FRACTURES OF THE SCAPHOID

Fractures of the scaphoid are among the most common fractures of the wrist after fractures of the distal radius and represent the most common fracture of a carpal bone.150,393,537 The position of the scaphoid on the radial side of the wrist, as a proximal extension of the thumb ray, makes it vulnerable to injury. Not only does the scaphoid mechanically link the proximal and distal carpal rows, but it is also firmly attached at both ends to strong ligament systems that limit and control its motion.47 It is self-evident that the scaphoid flexes with wrist flexion and extends with wrist extension, but it also flexes during radial deviation and extends with ulnar deviation. These factors make immobilization of scaphoid fractures difficult, especially when there is displacement. This change in position of the scaphoid during different planes of wrist motion confirms the scaphoid's role as the mechanistic key that controls wrist stability and serves as the principal bony support between the proximal and distal carpal rows and for carrying compressive loads from the hand across the wrist to the distal forearm. There are two different mechanisms of scaphoid fracture that may explain the differences in clinical presentation-compression injury and hyperextension, bending injury (Fig. 12-86). The compression fracture from a more longitudinal load or impaction of the wrist leads to intraction of the scaphoid without displacement. Tensile stresses generated palmarly when excessive hyperextension is applied to the wrist and when tensile forces exceed bone strength produce a fracture through the scaphoid that commonly results in fracture displacement. As a result of these two different mechanisms, scaphoid fractures can present as nondisplaced, stable fractures or as displaced, unstable fractures.138

Fig. 12-86 65%-waist; 15%-proximal pole; 10%-distal body; 8%-tuberosity; 2%-distal articular surface.

The scaphoid is an irregularly shaped bone, more resembling a deformed peanut than the boat for which it is named. It rests in a plane at 45° to the longitudinal axis of the wrist. Articular cartilage covers 80% of the surface. The proximal pole is constrained to the lunate by an interosseous ligament. The distal pole has a V-shaped scaphotrapezial ligament, a scaphocapitate ligament, and a dorsal capsule. It rests on and can be attached along the ulnar aspect of the waist to the radioscaphocapitate ligament. The only other capsular influence is where the dorsal intercarpal ligament inserts obliquely on a roughened ridge and brings the primary blood supply that enters the scaphoid. Otherwise, the scaphoid has no ligamentous or tendinous attachments and acts with the rest of the proximal carpal row as 'intercalated segments' subjected to the forces acting on them.89,309 Compressive forces, acting across a three-link structure, cause a zig-zag collapse deformity. With a scaphoid fracture, the distal scaphoid tends to flex and the proximal scaphoid extends with the proximal carpal row. As a consequence, angulation occurs at the fracture site, which gaps open dorsally and gradually assumes the so-called humpback deformity.18 Studies have shown that this deformity may occur at the time of fracture and result in immediate malposition of the scaphoid fragments into radial as well as dorsal angulation.490 Failure to correct such deformity leads to fracture malalignment, nonunion, or malunion.322,342

Despite the lack of direct tendon attachment, joint compressive forces, trapezial-scaphoid shear stress, and capitolunate rotation moments exert control on the scaphoid. As a consequence of these biologic and mechanical factors, scaphoid fractures have a high incidence of nonunion (8% to 10%), frequent malunion, and late sequelae of carpal instability and post-traumatic arthritis. Next we examine the diagnosis and treatment of acute scaphoid fractures and address the treatment options available when scaphoid union is either delayed or absent.

Acute Scaphoid Fractures

Acute fractures of the scaphoid were first recognized in 1889 by Cousin and Destot145 before the discovery of x-ray. A clear description was made later, in 1919, by Mouchet and Jeanne.268 Scaphoid fractures are usually an injury of young men occurring after a fall, athletic injury, or motor vehicle accident. The mechanism of fracture is usually considered a bending fracture with compression dorsal and tension palmar. However, axial loading compression injuries have been suggested as another mechanism, particularly in the nondisplaced, stable fracture.256a Scaphoid fractures in children are uncommon, because the physis of the distal radius usually fails first.7,103,173,235,311,531 Concomitant fractures of the distal radius and scaphoid have been reported.256b,530a,531 Similarly, in the elderly, the distal radial metaphysis usually fails with fracture before the scaphoid fractures.

