Acknowledgments:
I would like to give full acknowledgment to the authors of the previous version of this chapter, Dr. William B. Geissler and the late Dr. Joseph F. Slade. Their chapter was the foundation of the current chapter; I have maintained many of their principles but have updated the chapter with my own thoughts, influenced by prime mentors of mine, Drs. Martin Posner, Scott Wolfe, and Michael Hausman. Dr. Slade was one of my mentors and teachers from residency. Most know of his contributions to hand and upper extremity surgery and his continual willingness to teach and instruct worldwide. His dedication and enthusiasm for hand surgery are legendary and are an inspiration to us all. Thank you also to Dr. Geissler, who continues to be a pioneer in our specialty. Acknowledgments to Dr. Dean G. Sotereanos and Dr. James P. Higgins, who authored two of the Case Studies for this chapter available on ExpertConsult.com . I also wish to acknowledge Zina Model, BA, for editorial assistance.
Scaphoid Fractures and Nonunion
The treatment of scaphoid fractures requires knowledge of the blood supply, surgical approaches, and effects that fractures and nonunions of the scaphoid have on carpal kinematics, stability, and arthritis. Vigilant care of these fractures can usually lead to a functional result for the patient. However, incorrect fracture healing can potentially lead to a relentless downward spiral of wear and cartilage damage. Chronic pain and dysfunction of the wrist results, which affects both hand function and the entire upper extremity.
Within the past two decades, methods of scaphoid repair have been developed to minimize additional surgical trauma and optimize stabilization until healing. Minimally invasive fixation has been demonstrated to have a higher union rate than cast treatment and has relatively few complications. This approach allows the patient or athlete to return to work or sports within weeks or months, whereas a failed attempt at healing with cast immobilization can result in months of lost time, compounded by the increased complexity, cost, and complications of nonunion repair. This chapter will explore the mechanics, biologic factors, and modern treatment regimens for fractures of the scaphoid and neighboring carpal bones.
General Considerations in Fractures and Nonunion of the Scaphoid
Incidence and Cause of Scaphoid Fractures
The scaphoid bone garners more interest in upper extremity surgery for its weight and size than any other bone because it is the “keystone” of the carpus. In architecture, the keystone is the central stone at the summit of an arch, locking the whole together. Likewise, the scaphoid links the carpus together. Pathologic conditions of the scaphoid can affect the entire wrist.
The scaphoid is not only important but it is the most commonly fractured carpal bone. Scaphoid fractures account for 60% to 70% of all carpal fractures and are second in frequency of wrist fractures only to distal radius fractures. The majority of injuries are low-energy injuries, either from a sporting event (59%) or from a fall onto an outstretched wrist (35%); the remainder result from high-energy trauma such as a fall from a height or a motor vehicle injury. Howe documented that 82% of the scaphoid fractures in Norway occur in males, with an average age of 25 years (range, 11 to 79 years). The age-specific incidence in males remained significantly higher than that in females until age 60 years, at which point the incidences were similar. The annual incidence was 43 per 100,000 people. The statistics were similar in Larsen’s series; the mechanism for scaphoid fracture was a fall in 69% of cases and a blow to the wrist in 28% of cases.
More recently, Wolf studied a large U.S. military population and found a greater incidence of scaphoid fracture than the previous data had shown, 121 per 100,000 person-years. Males and the 20- to 24-year-old age group were associated with higher rates of scaphoid injury. The more active nature of the occupations of this population may explain this higher incidence. Van Tassel and colleagues showed a peak incidence in scaphoid fractures in the second decade, and few after age 50 years ( Figure 16.1 ).
Pertinent Anatomy of the Scaphoid
Bony and Ligamentous Anatomy.
The shape of the scaphoid bone has been described with several terms: as a boat (“skaphos” in Greek), as a twisted peanut, and as bean shaped. The complex shape of the bone can present challenges to reconstruction and fixation. Approximately 80% of the scaphoid is covered by cartilage, limiting ligamentous attachment and vascular supply ( Figure 16.2 ). The scaphoid is divided into three regions: proximal pole, waist, and distal pole (tubercle). The proximal pole articulates with the scaphoid fossa of the distal radius and the lunate. The scaphoid is oriented in the carpus with an intrascaphoid angle averaging 40 ± 3 degrees in the coronal plane and 32 ± 5 degrees in the sagittal plane.
The scaphoid is the only carpal bone that bridges the proximal and distal carpal rows and acts as a tie-rod. The carpal rows are supported by stout intrinsic ligaments and reinforced by a complex system of volar and dorsal extrinsic ligaments ( Figure 16.3 ). The scapholunate interosseous ligament (SLIL) is a stout ligament connecting the scaphoid to the lunate and is the primary stabilizer. The dorsal aspect of this ligament is composed of transverse collagen fibers, whereas the palmar ligament is composed of oblique collagen fibers inserting to the volar capsular ligaments. The dorsal portion is twice as strong as the anterior portion. Only 20 to 30 degrees of motion is possible at an intact scapholunate interval. The dorsal and palmar regions are critical in maintaining normal carpal kinematics and function of the scapholunate interval. The dorsal region resists palmar-dorsal translation and gap, whereas the volar portion resists rotation. The proximal fibrocartilaginous region is the weakest mechanically and is well suited to accept the compression and shear loads at the radiocarpal joint. The radioscaphocapitate (RSC) ligament originates from the volar radial aspect of the radius, crosses the volar concavity of the scaphoid waist, and proceeds ulnarly toward the capitate, acting as a fulcrum around which the scaphoid rotates. The scaphoid can also fracture around this fulcrum at the waist. The scaphocapitate ligament originates from the distal scaphoid at the border between the trapezoid facet and the capitate facet. It inserts into the volar waist of the capitate distal to the RSC ligament. This ligament, along with the scaphotrapezial ligament, functions as a primary restraint of the distal pole.
