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Management of Scaphoid Nonunions Thomas E. Trumble, MD, Peter Salas, MD, Traci Barthel, MD, and Kearny Q. Robert III, MD Abstract Scaphoid nonunions are rarely symptomatic in the early stages, and the success rate of management decreas- es with thedurationof the nonunion. 1-4 Scaphoid nonunions occur when fractures are not diagnosed and managed initially or when they have not healed with cast immobilization within 6 months of injury. Fractures that do not show signs of radiographic healing after 6 to 8 weeks of cast immobilization and fractures diagnosed 6 weeks after injury are less likely to heal. Af- ter an even longer duration, unman- aged scaphoid nonunions frequently cause wrist pain and lead to progressive arthrosis. 5,6 Because it is not usually possible to determine how long a nonunion has been present or how many patients with asymptomatic nonunions occur in a particular population, the natural history of scaphoid nonunions has not been clearly delineated. 1-3 Conse- quently, the risk for developing wrist arthrosis from a scaphoid nonunion cannot be calculated. However, a growing body of data suggests that most symptomatic nonunions even- tually develop a collapse deformity, followed by onset of wrist arthrosis. 4,6-8 During the last 15 years, major ad- vances have occurred in the ability to diagnose scaphoid nonunions and evaluate collapse deformity using computed tomography (CT). Osteone- crosis can be detected in the proximal pole of the scaphoid with magnetic resonance imaging (MRI), enabling better planning for surgery. 9 Fracture fixation has improved with the development of specially designed screws that can stabilize a bone covered by articular surface at both ends with fragile blood supply entering between the two cartilaginous ends. Anatomy and Pathophysiology The articular surfaces of the proximal and distal poles of the scaphoid are rotated with respect to each other. The plane of the scaphoid is tilted both volarly and radially with respect to the central axis of the forearm; this obliq- uity adds to the complexity of surgical management. The proximal half of the scaphoid iscovered almost com- pletely with articular surface withfew, if any, perforating vessels. Thus, the vascularity of the scaphoid is based primarily on retrograde blood flow. Vessels entering the scaphoid through the dorsal ridge supply blood to 70% to 80% of the bone, and vessels that enter it through the volar branches of the artery supply the remaining 20% to 30% 10 (Fig. 1). Because the scaphoid is a vital link between the proximal and distal carpal rows, a scaphoid fracture can se- verely disrupt carpal mechanics. Me- chanical instability allows fracture displacement, whichimpedes healing Dr. Trumble is Professor and Chief, Hand and Mi- crovascular Surgery Service, University of Wash- ington Medical Center, Seattle, WA. Dr. Salas is Fellow, Hand Surgery, Department ofOrthopaedic Surgery and Sports Medicine, UniversityofWash- ington, Seattle. Dr. Barthel is Fellow, Hand Sur- gery, Department of Orthopaedic Surgery and Sports Medicine, University of Washington. Dr. Robert is Fellow, Hand Surgery, Department of Orthopaedic Surgery and Sports Medicine, Uni- versity of Washington. None of the following authors or the departments with which theyare affiliated has received anything of value from or owns stock in a commercial com- pany or institution related directly or indirectly to the subjectofthis article: Dr. Trumble, Dr. Salas, Dr. Barthel. Dr. Robert or the department with which he is affiliated has received research or in- stitutional support from Synthes USA. Reprint requests: Dr. Trumble, University of Washington Medical Center, Box 356500, 1959 NE Pacific, Seattle, WA 98195. Copyright 2003 by the American Academy of Orthopaedic Surgeons. Scaphoid nonunions result in a predictable pattern of wrist arthrosis. To minimize the incidence of arthrosis, the goal of treatment should be consolidation of the fracture with the scaphoid in anatomic alignment. Computed tomography and magnetic resonance imaging scans can aid evaluation of carpal collapse, scaphoid collapse, scaphoid nonunion, bone loss, and detection of osteonecrosis. Nonunion of the scaphoid waist may result in a humpback deformity, increasing the chances of further collapse and arthrosis. This collapse deformity must be approached volarly with an intercalary bone graft and internal fixation. A dorsal approach to proximal scaphoid nonunions allows easier access for removing the necrotic bone from the proximal pole and applying accurate screw or pin fixation. Vascularized bone graft is recommended to manage scaphoid nonunions with osteonecrosis. J Am Acad Orthop Surg 2003;11:380-391 380 Journal of the American Academy of Orthopaedic Surgeons and causes abnormal carpal kinemat- ics and loading, leading to wrist arthrosis. 