because of the smaller surface areas of the two or three fused bones relative to the large torques applied by the supporting wrist ligaments (5). The postoperative range of motion at the triscaphe joint is approximately 66% of normal, compared with only 33% 50% of normal at the radioscapholunate, scapholunatocapitate, and scaphocapitate joints (3). The range of radioscapholunate motion improves if distal scaphoid resection is concomitantly performed (11). Relief of pain from degenerative or posttraumatic arthritis is good to excellent in most outcome studies as measured with DASH (Disabilities of the Arm, Shoulder, and Hand) standardized survey scores (12,13). Outcomes are poorer for radioscapholunate arthrodesis for rheumatoid arthritis, with continued midcarpal destruction and carpal collapse at 5 years (14,15). Four-Corner Arthrodesis. Four-corner arthrodesis involves fusion between the hamate, lunate, capitate, and triquetral bones, with concurrent scaphoid excision (Fig 4). Indications for four-corner fusion

4 1640 October Special Issue 2011 radiographics.rsna.org Figure 5. Normal carpal alignment in four-corner arthrodesis. Lateral radiograph obtained in a patient who had undergone four-corner arthrodesis performed with staples (a) and diagram of the wrist (lateral view) (b) show the expected position of the carpus (neutral to slightly volar intercalated position) to prevent dorsal radiocarpal impingement with extension. Figure 6. Complication of arthrodesis performed with a circular fusion plate. As seen on a lateral radiograph (a) and sagittal (b) and coronal (c) reformatted CT images (bone window), the proximal aspect of the plate is below the dorsal lip of the radius (arrow in a and b) and the lunate bone is dorsally tilted, resulting in dorsal impingement with extension and potentially causing trauma to the radiocarpal joint as well as fracture of the screws and plate. The radiolucent area in the distal radius represents the bone graft donor site. include scapholunate advanced collapse, midcarpal instability, and scaphoid fracture nonunion with secondary osteoarthritis (15). The goals of the procedure are to relieve pain and restore wrist stability and height while providing a more physiologic motion through the preserved radiolunate and ulnocarpal joints. Normally, 30% 36% of wrist flexion occurs at the midcarpal joint, whereas 63% 70% occurs at the radiocarpal joint (16). Thus, there will be a compensatory increase in motion at the unfused joint. Postoperatively, patients maintain 40% 60% of normal flexion-extension motion and 75% 80% of normal grip strength (3). On lateral radiographs and sagittal CT scans, the midcarpal joint should be held in a neutral to slightly volar intercalated position (Fig 5) to avoid dorsal radiocarpal impingement (6). By weeks, the radiologist should see complete fusion. As with limited wrist arthrodesis, the bone graft donor site will be noted in the iliac crest or distal radius. Since the 1980s, K wires, staples, or screws have been used for the procedure. Over the past decade, circular locking plates have also been used. However, nonunion rates are higher for four-corner fusion performed with a dorsal circular plate (10% 62%) versus other hardware (<10%) (17,18). It is also more difficult to radiographically visualize the degree of fusion through the radiopaque plate, and the hardware is prone to screw fracture and dorsal plate impingement (Fig 6). A new type of plate used for four-corner fusion is the Xpode fusion plate (TriMed, Santa Clarita, Calif) (Fig 7) (19). Eight or 10 threaded screws are angled and lock into the plate, which

