Percutaneous Fixation of Scaphoid Fractures

Transcription

1 Percutaneous Fixation of Scaphoid Fractures Andrew P. Gutow, MD Abstract Recent advances in techniques and implants have led to renewed interest in percutaneous screw fixation of acute scaphoid fractures. The closed (cast) treatment of acute scaphoid fractures generally has good outcome, with bony union resulting; however, closed treatment can result in delayed union, nonunion, malunion, castinduced joint stiffness, and lost time from employment and avocations. Acute percutaneous fixation of scaphoid fracture has been proposed as a means to minimize some of the complications of closed (cast) treatment. Percutaneous treatment of both nondisplaced and displaced scaphoid fractures reportedly can achieve a nearly 100% union rate with minimal complications. Fixation of scaphoid fractures with headless compression screws can be done using both volar and dorsal approaches. The fracture reduction and alignment are assessed by fluoroscopy and arthroscopy. Appropriately performed acute percutaneous internal fixation is now a standard treatment option for a selected group of patients with acute scaphoid fracture. Dr. Gutow is Adjunct Clinical Associate Professor, Department of Orthopedic Surgery, Stanford University, Palo Alto, CA. Dr. Gutow has received research support and paid travel from Acumed, LLC. Reprint requests: Dr. Gutow, Department of Orthopedics, Palo Alto Medical Foundation, 795 El Camino Real, Palo Alto, CA J Am Acad Orthop Surg 2007;15: Copyright 2007 by the American Academy of Orthopaedic Surgeons. Despite surgical experience of nearly a century in the treatment of acute scaphoid fractures, the ideal management of this injury remains undetermined. 1,2 Current techniques include treatment with short arm wrist cast, short arm thumb spica cast, long arm thumb spica cast, open reduction and pin or screw fixation, and closed percutaneous screw fixation. Without adequate treatment, there is a risk of scaphoid nonunion or malunion, both of which subsequently can result in arthritis. Even with treatment, however, complications can result from both cast immobilization and internal fixation. Despite appropriate cast treatment, some scaphoid fractures carry a risk of nonunion of from 5% to 55%, depending on the fracture type. Also, fractures treated to successful union with a cast can result in wrist pain secondary to arthritis because of scaphoid fracture malunion. 3-7 Moreover, acute scaphoid fractures typically occur in a young, working population (average age, 25 years) at an incidence of 23 to 43 per 100,000 persons per year; thus, the morbidity of the treatment itself in terms of time off work and activities is significant. 8,9 These young, active patients prefer not to spend prolonged periods of time in a cast; their preference is to undergo a single course of definitive treatment. Percutaneous fixation of scaphoid fractures with headed cannulated screws was first performed in Germany by Streli, 10 beginning in 1962, 474 Journal of the American Academy of Orthopaedic Surgeons

2 Andrew P. Gutow, MD Figure 1 First published example of percutaneous or minimal incision fixation by Streli. This was done through a volar approach with a cannulated headed screw of his design. Streli achieved a 70% union rate in cases of delayed unions and pseudarthrosis. (Reprinted with permission from Streli R: Percutaneous screwing of the navicular bone of the hand with a compression drill screw [a new method] [German]. Zentralbl Chir 1970;95: ) as a modification of the technique of open reduction with solid bone screws of McLaughlin 11 (Figure 1). A series of more than 200 cases treated using the Streli traction-assisted volar technique and headed cannulated screw was subsequently reported by Wozasek and Moser 12 in 1991 to have an 89% union rate for acute fractures. The development of the headless cannulated compression screw has led to greater ease of screw insertion and has resulted in recent reports of acute percutaneous fixation of scaphoid fractures with union rates in some series of 100%. 2,13-19 Classification of Stability Adequate radiographs are a necessity to diagnose and classify a scaphoid fracture. The standard three radiographic views of the wrist should be augmented by the posteroanterior scaphoid view with the wrist in ulnar deviation and 45 of extension, which places the long axis of the scaphoid more nearly perpendicular to the x-ray beam. A computed tomography (CT) scan often shows greater displacement than typically can be appreciated on routine radiographs and therefore is recommended in cases in which displacement is questionable. CT can help plan treatment by demonstrating the exact amount of fracture displacement (step-off) and by showing loss of intrascaphoid and intercarpal alignment. Magnetic resonance imaging also can be of value to diagnose scaphoid displacement of occult acute fractures, especially of the proximal pole, which may require fixation, and avascular necrosis. Division of fractures into aligned or malaligned and into stable or unstable fractures can guide treatment by predicting stability and, thus, potential for healing with cast treatment. 