6,11-14 Normally, the connec- tion of the scaphoid to the lunate via the scapholunate interosseous ligament draws the lunate into a flexed position as the wrist moves from ulnar to radial deviation. Scaphoid collapse with palmar flexion of the distal pole reduces the carpal height and allows the lunate to rotate in a dorsal intercalated segmental instability (DISI) pattern. A pattern of arthritis known as scaphoid nonunion advanced collapse occurs once a DISI deformity becomes fixed from loss of mechanical integrity of the scaphoid. This deformity closely resembles the pattern of arthrosis that results from chronic disruption of the scapholunate interosseous ligament. Most scaphoid fractures occur as a result of a fall, sports injury, or ve- hicular accident. Whenthe hand is out- stretched and the wrist is in ulnar deviation, the scaphoid is aligned (and colinear) with the axis of the radius, which produces a bending moment. Thus, the distalportion of the scaphoid is forced into palmar flexion, and an acute humpback deformity is creat- ed as the fracture occurs with comminution of the volar scaphoid waist. Etiology and Prevention The most frequently cited factors in- volved in thedevelopment of scaphoid nonunion are tenuous blood supply in the scaphoid (especially the proximal pole), delay in diagnosis and management, fracture displacement/ comminution, and inadequate immobilization or poor patient compliance. These injuries often are perceived to be simple wrist sprains, an oversight that contributes to delay in diagnosis. Adequate radiographs and careful physical examination are helpful but not foolproof in diagnosing acute scaphoid fracture.Acute scaphoid fractures with collapse into a malalign- ment or a humpback deformity or with displacement ≥1.0 mm, an intrascaphoid angle >45°, or a height-to- length ratio >0.65 15,16 have a higher incidence of malunion and nonunion. 6,17 Comminution results in a highly unstable fracture that requires internal fixation to avoid a collapse deformity. Patient compliance is difficult to measure at the beginning of casting. Many patients express anx- iety about prolonged cast immobilization, especially active individuals aged 18 to 28 years. 18 Some nonunions may be preventable with earlier surgical management in patients with poor prognostic features (Table 1). Spontaneous healing of scaphoid nonunions without specific treatment has been reported, but that outcome is extremely rare. 20 Although asymptomatic nonunions without evidence of carpal collapse have been identi- fied, several studies have reported radiographic evidence of radiocarpal arthrosis within 10 years in almost all patients with scaphoid nonunion. 1,2,21 These studies may be subject to sam- pling bias in that they have included only patients who presented with symptoms, thus underrepresenting those who were asymptomatic. None- theless, they offer strong evidence sup- porting surgical management of scaphoid nonunions to prevent further carpal collapse and degenerative wrist arthrosis. Evaluation Physical Examination Scaphoid nonunion can be insid- ious in onset and may not be associated with a definite history of trau- ma. Patients may complain of a vague ache involving the wrist. The most common presentation is pain and loss of wrist motion. Some athletes mod- Figure 1 Radial view. The primary blood supply to the scaphoid is through the dorsal branch of the radial artery. MCI = first metacarpal, R = radius, S = scaphoid, Tz = trapezium. Table 1 Prevention of Scaphoid Nonunions 6,15,19 To prevent scaphoid nonunions and malunions, surgical treatment is recommended with any of the following: Fracture displacement ≥1.0 mm Fracture comminution Any proximal pole fracture Delay in diagnosis and initial treatment Fracture angulation in the sagittal plane with a lateral intrascaphoid angle >45° or a height-to-length ratio >0.65 Poor patient compliance as evaluated from the patient interview Thomas E. Trumble, MD, et al Vol 11, No 6, November/December 2003 381 ify their activities, such as doing knuckle pushups rather than using their palms. Such adaptive behaviors may indicate the necessity of radiographs and appropriate diagnostic tests. Pain to palpation in the anatomic snuffbox is a less reliable way of diagnosing scaphoid nonunion. Radiographic Evaluation Standard radiographs of a patient with a suspected scaphoid nonunion should include the following views: posteroanterior, lateral wrist, scaphoid (posteroanterior in ulnar deviation), and oblique with 45° to 60° of pronation. Theseradiographs also may reveal evidence of arthritis, including scaphoid sclerosis, cyst formation, and bone resorption. Careful examination of the lateral radiographs will help determine whether DISI with dorsal rotation of the lunate is present. A scapholunate angle >60° or a radiolu- nate angle >30° indicates a DISI deformity. 