5 RG Volume 31 Number 6 Petscavage et al 1641 Figure 7. Normal findings after fourcorner arthrodesis with an Xpode fusion plate (TriMed). Posteroanterior (a) and lateral (b) radiographs show an Xpode fusion plate (arrow in a) secured with eight locking screws. The biocompatible polymer plate material is radiolucent, allowing better visualization of the degree of fusion over time. The site of prior radial styloidectomy is also noted, as well as the bone graft donor site in the distal radius. Complications arise in approximately 13.5% of cases of four-corner arthrodesis, most commonly from dorsal radiocarpal impingement (21,22). Other complications include malunion from incomplete correction of lunate dorsiflexion, hardware irritation and impingement, hardware loosening (Fig 8), and deep infection (23). Figure 8. Hardware complication of four-corner arthrodesis performed with a bone graft and screws. Posteroanterior radiograph obtained 7 months after surgery shows loosening of the horizontally oriented screw and a radiolucent area (black arrow). There is also nonunion, which is seen as lack of osseous bridging across the bones. Note the attempted fusion of the first carpometacarpal joint with two screws, one of which has become loosened (white arrow). is made of a biocompatible radiolucent polymer, allowing visualization of the degree of fusion across the four corners. There is still the risk of dorsal rim impingement, backing out or fracture of screws, and breakdown of the polymer material, resulting in foreign body reaction. A preliminary outcome study shows significantly lower failure rates and increased stability and extension with cyclic loading of the Xpode plate (TriMed) compared with the spider plate (a type of circular plate) and K wires (20). Total Wrist Arthrodesis. In total wrist arthrodesis, the distal radius is fused across the proximal and distal carpal rows to the base of the third metacarpal bone. The goals of total wrist arthrodesis are (a) to provide pain relief by removing destroyed cartilage, and (b) to prevent future degenerative changes (24). Total wrist arthrodesis is performed at the expense of a loss of wrist motion and shock absorption. Indications for this procedure include primary or posttraumatic arthritis, intercalated segment instability, inflammatory arthritis, carpal osteonecrosis, severe spastic wrist deformity, and bone loss from tumor or trauma (25). Absolute contraindications include an open distal radius epiphyseal plate in the skeletally immature patient, the absence of satisfactory soft-tissue coverage, and the presence of an active wrist infection (24). Total wrist arthrodesis is currently most commonly performed with use of a precontoured dorsal locking plate (Fig 9). The plate is low profile, so that there is little soft-tissue irritation and improved blood supply to support the fusion (26). Proximal screws lock to the plate at a fixed angle to create a stronger hold, with distal compression screws to increase joint stability.

6 1642 October Special Issue 2011 radiographics.rsna.org Figure 9. Normal findings after total wrist arthrodesis performed with a low-profile precontoured dorsal locking plate. On posteroanterior (a) and lateral (b) radiographs, the plate is flush with the bone and is held in place by proximal locking screws and, for increased stability, by distal compression screws. The bone graft bridges the radiocarpal articulations. Complete fusion should be seen across at least six cortices by 6 months after surgery. Figure 10. Normal findings after total wrist arthrodesis performed with a straight dorsal plate. Posteroanterior (a) and lateral (b) radiographs show the straight dorsal plate and screws that were used for the procedure. There are at least six critical cortices of fixation to fuse namely, the radioscaphoid, radiolunate, scaphocapitate, capitolunate, and capitotrapezoid joints and the third metacarpal bone but doing so creates the risk of fracture through the third metacarpal bone at the screw hole. Straight plates are also available for use in total wrist arthrodesis for stabilization, interposition of corticocancellous bone graft, or replacement of larger carpal defects caused by trauma or tumor (Fig 10) (6). Alternatively, large Steinmann pins have been used in patients with rheumatoid arthritis. Ultimately, fixation with a dorsal compression plate has better nonunion rates (2% 4%) than do older methods of fixation (up to 19%) (27). At imaging, the total wrist fusion should be at an approximately 10 angle of dorsiflexion for optimal grip strength in patients without rheumatoid arthritis, and in a neutral to slightly flexed position in patients with inflammatory arthritis (28). The plate should be flush with the dorsal bone cortex, with good purchase of the screws. The fusion should occur across at least six cortices and should be complete within approximately 6 months. At 12 months, the plate can be removed; however, doing so poses the risk of fracture through the old screw tracks.

7 RG Volume 31 Number 6 Petscavage et al 1643 Figures 11, 12. (11) Soft-tissue complication of total wrist arthrodesis performed with a precontoured dorsal locking plate. (a) Lateral radiograph obtained 1 month after the procedure shows soft-tissue swelling and air in the dorsal soft tissues (arrowhead). (b) Color Doppler US image shows fluid tracking in the subcutaneous dorsal soft tissues with increased flow. At surgery, the patient was found to have a small abscess and cellulitis. (12) Hardware complications of total wrist arthrodesis. (a) Lateral radiograph obtained in a patient who had undergone total wrist arthrodesis with a precurved dorsal plate and screws shows loss of purchase of the three distal compression screws, with loosening of the distal plate (arrowhead). (b) Posteroanterior radiograph obtained in a different patient who had undergone total wrist arthrodesis with a straight plate shows perihardware fracture adjacent to the proximal plate tip. The gracile underlying bones are the result of a congenital contractile disorder of the extremity. (c) Lateral radiograph obtained in a third patient who had undergone total wrist arthrodesis with a precurved dorsal plate shows fracture of the most distal screw. The most common type of postoperative complication is soft tissue in nature, due to large soft-tissue flaps, extensive bone preparation, and thin subcutaneous skin in patients with inflammatory arthropathy who are taking oral steroids (27). Soft-tissue complications include hematoma, minor skin dehiscence in up to 20% 30% of patients (28), and infection (0.5% 3%) (28,29). In 35% 65% of cases, the dorsal plate can be felt as a painful prominence or form a painful dorsal bursa (30). Ultrasonography (US) or CT can be helpful in differentiating simple