The patient often presents to the emergency department complaining of wrist pain and may be diagnosed as having a 'sprain' of the wrist. In sports injuries it is not uncommon for the wrist injury to go unnoticed, with the request for evaluation and treatment delayed.342 Fractures of the scaphoid in adolescents, previously believed uncommon, are now being reported more frequently and with different clinical appearance.377a,500a

Signs and Symptoms

The diagnosis of a scaphoid fracture is made on clinical examination where the index of suspicion is raised and by proper radiographic examination, by which the diagnosis is confirmed (see Fig. 12-47B).146 Clinical examination should demonstrate tenderness in the snuffbox region of the wrist, over the tuberosity, or on the proximal pole of the scaphoid just distal to Lister's tubercle. Range of motion is reduced but not dramatically. There is usually pain at the extremes of motion. Swelling or ecchymosis is not present except in fracture-dislocations. Clearly, these same physical findings may be present with ligamentous injuries of the wrist, and thus whenever there are any findings suggestive of a scaphoid fracture,124,146 the patient should be treated for a suspected scaphoid fracture.103

Radiographic Examination

Radiographic diagnosis of a scaphoid fracture often requires special views and occasionally special tests.160,173,468 The emergency posteroanterior and lateral x-rays146 should also include a scaphoid view (see Fig. 12-22), which puts the scaphoid in profile. Motion views of the wrist (Fig. 12-87) (flexion-extension and radial and ulnar deviation) may demonstrate fracture displacement, which is an indication of an unstable scaphoid fracture. These same x-rays should be repeated at 2 to 3 weeks if the initial films were negative. It is imperative for the treating physician to make the diagnosis at this time, because a delay in diagnosis increases the incidence of scaphoid nonunion.160 If a diagnosis still cannot be confirmed with confidence on routine films, a technetium bone scan (Fig. 12-88),45,202,411,417 polytomography (Fig. 12-89),58,223,403 or MRI (Fig. 12-90 and Fig. 12-91)51,261a of the wrist is recommended, in that order of preference.222,411,417,438,525a Ultrasonography and intrasound vibration examination have also been used to detect the occult, undiagnosed scaphoid fracture.102,181a We have been impressed with the ability of both CT scanning276a and MRI to clearly show a scaphoid fracture when both plain films and even polytomography were not diagnostic of a fracture.57,261a Most authorities recommend bone scintigraphy as the procedure of choice for a suspected but unconfirmed fracture.45,202,444a,525a,525b

Fig. 12-22 Incidenta oblica scafoido-radiala (AP In supinatie). A) Antebratul este asezat pe masa cu radiocarpul asezat in centrul casetei; B) Antebratul este rotat in pronatie de 45 grade sprijinit pe support; C) Aceasta incidenta pune in evidenta scafoidul pe toata lungimea de profil (stg); prin comparatie incidenta oblica ulnara arata suprapunerea capitatului Si al semilunarului peste scafoid cu evidentierea buna a articulatiei scafo-radiale (dr)

When instability of the scaphoid is suspected, careful analysis of the lateral x-ray for intrascaphoid angulation or a dorsally tilted lunate is recommended (Fig. 12-92). Motion views comparing scaphoid position during radial and ulnar deviation may also demonstrate motion at the fracture site (see Fig. 12-87). Polytomography, however, is a good method to determine scaphoid displacement.51 Lateral tomography or lateral CT (and axial) scanning can be used to measure the exact degree of intrascaphoid angulation or displacement (see Fig. 12-92).332,468 Three-dimensional imaging of scaphoid fractures and fracture nonunions has been reported both to assess displacement mechanisms as well as to plan treatment.45a From biplanar trispiral tomography, we have studied the range of normal angulation of the scaphoid to detect displacement and instability.490,491 Measurements appear to be reproducible to within 5° and, when compared with the uninvolved scaphoid, provide information to assess not only the presence of displacement but the accuracy of reduction. Three-dimensional representation of the scaphoid using CT scanning and three-dimensional imaging provides the ability to describe displacement in all three planes and has promising clinical application.45