7,20,21 The location and orientation of the fracture, as described in both the Russe 22 and Herbert 21 systems, give some prediction of stability (Table 1, Figure 2). However, the criteria detailed in the Mayo system 20 seem best supported by clinical series, which show higher rates of nonunion with cast treatment of unstable fractures in comparison Table 1 Herbert s Classification of Scaphoid Fractures Type A A1 A2 B B1 B2 B3 B4 C D D1 D2 Description Stable acute fracture Tubercle fracture Incomplete waist crack fracture Unstable acute fracture Distal third oblique fracture Complete displaced or mobile waist fracture Proximal pole fracture Transscaphoid carpal fracture-dislocation Delayed union Established nonunion Fibrous nonunion (stable) Displaced nonunion (unstable) Adapted with permission from Herbert TJ: The Fractured Scaphoid. St. Louis, MO: Quality Medical Publishing, 1990, p 52. with stable fractures. Cooney et al 20 define instability for scaphoid waist fractures as a step-off 1 mm, significant comminution, or angulation (malalignment) as evidenced by internal loss of internal scaphoid alignment or loss of intercarpal alignment 20 (Table 2). Proximal pole scaphoid fractures, regardless of amount of displacement, also are included in the unstable group. With cast treatment, nonunion rates of up to 55% have been reported for displaced fractures (gap >1 mm) and for up to 33% of angulated fractures. 3,7 Weber 7 suggested that displacement or angulation implies injury to the surrounding stabilizing ligaments, with greater surrounding injury with displaced fractures than with angulated fractures. Proximal pole fractures are unstable even when initially aligned, and they have a 30% inci- Volume 15, Number 8, August

3 Percutaneous Fixation of Scaphoid Fractures Figure 2 Table 2 Mayo Classification of Acute Scaphoid Fractures Stable Displacement <1 mm Normal intercarpal alignment Distal pole fractures Unstable Displacement >1 mm Lateral intrascaphoid angle >35 Bone loss or comminution Perilunate fracture dislocation Dorsal intercalated segmental instability (DISI) alignment Proximal pole fractures Adapted with permission from Cooney WP III: Scaphoid fractures: Current treatments and techniques. Instr Course Lect 2003;52: A, Russe classification of scaphoid fractures. B, Herbert classification of scaphoid fractures. (Panel A adapted with permission from Russe O: Fracture of the carpal navicular: Diagnosis, non-operative treatment, and operative treatment. J Bone Joint Surg Am 1960;42: Panel B adapted with permission from Herbert TJ: The Fractured Scaphoid. St. Louis, MO: Quality Medical Publishing, 1990, p 52.) dence of nonunion when treated in a cast. 2,7,23 Percutaneous Fixation The widespread use of percutaneous fixation of scaphoid fractures, as first suggested by Streli, required both improved fluoroscopic imaging for better screw placement and the development of a more easily placed screw. The headless compression screw developed by Herbert, 21 and the modification of this into a headless cannulated screw by Whipple 24 and others, made this possible. 13,14,24,25 With the use of a headless compression screw, Haddad and Goddard 14 modified Streli s technique of traction-assisted minimal incision volar fixation, placing the screw from distal to proximal using the scaphotrapezial joint, if needed. Others used this same volar approach without traction, with the wrist extended on an arm board. 13,15,16 Whipple 24 added the use of arthroscopy to assist in reduction and developed a cannulated headless screw to allow for percutaneous insertion. Slade et al 25 expanded on Whipple s concept of arthroscopic assistance with a dorsal, arthroscopy-assisted, percutaneous approach, using the ring sign of the flexed scaphoid to aid in guidewire placement within the center of the scaphoid. The overall results of recent series of percutaneous fixation of scaphoid fractures have been a 100% union rate for surgically fixed fractures from both the volar and dorsal approach (Table 3). Prospective randomized studies comparing acute fixation to closed (cast) treatment of stable fracture has shown that patients with surgically fixed fractures have a faster rate of healing and earlier return to work 16,17 (Table 3). Implant Types A variety of compression screws is available. The salient differences are the headed versus headless design, 476 Journal of the American Academy of Orthopaedic Surgeons

4 Andrew P. Gutow, MD Table 3 Outcome of Percutaneous Fixation of Scaphoid Fracture Study Approach Implant Retrospective Series Streli 10 Wozasek and Moser 12 Volar minimal access traction assisted Volar minimal access traction assisted Headed cannulated screw Headed cannulated screw Ledoux et al 15 Volar minimal access Headless solid (Herbert screw ) Inoue and Shionoya 13 Volar minimal access Headless solid (Herbert screw ) Haddad and Goddard 14 Volar percutaneous traction assisted Headless cannulated (Acutrak ) Yipetal 19 Volar minimal access Headed cannulated screw Slade et al 2 Slade et al 18 Prospective Randomized Series Dorsal percutaneous arthroscopic assisted Dorsal percutaneous arthroscopic assisted Headless cannulated (Acutrak ) Headless cannulated (Acutrak ) No. of Fractures, Type Union Rate (%)* 6 delayed union, 4 