Vascular Anatomy.
The blood supply of the scaphoid bone is not robust, because it is predominantly retrograde. The major blood supply to the scaphoid is via the radial artery: Seventy percent to 80% of the intraosseous and proximal pole vascular supply is from branches of the radial artery entering distally through the dorsal ridge of the scaphoid between the proximal and distal articular surfaces. The radial artery or the superficial palmar arch also give volar branches that enter in the region of the tubercle and provide the blood supply to 20% to 30% of the bone in the region of the distal pole ( Figure 16.4 ). The proximal pole also gets blood supply from the radioscapholunate ligament (ligament of Testut, a neurovascular conduit) and directs scapholunate branches from the palmar and dorsal transverse carpal arches. Handley and colleagues found that the venous drainage from the proximal pole of the scaphoid was via the dorsal ridge into the venae comitantes of the radial artery.
The more proximal the fracture, the more likely the bone is to be dysvascular and the higher the risk of nonunion. Proximal pole fractures have been reported to have an incidence of avascular necrosis (AVN) of 13% to 50%. Knowledge of the vascular anatomy has implications for sensible approaches to the scaphoid. Combined palmar and dorsal approaches taking off the soft tissue at the tubercle and the dorsal ridge would not be advisable. During the dorsal approach to the scaphoid, the majority of the dorsal ridge tissue and vessels can and should be left intact.
Biomechanics of Scaphoid Fractures and Implications of Nonunion
Although the exact mechanism of fracture is not completely understood, hyperextension past 95 degrees is the usual position of injury, but other mechanisms such as axial loading have also been postulated to produce scaphoid fractures, as has hyperflexion of the wrist. With the hyperextension mechanism, a fracture of the scaphoid usually begins at the volar waist with a tensile failure; the forces propagate to the dorsal surface with compression loading, until failure occurs. In a cadaveric study, wrists placed in extreme dorsiflexion and ulnar deviation produced fractures through the scaphoid waist as the scaphoid impinged on the dorsal rim of the radius. Proximal scaphoid fractures resulted from dorsal subluxation during forced hyperextension. Carpal dislocations and scapholunate ligament tears were reproduced with wrist extension and ulnar deviation, combined with intercarpal supination.
As with any fracture, the potential for healing relies on the fracture’s location, vascularity, and stability. Nonunion occurs in 10% to 15% of all scaphoid fractures. The risk of nonunion increases with:
- 1.
Delay of treatment for more than 4 weeks
- 2.
Proximal pole fractures
- 3.
Fracture displacement greater than 1 mm
- 4.
Osteonecrosis
- 5.
Tobacco use
- 6.
Associated carpal instability (DISI = dorsal intercalated segmental instability with a scapholunate angle > 60 degrees and a capitolunate angle > 15 degrees) secondary to humpback (flexed with intrascaphoid angle > 45 degrees; the normal intrascaphoid angle is 24 degrees) scaphoid positioning ( Figure 16.5 ).
FIGURE 16.5
Example of intrascaphoid angle of 66 degrees.
(From Trumble TE, Gilbert M, Murray LW, et al: Displaced scaphoid fractures treated with open reduction and internal fixation with a cannulated screw. J Bone Joint Surg Am 82(5):633–641, 2000.)
For nondisplaced waist fractures treated with casting, nonunion rates are 5% to 12%. Nonunion rates for displaced scaphoid fractures treated nonoperatively are higher, reaching 50%.
Untreated displaced fractures of the waist are subject to varying degrees of these forces and will usually angulate as the volar bone is reabsorbed, yielding a “humpback” of flexion deformity of the scaphoid. Simultaneous extension of the lunate through its attachment to the triquetrum results in a DISI deformity. Ultimate treatment of a humpback scaphoid nonunion with DISI requires both restitution of scaphoid anatomy and reversal of the secondary changes in carpal kinematics.
Untreated scaphoid nonunion will predictably progress to arthritic change, in what has been termed scaphoid nonunion advanced collapse (SNAC). Arthritic change arises at the radial styloid articulation with the distal scaphoid pole and is followed by degeneration of the midcarpal joint and ultimately by pancarpal arthritis. Arthritic changes have been found in 97% of the patients assessed at least 5 years after injury, with the degree of arthritic changes being proportionate to the duration of nonunion. Patients generally present with escalating mechanical pain, with limitations in range of motion. Duppe reviewed 30-year follow-up results of scaphoid fractures treated with thumb spica short-arm casts. Ten percent of the patients developed nonunion; 60% of these demonstrated radiographic evidence of radiocarpal osteoarthrosis, while only 2% of the healed group demonstrated degenerative change.
Examination and Imaging of the Scaphoid
Clinical Presentation
The patient usually presents with pain on the radial side of the wrist. There may be swelling on the radial side, as well. There is usually a history of trauma, such as falling on an outstretched hand, collision of the wrist against a person or heavy obstacle, or possibly a direct blow against an object. There may be limited range of motion and pain when applying extended wrist loading or positioning the wrist in extreme positions of flexion or extension.
Physical Examination
Physical examination starts with visual inspection. Wrists with acute fractures may have swelling and bruising in the radial aspect of the wrist. There may be limited range of motion. Wrists with chronic injury may have swelling in the dorsoradial wrist. “Snuffbox tenderness” has become synonymous with scaphoid fracture, but this applies predominantly to waist fractures, which represent 70% of scaphoid fractures. The second most common type of scaphoid fracture is proximal pole fracture, at 20%. The least common is distal pole fracture, at 10%. Fractures tend to occur at the waist partly because the RSC ligament acts as a fulcrum over which the scaphoid waist fractures ( Figure 16.6 ).