Fig. 12-92 Angularea scafoidului. A) Scafoid normal si scafoid cu deformare in cocoasa. Unghiul intrascafoidian (IS)  lateral normal este 35+/-5 grade. B)Fractura scafoid bilaterala cu deplasare vicios consolidata cu IS anormal de 50 (sus) si normal de 28 (jos), in ciuda cominutiei dorsale; C) Unghiul capitulo-lunat poate fi util in stabilirea instabilitatii fracturii: sus de 35 grade, jos de 25 de grade. Ambele unghiuri confirma instabilitatea carpiana asociata cu fractura de scafoid cu deplasare.

Differentiation between an acute scaphoid fracture and a scaphoid nonunion is important for planning treatment, and only proper x-rays can make the difference evident. Not uncommonly, a second injury will draw attention to a minimally symptomatic nonunion aggravated by the recent event. The acute scaphoid fracture is represented by a single line through the bone, occasionally with dorsalradial comminution and dorsal angulation. Late presentation of a fracture or established nonunion, conversely, will demonstrate resorption at the fracture site (evident as a space between the fragments), subchondral sclerosis, and displacement on both the posteroanterior and lateral x-rays.12 A true pseudarthrosis separates delayed acute fracture from established nonunions. The longer the period of time since injury, the greater the cystic resorption, the denser the sclerosis, the more prominent the shortening of the scaphoid, and the greater the loss of carpal height. Secondary degenerative changes are usually present by 10 to 15 years.322

Classification

Fractures of the scaphoid may be classified either by the location of the fracture within the bone or by the amount of fracture displacement (stability).

Location

Classification by anatomical location has many proponents, some of whom attempt to correlate fracture union rate with the site of injury (see Fig. 12-86). Five different fracture sites have been described: tuberosity, distal third, waist, proximal third, and distal osteochondral fractures.116,537 All but the tuberosity fractures are intra-articular to a greater or lesser degree.122,252,443 From a series of scaphoid fractures carefully studied, waist fractures accounted for 80%, proximal pole, 15%; tuberosity, 4%; and distal articular, 1%. Nonunion of the distal scaphoid has only recently been recognized and reported.384a The other anatomical classification is based on the direction of the fracture, with horizontal, oblique, avulsion, and comminuted types described.

The healing time for these different fracture types ranges from 4 to 6 weeks for tuberosity fractures, 10 to 12 weeks for distal third and waist fractures, and 12 to 20 weeks for proximal pole fractures.

The blood supply of the scaphoid is critical in regard to fracture location. Gelberman's work214 confirmed earlier studies demonstrating that the major blood supply comes from the scaphoid branches of the radial artery, entering the dorsal ridge and supplying 70% to 80% of the bone, including the proximal pole. The second major group of vessels enters the scaphoid tubercle, perfusing only the distal 30% of the bone. With fractures through the waist and proximal third, revascularization will occur only with fracture healing. One can assume that with proper treatment nearly 100% of tuberosity and distal third scaphoid will heal; 80% to 90% of fractures at the waist will heal; and only 60% to 70% of proximal pole fractures will heal. Similarly, oblique or shear fractures have been shown to have delayed healing in comparison to horizontal fractures. Comminuted or distracted osteochrondral fractures will have the poorest rate of union.