pseudarthrosis 146 acute, 33 delayed and nonunion 19 acute, 4 nonunion (acute), 81.8 (delayed/ nonunion) acute acute acute acute, 9 delayed nonunion 100 Bond et al 16 Volar percutaneous Headless cannulated (Acutrak ) Adolfsson et al 17 Volar percutaneous Headless cannulated (Acutrak ) * In prospective randomized series, union rate for surgically treated Zimmer, Warsaw, IN Acumed, LLC, Hillsboro, OR 11 acute stable nondisplaced 25 acute stable nondisplaced cannulated versus noncannulated screws, full versus partial threading, screw diameter, and the method of applying compression (Figure 3). Although the amount of compression generated by various internal fixation screws has been extensively studied, rigidity of fixation is probably the most important factor in promoting healing of scaphoid fractures. Absolute rigidity of a metal screw is directly proportional to the radius to the fourth power (r 4 ) of the screw; 26 however, for scaphoid fractures, the rigidity of the screw bone construct is directly proportional to the surface area of bone contacted on each side of the fracture by the screw. This surface area of cancellous bone resisting bending is a function of the diameter of the screw and the length of screw on each side of the fracture. A more centrally placed screw is generally longer and has more length of screw on each side of the fracture than does a peripherally placed screw. In their clinical series, Cosio and Camp 27 showed healing of 77% of established nonunions simply by the percutaneous insertion of multiple in wires, which provided rigidity and resistance to bending but no compression. The greater compression that some screws provide may favor healing by promoting primary bone healing at the fracture site, speeding the healing process, and increasing the rigidity of the bone screw construct because of the direct interdigitation of the fracture fragments; however, no in vivo data show an advantage of greater compression. In choosing an implant for fixation of scaphoid fractures, one must balance the benefits of rigidity (which are increased by the use of the largest screw) with the difficulties of Volume 15, Number 8, August

5 Percutaneous Fixation of Scaphoid Fractures Figure 3 Headless compression screws commonly used for fixation of scaphoid fractures. A, Herbert solid variable pitch (Zimmer, Warsaw, IN). B, Zimmer Herbert/Whipple cannulated variable pitch. C, Acutrak cannulated variable pitch fully threaded (Acumed, Hillsboro, OR). D, Twin-Fix two-part variable compression (Stryker, Kalamazoo, MI). In addition, cannulated Herbert-type screws are available (Millennium Compression Screw, Millennium Medical Technologies, Santa Fe, NM). Figure 4 Intraoperative view of a large-diameter screw demonstrating the size of the trailing end of a 4.0-mm diameter (standard Acutrak) screw in the proximal pole of the scaphoid. (Courtesy of Andrew Gutow, MD.) placing a larger implant totally within the body of the scaphoid. Some surgeons have expressed concern regarding the size of the hole that a larger size screw (eg, Acutrak of standard size with a 4.0-mm trailing edge diameter) might make in the proximal scaphoid (ie, the area of radiocarpal articulation) (Figure 4). To date; however, radiocarpal arthrosis has not been regarded as an issue in clinical series. 18,28 For percutaneous or minimal incision fixation, a cannulated headless compression screw is preferred. Cannulation allows the use of a guidewire, which gives better control over screw placement. A headless design allows for the screw to be buried fully in the bone, thereby allowing more central screw placement in the scaphoid. Also, the headless design obviates such problems as erosion of the end of a headed screw into the surrounding bone, as is seen with distally placed screw heads eroding into the trapezium. 19 Central placement is achieved by implantation through either the radiocarpal joint proximally or the scaphotrapezial joint distally. Surgeons using the larger-diameter rigid screws (4.0-mm trailing edge diameter) have reported successful healing using immobilization with a removable splint after surgery; 2,14,16 others favor cast immobilization except for the most stable nondisplaced fractures. 29 However, with rigid fixation, extended cast immobilization appears to be unnecessary. The results of clinical series suggest that, when a long and sufficiently rigid screw is used in good bone, adequate fixation will result. With rigid fixation, postoperative casting may not be needed, and it is safe to start a controlled motion program combining a removable splint with range-of-motion exercises and gripping exercises for axial loading. Herbert 21 has argued that better fixation is maintained with early loading by preventing disuse osteopenia, which can result from cast immobilization. Screw Position The position of the implant near the central axis of the scaphoid is important to the success of internal fixation. The less stable the fracture, the more critical the central position is (Figure 5). For scaphoid waist fractures, clinical studies have shown a higher union rate, and cadaveric studies a greater resistance to failure under bending loads, for screws placed in the central third of both the proximal and distal poles. 