The full physical examination of the scaphoid bone should include all of its parts: the waist, distal pole, and proximal pole. To palpate the anatomic snuffbox for the waist examination, palpate just distal to the radial styloid in the “soft spot.” The distal pole should be palpated at the scaphoid tubercle on the palmar aspect of the wrist. To do this, place the index finger in the anatomic snuffbox and place the thumb on the palmar aspect just distal to the anatomic snuffbox. The prominent bone palpated is the distal pole of the scaphoid. With radial deviation of the wrist, this prominence should move palmarly toward the examiner’s thumb. This distal pole should be checked for tenderness. The proximal pole is palpated dorsally in line with the second ray just distal to the dorsal radius lip. The scapholunate ligament is in line between the second and third rays just distal to the dorsal radius lip and corresponds to the 3-4 wrist arthroscopy portal. The proximal pole is just radial to this scapholunate ligament/3-4 portal area. In diagnosing scaphoid fracture, physical examination is sensitive but its specificity is low, ranging from 74% to 80%.
Diagnostic Imaging of Scaphoid Fractures and Nonunion
Computed Tomography.
Computed tomography (CT) scanning helps elucidate scaphoid fracture displacement, bony morphologic findings, gapping, sclerosis, cysts, and evidence of healing. CT is particularly helpful in addressing nonunions. It is important that CT scans are taken with overlapping 1-mm cuts along the long axis of the scaphoid and with coronal and sagittal reconstructions. CT scans have particular utility in evaluating for healing after scaphoid surgery, especially because radiographs are often indeterminate. CT scanning has also demonstrated some utility in evaluating the vascularity of the proximal pole of the scaphoid. Increased radiodensity of the proximal pole is a sign of dysvascularity.
Magnetic Resonance Imaging.
Magnetic resonance imaging (MRI) is best to determine whether there is occult scaphoid fracture. Specificity is 90% and sensitivity is between 90% and 100%, as opposed to bone scintigraphy, which is 92% to 95% sensitive and 60% to 95% specific.
Use of MRI to assess bony vascularity is controversial. Some authors advocate its use, whereas others present cogent arguments questioning its efficacy and utility. MRI findings of hypointense areas of bone on both T1-weighted and T2-weighted sequences have been suggested to be correlated with AVN. However, subsequent studies have shown poor correlation, and almost no data exist correlating MRI findings with operative or nonoperative healing rates.
In a study of 88 patients for which imaging results were compared with findings of intraoperative bleeding, Schmitt and colleagues concluded that viability of the proximal fragment in scaphoid nonunion can be significantly better assessed with contrast-enhanced MRI than with nonenhanced MRI. Contrast-enhanced MRI has demonstrated significantly improved sensitivity (77% vs. 6%; p < .001) in detecting scaphoid AVN compared with nonenhanced MRI. However, this study suggests that, even with contrast enhancement, MRI might fail to detect proximal pole AVN in nearly a quarter of cases. This might be due to ingrowth of nonspecific inflammatory tissue into the proximal pole from the nonunion site, resulting in contrast enhancement despite the necrotic bone. Additional techniques for improving the sensitivity of MRI, such as dynamic gadolinium enhancement, are being developed and investigated, but they are still currently inferior to standard gadolinium-enhanced MRI. Therefore, MRI with or without contrast enhancement might be helpful in assessing the vascularity of the bone, but the entire picture must be taken into account using the patient history and CT imaging. Even though MRI with gadolinium was thought to have a better correlation with intraoperative scaphoid bleeding assessment, MRI with gadolinium still could not predict fracture healing in a paper by Dawson and colleagues.
One of the strongest arguments against MRI was presented by Willems and colleagues, who studied vascularized bone grafting in a canine carpal AVN model. AVN was induced in carpal bones by excising bones, deep freezing, and coating in cyanoacrylate and then reimplanting them. A vascularized bone graft from the radius was implanted in the avascular carpal bone. The contralateral side served as an untreated ischemic control. Bone blood flow, bone volume, radiography, histomorphometry, histology, and MRI were analyzed at 4 weeks. T1 and T2 signals on MRI did not correlate with quantitative bone blood flow measurements. Necrotic bones with no blood flow had normal T1 and T2 signals, whereas revascularized bones had signal changes when compared with adjacent carpal bones. A major point of this work is that MRI did not necessarily correlate with known blood flow to the carpal bone in an animal model.
Controversy about MRI is complicated by differences in techniques and image quality, which depend on programming of the image acquisition parameters and reading of the images and on the MRI machines, magnet power, and specialized wrist coils used; all of these factors influence the quality of information presented.
Preferred Modes of Diagnostic Imaging.
I prefer to take five radiographic views for the assessment of scaphoid fractures: wrist posteroanterior (PA), lateral, and oblique views; scaphoid view; and clenched pencil view. It is important to take a true scaphoid pisiform capitate (SPC) lateral radiograph of the wrist, wherein the palmar cortex of the pisiform bone overlays the interval between the palmar cortex of the distal scaphoid pole and the palmar cortex of the capitate. This allows true assessment of the carpal alignment.
A predictable scaphoid view is taken where a fist is made, with the thumb covering the dorsum of the middle phalanges of the index and middle fingers. The pronated forearm and hand are placed on the radiography table. The wrist is placed in ulnar deviation ( Figure 16.7 ). The rationale behind this position is to take the scaphoid out of its usual position of flexion and pronation. With the thumb in the above position, the wrist is extended and supinated slightly. Ulnar deviation and wrist extension extend the proximal carpal row. This view allows a full view of the scaphoid bone with minimal overlap from neighboring bones.
A clenched pencil view is also taken. This is the best view to assess associated dynamic scapholunate widening ( Figure 16.8, A and B ) and in my experience also shows SNAC and SLAC (scapholunate advanced collapse) wrist changes better than standard PA views.