4,22 If a DISI deformity is present, it can be difficult to correct both the alignment of the scaphoid and the normal scaphoid-lunate relationship. When radiographs are equivocal, CT scans are useful in detecting scaphoid nonunions or incomplete unions. They also aid surgical planning (ie, bone graft type and location) in patients with extensive areas of collapse and/or bone resorption. In addition, CT scans provide more precise definition of the osseous anatomy and measurement of intrascaphoid angles. When definitive evaluation of fracture healing is needed, such as before re- turning to heavy work or contact sports, CT scans of the sagittal plane of the scaphoid (not the wrist) are done to quantify cortical bridging. 4 Carpal collapse in the sagittal plane of the scaphoid can be deter- mined by measuring the lateral intrascaphoid angle 6 (Fig. 2, A) or the height-to-length ratio 15,16 (Fig. 2, B)on sagittal CT scans. 23 The mean lateral intrascaphoid angle is 24° in patients with a normal scaphoid. 6 An angle >45° is associated with an increased incidence of arthrosis even in fractures that have healed. 6 Bain and col- leagues 15,16 reported greater observ- er reliability with the height-to-length ratio than with intrascaphoid angles. A height-to-length ratio >0.65 corre- sponded to significant scaphoid collapse; however, clinical correlation with management options was not evaluated. MRI scans canbe used todetect oc- cult acute scaphoid fractures, 24 evaluate scaphoid nonunions, and assess viability of thefracture fragments.Be- cause the vascularity of the proximal pole can be difficult to assess on plain radiographs, MRI should be strong- ly considered in cases of scaphoid waist nonunions. However, if plain radiographs clearly show osteonecrosis, MRI is not necessary. Proximal pole scaphoid nonunions may be as- sumed to be dysvascular, and empir- ic management can be initiated with vascularized bone grafting. Howev- er, it is important to accurately evaluate nonunions of the waist andprox- imal one third of the scaphoid (Fig. 3). The more proximal the initial injury, the greater the likelihood of developing osteonecrosis. Additionally, MRI is indicatedin patients withnon- unions refractory to previous surgery to determine the extent of necrotic bone. Fractures/nonunions with low signal on both T1- and T2-weighted sequences seem to be associated with the greatest compromise of vascular supply and have suboptimal healing rates after nonvascularized grafts 9 (Fig. 3, B). Proximal fragments with hypointense T1-weighted marrow signal have demonstrated osteonecrosis, empty bone lacunae, and poor uptake of fluorescent bone labels on biopsy. 9 In contrast, retention of some proximal pole signal has been asso- Figure 2 A, Sagittal CT scan of a displaced fracture with a lateral intrascaphoid angle of 66°. The lateral intrascaphoid angle (normal, ≤30°) is formed by lines (a and d) perpendicular to the diameters of the proximal and distal poles (b and c). B, Sagittal CT scan of an intact scaphoid. The height-to-length ratio should average <0.65. A greater ratio indicates collapse of the scaphoid. (Reprinted with permission from 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;82:633-641.) Management of Scaphoid Nonunions 382 Journal of the American Academy of Orthopaedic Surgeons ciated with viable bone on histologic examination and normal uptake of fluorescent labels. 9 Management Surgical management of established scaphoid nonunions is necessary giv- en the strong likelihood of eventual development of radiocarpal arthrosis with a persistent nonunion. Patients younger than 40 years with a short duration of nonunion (<2 years) have the best prognosis in the absence of osteonecrosis of the proximal pole.CT and MRI scanscan help evaluatenon- union in patients with minimal arthrosis present on plain radiographs. If a significant collapse exists, the extent of bone resorption and the location of the fracture can be difficult to ascertain.ACT scan will helpin planning the surgical reconstruction. If osteonecrosis is suspected, an MRI scan should be obtained to plan the type of graft to be used. Most hand surgeons recommend open reduction and internal fixation of the nonunion combined with bone graft. 19,24-28 Cast immobilization for scaphoid nonunion is not as effective as surgical intervention. Electrical stimulation cannot beused as the sole treatment, but it can be used in conjunction with either casting or surgery. Overall success rates for healing with the combination of cast immobilization and pulsed electromagnetic fields is 69%. 29 Previously, stimulation requiredan invasive technique for proper electrode positioning, but the advent of pulsed ultra- sound or electromagnetic fields has eliminated this difficulty. 30 Concom- itant long arm casting has been associated with a higher likelihood of healing when bone stimulators are used. Patients with nonunions of more than 5 years’ duration or with proximal pole nonunions have lessfa- vorable outcomes. 