8 1644 October Special Issue 2011 radiographics.rsna.org Figure 13. Normal findings after proximal row carpectomy. On posteroanterior (a) and lateral (b) radiographs, the scaphoid, lunate, and triquetral bones have been resected, with a new articulation between the lunate fossa of the distal radius and the capitate bone. The 2-mm residual joint space (arrow in a) is a normal postoperative finding. Note also the volar plate with screw fixation (arrowhead in a) across a distal radius osteotomy for prior treatment of a fracture nonunion. Figure 14. Progressive osteoarthritis as a complication of proximal row carpectomy in a 55-year-old woman. Posteroanterior (a) and lateral (b) radiographs obtained 10 years after surgery show severe narrowing of the capitate-radial articulation with osteophyte formation, subchondral sclerosis, and irregular bone surfaces (arrow in a). fluid collections from more complex abscesses (Fig 11). Additional soft-tissue injuries include carpal tunnel syndrome (10% 25% of cases) and extensor tendon adhesions (27). Hardware complications include perihardware fracture, fracture of screws, and loss of purchase of the dorsal plate (Fig 12). Proximal Row Carpectomy Proximal row carpectomy is a motion-sparing surgical alternative to arthrodesis in patients with isolated scaphoradial osteoarthritis due to scaphoid fracture nonunion or scapholunate advanced collapse, progressive Kienböck disease, a failed lunate bone prosthesis, or chronic perilunate dislocation (31). The procedure is contraindicated in patients with capitolunate or inflammatory arthritis (32). Physiologically, the procedure changes the radiocarpal joint from a complex joint to a simple hinge joint (33). Advantages of proximal row carpectomy compared with arthrodesis include preservation of a functional range of motion, greater postoperative wrist strength, less time to recovery, and technical ease of the procedure (34). Because no hardware is used, there is a lower risk of hardware-related or postoperative complications. The scaphoid, lunate, and triquetral bones are surgically removed, creating a new articulation between the capitate bone and the lunate fossa of the distal radius (Fig 13). At imaging, an approximately 2-mm residual joint space is present. Progressive osteoarthritis of the radiocarpal joint is the most common complication of proximal row carpectomy (Fig 14), seen at follow-up years after the procedure as joint space narrowing to 1 mm or less, with osteophyte formation and subchondral sclerosis and cysts (34,35).

9 RG Volume 31 Number 6 Petscavage et al 1645 Figure 15. Normal findings after total wrist arthroplasty performed with a Swanson silicone implant. Posteroanterior (a) and lateral (b) radiographs show the implant, with the silicone having very low radiodensity (arrows). Proximal row carpectomy and distal ulnar resection are routinely performed with this type of wrist arthroplasty. Because of subsidence, fracture, continued pain, and disease progression, this type of arthroplasty is now performed only infrequently, although radiologists may still encounter patients with a Swanson silicone implant. Other postoperative complications are usually soft tissue in nature and include infection, hematoma, and tendon injury. Retrospective outcome studies show that patients retain over 80% of normal grip strength and 60% of normal motion postoperatively (3). Short-term outcome studies comparing limited or partial arthrodesis with proximal row carpectomy show no statistical differences with respect to motion, grip strength, or subjective patient outcomes (36,37). Wrist Arthroplasty Wrist arthroplasty is another motion-sparing surgical alternative to arthrodesis. There are two kinds of wrist arthroplasty: total wrist arthroplasty and distal radial ulnar joint (DRUJ) arthroplasty. Total Wrist Arthroplasty. The goals of total wrist arthroplasty include pain relief, primarily in patients with rheumatoid arthritis, but also in those with posttraumatic or primary osteoarthritis and failed arthrodesis (38). The advantages of total wrist arthroplasty compared with arthrodesis include the retention of a partial range of motion for daily and avocational activities. For successful arthroplasty, patients must have adequate bone stock and quality to support the hardware, as well as intact extensor carpi radialis brevis and longus tendons (39). The first wrist arthroplasty was performed in 1890 by Gluck, who used an ivory prosthesis to treat a patient with tuberculous arthritis of the wrist (40). In 1967, Swanson placed a doublestemmed, flexible-hinge silicone implant at the radiocarpal joint (Fig 15) (41). However, high rates of implant fracture, pain at 5 years in 50% of patients, complications of particle disease and osteolysis, and revision rates of 25% 36% resulted in the need for new designs (41). Over the past few decades, several metal wrist devices with semiconstrained or ball-and-socket designs have been used but have proved to be unstable, with loosening, subsidence, and imbalance (42). The universal total wrist prosthesis was designed by Menon in 1990 and combines the concepts of containing fixation within the carpus, stabilizing distal component fixation using screws, and performing intercarpal fusion (43). The latest version of the universal total wrist prosthesis has an elliptic design, resulting in lower dislocation rates. The Remotion total wrist prosthesis (Small Bone Innovations, Morrisville, Pa) is another currently used prosthesis with a similar nonconstrained design. These nonconstrained implants have a flat distal titanium component with a central capitate prong to support axial load transmission. The distal part is attached to the capitate bone with a peg and anchored to the trapezoid and hamate bones with radial- and ulnar-sided screws (Fig 16) (43). The proximal carpal row is resected. The titanium proximal-radial component has a 20 inclination ulnar tilt to mimic the natural