Stability

The second major classification of scaphoid fractures subdivides them into either stable or unstable fractures.116,252 A stable fracture is one that is nondisplaced, and it may have an intact cartilage envelope. That is, the fracture may occur within the bony substance of the scaphoid, usually from an impaction rather than a bending mechanism, incompletely separating the two fracture components. X-rays in two planes, as well as motion views, do not show any step-off or displacement of these fractures. The unstable scaphoid fracture, conversely, is by definition displaced with a step-off of 1 mm or more of angulation of the scaphoid in a lateral x-ray (Fig. 12-93). Rotational displacement can also be detected. The rate of fracture union and options for treatment change dramatically when one compares unstable and stable scaphoid fractures. Unstable fractures can be simply displacement from bending fracture mechanisms or from high energy, leading to fracture-dislocations of the wrist.

Fig. 12-93 Fractura instabila

Treatment

Nondisplaced Fractures

The primary treatment for acute fractures of the scaphoid is cast or splint immobilization.506,559b As mentioned earlier, when there is any question regarding the presence of a scaphoid fracture, cast immobilization is recommended for 2 to 3 weeks until the diagnosis can be reassessed. The debate between long- and short-arm casts, as well as the position of immobilization, has not been definitely answered, but findings of recent studies should influence our decision.35a,395 In one prospective study, Gellman and coauthors compared short- and long-thumb spica casts and noted decreased time to union and reduced rates of delayed union and nonunion with a long-arm thumb spica cast.217 The findings in this study agree with those of earlier reports84,183,226,537 that noted higher rates of healing with a long-arm cast for 4 to 6 weeks. Conversely, those surgeons who prefer a short-arm thumb spica cast point to 95% union rates in their personal series. Furthermore, a study from Nottingham, England, suggests that the thumb does not need to be included, provided the wrist is immobilized in the treatment of the acute, nondisplaced fracture.105a Tuberosity fractures are undoubtedly suitable for a short-arm cast, while patients with proximal pole fractures are candidates for a long-arm cast (if not open fracture treatment).

The recommended position of immobilization for scaphoid fractures varies from full extension to slight flexion, with varying degrees of radial or ulnar deviation. The amount of fracture displacement, alignment in both the posteroanterior and lateral planes, and associated injuries have been analyzed by several biomechanical studies, suggesting that a position of neutral flexion-extension and slight ulnar deviation is the preferred position of nondisplaced and minimally displaced scaphoid fractures. To reduce the stress produced by the volar and radiocapitate ligament, Weber and Chao553 recommended radial deviation and palmar flexion. This position makes radiographic assessment difficult. From an analysis of simulated displaced fractures it would appear that slight radial or ulnar deviation is acceptable, along with neutral flexion-extension. If the effect of lunate extension on dorsal gapping of the fracture site is important, then an attempt at flexing the lunate should help control the scaphoid reduction. This can be accomplished by careful molding of the cast. A depression is created over the capitate neck while displacing the carpometacarpal area relative to the forearm. The capitate tends to derotate the lunate and proximal pole, providing better coaptation of the fracture fragments (Fig. 12-94).

Fig. 12-94 Reducerea ortopedica a unei fracturi de scafoid cu deplasare prin presiune in trei puncte. In sus se apasa de pe fata palmara extremitatea distala a scafoidului iar in jos se apasa pe fata dorsala pe capitat si semilunar.Deplasarea capitatului palmar roteste semilunarul si polul proximal al scafoidului in flexie si inchide lacuna posterioara.

For nondisplaced stable scaphoid fractures (Fig. 12-95), we recommend a long-arm thumb spica cast, with the wrist in neutral deviation and neutral flexion-extension for 6 weeks, followed by a short-arm thumb spica cast until there is radiographic union confirmed by polytomography.116 The union rate should exceed 95%. Delay in recognition, delay in initial treatment, and proximal third location of the fracture all negatively influence fracture healing.