30,31 The greater strength of the central position may be a function of the fact that a centrally placed screw provides more threads across the fracture site in both poles. Biomechanical testing of proximal pole fractures has shown that fixation from proximal to distal provides greater resistance to bending failure probably because of the ability to engage more of the small proximal pole by means of screw fixation. 32 Slade believes that four is the critical number of threads on each side of the fracture needed to stabilize the scaphoid (JF Slade III, MD, personal communication, 2004). Surgeons have shown slightly greater ease in placement of screws centrally from the dorsal approach than from the volar side, but the clinical significance of this is not clear for waist fractures. 28,33 Indications and Contraindications Nondisplaced scaphoid waist fractures are a primary indication for percutaneous screw fixation. For these stable fractures, the methods of percutaneous fixation described above work well. In all patients with rigid internal fixation, early postoperative mobilization with a removable splint is recommended. In the patient with nondisplaced scaphoid fracture, deciding between surgery and closed (cast) treatment is based on patient age, handedness, type of work, and the patient s personal preference. 478 Journal of the American Academy of Orthopaedic Surgeons

6 Andrew P. Gutow, MD Figure 5 A, Anteroposterior radiograph of a minimally displaced scaphoid waist fracture fixed via a dorsal minimal incision in a 26-yearold man. B, Placement of a standard-size screw in the central third of both poles of the scaphoid provides for the most screw threads in each fragment, greatest stability, and rapidity of fracture healing. C, Clear evidence of fracture healing at 8 weeks postoperatively. Acute unstable scaphoid waist fractures are a second indication for primary internal fixation of the scaphoid and a relative indication for percutaneous fixation. With unstable fractures, internal fixation must be performed on a reduced and aligned fracture. When this cannot be achieved closed, open reduction is needed. For fractures without a gap or malalignment, all of the methods of percutaneous screw fixation discussed above are acceptable. For scaphoid fractures that require reduction, the surgeon may choose the volar traction-assisted approach; the dorsal minimal incision approach, with manual reduction as the guidewire is advanced; or the dorsal approach with arthroscopy-assisted reduction. When significant comminution is encountered, percutaneous bone grafting with placement of bone down the drilled passageway can be performed. 12 Proximal pole fractures are a third indication for internal fixation. Proximal pole fractures should be treated using a percutaneous or open dorsal approach to ensure adequate fixation of the small proximal pole. The headless screw must be fully buried beneath the articular cartilage of the proximal scaphoid to avoid radioscaphoid impingement. Percutaneous fixation of acute scaphoid fractures is contraindicated in cases in which adequate reduction cannot be achieved in a closed manner. Surgical Anatomy Percutaneous fixation requires knowledge of bone anatomy as well as of the location of the surrounding tendons, nerves, and vessels. Keeping in mind the flexed posture of the scaphoid relative to the longitudinal alignment of the distal radius, the central axis of the scaphoid can be found using anatomic markers as well as fluoroscopy. From the proximal approach, the distal aiming point is the center of the scaphotrapezial joint or the base of the thumb. From the distal approach, the proximal aiming point is the ulnar proximal corner of the scaphoid at the insertion of the scapholunate ligament. Just radial to this aiming point is the starting point for proximal screw insertion. Clinical series and dissections of cadavers have shown both dorsal and volar percutaneous approaches to be safe when attention to technical details is maintained that is, spreading down to bone volarly or to the capsule dorsally before inserting the lead drill or scaphoid reamer 34,35 (Figure 6). Volarly, the starting point at the scaphotrapezial joint through the proximal thenar muscles is at a safe distance from the median nerve motor branch and from the radial artery, although a small terminal branch of the radial nerve can be at risk. Dorsally, the starting point is just proximal to the standard 3-4 radiocarpal arthroscopy portal. Volume 15, Number 8, August