For better detail of bony anatomy, especially in patients with small proximal poles, comminution, or nonunion, I obtain a CT scan without contrast at 1-mm cuts, along the long axis of the scaphoid with coronal and sagittal reconstructions. If the status of the cartilage is in question, I obtain an MRI without contrast with cartilage-sensitive sequencing.
Scaphoid healing cannot be reliably determined by standard radiographs at 3 months; consequently, CT provides enhanced resolution and definitive information regarding healing. Most acutely treated scaphoid fractures require approximately 10 to 12 weeks to heal. I obtain a CT scan at 3 months to determine healing and before allowing full return to heavy occupational demands, sports, or recreational pursuits.
Scaphoid Fracture Classification and Implications for Treatment
Scaphoid fractures have been classified by fracture location (proximal, waist, or distal), plane (transverse or oblique), and stability (stable or unstable). The goal of a fracture classification is to guide management of injuries, in order to enable rapid healing with minimal complications and allow return to activities of daily living, work, and sports or hobbies. The consequences of failed healing include wrist pain, loss of wrist motion, loss of grip strength, loss of productivity, and premature articular degeneration. Of particular importance is identifying which scaphoid fractures require surgical intervention to heal. A failure to identify an unstable scaphoid fracture and treat it accordingly will predictably result in 6 months or more of additional treatment and restricted activities.
One of the earliest efforts to identify unstable fractures was to examine the scaphoid fracture plane. Russe recognized that oblique fractures were unstable and difficult to control with immobilization and that they resulted in an increased rate of nonunion. Herbert and Fisher classified scaphoid fractures according to their stability. Stable fractures, classified as type A, included incomplete fractures or fractures of the scaphoid tubercle. The authors stated that these fractures could be safely treated with immobilization with expectation of a high rate of union. All other fractures were considered potentially unstable and merited rigid fixation, a point of some controversy. Despite the assertions of these authors, however, Desai and colleagues were unable to predict fracture union with closed treatment using either the Russe or the Herbert classification system.
Cooney and colleagues attempted to further define unstable injuries. These included fractures with more than 1 mm of displacement, a lateral intrascaphoid angle of more than 35 degrees, bone loss or comminution, perilunate fracture-dislocation, DISI alignment, and proximal pole fractures. He advocated open surgical fixation for all unstable injuries.
Preferred Method of Classification
I prefer to use a classification method that mimics actual cases that present to the surgeon. It borrows from some elements of the Herbert and Fisher classification and from Cooney’s definition of an unstable injury. It also includes a classification of scaphoid nonunions.
Stable Acute Fractures
Distal pole fracture, nondisplaced
Incomplete fracture through waist
Negative radiographs, positive MRI
Unstable Acute Fractures
Waist fracture, visible on radiographs
Proximal pole fracture
Displaced fracture
(displacement is defined as DISI malalignment of 1 mm [DISI = dorsal intercalated instability with scapholunate angle > 60 degrees and capitolunate angle >15 degrees])
Scaphoid fracture as part of perilunate fracture-dislocation
Nonunion
Nonunion of waist fracture, no arthritis, acceptable alignment, stable
Nonunion of waist fracture, no to minimal (only SNAC I) arthritis, humpback deformity
Nonunion of proximal pole fracture, no arthritis
Nonunion of waist fracture, arthritis, SNAC II to III, nonreconstructable, distal pole grossly deformed
Nonunion of proximal pole fracture, no arthritis, not salvageable (proximal pole <5 mm)
For completeness, two other classification schemes of scaphoid nonunion are shown in Tables 16.1 and 16.2 .
| Type | Description |
|---|---|
| Type 1 | Delayed presentation for 4 to 12 weeks |
| Type 2 | Fibrous union, minimal fracture line |
| Type 3 | Minimal sclerosis of less than 1 mm |
| Type 4 | Cystic formation of 1 to 5 mm |
| Type 5 | Humpback deformity with cystic change of more than 5 mm |
| Type 6 | Wrist arthrosis |
| Grade | Description |
|---|---|
| I | Linear nonunion without altered scaphoid form, instability, or intracarpal malalignment |
| IIA | Stable nonunion with incipient bone resorption at fracture line, without instability or malalignment |
| IIB | More or less mobile nonunion with anterior defect and proximal pole flexion on distal tubercle inducing DISI |
| III | More or less mobile displacement nonunion with instability or reducible malalignment with |
| IIIA: isolated styloscaphoid arthritis | |
| IIIB: radial and/or intracarpal arthritis | |
| IV | Proximal fragment necrosis with |
| IVA: malalignment | |
| IVB: radioscaphoid and/or intracarpal arthritis |
Management of Scaphoid Fractures
Up to 25% of scaphoid fractures are not visible on initial radiographs (see Preferred Modes of Diagnostic Imaging , above). Unless the x-ray beam lies in the same plane as the fracture, the fracture line may be missed. Because failure to treat a stable scaphoid fracture within 4 weeks increases the nonunion rate, all clinically suspected scaphoid fractures are treated as fractures with short-arm thumb spica cast immobilization until the cause of the symptoms is clarified ( Table 16.3 ). Follow-up radiographs and clinical examination without the cast are performed at 10 to 14 days. If a fracture is clinically suspected in the presence of negative follow-up radiographs, we prefer MRI. At our institution, MRI is the most reliable imaging modality for the diagnosis of acute and occult fractures and is generally diagnostic within 24 hours of injury.
| Type of Fracture | Treatment |
|---|---|
| Stable Fractures, Nondisplaced (Obtain CT Scan to Ensure the Fracture Is Completely Nondisplaced, Especially on Sagittal View) | |
| Tubercle fracture | Short-arm cast for 6 to 8 weeks |
| Distal third fracture or incomplete fracture | Short-arm cast for 6 to 8 weeks |
| Waist fracture | Short-arm thumb spica cast until healed, especially for pediatric patients and sedentary or low-demand patients, preference for nonoperative treatment |
| Mini-open internal fixation (APM: dorsal approach), especially for active, young, manual worker, athlete, or worker in high-demand occupation, preference for early range of motion | |
| Proximal pole fracture, nondisplaced | Mini-open internal fixation, dorsal approach |
| Unstable Fractures | |
| Displacement of more than 1 mm Lateral intrascaphoid angle of more than 35 degrees Bone loss or comminution Perilunate fracture-dislocation Dorsal intercalated segmental instability alignment (DISI = dorsal intercalated instability with scapholunate angle > 60 degrees and capitolunate angle > 15 degrees) | Mini-open internal fixation (APM: dorsal approach) |
The obvious goal is to attain healing of the scaphoid fracture in an anatomic position while maintaining carpal alignment. Patients with union have better functional results. Table 16.3 summarizes treatment options.