10 1646 October Special Issue 2011 radiographics.rsna.org Figure 16. Normal findings after arthroplasty performed with a universal total wrist prosthesis. Posteroanterior (a) and lateral (b) radiographs show a total wrist prosthesis and ulnar head implant (arrowhead in a). The proximal-radial component (white arrow in a) has an elliptic surface, mimicking normal radial inclination. The radial component articulates with a radiolucent polyethylene carpal component. The distal component (black arrow in a) is affixed to the distal carpal row and the base of the second metacarpal bone with a central peg and two screws. Figure 17. Loosening of the prosthesis as a complication of total wrist arthroplasty. (a) Posteroanterior radiograph shows loosening of the distal component of a total wrist prosthesis (white arrow) and fracture of the screw on the ulnar side of the prosthesis (black arrow). (b) Lateral radiograph shows abnormal inclination and articulation between the distal and proximal components. radius, sits against the scaphoid bone and lunate fossa, and preserves the peripheral rim of the distal radius and ligamentous and soft-tissue attachments. A radiolucent polyethylene insert is placed between the cemented titanium components. The primary elliptic articulation occurs with the radial component, permitting motions of flexionextension and radioulnar deviation. On radiographs, carpal height and alignment should be restored to neutral (44). No dislocation or subluxation between components should be seen. Currently, instead of ulnar head resection, which was associated with complications and instability, a prosthetic ulnar head is placed. Reported complications primarily reflect the progressive nature of inflammatory arthritis in combination with physical forces exerted on the implant by the patient (45). Potential long-term complications include fracture, DRUJ impinge-

11 RG Volume 31 Number 6 Petscavage et al 1647 Figure 18. Normal findings after Scheker total DRUJ arthroplasty. Posteroanterior (a) and oblique (b) radiographs show a Scheker prosthesis, with the fluted ulnar stem (arrowhead) articulating via the hemisocket and polymer ball (arrow) to a radial plate. ment or instability, loosening of the implant (particularly the distal component) (Fig 17), screw fracture, polyethylene wear and particle disease, subsidence, extensor carpi radialis tendon laceration or adhesions, and infection (46). Outcome studies show pain relief of 90% or more and retention of a partial range of motion. Current prostheses allow 60 of extension, 40 of flexion, and 20 of radial and ulnar deviation (44). However, minor and major complication rates are higher than for total wrist arthrodesis. DRUJ Arthroplasty. The DRUJ is particularly important for pronation and supination, grip and lift functions, wrist stability, and load transmission at the elbow and forearm. Arthritis and chronic instability at the DRUJ can result in pain and limited motion. Historically, distal ulnar resection was the treatment of choice, but this procedure has been shown to destabilize the forearm and wrist and result in impingement (46). DRUJ arthroplasty is a new option for the treatment of pain and limitations at the DRUJ. Both constrained and nonconstrained options and total and hemiarthroplasty designs exist. The Scheker prosthesis (Fig 18) is a semiconstrained device for the treatment of symptomatic DRUJ with insufficient supporting soft tissues in patients with inflammatory, degenerative, or posttraumatic arthritis; Madelung deformity; or failure of other surgical management (47). Contraindications include immature skeleton, severe osteoporosis, or less than 11 cm of proximal ulna remaining. Outcome studies show a significant decrease in subjective pain scores and better range of motion and functional scores than with ulnar resection (47). The ulnar component is a fluted cobalt chromium stem and peg. The peg fits inside an ultrahigh-molecular-weight polymer ball that sits in the hemisocket of a cobalt chromium radial plate. The peg moves freely within the ball, and the ball within the socket, for full supination and pronation (48). In addition, the reconstruction of the ulnar component to the distal radius reestablishes lifting capability (48). Potential complications include osteolysis around the ulnar stem, screw fracture or loosening (Fig 19), perihardware fracture, damage to the ball and stem from excessive weight bearing, soft-tissue infection, extensor carpi ulnaris tenosynovitis, and heterotopic ossification (48).