Displaced Fractures

Author's Preferred Method of Treatment. Displaced fractures of the scaphoid require treatment different from that for nondisplaced fractures. A displaced fracture, by definition, is one with greater than 1 mm of step-off or more than 60° of scapholunate or 15° of lunatocapitate angulation as observed on either plain x-rays or tomography.117 The degree of instability may vary, and thus there are different choices for fracture treatment. We believe that there is still a role for a carefully applied long-arm thumb spica cast in the treatment of displaced scaphoid fractures, provided that the fracture can be acceptably reduced and the reduction maintained. To effect the reduction, three-point pressure on the tubercle of the distal scaphoid palmarly is combined with dorsal pressure over the capitate and dorsal support at the distal radius, which helps reduce and maintain the dorsal lunate angulation (see Fig. 12-94). An acceptable reduction includes alignment with less than 1 mm of displacement and a scapholunate angle of not more than 60°. With lateral tomography (or CT scanning), lateral intrascaphoid angulation should not exceed 25° ± 5°, and the posteroanterior angulation should be not more than 35° ± 5°.

If an accurate fracture reduction cannot be obtained, then other methods of treatment should be considered. These include closed reduction and percutaneous pin fixation, open reduction and pin fixation,167 and open reduction and compression screw fixation (Fig. 12-96 and Fig. 12-97).88,140,251,253,310 For acute displaced fractures that cannot be easily reduced, we recommend open reduction and Kirschner-wire or compression screw fixation of the scaphoid. The technique we prefer is to realign the proximal scaphoid and lunate to the distal radius and secure them with Kirschner wires. The proximal fracture components are stabilized by this procedure. The distal scaphoid can then be reduced onto the proximal fragments and fixed in that position. In addition to Kirschner-wire fixation or compression screw (AO, Herbert), a long-arm thumb spica cast is maintained for 6 weeks. After Kischner-wire removal, a short-arm cast is applied until fracture healing is confirmed radiographically (preferably with polytomography or CT scan).

Fig. 12-97 A) Insertia unui surub de compresiune. Reducerea cu brosa K se face inainte de introducerea surubului (vedere din proximal spre distal (sus) si lateral-radial (jos). B) Fractura cominutiva 1/3 distala scafoid redusa si fixata cu brosa si surub Herbert. Corectia inclinarii dorsale a semilunarului s-a efectuat anterior de reducerea scafoidului si fixata cu o brosa. C) Incidenta laterala a sintezei.

With the advent of new compression screws and staples for the scaphoid, internal fixation has become more popular.88,253,301,301a,310,346,442,443a,492a,559a These procedures provide more rigid fixation for the scaphoid and allow earlier wrist motion.446a A number of authors have reported their experience with such techniques, but consensus on the role of screw fixation appears to suggest a definite role for early internal fixation of the scaphoid.1,110a,121,187,253a,310,389,397,442 Several authors have reported significant problems with screw fixation of acute scaphoid fractures.1,212,353,389 We reviewed 20 patients with displaced scaphoid fractures in which open reduction and internal fixation was performed early, less than 6 weeks. Nineteen of 20 healed. A comminuted fracture had delayed healing and required a Russe bone graft. Motion and strength were improved over cast immobilization, and patients returned to work and other activities by an average of 3 months. Although strong fixation is provided initially, should fracture union not occur, loosening of the screw and loss of fixation has been reported. A biomechanical analysis compared the fixation strength of different bone screws and noted less interfragmentary compression with the Herbert screw than was anticipated from its unique design of differential thread-pitch between the distal and proximal screw ends. The correct application of fracture reduction and alignment devices is essential for anatomical screw placement.110a The development of cannulated screws placed over a Kirschner wire or use of intraoperative imaging has improved the technical factors associated with fracture fixation.70

The current role for compression screw fixation of scaphoid fractures is limited to displaced fractures, displaced proximal pole fractures,140 and fracture-dislocations.150 Postfixation cast immobilization is recommended despite proposals for early motion at 2 to 3 weeks.251 Conclusive studies comparing compression screws with Kirschner wires or cast immobilization of displaced scaphoid fractures are needed. However, the role of open reduction and screw fixation is more commonly recommended and being used.