Stable Acute Fractures
Distal Pole Fractures.
Distal pole and tubercle fractures of the scaphoid are generally treated nonoperatively. The distal pole of the scaphoid is well vascularized, and distal scaphoid pole fractures have a high rate of union after 6 to 8 weeks of plaster immobilization in a short-arm cast. The two predominant distal fracture types treated in plaster immobilization are (1) avulsion fractures from the radiopalmar lip of the scaphoid tuberosity and (2) impaction fractures of the radial half of the distal scaphoid articular surface. However, malunion of impacted radial-sided compression fractures may result in symptomatic degenerative arthritis. When in doubt, CT can delineate the articular surface, and operative fixation can be implemented if deemed necessary to try to reduce the risk of late degenerative arthritis of the scaphotrapezial joint.
Incomplete Fracture Through the Waist, Negative Radiographs, Positive MRI Studies.
Incomplete fractures through the waist and injuries that have negative radiographs but positive MRI views for signal change probably need even less strict immobilization. Depending on the patient, a short-arm thumb spica cast or, in particularly compliant patients, a thumb spica splint has been used. Other authors recommend internal percutaneous fixation for these fractures (see the following).
Unstable Acute Fractures
Waist Fracture, “Nondisplaced.”
Even if a scaphoid fracture is visible but is “nondisplaced” on radiographs, it is arguably displaced and may be seen as a flexion deformity in the sagittal plane via CT scan. Therefore, an argument can be made for fixing all scaphoid fractures where a fracture line is seen on plain radiographs. In addition, there is evidence that fixing nondisplaced fractures allows for faster healing and earlier return to work. Bond and colleagues demonstrated that in a prospective study of 25 patients randomized to cast or screw treatment, union rates (time to healing) were significantly faster for the group who had surgery (7 vs. 12 weeks) and the return to work time was also significantly faster for this group (8 vs. 15 weeks).
The choice of operative or nonoperative treatment must be individualized based on the discussion of pros and cons of treatment with the patient. If a cast is chosen, there are controversies about what type of cast to use. There is no agreement in the literature as to the optimum position of immobilization (extension, ulnar deviation, neutral) or type of cast (thumb spica, interphalangeal [IP] free, IP included, long arm, short arm), suggesting that many waist fractures can be treated in a variety of positions and casts.
Controversies include short-arm versus long-arm casting and whether to include the thumb. In a prospective, randomized trial of long-arm versus short-arm thumb spica casting, there was significantly faster healing with long-arm casting (9.5 vs. 12.7 weeks). The nonunion rate was not different, with numbers tested at 0 with long-arm casting and 2 with short-arm casting. The authors recommended long-arm thumb spica casting for the first 6 weeks, followed by short-arm casting until healing. Immobilization of the elbow produced no long-term disability. Displaced fractures were excluded from this study, and the minimum follow-up was 6 months. This carefully conducted study is probably the best evidence in favor of the long-arm cast for the initial immobilization period.
In a cadaveric study, there was motion of 1 to 4 mm in simulated scaphoid fractures treated with a short-arm thumb spica cast. Therefore, the authors recommended a long-arm thumb spica cast. Other indirect evidence that short-arm cast immobilization with the thumb free is inadequate is that in a series by Dias and colleagues; with this method of immobilization, 23% did not unite at 12 weeks.
In the most recent literature, Symes and Stothard performed a systematic review of cast versus surgery for acute scaphoid fractures. The rate of nonunion was three times less for surgery, and recovery was quicker. However, there were more complications with surgery. In the end, there was no difference in pain, cost, functional outcome, or patient satisfaction, though the secondary costs and morbidity of nonunion treatment were not taken into account. In two trials that compared long-arm casts versus short-arm casts and thumb spica casts versus short-arm cast, there was no difference in outcome. Alshryda and associates performed a metaanalysis of 13 level I studies (randomized controlled trial [RCT]) and concluded that for closed treatment there is no difference between short-arm and long-arm casting or between thumb spica and short-arm casting. Union rates are the same for surgical and nonoperative treatment for undisplaced fractures. Surgery is recommended for displaced fractures.
Taking all the above factors into account, I obtain a CT scan to ensure that a “nondisplaced” fracture on a radiograph is truly nondisplaced. I not uncommonly see fractures that seem to be nondisplaced on radiographs but are shown as displaced on CT scans, especially on sagittal views where the fracture is flexed at the waist. If the fracture is truly nondisplaced, I discuss with the patient the pros and cons of operative and nonoperative care. If the patient opts for nonoperative care, I prefer to treat with short-arm thumb spica casting until the fracture is healed. If healing has not occurred by 3 months and/or there are no longer interval changes, I consider operative intervention. If the fracture is displaced on CT scanning, I recommend operative intervention.
Proximal Pole Fracture.