12 1648 October Special Issue 2011 radiographics.rsna.org Figure 19. Screw loosening after Scheker total DRUJ arthroplasty. Posteroanterior radiograph shows loosening of the most proximal screw (arrow) in the radial plate of a Scheker prosthesis. Other potential complications include fracture, osteolysis around the ulnar component, polymer ball wear, and soft-tissue infection or tendon injury. Prior total wrist arthrodesis is incidentally noted. Figure 20. Sigmoid notch implant (nonconstrained DRUJ arthroplasty). Posteroanterior (a) and oblique (b) radiographs show a sigmoid notch implant (white arrow), an insert that slides on a radial plate and is secured with a peg and screw. The insert articulates with an ulnar head component (straight black arrow in a). There are no screws linking the ulnar and sigmoid components. Note also the wires and headless screw traversing the second carpometacarpal joint (curved arrow in a). Alternatively, the DRUJ can be replaced using nonconstrained arthroplasty. The sigmoid notch implant is a polyethylene insert that slides on a metal radial plate and is secured with a peg and screw (Fig 20) (49). The insert articulates with an ulnar head component. Because there is no link between the components, malarticulation and dislocation are potential complications. A soft-tissue envelope around the implant is crucial to prevent these complications. The device was introduced in 2009; to our knowledge, however, no outcome studies have yet been reported. Ulnar head arthroplasty is a hemiarthroplasty alternative to (a) ulnar head resection for DRUJ arthritis and instability or (b) resection of a distal ulnar neoplasm (Fig 21). This implant requires an intact sigmoid notch and reconstruction of the soft-tissue attachments between the radius, ulna, and carpus to resist tensile forces in the forearm and wrist (46). Implants are composed of cobalt chromium, pyrolytic carbon, or ceramic material, with both extended and nonextended versions available. The implant is positioned in the medullary canal of the distal ulna. Suture sites are present on the ulnar head for soft-tissue attachment. Potential complications include dorsoradial subluxation of the implant (Fig 22), perihardware fracture, neuroma formation, carpal impingement, distal radius impingement, osteolysis around the collar of the prosthesis related to stress shielding around the implant, and sigmoid fossa remodeling (Fig 23). The latter two appear to stabilize over time and have not been shown to result in failure or symptoms in the short term, although longterm follow-up is needed (50). Conclusions Because of the high prevalence of wrist arthritis, radiologists often encounter radiographs and cross-sectional images of patients who have undergone wrist arthrodesis, carpectomy, or arthroplasty. It is imperative for radiologists to understand current techniques and stay abreast of advances in techniques and hardware, such as the sigmoid notch implant and Xpode fusion plate (TriMed). Familiarity with normal and abnormal postoperative imaging findings aids in assessment of complications and early failure. References 1. Lakshmanan P, Sher L. Wrist arthritis. Available at: Updated January 23, Accessed February 1, 2011.