Scaphoid Nonunion

Treatment

Stable Nonunions

In the treatment of nonunion of the scaphoid it is essential to maintain the important principles of fracture healing and at the same time secure correct scaphoid alignment. Should an asymptomatic patient with scaphoid nonunion have surgical treatment recommended? Today, more longitudinal or outcome studies do favor operative intervention to prevent the late sequelae of traumatic arthritis.157a,342,462 Four principles to follow include (1) preservation of blood supply, (2) bone apposition by inlay graft, (3) internal fixation for fracture stability, and (4) correction of carpal instability.117,358,400 Failure of scaphoid bone grafting appears to be associated with inadequate vascularization, unsatisfactory fracture immobilization, insufficient length of immobilization, and instability or displacement. A number of questions are currently being asked regarding the treatment of choice for a nondisplaced scaphoid nonunion. What is the effect of operative approach on the blood supply? How should avascular necrosis of the scaphoid be confirmed? Is there a role for electrical stimulation of nondisplaced scaphoid nonunions? Is internal fixation of the scaphoid nonunion necessary when the nonunion is not displaced?

Russe Bone Graft. From a survey of the literature24,156,395 and our experience, it appears that a Rüsse-type inlay bone graft of the scaphoid is the treatment of choice to which other procedures should be compared (Fig. 12-98).463,501,506 From a review of four different treatment options, the volar Russe463 type or dorsal-radial Matti34,351 type had union rates of 86% and 92%, respectively.117 Studies by others confirm the excellent results associated with the Russe procedure and report union rates of 85% to 97% for Russe grafting of stable scaphoid nonunions.24,34,155,395 The need for internal fixation of nondisplaced fractures has been questioned by some, but one study demonstrated a 97% healing rate after combining a Russe procedure with internal fixation.

Author's Preferred Method of Treatment. Our preference and treatment of choice for scaphoid nonunion is palmar grafting similar to the approach modified by Russe.112 The bone graft is a combination corticocancellous graft. Russe (as reported by Green has recommended using a double cortical graft placed side by side (see Fig. 12-98). His technique emphasized the need to remove the avascular bone and fibrous tissue through a palmar bone window, thoroughly excavating both the proximal and distal poles with a curette. We prefer a corticocancellous graft from the iliac crest, which is inset palmarly and serves to bridge the fracture gap and correct any displacement or angulation of the scaphoid that has occurred (Fig. 12-99). Supplemental fixation with a Kirschner wire or wires is preferred. Postoperative immobilization in a long-arm thumb spica cast is maintained for 6 weeks. The Kirschner wires are removed and a short-arm thumb spica cast is worn until fracture union is demonstrated on tomography. A radial styloid or radial metaphysis bone graft can be selected, but the ilium offers a stronger, more compact, trabecular graft that is easier to sculpt for proper fill. Vascularized bone grafts from the distal radius (radial artery or distal ulna (ulnar artery)236 have also been described.

Fig. 12-98 Grefele osoase Russe. Doua bare corticospongioase sunt ate in excavatia de la nivelul scafoidului printr-un abord volar. Cavitatea restanta se umple cu bucati de spongie. Suprafata interioara chiuretata a scafoidului se inspecteaza pt a evidentia vascularizatia.

Fig. 12-99 Tehnica Russe originala consta in impachetarea grefelor cortico-spongioase in jgheabul chiuretat prin cortexul  volar al ambelor fragmente (stg). Deoarece cortexul volar este deseori scurtat prin eroziunea fragmentelor este dificila refacrea lungimii fara introducerea unei grefe corticale (centru). Modificarea adusa de noi tehnicii originale consta in folosirea unei grefe cortico-spongioase "cu aripi" recoltata din creasta iliaca care este impactata in jgheabul volar pt a reface lungimea.