Proximal pole nonunion may be attributed to impaired vascularity or instability of the proximal fragment. Proximal pole fractures are considered unstable, whether or not they are displaced, because of their small size, their tenuous blood supply, their interarticular location, and the relatively large moment arms across the fracture site. Rettig and Raskin reported 100% healing of 17 proximal pole fractures treated acutely with operative screw fixation through a dorsal approach. There is consensus that proximal pole fractures cannot be reliably treated nonoperatively. Consequently, I believe that any proximal pole fracture, whether nondisplaced or displaced, should be fixed operatively. The nonunion rate is higher for proximal pole fractures if treated closed. Because of the position of the fracture in that the proximal pole is dorsal, proximal pole fractures are best fixed from the dorsal approach.
Mechanics of Fracture Fixation
Bone healing requires viable bone cells, an adequate blood supply, and stabilization of the fracture site. For a fixation device to be successful in providing rigid fixation of scaphoid fractures, it must be able to resist complex bending, shearing, and translational forces during normal functional loading. Because the majority of the scaphoid is covered with cartilage, fracture callus is not produced, so primary bone healing is entirely dependent on rigid stabilization of the fracture fragments until healing.
The mechanical effectiveness of internal fixation is determined by the bone quality, fracture geometry, fracture reduction, choice of implant, and implant placement. While all five of these independent variables are important, bone quality and fracture geometry are intrinsic to the patient. Fracture reduction, choice of implant, and implant placement are all under the surgeon’s control. Fracture reduction and placement of the implant in the biomechanically ideal position are the most important of the five variables. Trumble and colleagues observed that screws placed in the central third of the scaphoid were associated with significantly shorter healing times than screws placed outside of the central third axis ( p < .05). To explain this observation, McAdams and colleagues simulated scaphoid waist fractures and compared screws placed in the central axis with screws placed eccentrically. This study demonstrated that screws centrally placed in the proximal fragment of the scaphoid had superior results compared with screws placed in an eccentric position. Fixation with central placement of the screw demonstrated 43% greater stiffness, 113% greater load at 2 mm of displacement, and 39% greater load at failure.
Biomechanically, the longer the screw, the more rigid the fixation, because longer screws reduce forces at the fracture site and bending forces are spread along the screws. In a cadaveric study by Slade and colleagues, short or long screws were placed along the central scaphoid axis after an osteotomy was simulated at the waist. Scaphoids that were repaired with longer screws were significantly stiffer than those repaired with short screws. When rigid fixation cannot be provided by a central screw placement alone (as in extreme proximal pole fractures and nonunions), augmentation may be necessary to prevent micromotion at the fracture site. Supplemental fixation can be applied from the distal scaphoid to the capitate using a 0.045-inch or 0.062-inch Kirschner wire or a mini–headless screw. If a Kirschner wire is placed, it should be buried, because it usually has to stay in place for 3 months until the bone is healed.
Techniques for Rigid Fixation
Implants for Rigid Fixation of Scaphoid Fractures
Implants used included Kirschner wires, AO compression screws, headless compression screws, plates, and bioabsorbable implants. Solid and cannulated screws are available from several manufacturers. Any implant used must reduce bending, shearing, and translational forces acting at a fracture site.
Kirschner Wires
Although Kirschner wires are easy to insert, they have a narrow role for scaphoid fixation today, given the relatively insecure fixation and minimal compression afforded by these implants. Kirschner wire fixation must be supplemented with a cast until healing, and a separate procedure for Kirschner wire removal is required. In multitrauma situations or open fractures, rapid stabilization of an unstable scaphoid fracture may be expedient.
Screws
In 1954, McLaughlin described fractures of the scaphoid as “an unsolved problem.” His main interest was returning a “breadwinner” to work with a treatment that would “hold bone fragments in apposition” until healing. He reported on the fixation of scaphoid fractures using solid lag screws. The operative procedure was technically challenging, the optimal screw position was not always achieved, and the incidence of nonunion in unstable fractures was not substantially reduced over that obtained by casting alone.
Herbert and Fisher in 1984 presented the results of the first headless screw used to treat 158 patients from 1977 to 1981. The rate of union was 100% for acute fractures and 83% overall. This screw revolutionized bone fixation because it permitted compression of a fracture with two heads of differential pitches ( Figure 16.9 ). The embedded threaded heads of headless screws are placed in the densest bone of both poles for maximum bony purchase. This paper also demonstrated that screws placed perpendicular to an acute fracture plane using compression and rigid fixation could successfully heal an acute fracture. The implant, however, is not technically easy to insert, and other centers reported lower rates of union with screw fixation of acute scaphoid fractures secondary to technical problems.
The next major development in headless screw design was the cannulated compression screw. This device greatly simplified accurate placement of the screw within the scaphoid bone by using a thin guidewire placed under fluoroscopic control. A fully threaded, variable-pitch implant, the Acutrak screw (AcuMed, Hillsboro, OR), demonstrated compression comparable to that of a standard 4-mm compression screw and greater compression when compared with the Herbert screw in biomechanical testing. Several manufacturers have developed cannulated compression screws with unique advantages and disadvantages. There have been a number of recent biomechanical studies comparing headless compression screws. Most second-generation headless compression screws achieve adequate compression, the compression decreases by 50% 12 hours after placement, and the compression does not necessarily correlate with the feel of torque on the screwdriver.
What is unknown is how much compression is necessary for bone healing. Few clinical studies exist with which to compare implants, and which screw to use is still largely a matter of surgeon preference.
Other Implants.
Bailey reported on the mechanics of a bioresorbable cannulated screw composed of poly-L-lactic acid and hydroxyapatite that was developed for small bone fracture fixation. The bioresorbable screw has been shown to have good compressive properties compared with commonly used small bone fragment compression screws, but no clinical data have been presented.
Staple Fixation.
The use of staples has had its proponents as a means of achieving stable fixation. Early studies demonstrated simple application and satisfactory healing rates among patients with scaphoid nonunions and acute fractures but long-term degenerative changes secondary to hardware impingement. New staples with memory achieve compression after insertion as they warm to body temperature. These staples might be indicated for fractures or nonunions requiring open reduction through a palmar approach, and clinical data are lacking at this time.