22 Because union rates with pulsed electromagnetic fields are inferior to those with surgery, it should be used as an adjunct to surgery or in cases in which surgery is not feasible and cast immobilization is the only option. Management hinges onwhether osteonecrosis of the proximal pole is present. When a scaphoid nonunion is present with normal vascularity of the proximal pole, internalfixation and nonvascularized grafting is recommended, with the approach directed by the site of the fracture. Initially, after excision of the sclerotic bone, cancellous autograft was packed into the nonunion defect through a dorsal approach. Russe 31 modified this meth- od by advocatinga volar approach and use of an oblong-shaped graft. Russe also reported another modification in which two matching corticocancellous iliac crest grafts were implanted with their cancellous sides facing each other. 31 However, one study, following a technique advocated by Russe, demonstrated only a 71% union rate. Heal- ing was less likely with proximal pole nonunions and in the presence of osteonecrosis. 32 The location of the nonunion helps to determine the surgical approach. A dorsal approach is used for proximal pole nonunions and a volar approach for scaphoid waist nonunions. 33,34 Studies by Inoue and Shionoya 35 and Robbins et al 36 have demonstrated that proximal pole nonunions can heal with stable internal fixation and bone grafting. How- ever, Green 32 showed that the rate of healing correlated directly with the vascularity of the proximal pole. Un- fortunately, fibrous unions and persistent nonunions tend to develop when osteonecrosis of the proximal pole is present. Such conditions often are refractory to traditional grafting methods, evenwhen augmented with internal fixation. Vascularized bone grafts are used for proximal pole nonunions and occasionally for scaphoid waist fractures with osteonecrosis, or when traditional bone grafting has failed to achieve union. Intercarpal instability requires careful attention to correct any humpback deformity at the nonunion site, usually through placement of a volarly based wedge graft. Early vascularized grafts often were based on a pedicle from the pronator quadratus muscle insertion on the distal radius, but this graft was difficult to place because of the short, bulkypedicle. More recent reports have advocated the use of a variety of sources, including the ulnar artery, the first dorsal metacarpal artery, and even a free vascularized graft from the iliac crest. 37,38 Figure 3 A, T1-weighted coronal MRI scan showing normal signal intensity from the proximal pole to thescaphoid despite fracture, indicating normal vascularity of the proximal pole. B, T1-weighted MRI scan showing the loss of signal from the proximal pole of the scaphoid (arrow), consistent with osteonecrosis. (Reprinted with permission from Trumble TE: Avas- cular necrosis after scaphoid fracture: A correlation of magnetic resonance imaging and his- tology. J Hand Surg [Am] 1990;15:757-764.) Thomas E. Trumble, MD, et al Vol 11, No 6, November/December 2003 383 Fernandez and Eggli 39 modified the Hori technique 40 of implanting thevas- cular bundle from the second dorsal intermetacarpal artery into the nonunion site, in additionto a wedge bone graft. Although the vascular pedicle lacked an osseous component, union was achieved in 10 of 11 patients at a mean of 10 weeks after surgery. The most frequently used donor sites include the dorsoradial aspect ofthe distal radius and the index metacarpal (based on the first dorsal metacarpal artery). 41-43 When osteonecrosis of the proximal pole is present, a dorsal approach can be used with either a vascularized bone graft from the distal radius 41 or, in selected cases requiring a very small graft, a second metacarpal bone graft. 42 The unsolved re- constructive problem is the scaphoid nonunion with osteonecrosis and collapse requiring a volar wedge with a vascularized graft. Possible solutions include (1) a dorsal approach with a radial styloidectomy to facilitate placing the Zaidemberg graft volarly, (2) a dorsal approach with a vascularized second metacarpal bone graft that has a pedicle allowing it to be rotated volarly, and (3) two separate approach- es using a standard Fernandez 39,44,45 volar bone graft and a second dorsal approach for a Zaidemberg vascularized bone graft or second metacarpal vascularized bone graft. 22 One criticism of the use of bone graft alone is the long period of postoperative immobilization that often is required (usually >6 months). For this reason, the addition of supplemental internal fixation recently has gained favor, with a gratifying in- crease in union rates (consistently >90%) and a reduction in duration of immobilization. 4,35,46-49 Internal fixation in conjunction with bone grafting can be done with staples, wires, and screws. However, staples may cause distraction of the fracture site and rarely are used. Multiple Kirsch- ner wires (K-wires) can provide fixation but not the compressive effect that is achieved with screw fixation. The wires must be removed eventu- ally, but they may have to beremoved before union if they migrate or be- come prominent. Although K-wires initially were used to stabilize the scaphoid, screws with threads attheir ends or along their entire course can be buried beneath the articular surfaces to prevent impingement. Sev- eral screws have been specifically designed for use in the scaphoid. The Herbert screw is a double-threaded noncannulated screw with a differen- tial pitch that allows for compression at the fracture site. Its insertion can be facilitated with a positioning jig. The Herbert-Whipple screw, its cannulated counterpart, may allow more optimal positioning via placement of an initial guidewire. 