The presence of diminished vascularity of the proximal scaphoid79 is not a contraindication to a palmar inlay bone graft. If fracture union can be achieved, the relative avascularity will improve. The time to union is, however, slower, and the rate of nonunion is increased. Therefore, it is advantageous to confirm avascular necrosis to determine length and prognosis for successful treatment. Methods of assessing avascular necrosis include bone scan, tomography, and MRI.175 The latter technique is undoubtedly the most sensitive and specific. It can provide sequential information on revascularization of the scaphoid.433a Tomography is a better method of assessing fracture union and may be just as sensitive and specific in determining avascular changes. The only definitive test for confirming avascular necrosis, however, is the observation at surgery of the presence or absence of bleeding from bone. Green231 reported that when the proximal pole was completely avascular (total lack of bone bleeding) the likelihood of successful healing with a graft was virtually nil. If the proximal scaphoid is completely avascular (Preiser's disease537a), an alternative procedure such as intercarpal fusion,548 excision of the proximal scaphoid,158 interposition arthroplasty,46 proximal row carpectomy,144a or scaphoid allograft98 should be considered. Another alternative is some type of vascularized bone graft.562

Electrical Stimulation. Electrical stimulation (pulsed electromagnetic stimulation [PEMS]) has been proposed for nondisplaced scaphoid nonunion.5 Studies suggest that it has a role for fractures 3 to 6 months old. In a study of 44 nonunited fractures that were at least 6 months old, union was achieved in 35, combining electrical stimulation and a thumb spica cast.199 This study and an unpublished report43 demonstrated better union with a long-arm cast than a short-arm thumb spica cast. Union rates from these series were 80% and 92%, respectively. The length of stimulation varied from 8 to 10 hours per day.

The controversy regarding the use of electrical stimulation in the treatment of scaphoid nonunions, however, remains unsettled, because there have been no controlled patient series comparing cast immobilization alone with electrical stimulation in these studies. Its use in unstable, angulated, displaced nonunions is not indicated. Newer types of pulsed electromagnetic fields with a shorter stimulation period are now available (Orthologic Co., Phoenix, AZ), but there have been no published reports on their use in treatment of scaphoid nonunions.

Unstable Nonunions

From the work of Fisk182,183 and later from that of Linscheid and colleagues,329 instability of the carpus as a result of scaphoid nonunion has had increased recognition. Displaced scaphoid fractures are more difficult to diagnose168 and treat, and nonunions of the scaphoid with displacement have a lower rate of union with an increased potential for radioscaphoid arthritis.95,117,307,342,462 Techniques to improve scaphoid alignment by palmar and radiopalmar bone grafting have been developed to correct scaphoid malalignment18,184 and to restore normal scaphoid length.177,178 A number of authors have reported their experience with interposition bone grafting for displaced scaphoid nonunions with internal fixation such as the Herbert screw,70,121,346 conventional lag screw,178 Enders plate,258a and multiple Kirschner wires,177 reporting results equal to or superior to the Rüsse graft.452b Comparative studies on this issue, however, are only a few.405a

Authors' Preferred Method of Treatment

The indications for interposition grafting include gross motion at the nonunion site, scaphoid resorption, and loss of carpal height.184,331 A dorsal-radial operative approach (Fig. 12-100) can be utilized with Kirschner wire internal fixation. More commonly, the operative procedure involves an anterior interposition bone graft, with size based on comparative scaphoid views of the opposite wrist and intraoperative measurements. An extended palmar Russe approach between the radial artery and flexor carpi radialis is used to expose the scaphoid. A gap is noted as the nonunion is debrided. With the two fragments gently distracted and aligned, reduction is held with a Kirschner wire. The size of the defect is measured in width and depth, and with an oscillating saw the exact dimensions of the graft are removed from the iliac crest. With the graft in place and the scaphoid reduced and held with a Kirschner wire, a Herbert screw is inserted by the technique described by its originator (Fig. 12-101). If there is marked DISI angulation of the lunate, it is best to reduce the lunate and proximal scaphoid by flexing the wrist and pinning the lunate in a reduced position through the radial styloid first.331 An alternative procedure is to use multiple Kirschner wires as described by Fernandez (see Fig. 12-89) or dorsal-radial operative approach (see Fig. 12-100).177 Displaced, small proximal pole fractures are best approached dorsally.156a,546a