7 Percutaneous Fixation of Scaphoid Fractures Figure 6 A, Volar dissection demonstrating the entry point (arrow) through the proximal aspect of the thenar muscles. B, Dorsal dissection demonstrating the starting point (arrow) through the distal aspect of the extensor retinaculum between the second and fourth compartments. (Courtesy of Irfan Ansari, MD, and Andrew Gutow, MD.) Surgical Techniques Whether the volar or dorsal approach is used, percutaneous fixation can be performed with or without traction assistance (Figure 7) and with or without arthroscopic guidance. Streli first treated scaphoid delayed unions and pseudarthrosis with a volar percutaneous approach using a 1-cm volar incision and 1-mm guidewire. 10 He suspended the hand by a finger trap placed on the thumb to provide clear radiographic imaging; doing so allowed him to obtain orthogonal views by pronating and supinating the forearm. This important concept of complete 180 visualization of the scaphoid is central to successful percutaneous fixation. In this initial series of 10 cases, 5 of 6 cases of delayed unions and 2 of 4 cases of established pseudarthrosis healed. Wozasek and Moser 36 modified the Streli technique to include percutaneous bone grafting of established scaphoid nonunions, although the grafting was begun once the series was under way. The authors used a headed cannulated screw with a washer; the screw had a 4.8- mm diameter thread and a 2.9-mm core diameter. Of 280 cases spanning a 15-year period, the authors reported that 89% of acute fractures healed, 81.8% of delayed unions healed, and 42.8% of sclerotic nonunions healed. The 11% nonunion rate for acute scaphoid fractures may have been the result of limitations on the ideal placement of the headed lag screw; these limitations occurred secondary to the screw design and the radiographic imaging available. The use of a headless variable pitch screw for minimal incision or percutaneous fixation was first reported by Ledoux et al 15 in 1995 and Inoue and Shionoya 13 in The solid (ie, noncannulated) Herbert screw was used in both studies. Authors of both studies achieved 100% union in a total of 63 cases; the approach was through a small volar incision. Inoue and Shionoya 13 positioned the wrist in extension over towels, made a 1-cm incision over the volar scaphoid, and opened the scaphotrapezial joint. A 1.2-mm guidewire was placed first, under fluoroscopic guidance, and then removed. Drilling of the scaphoid was performed down the same path followed by the freehand insertion of the Herbert screw through the same drill path. Biplanar imaging confirmed the proper length and placement of the Herbert screw. The use of a headless cannulated screw with placement of a percutaneous guidewire from the volar approach was popularized by several authors during the late 1990s and early 2000s. 16,18,19,28 Haddad and Goddard 37 reported a modification of the Streli traction-assisted volar approach; they minimized the incision using a large 12-gauge angiocatheter needle as a drill guide to open the scaphotrapezial joint and to aid in placing the guidewire (Figure 7). Haddad and Goddard 37 believed that placing the thumb in traction, which puts the wrist in extension and ulnar deviation, can help reduce the acute unstable fracture. Most authors used a modification of the method of Ledoux et al 15 and Inoue and Shionoya, 13 that is, the forearm is supinated and the wrist extended on towels, the imaging device is above and below the arm board, and and pronation and supination are used to visualize the scaphoid. 16,17,29 This extended volar technique is most suited to stable, aligned fractures. Whipple 24 developed a cannulated version of the headless variablepitch Herbert screw to allow for more accurate percutaneous screw placement and arthroscopy-assisted reduction. Slade et al 2 adopted Whipple s technique of arthroscopic assistance to a dorsal percutaneous approach; these authors thought that the central axis of the scaphoid was better found via a dorsal starting point, especially for proximal pole fractures (Figure 8). They located the central axis of the scaphoid for guidewire placement using the ring sign of the scaphoid, which can be seen on fluoroscopy when the wrist is flexed and pronated, thereby placing the proximal and distal poles of the scaphoid in alignment. Follow- 480 Journal of the American Academy of Orthopaedic Surgeons

8 Andrew P. Gutow, MD ing placement of the guidewire from the dorsal approach and before screw implantation, Slade at al 2 drove the guidewire in a volar direction through the thenar eminence and thumb until its proximal trailing edge was just buried in the scaphoid. The wrist was then extended to achieve standard views of the scaphoid and to use midcarpal and radiocarpal arthroscopy to assess reduction and to look for associated intercarpal ligament injuries. During this process, the guidewire also may be drilled more distally across the fracture, allowing reduction to be performed if needed. 2 Gutow and Dacus 28 modified the technique of Slade et al 2 for dorsal fixation, using a small incision without arthroscopic assistance using either a full-sized fluoroscopy unit (Figure 9) or a mini fluoroscopy unit. On a radiolucent arm board, the forearm is pronated and the wrist, flexed. A small surgical approach (5- mm incision) is performed for direct visualization of the proximal pole of the scaphoid and for placement of the guidewire. The scapholunate ligament is directly visualized so that, if ligament injuries are present, they can be addressed. The guidewire starting point on the proximal pole of the scaphoid is directly visualized; multiple attempts at gaining a starting point are not needed. Reduction of the scaphoid can be performed with flexed fractures by placing the guidewire in the proximal pole and then applying dorsal pressure to the distal pole of the scaphoid. With the scaphoid