4 The Acutrak screw (Acumed, Hillsboro, OR) 50,51 is cannulated and has a tapered diam- eter. Regardless of the type of screw used, accurate centering of the implant is critical. Trumble and col- leagues 4,17,52 found that successful positioning of screws within the central third of the proximal pole was signif- icantly (P< 0.05) more likely with cannulated implants, and time to union was reduced more than 50%. Salvage procedures, such as radial styloidectomy, proximal row carpectomy, limited intercarpal ar- throdesis, and complete wrist fusion, are reserved for cases of severe degenerative arthrosis. Surgical Techniques Scaphoid Waist Nonunions With a Viable Proximal Pole Scaphoid waist fractures with a viable proximal pole should be approached volarly to preserve the remaining dorsal blood supply. Unlike the acute fractures that can be approached using a small incision over the scaphotrapezial joint, the Russe technique is used, with an incision made along the course of the flexor carpi radialis (FCR) longus muscle, extending distally along the border of the glabrous skin of the thenar em- inence (Fig. 4, A). Splitting the sheath Figure 4 A, The sheath of the flexor carpi radialis (as noted by the pen) is incised to expose the capsule overlying the scaphoid. B, The scaphoid nonunion is exposed by incising the floor of the flexor carpi radialis sheath that forms the volar capsule of the radioscaphoid articulation. If possible, the radioscaphocapitate ligament is preserved. FCR = flexor carpi radialis, PQ = pronator quadratus muscle, R = radius, S = scaphoid, Tz = trapezium. Management of Scaphoid Nonunions 384 Journal of the American Academy of Orthopaedic Surgeons of the FCR allows it to be retracted ulnarly to protect the palmar cutane- ous branch of the median nerve. The floor of the FCR sheath is incised longitudinally to expose the distal pole and waist of the scaphoid (Fig. 4, B). Preservation of as much of the radioscaphocapitate ligament as possible is important because it helps to con- tain the proximal pole and prevent it from subluxating volarly. 4,17 If cannulated screws are used, it is not necessary to completelydivide the radioscaphocapitate to facilitate placement of the guide. The humpback deformity must be corrected to allow stable fixation with the screw in the long axis of the scaphoid 4,6 (Fig. 5). Small osteotomes are used to wedge the collapsed scaphoid into its correct alignment (Fig. 6). Care must be tak- en not to disrupt the dorsal cortex of the scaphoid, which can damage any remaining blood supply to the proximal pole andmake the fracture highly unstable. Full excavation of the nonunion site is accomplished with fine curettes and a high-speed burr with saline irrigation. The burr is required largely to remove sclerotic por- tions of the proximal pole. Dental picks or K-wire joysticks can help re- duce the scaphoid nonunion. With a volar approach, the inner wall of thedorsal cortex canbe notched to accommodate the wedge graft. The dorsal cortex serves as a hinge around which the distal fragment can be rotated as it is reduced with wrist dor- siflexion. Because the screw fixation offers significant stability, a cancellous rather thancorticocancellous bone graft can be used; the guidewire prevents scaphoid collapse as the screw com- presses the fracture site. When large segments of the volar cortex are miss- ing, the corticocancellous graft aids stability, especially if it can be com- pressed with the scaphoid screw. To provide the best access for insertion of a screw into the long axis of the scaphoid, it is important to remove the small volar lip of the trapezium with a rongeur. Failure to do so can result in a screw that is placed too dorsal and too close to the fracture line in the proximal pole (Fig. 7). The guidewire is inserted with a power drill upto the limits ofthe subchondral bone to measure the length of the screw. With an unstable nonunion, a second wire is placed intothe scaphoid to prevent rotation of the fragments during screw insertion. This derotation wire helps stabilize scaphoid alignment while the screw is placed into the center of the proximal pole. When large bone grafts are needed, rendering the screw fixation less stable, the derotation wire can be left in place for approximately 3 months 53 (Fig. 7). The guidewire then is driven into the radius to prevent it from dislodging. The cannulated drill and tap prepare the path for the screw, and progress is monitored with fluoroscopy.After the screw is inserted, the guidewire is removed and plain radiographs are made to con- firm the position of the screw (Fig. 8). Inlay grafting