Plate Fixation.
Plate fixation has also been used to stabilize scaphoid fractures. Huene and Huene reported their experience in 1991. The Ender blade plate is suitable for adding stability in scaphoid nonunions with AVN, cystic degeneration, and osseous size discrepancy or compromise. Plate fixation can be used with scaphoid nonunion humpback deformity. Dodds and colleagues presented a combination of volar buttress plating and a vascularized volar distal radius wedge autograft pedicled on the volar carpal artery for salvage treatment of chronic scaphoid nonunion. Ghoneim reported on healing of 13 of 14 scaphoid nonunions with an iliac crest wedge graft and a volar miniplate of 1.5 or 2 mm.
Surgical Treatment Methods
Author’s Preferred Treatment Method: Dorsal Approach ( Figure 16.10 )
Scaphoid Open Reduction and Internal Fixation From the Dorsal Approach/Mini-Open Approach.
The tourniquet is placed proximally on the arm and draped to allow full motion of the extremity. A small (≈2-3 cm) longitudinal or transverse incision should be made over the proximal pole at the position of the scapholunate ligament. A miniincision is safer than the purely percutaneous method when approaching from the dorsal wrist. Weinberg and colleagues have shown that there is a 13% chance of tendon injury with a purely percutaneous technique.
The incision is just radial to the area that corresponds with the 3-4 arthroscopic portal. This area is also in line between the second and third metacarpal interspaces, and just distal to the dorsal lip of the radius. The extensor pollicis longus (EPL) is carefully identified and the second and third dorsal compartment tendons are retracted radially. For the mini-open approach, the capsule is opened with a mini inverted-“T” incision. If more exposure is necessary, a ligament-sparing approach can be used (see Chapter 13 ).
Extreme care is taken to avoid disruption of the dorsal fibers of the SLIL when reflecting the capsular flap. Dissection in a plane tangential to the dorsal surfaces of the scaphoid and the lunate can be performed with a scalpel or Beaver blade. The distal boundaries of dissection of the scaphoid are determined by the vascular supply along the dorsal ridge. Care is taken not to disrupt the blood vessels entering the waist of the scaphoid. Retractors are placed deeper to retract the capsule. If the scaphoid is displaced, the hematoma should be evacuated and the scaphoid reduced, possibly with the aid of smooth Kirschner-wire joysticks, if necessary. The wrist is flexed and the entrance point on the scaphoid is identified 1 to 2 mm radial to the membranous portion of the scapholunate ligament and in the midportion of the scaphoid in the sagittal plane. The guidewire for the headless compression screw is started there; the surgeon should aim the wire for the articular base of the thumb metacarpal (because the scaphoid distal pole, trapezium, and metacarpal base are collinear). Once this wire is placed, the surgeon must not extend the wrist, because this will bend the wire at the radiocarpal joint and not allow overdrilling and screw placement. Fluoroscopic images are taken to assess the fracture and wire position. Posteroanterior (PA), lateral, and oblique images are taken. It is important to take several oblique views to ensure that there is no screw penetration out of the scaphoid in any view. In order to obtain the PA images while keeping the wrist flexed, it is imperative to flex the elbow. A center-center position of the guidewire in all views (PA, lateral, and oblique) should be obtained. Although a screw that is shorter and perpendicular to the fracture is as effective as a long-axis screw, I generally prefer a screw in the most central portion of the bone. In a retrospective review of 34 patients, time to union is shorter when the screw is placed in the central third.
Once the wire position is determined to be optimal, the wire is advanced to the subchondral bone on the distal end of the scaphoid bone. This distance is then measured. The appropriate screw length is shorter than this distance by at least 4 mm; I often use a screw even shorter than this. For an adult man, 20 mm is often an appropriate length. The screw should be relatively long but should definitely not be too long. If the screw is too long, it can distract the fracture if it hits the unyielding distal subchondral bone or protrude out of the bone distally or proximally. Once this length is determined, the guidewire is driven into the trapezium bone and out of the thenar skin, so that wire retrieval can be easily accomplished should the wire break during drilling or screw insertion. A second, antirotation wire may be placed. The wire is overdrilled with a cannulated drill. Although some of the systems tout a “self-drilling” screw, my preference is to overdrill to the subchondral bone on the far end of the scaphoid bone as determined by fluoroscopy. After drilling, I believe it to be imperative to countersink the proximal hole. Most systems come with a countersink. This is to decrease the hoop stresses placed on the proximal bone which can cause a fracture in the proximal bone. After countersinking, a screw of the appropriate size is placed, making sure that it is well seated below the cartilage and into the proximal subchondral bone. A study by Hart and colleagues showed that the torque of the screw turns felt by the surgeon does not correlate with fracture compression. After the screw is placed, it is important to remove the guidewire and check all fluoroscopic views (PA, lateral, supinated and pronated oblique views) to ensure an excellent position of fracture reduction and hardware placement. If unsure about screw position, live fluoroscopy should be used, rotating the scaphoid dynamically. The capsule is closed with absorbable braided suture. The tourniquet is released and hemostasis achieved. The skin is closed and a well-padded short-arm splint is placed. Depending on fracture stability and patient compliance, a postoperative short-arm thermoplastic splint or short-arm cast may be placed at 2 weeks until the bone is healed; this may take 6 to 10 weeks following operation. Fracture healing is determined clinically by lack of tenderness and by imaging with radiographs and with CT scanning if there is any radiographic ambiguity.