reduced, the guidewire is drilled into the distal pole. In these cases, a second eccentric guidewire can be temporarily placed to prevent loss of reduction or rotation displacement of the scaphoid during the overdrilling and insertion of the fixation screw. Union and rapid return of wrist function with both volar and dorsal techniques have been reported (Table 3). Most surgeons performing percutaneous fixation of acute Figure 7 Nontraction (A) and traction-assisted (B-D) volar percutaneous approaches. A, Under control of a standard C-arm, the arm is supinated and extended on a radiolucent arm board. A lateral view is obtained by pronating the forearm without moving the C-arm. The guidewire is started into the distal pole of the scaphoid at the scaphotrapezial joint using fluoroscopic guidance. A second eccentric guidewire may be used as anti-rotation wire during implantation of the screw. B, The arm is hung from a single finger trap placed around the thumb. C, A C-arm is positioned around the hand coming from the opposite side of the patient. With the wrist suspended from the thumb finger trap, one can move the scaphoid into the center of rotation of the forearm axis. The forearm is pronated and supinated to gain posteroanterior and lateral views. D, A 12-gauge needle is used to enter and lever open the scaphotrapezial joint; the needle then serves as a drill guide for the guidewire. (Panel A reprinted with permission from Bond CD, Shin AY, McBride MT, Dao KD: Percutaneous screw fixation or cast immobilization for nondisplaced scaphoid fractures. J Bone Joint Surg Am 2001;83: Panel B modified courtesy of Nicholas Goddard, MB. Panels C and D reprinted with permission from Haddad FS, Goddard NJ: Acute percutaneous scaphoid fixation: A pilot study. J Bone Joint Surg Br 1998;80:95-99.) Volume 15, Number 8, August

9 Percutaneous Fixation of Scaphoid Fractures Figure 8 Dorsal arthroscopy-assisted approaches. A, Dorsal approach. The arm is held in the air, and the guidewire is started in dorsally using a mini C-arm unit to visualize the scaphoid ring sign. B, After the guidewire is drilled out volarly, the hand is hung in finger traps. C, Midcarpal arthroscopy is used to confirm reduction. D, The screw is implanted from a dorsal to palmar direction in the center of the proximal pole of the scaphoid. (Courtesy of Joseph F. Slade III, MD.) scaphoid fractures recommend a program of rapid mobilization of the wrist for acute fractures, with application of a volar forearm splint or thumb spica at the time of surgery, followed by use of a removable thumb spica splint. The removable splint is applied at the first postoperative visit and worn full time until union is confirmed. CT is recommended to determine when union has occurred. This is particularly true in patients with fracture comminution (Figure 10). Unprotected activity is not allowed until bridging bone is seen. For nondisplaced fractures, a CT scan may not always be needed to prove union 16 (Figure 5). Complications of Percutaneous Fixation Complications of percutaneous fixation of the scaphoid include failure to achieve anatomic reduction, scaphoid subsidence or shortening with secondary screw penetration, injuries to soft tissue (eg, cutaneous nerves, tendons, radial artery), incorrect placement of a fixation screw, and failure to recognize concomitant injuries. Accurate fracture reduction is paramount. When reduction cannot be achieved or confirmed in a closed manner, conversion to a standard volar or dorsal approach is needed. 21 Adequacy of reduction can be confirmed with fluoroscopy or by midcarpal arthroscopy. Damage to surrounding structures can be avoided by careful spreading down to the tubercle of the scaphoid, with the volar approach, and with soft-tissue spreading down to the wrist capsule, with the dorsal approach. A valuable technique is that of Haddad and Goddard: choosing the correct starting point and then tapping a 12- or 14-gauge angiocatheter needle into the scaphoid as a drilling guide for the wire. 14 With this wire guide in place, even if the wire has to be reaimed, a new starting point is not needed. Alternatively, a minimal access dorsal incision can be used so that the starting point is always under direct visualization. 28 The most common errors of screw placement include using too long a screw or too eccentric a screw. Internal fixation must be placed down the central axis of the scaphoid, not only to achieve the best strength but also to avoid penetrating the scaphocapitate joint. Double-checking of the guidewire position with multiple radiographic views is required before drilling or screw insertion. The screw length should be sufficiently shorter than the measured length of the scaphoid to allow for complete implantation of the screw in the bone. When measuring against the curved articular surface of the proximal scaphoid, a screw that is 3 to 4 mm shorter than the measured scaphoid length should be used. From distally, where the surface is less curved at the point of measurement, a screw that is 2 to 3 mm shorter than the scaphoid should be adequately buried. Use of a screw that is available in 1 mm increments of length may help with selecting the correct screw length. Care must be taken when drilling so as not to drill too far, thus penetrating the far cortex. Use of hand drills instead of powered drilling may help avoid overdrilling. Hand drilling also decreases the risk of breaking off a guidewire in the scaphoid. One tech- 482 Journal of the American Academy of Orthopaedic Surgeons