does not achieve adequate correction of deformity in scaphoid nonunions with palmar flexion of the distal fragment. This deformity must be corrected to allow for stable screw fixation in the long axis of the scaphoid. These humpback scaphoids may be associated with the DISI pattern of carpal collapse, in which the lunate assumes a relative- ly fixed dorsiflexed position. Fisk 54 noted that the position of the lunate can be corrected by filling the defect of the scaphoid nonunion with a trap- ezoidal bone graft. Because the broad base of the defect faces volarly, the Figure 5 Awedge of bone graft used to correct the humpback deformity. Axial placement of the screw stabilizes the correction. Figure 6 A, Small osteotomes can be used to correct the humpback deformity of the scaphoid nonunion. B and C, Cancellous or tricortical bone graft can be harvested from the iliac crest or distal radius to help maintain the corrected position of the scaphoid. Supplemental internal fixation is recommended. S = scaphoid, Tz = trapezium. Thomas E. Trumble, MD, et al Vol 11, No 6, November/December 2003 385 wedge autograft is inserted so its apex is positioned dorsally, thus abolish- ing the humpbackdeformity. Fisk used a radial approach to the scaphoid and radial styloid bone graft without internal fixation. Fernandez 44 modified this technique by using graft from the iliac crest and a volar incision with internal fixation (Fig. 6). Recent reports on the Fisk-Fernandez technique show union rates that consistently exceed 90%, with fairly rapid healing (in the absence of osteonecrosis) that obvi- ates the need for prolonged immobilization. 4,35,46-49 Cannulated screw fixation improves the accuracy of screw placement in these difficult nonunions. 4 Better functional scores, including range-of-motion arcs, were obtained when DISI collapse was corrected with adequate restoration of scaphoid height. 55 One report suggests that the correction is more pre- dictably obtained with proper lunate reduction and temporary radiolu- nate pinning done before placement of the scaphoid graft. 56 The radiolu- nate pin is removed at the conclusion of the procedure. However, the lunate may remain in a dorsally rotated position despite correction of the humpback deformity, especially in long-standing nonunions. Proximal Pole Nonunions With an Avascular Proximal Pole The dorsal approach is preferred for proximal pole fractures because the smallproximal fragmentoften can be difficult to target from thevolar approach. Also, placing the screw volarly can displace the proximal pole. 36 Usually the fracture line of a nonunion occurs from distal volar to proximal dorsal. Thus, a screw may not cross the nonunion if a volar approach is used (Fig. 9, A). The dorsal approach allows screw placement in the central portion of the proximal pole fragment (Fig. 9, B). Realizing that the vascular supply of the proximal fragment already has been sig- nificantly compromised by a fracture mitigates concerns that a dorsal approach might further threaten vascularity. Implants can be inserted either freehand or with the use of a guidewire advanced from proximal to distal toward the trapezium. Im- plants must be countersunk ade- quately because insertion is performed in the center of the articular surface of the proximal pole. The dorsal approach is performed using a small longitudinal incision made in the midline of the wrist cen- tered over the radiocarpal joint. The sheath of the extensor pollicis longus (EPL) muscle is released, and a longitudinal incision is made in the capsule of the radiocarpal joint. The capsule and fourth dorsal compartment are sharplydissected offthe dorsal lip of the radius to expose the scapholunate articulation (Fig. 10). Because the nonunion site can be difficult to identify, a needle often is used under fluoroscopy as a guide pin to help lo- cate thecorrect plane of the nonunion. Small curettes are used to remove the necrotic bone without disrupting significant amounts of the articular car- tilage. Occasionally, a high-speed burr is necessary to remove the dense necrotic bone. It is important to protect the vessels entering the distal dorsal ridge of the scaphoid. The entry sitefor the screw just ad- jacent to the scapholunate interosseous ligament can be visualized by flexing the wrist. The noncannulated Herbert screw can be inserted freehand, or a cannulated screw can be used. The guide pin position is con- firmed with fluoroscopy and then driven up to the subchondral bone of the distal pole. The length of the screw is measured with a depth gauge. Frequently, placement ofa second derotational K-wire will prevent the screw insertion from displacing the proximal pole fragment. The guide pin then is driven into the trapezium to prevent it from dislodging. The hole is drilled and tapped before inserting the screw. In small proximal pole fragments, the guide pin is removed and a noncannulated Herbert screw is inserted because it leaves a Figure 7 The volar lip of the trapezium is removed and the cannulated