13 RG Volume 31 Number 6 Petscavage et al 1649 Figure 21. Normal findings after ulnar head arthroplasty. Posteroanterior (a) and lateral (b) radiographs show no osteolysis around the rim of the prosthesis, with the stem centered in the medullary canal. The head articulates with the sigmoid notch of the distal radius. Soft-tissue suture attachments are noted on the lateral view (arrow in b). Note the volar plate with screw fixation across a distal radius osteotomy that had been performed for malunion from prior distal radius fracture. The osteotomy is not a standard part of ulnar head arthroplasty. Figure 23. Complications of ulnar head arthroplasty. Posteroanterior radiograph shows osteolysis around the head-neck junction of the implant (arrow) and impingement with remodeling of the sigmoid notch of the distal radius (arrowhead). In the short term, these findings appear to stabilize and do not indicate failure. However, long-term issues associated with these findings are not known. Figure 22. Subluxation as a complication of ulnar head arthroplasty. Posteroanterior (a) and lateral (b) radiographs show an ulnar head prosthesis and a straight dorsal plate. The ulnar head is dorsally and radially subluxated (arrow), with remodeling of the sigmoid notch of the ulna. This complication leads to instability at the DRUJ. 2. Hämäläinen M, Kammonen M, Lehtimäki M, et al. Epidemiology of wrist involvement in rheumatoid arthritis. J Rheumatol 1992;17: Weiss KE, Rodner CM. Osteoarthritis of the wrist. J Hand Surg Am 2007;32(5): Ely LW. A study of joint tuberculosis. Surg Gynecol Obstet 1910;10: Wysocki RW, Cohen MS. Complications of limited and total wrist arthrodesis. Hand Clin 2010;26(2): Boyer MI. Hand surgery. Philadelphia, Pa: Lippincott Williams & Wilkins, Rogers WD, Watson HK. Radial styloid impingement after triscaphe arthrodesis. J Hand Surg Am 1989;14(2 pt 1): Watson HK, Weinzweig J, Guidera PM, Zeppieri J, Ashmead D. One thousand intercarpal arthrodeses. J Hand Surg Br 1999;24(3): Hom S, Ruby LK. Attempted scapholunate arthrodesis for chronic scapholunate dissociation. J Hand Surg Am 1991;16(2):

14 1650 October Special Issue 2011 radiographics.rsna.org 10. McCombe D, Ireland DC, McNab I. Distal scaphoid excision after radioscaphoid arthrodesis. J Hand Surg Am 2001;26(5): Viegas SF. Limited arthrodesis for scaphoid nonunion. J Hand Surg Am 1994;19(1): Goubier JN, Bauer B, Alnot JY, Teboul F. Scaphotrapezio-trapezoidal arthrodesis for scapho-trapeziotrapezoidal osteoarthritis [in French]. Chir Main 2006;25(5): Meier R, Prommersberger KJ, Krimmer H. Scaphotrapezio-trapezoid arthrodesis (triscaphe arthrodesis) [in German]. Handchir Mikrochir Plast Chir 2003;35(5): Herren DB, Ishikawa H. Partial arthrodesis for the rheumatoid wrist. Hand Clin 2005;21(4): Goldfarb CA, Stern PJ, Kiefhaber TR. Palmar midcarpal instability: the results of treatment with 4-corner arthrodesis. J Hand Surg Am 2004;29(2): Ruby LK, Cooney WP 3rd, An KN, Linscheid RL, Chao EY. Relative motion of selected carpal bones: a kinematic analysis of the normal wrist. 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15 Teaching Points October Special Issue 2011 Imaging Assessment of the Postoperative Arthritic Wrist Jonelle M. Petscavage, MD, MPH Alice S. Ha, MD Felix S. Chew, MD RadioGraphics 2011; 31: Published online /rg Content Code: Page 1638 Limited wrist arthrodesis is designed to treat isolated pain and instability related to ligament tears, osteoarthritis, or scapholunate advanced collapse while preserving motion at other normal joints (5). Page 1640 (Figure on page 1640) On lateral radiographs and sagittal CT scans, the midcarpal joint should be held in a neutral to slightly volar intercalated position (Fig 5) to avoid dorsal radiocarpal impingement (6). Page 1643 The most common type of postoperative complication is soft tissue in nature, due to large soft-tissue flaps, extensive bone preparation, and thin subcutaneous skin in patients with inflammatory arthropathy who are taking oral steroids (27). Soft-tissue complications include hematoma, minor skin dehiscence in up to 20% 30% of patients (28), and infection (0.5% 3%) (28,29). In 35% 65% of cases, the dorsal plate can be felt as a painful prominence or form a painful dorsal bursa (30). Page 1644 (Figure on page 1644) Progressive osteoarthritis of the radiocarpal joint is the most common complication of proximal row carpectomy (Fig 14), seen at follow-up years after the procedure as joint space narrowing to 1 mm or less, with osteophyte formation and subchondral sclerosis and cysts (34,35). Page 1647 (Figure on page 1647) The Scheker prosthesis (Fig 18) is a semiconstrained device for the treatment of symptomatic DRUJ with insufficient supporting soft tissues in patients with inflammatory, degenerative, or posttraumatic arthritis; Madelung deformity; or failure of other surgical management (47).