10 Andrew P. Gutow, MD Figure 9 Figure 10 In cases with comminution or with questions regarding healing, computed tomography is required to decide when to allow unprotected activity. Here, following dorsal percutaneous fixation of a comminuted scaphoid fracture with a cannulated screw, a computed tomography scan demonstrates healing of the dorsal cortex prior to healing of the volar cortex. (Courtesy of Andrew Gutow, MD.) Occasionally with a scaphoid fracture, a ligament injury (eg, scapholunate ligament) can occur, requiring treatment. The authors of one series of arthroscopy-assisted fixations of scaphoid nonunion found 8 intercarpal ligament injuries in 15 patients. Two of these were Geissler grade III, which required surgical treatment. 18 Careful evaluation of preoperative radiographs for evidence of carpal instability can help make this diagnosis. Radiocarpal and midcarpal arthroscopy provides the best means to diagnose these ligament injuries. Dorsal minimal incision with the wrist flexed on an arm board (author s preferred technique). A, The forearm is placed pronated on a radiolucent arm board using either a standard or mini C-arm for radiographic visualization, with the wrist flexed over a bump. B, Using fluoroscopic guidance, the proximal pole of the scaphoid is identified, and a 5-mm incision is made dorsally over the radiocarpal joint at the ulnar aspect of the proximal pole of the scaphoid. The distal aspect of the extensor retinaculum is incised, if needed, the dorsal wrist joint capsule is opened, and hematoma is drained from the wrist. Using two small Ragnell-style retractors, the proximal pole of the scaphoid and the scapholunate ligament are visualized. A guidewire is started into the proximal pole of the scaphoid under direct visualization, aiming for the base of the thumb (carpometacarpal joint). C, Fluoroscopic guidance can be used; the oblique view is the most helpful. D, Only the skin is sutured; closure of the small arthrotomy is not necessary. (Courtesy of Andrew Gutow, MD.) nique is to use power reaming to penetrate the first cortex and then switch to hand reaming. Too long a screw also can result in distraction of the fracture by the tip of the screw pushing against the far cortex. Rotational displacement of scaphoid fractures during screw implantation can be prevented by the placement of a second eccentric Kirschner wire before scaphoid drilling and screw placement. Summary Percutaneous fixation is an effective method of treating nondisplaced scaphoid fractures. Acute percutaneous fixation can result in nearly 100% solid fracture union. It can allow patients to return to work and avocations more rapidly than can closed (cast) treatment. For stable fractures, the major advantage of percutaneous fixation is more rapid return to activities and avoidance of cast wear. 16,38 For unstable scaphoid fractures, percutaneous fixation may provide a higher union rate, avoidance of soft-tissue injury associated with open procedures, healing in poor alignment, and faster rehabilitation. The choice of a volar or dorsal approach is one of surgeon preference except in cases of proximal pole fractures; these should be approached dorsally. The use of adjunctive arthroscopy at the time of fracture fixation allows one to determine accu- Volume 15, Number 8, August

11 Percutaneous Fixation of Scaphoid Fractures rate scaphoid fracture reduction and the diagnosis and treatment of concomitant ligament injuries. Early mobilization of the wrist and hand is aided by using the longest and largest-diameter screw that can be implanted. Early mobilization provides for faster return of motion and, possibly, of strength. Also, fibrocartilage resurfacing of the insertion hole made in articular cartilage during the implantation of the screw may be enhanced. Early mobilization also may prevent disuse osteopenia. A careful, well-planned surgical technique and experience with arthroscopy are required to apply the arthroscopic procedures; precise biplanar imaging is needed for the limited volar and dorsal surgical approach techniques using cannulated screw fixation. References Evidence-based Medicine: There is one level I study (reference 38) and seven level II studies (references 6, 11, 16, 17, 23, 27, and 38). The remaining references are level III/IV cohort and case-control studies. Citation numbers printed in bold type indicate references published within the past 5 years. 