scaphoid screw is inserted into the long axis of the scaphoid to obtain excellent purchase in the proximal pole. If the lip of the trapezium is not removed, the starting point for the screw is too volar and the proximal end of the screw is placed too dorsal. The guidewire prevents rotation of the small fracture fragment during screw placement. Figure 8 Anteroposterior radiograph. The cannulated screw is placed in the center of the scaphoid proximal pole (arrows), which will ensure the best compression of the nonunion and the most stable configuration. Management of Scaphoid Nonunions 386 Journal of the American Academy of Orthopaedic Surgeons smaller defect or footprint in the car- tilage of the proximal pole. A mini- Acutrak screw can also be used. Vascularized Bone Grafting for Proximal Pole Nonunions With Osteonecrosis The vascularized bone graft described by Zaidemberg et al 41 relies on the arterial branch of the radial artery that courses between the first and second dorsal compartments 27 (1,2 in- tracompartmental supraretinacular artery [1,2 ICSRA]) (Fig. 11). This graft provides blood supply as well as the bone graft to fill the bone void in the nonunion. The 1,2 ICSRA lies deep to the tendons of the first dorsal compartment and travels in a distal-to- proximal direction between the two compartments.Adorsoradial approach allows for harvesting of the graft as well as exposure of the scaphoid nonunion as an extension of the dorsal approach for the viable proximal pole. The incision begins over the midline of the dorsal region of the wrist and curves proximal and radial over the interval between the first and second dorsal compartments. The third dorsal compartment, which contains the EPL muscle, is released, and the EPL muscle is retracted radially. The sen- sory branch of the radial nerve is iden- tified exiting from between the bra- chioradialis and the extensor carpi radialis longus muscles. The extensor carpi radialis longus is retracted ulnarly, and the capsule of the wrist is incised longitudinally to expose the scaphoid. The vascularized bone graft is harvested withan elliptical paddleof corticocancellous bone, periosteum, and retinaculum supplied by the recur- rent vessel from the radial artery. The 1,2 ICSRA is visible as a thin red line in the groove between the first and second dorsal compartments. The vessel originates distally from the radius and pierces the volar wall of the first dorsal compartment. The first dorsal compartment is released along its palmar surfaceand the tendons retracted. The artery is mobilized by making parallel incisions in the periosteum between the two compartments, tracing the course of the artery from distal to proximal. Once a 2.0- to 2.5-cm pedicle has been prepared, the periosteum around the planned donor site is incised as an ellipse or rectangle. Afine oscillating saw with constant irrigation is used to cut three sides of the graft. Small osteotomes then are used to complete the eleva- tion of the graft. After preparation of the scaphoid nonunion site, the vascularized graft is rotated into the defect and secured with either K-wires or a scaphoid screw. The capsule is closed loosely to avoid strangulation of the vascular pedicle. Union was achieved in all 11 patients included in the original article Figure 9 A, Volar screw insertion in a proximal pole fracture. The proximal threads of the cannulated screw do not cross the nonunion site. B, Dorsal screw placement results in stable fixation of the proximal pole fracture. Figure 10 A, The proximal pole nonunion is approached dorsally by incising the third dorsal compartment and sharply elevating the fourth dorsal compartment off the capsule. B, A screw and derotational K-wire in the scaphoid for fixation of a proximal pole fragment. C = capitate, L = lunate, S = scaphoid. Thomas E. Trumble, MD, et al Vol 11, No 6, November/December 2003 387 by Zaidemberg et al. 41 Although union rates associated with the var- ious vascularized bone grafts appear to be high, the infrequent use of these grafts makes it difficult to determine the superiority of this technique over others. Nonetheless, vascularized bone grafting clearly has a role in the treatment of scaphoid nonunions. Scaphoid Waist Nonunions With an Avascular Proximal Fragment Scaphoid waist fractures with osteonecrosis of the proximal fragment can be managed with a vascularized bone graft through a dorsalapproach, using internal fixation with a scaphoid screw, as described for proximal pole fractures. The deformity is best corrected with a volar bone graft. In cases with a severe humpback deformity, the graft can be placed volarly by rotating the graft under the radial artery. Often, additional nonvascularized bone graft is required to help fill the void left by the removal of necrotic bone. The radial styloid can be removed to improve the exposure and to avoid later impingement when the scaphoid deformity cannot be corrected. Salvage Procedures for Scaphoid Nonunions With Arthritis Once significant radiocarpal or intercarpal arthrosis has developed because of a scaphoid nonunion, bone grafting and/or internal fixation is unlikely to produce a successful result. A different armamentarium of salvage procedures is needed to treat scaphoid nonunion advanced collapse (SNAC). As the scaphoid collapses, the car- pus rotates into a fixed DISI pattern with progression of arthritis that resembles the four stages of the arthritis from a scapholunate ligament disruption. 