The results of treatment in our series demonstrated a union rate of 81%, although two cases required a secondary interposition graft.121 Carpal instability as measured by the scapholunate angle was corrected from a preoperative mean of 65° to a postoperative mean of 54°. The capitolunate angle improved from 15° to 3.5°, and the carpal height ratio improved from 0.51 to postoperative 0.54. Complications were related to incorrect placement of the Herbert screw and to resorption of the bone graft. This was usually associated with failure of healing to the proximal pole. Interposition grafting is preferred when the palmar gap exceeds 3 mm or more. A modification of the Russe procedure using a cross-shaped corticocancellous graft or an extended Russe bicortical graft inserted into the troughs in either pole to prop the scaphoid open for restoration of length may also be used (see Fig. 12-99). Improved imaging may provide the technical basis for more accurate bone graft configuration, scaphoid reconstruction, and internal fixation, making interposition grafting more practical and easier for the surgeon.45a,405b

Fig. 12-100

A radial approach with partial radial styloidectomy may be indicated in patients with a severe humpback scaphoid deformity, to judge the necessary degree of corrective realignment. The dorsal osteophyte of the humpback should be excised to assist in the reduction. This procedure should be chosen with caution, because the traditional Matti-Russe graft has a superior union rate and is capable of correcting mild carpal instability. The Russe technique remains the gold standard to which other scaphoid grafting procedures must be compared.

It may be difficult to completely correct carpal instability in long-standing cases, and these patients may be better served by various salvage procedures.

Vascularized Bone Graft. A vascularized bone graft to the scaphoid562 for established nonunion is recommended for (1) avascular necrosis, (2) failed bone grafting procedure (eg, failed Russe or interposition graft), and (3) Preiser's disease. The vascular bone graft can be harvested from the distal radius (second dorsal compartment) or from the second metacarpal. A dorsal-radial approach is required (Fig. 12-102). We recommend harvesting the vascular graft first from the radius, using loop magnification. The radial artery branches are then dissected and followed to the radius. The rectangular bone graft is then harvested with great care taken to protect the vascular pedicle. The scaphoid is approached dorsoradially, and the nonunion site is excavated. Kirschner wires are positioned by retrograde insertion and then the vascularized bone graft is inserted. With the graft in place, the Kirschner wires are drilled across the nonunion site. A radial styloidectomy may be required because the breadth (width) of the scaphoid is usually increased.

For avascular necrosis of the scaphoid, one must remove all of the avascular bone (usually proximal third). The vascular graft is inlaid with care taken to protect the pedicle, and additional cancellous bone may be packed around the vascular graft. Kirschner wire fixation is used if the scaphoid appears unstable. For a failed primary bone graft, the previous graft fragments must be removed and a fresh surface created between the ends of each fragment. The vascular graft is inserted usually as an inlay graft or alternatively as an interposition graft. Kirschner wire or compression screw fixation is usually recommended. Cast immobilization is continued until tomograms show solid healing.

For Preiser's disease537a (avascular necrosis of the entire scaphoid), a vascularized bone graft is the procedure of choice if nonoperative methods (splint, rest, electrical stimulation) fail to resolve the problem. If the scaphoid begins to show collapse similar to that seen in a nonunion, bone grafting (preferably a vascularized graft from the distal radius) is recommended. The technique is similar to that described in the preceding paragraph except that the entire scaphoid is excavated of avascular bone. Cast immobilization is recommended as with a fracture nonunion. Long-term splint protection may be needed for up to 6 months because revascularization is a slow process in Preiser's disease.

Fig. 12-102