1. MacLennan A: The treatment of fracture of the carpal scaphoid and the indications for operation. Br Med J Oct 28, 1911: Slade JF III, Gutow AP, Geissler WB: Percutaneous internal fixation of scaphoid fractures via an arthroscopically assisted dorsal approach. J Bone Joint Surg Am 2002;84(suppl 2): Amadio PC, Berquist TH, Smith DK, Ilstrup DM, Cooney WP III, Linscheid RL: Scaphoid malunion. J Hand Surg [Am] 1989;14: Fernandez DL, Martin CJ, Gonzalez del Pino J: Scaphoid malunion: The significance of rotational malalignment. J Hand Surg [Br] 1998;23: Duppe H, Johnell O, Lundborg G, Karlsson M, Redlund-Johnell I: Longterm results of fracture of the scaphoid: A follow-up study of more than thirty years. J Bone Joint Surg Am 1994;76: Saedén B, Tornkvist H, Ponzer S, Höglund M: Fracture of the carpal scaphoid: A prospective, randomised 12-year follow-up comparing operative and conservative treatment. J Bone Joint Surg Br 2001;83: Weber ER: Biomechanical implications of scaphoid waist fractures. Clin Orthop Relat Res 1980;149: Hove LM: Epidemiology of scaphoid fractures in Bergen, Norway. Scand J Plast Reconstr Surg Hand Surg 1999; 33: Larsen CF, Brondum V, Skov O: Epidemiology of scaphoid fractures in Odense, Denmark. Acta Orthop Scand 1992;63: Streli R: Percutaneous screwing of the navicular bone of the hand with a compression drill screw (a new method) [German]. Zentralbl Chir 1970; 95: McLaughlin HL: Fracture of the carpal navicular (scaphoid) bone: Some observations based on treatment by open reduction and internal fixation. J Bone Joint Surg Am 1954;36: Wozasek GE, Moser KD: Percutaneous screw fixation for fractures of the scaphoid. J Bone Joint Surg Br 1991; 73: Inoue G, Shionoya K: Herbert screw fixation by limited access for acute fractures of the scaphoid. J Bone Joint Surg Br 1997;79: Haddad FS, Goddard NJ: Acute percutaneous scaphoid fixation: A pilot study. J Bone Joint Surg Br 1998;80: Ledoux P, Chahidi N, Moermans JP, Kinnen L: Percutaneous Herbert screw osteosynthesis of the scaphoid bone [French]. Acta Orthop Belg 1995;61: Bond CD, Shin AY, McBride MT, Dao KD: Percutaneous screw fixation or cast immobilization for nondisplaced scaphoid fractures. J Bone Joint Surg Am 2001;83: Adolfsson L, Lindau T, Arner M: Acutrak screw fixation versus cast immobilisation for undisplaced scaphoid waist fractures. J Hand Surg [Br] 2001;26: Slade JF, Geissler WB, Gutow AP, Merrell GA: Percutaneous internal fixation of selected scaphoid nonunions with an arthroscopically assisted dorsal approach. J Bone Joint Surg Am 2003;85(suppl 4): Yip HS, Wu WC, Chang RY, So TY: Percutaneous cannulated screw fixation of acute scaphoid waist fracture. JHandSurg[Br]2002;27: Cooney WP, Dobyns JH, Linscheid RL: Fractures of the scaphoid: A rational approach to management. Clin Orthop Relat Res 1980;149: Herbert TJ: The Fractured Scaphoid. St. Louis, MO: Quality Medical Publishing, Russe O: Fracture of the carpal navicular: Diagnosis, non-operative treatment, and operative treatment. J Bone Joint Surg Am 1960;42: Clay NR, Dias JJ, Costigan PS, Gregg PJ, Barton NJ: Need the thumb be immobilised in scaphoid fractures? A randomised prospective trial. J Bone Joint Surg Br 1991;73: Whipple TL: Stabilization of the fractured scaphoid under arthroscopic control. Orthop Clin North Am 1995;26: Slade JF III, Grauer JN, Mahoney JD: Arthroscopic reduction and percutaneous fixation of scaphoid fractures with a novel dorsal technique. Orthop Clin North Am 2001;32: Toby EB, Butler TE, McCormack TJ, Jayaraman G: A comparison of fixation screws for the scaphoid during application of cyclical bending loads. J Bone Joint Surg Am 1997;79: Cosio MQ, Camp RA: Percutaneous pinning of symptomatic scaphoid nonunions. J Hand Surg [Am] 1986; 11: Gutow AP, Dacus R: Accuracy of central placement of screws in scaphoid when fixed from a dorsal percutaneous approach under fluoroscopic guidance. Presented at the American Society for Surgery of the Hand 58th Annual Meeting. Chicago, IL, September 18-20, Cooney WP III: Scaphoid fractures: Current treatments and techniques. Instr Course Lect 2003;52: Trumble TE, Gilbert M, Murray LW, Smith J, Rafijah G, McCallister WV: Displaced scaphoid fractures treated with open reduction and internal fixation with a cannulated screw. J Bone Joint Surg Am 2000;82: McCallister WV, Knight J, Kaliappan R, Trumble TE: Central placement of the screw in simulated fractures of the scaphoid waist: A biomechanical study. J Bone Joint Surg Am 2003;85: Slade JF, Gutow AP, Noonan J, Westmoreland G, Hutton W: Strength of 484 Journal of the American Academy of Orthopaedic Surgeons

12 Andrew P. Gutow, MD internal fixation of proximal pole scaphoid fractures with cannulated screws. Presented at the American Society for Surgery of the Hand 55th Annual Meeting, Washington, DC, October 5-8, Chan KW, McAdams TR: Central screw placement in percutaneous screw scaphoid fixation: A cadaveric comparison of proximal and distal techniques. J Hand Surg [Am] 2004; 29: Kamineni S, Lavy CB: Percutaneous fixation of scaphoid fractures: An anatomical study. J Hand Surg [Br] 1999;24: Ansari I, Slade JF, Gutow AP: Percutaneous fixation of scaphoid fractures: An anatomic comparison of the volar and dorsal approaches. Presented at the American Society for Surgery of the Hand 56th Annual Meeting, Baltimore, MD, October 4-6, Wozasek GE, Moser KD: Indications for percutaneous screw fixation of scaphoid fractures [German]. Unfallchirurg 1991;94: Haddad FS, Goddard NJ: Acute percutaneous scaphoid fixation using a cannulated screw. Chir Main 1998;17: Dias JJ, Wildin CJ, Bhowal B, Thompson JR: Should acute scaphoid fractures be fixed? A randomized controlled trial. J Bone Joint Surg Am 2005;87: Volume 15, Number 8, August