11,57-61 Stage I shows beaking of the radial styloid. Stage II is marked by arthrosis of the radioscaphoid joint. Stage III occurs when the arthrosis extends to involve the capitolunate articulation. Stage IV is the presence of pancarpal arthrosis. In stage I, a radial styloidectomy can be done along with internal fixation and bone grafting of the scaphoid nonunion (Fig. 12). For stage IIarthro- sis, several options are available. Malerich et al 62 described excision of the distal pole as the site of impingement (Fig. 13). The proximal pole was maintained to prevent migration of the capitate. Ruch et al 63 performed arthroscopic excisionof the radialsty- loid and the distal pole of the scaphoid. Proximal row carpectomy andulnarfour-bonearthrodesis(capitate-lunate-triquetrum-hamate) with scaphoid excision also has been recommended. 64,65 Advantages of proximal row carpectomy include relative ease of the procedure, a shorter period of postoperative immobilization, and elimination of concerns about nonunion at the fusion site. 64 Apro- Figure 11 A through C, The vascular bone graft described by Zaidemberg is based on an artery that runs in a retrograde fashion between the first and second dorsal compartments. (Adapted with permission from Zaidemberg C, Siebert JW, Angrigiani C: A new vascularized bone graft for scaphoid nonunion. J Hand Surg [Am] 1991;16:474-478.) Management of Scaphoid Nonunions 388 Journal of the American Academy of Orthopaedic Surgeons gression of the arthrosis between the lunate and capitate has been reported, although the patients remained asymptomatic. 63 A four-bone arthro- desis combined with scaphoid excision is preferred for stage III SNAC. The developmentof advancedradio- lunate arthrosis (stage IV) usually is an indication for complete wrist fusion. Silicone carpal implants have a poor record because of problems of silicone synovitis, loosening, dislo- cation, and even breakage. 66,67 Their use after partial or complete excision of the scaphoid is not recommended. Summary Scaphoid nonunions are challenging because they may not always be symptomatic in their early stages; therefore, at delayed presentation, they can have greater bone loss, carpal collapse, and loss of blood supply. The natural history of nonunions is that eventual carpal collapse and degenerative arthrosis will ensue, usually within 10 years. When nonunions are recognized in stable position, bone grafting with use of supplemental fixation (typically, screws) yield union in almost all cases as long as the proximal pole of the scaphoid is free of osteonecrosis. A volar approach is appropriate for waist nonunions, whereas a dorsal approach is required for proximal pole nonunions to allow for proper implant positioning. Restoration of scaphoid length and correction of existing humpback deformity should be achieved to op- timize results. Proximal pole nonunions accompanied by osteonecrosis require the addition of a vascularized bone graft. Vascularized grafts also may be useful for nonunions that fail to heal after adequate fixation and traditional grafting methods. Salvage procedures, suchas radial styloidectomy, scaphoid excision with or without limited midcarpal fusion, proximal row carpectomy, and total wrist fusion, are reserved for cases with severe carpal collapse and arthrosis. Figure 12 A, Anteroposterior radiograph demonstrating a painful stage I SNAC arthrosis with beaking of the radial styloid (asterisk) and a “kissing” osteophyte on the scaphoid (arrow). B, Anteroposterior radiograph showing excision of the osteophytes, coupled with bone grafting and internal fixation of the scaphoid. The patient’s symptoms resolved. Figure 13 A, Anteroposterior radiograph demonstrating stage II SNAC arthrosis, with nar- rowing of the radioscaphoid articulation in addition to the beaking of the radial styloid. The capitolunate articulation (1) and the articulation between the proximal pole of the scaphoid and the capitate (2) are spared of arthritis. The arthritic changes occur between the distal pole of the scaphoid and the capitate (3) and between the radial styloid and the scaphoid (4). B, Excision of the distal pole of the scaphoid avoids impingement between the scaphoid and radius and preserves the midcarpal articular surface (arrowheads). (Reprinted with permission from Malerich MM, Clifford J, Eaton B, Eaton R, Littler JW: Distal scaphoid resection arthroplasty for the treatment of degenerative arthritis secondary to scaphoid nonunion. J Hand Surg [Am] 1999;24:1196-1205.) Thomas E. Trumble, MD, et al Vol 11, No 6, November/December 2003 389