Dorsal Percutaneous Slade Technique
The main difference in the Slade technique is that it is a percutaneous technique; as such the entrance point is identified by flexing the wrist and identifying the superimposed rings on fluoroscopy of the proximal and distal poles. The guidewire is placed down the center of the superimposed rings. The wire is advanced out of the radial aspect of the thumb so the wrist can be extended for standard wrist radiographs. When satisfactory wire placement is confirmed, the wrist is again flexed and the wire driven dorsally for the remainder of the procedure, which is identical to the author’s preferred method above.
Unstable Acute Fractures: Waist Fracture, Displaced
Acute waist fractures can be approached dorsally or palmarly. There are advantages and disadvantages to both approaches. The main advantage of the dorsal approach is that the fixation can get down the true axis better than the palmar approach. Many surgeons prefer dorsal percutaneous screw fixation because of the ease of access and the ability to place a screw closer to the central axis. The disadvantages of the dorsal approach are that it either (1) requires a miniopen approach to retract extensor tendons or (2) risks injury or rupture of the extensor tendons with a percutaneous approach. The dorsal approach also requires flexion of the wrist, which may theoretically displace an unstable fracture. The dorsal miniopen and Slade percutaneous approaches are described above.
The palmar approach may be used for waist fractures and the infrequent distal pole fracture that may require surgical fixation. An advantage of the palmar approach is that the entrance of the scaphoid tubercle is subcutaneous; thus there are no tendons in the path of the approach. A small (1-cm) incision may be used if needed to allow overdrilling of the guidewire and placement of the screw. Another advantage of the palmar approach is that the wrist is extended, theoretically helping to reduce the fracture. A disadvantage is that it is not possible to place the screw down the true axis of the bone because the trapezium blocks the entrance of the center of the distal scaphoid ( Figure 16.11, A ).
The placement of the screw is always oblique; the more proximal the fracture, the higher the chance of not engaging enough screw threads in the proximal fragment. Another concern is penetration of the dorsal surface of the bone by the screw. The optimal radiographic views for determining screw prominence are the oblique views as reported by Kim and colleagues ( Figure 16.12 ).
Like the dorsal approach, the percutaneous approach can be extended if necessary to openly reduce the fracture or treat a nonunion.
Scaphoid Open Reduction and Internal Fixation From the Palmar Approach
In the open volar approach, a hockey-stick incision is made beginning between the flexor carpi radialis (FCR) tendon and the radial artery in the distal forearm and angled across the distal wrist crease toward the base of the thumb. The FCR tendon is retracted ulnarly and the radial artery radially. The wrist capsule is entered through a longitudinal incision from the volar lip of the radius to the proximal tubercle of the trapezium. The capsule and intracapsular ligaments are carefully divided and reflected sharply off of the scaphoid with a scalpel. The capsule needs to be preserved, as it contains the RSC ligament and will be repaired at the close of the procedure. Some surgeons prefer to tag the ligaments at this stage with nonabsorbable sutures for later repair. The entire volar scaphoid is exposed. Reduction is performed by manipulation or with joysticks, and Kirschner wires are used to provide provisional fixation. Bone grafting can be performed as required for volar comminution or in subacute fractures, with the grafts harvested from the volar radius beneath the pronator quadratus by extending the incision an additional 2 to 3 cm. The scaphotrapezial joint is opened to place a central guidewire in preparation for final fixation. If necessary, a small amount of the proximal trapezium can be excised with a rongeur to clear an unobstructed path for the implant. Rigid internal fixation can be performed with the implant of choice.
With the volar approach, it is important to know that it is impossible to put the screw down the long axis of the scaphoid without violating the trapezium. Verstreken and colleagues have popularized a transtrapezial approach that enables more central screw position. Leventhal and associates performed a computational analysis to identify the ideal starting point (1.7 mm dorsal and 0.2 mm radial to the tip of the scaphoid tubercle) to enable the longest possible screw trajectory in the scaphoid without violating the trapezium.
Palmar Percutaneous Method
Streli was the first to describe volar percutaneous screw fixation of the scaphoid fracture in 1970 using traction applied through the thumb and a standard ASIF screw. In 1991, Wozasek and Moser reported on an adaptation of Streli’s technique using cannulated 2.9-mm screws via a volar percutaneous approach. Later, Bond and colleagues demonstrated faster healing and return to work with percutaneous screw fixation from the palmar approach compared with cast immobilization. They used modern cannulated headless compression screws.
Fractures suitable for treatment with the volar percutaneous (distal to proximal) approach are fractures at the waist and distal pole. Humpback deformities or scaphoid collapse with a DISI deformity usually require open reduction, bone grafting, and fixation. Unsuitable fractures include proximal pole fractures, which are best treated via a dorsal (proximal to distal) approach.
Author’s Preferred Method: Scaphoid Mini-Open Screw From the Palmar Approach
The tourniquet is placed proximally on the arm and the upper extremity draped to allow for full motion of the extremity and enable adequate visualization with fluoroscopy. A tourniquet is used at the surgeon’s discretion. A small longitudinal incision (≈1 cm, or just long enough to accommodate the drill bit/screw) is made over and just distal to the scaphoid tubercle. The wrist is hyperextended and ulnarly deviated over a bump. This moves the trapezium dorsally away from the entrance point on the scaphoid bone (see Figure 16.11, B ).
If the trapezium has a particularly palmar location, a rongeur may be needed to remove a small amount of bone to gain access to the entrance point. The guidewire is started as dorsally as possible on the scaphoid in the sagittal plane without impinging on the trapezium. On the coronal plane, a good landmark for the starting point is a third of the distance from the radial side of the distal pole of the scaphoid ( Figure 16.13 ). The surgeon should attempt to drop the hand to get as close as possible to the axis of the scaphoid ( Figure 16.14 ). Fluoroscopy is used to optimize guidewire placement.
Once the guidewire is placed, multiple minifluoroscopic views are taken, including anteroposterior (AP), lateral, and oblique views. It is imperative to take 45-degree oblique views in supination and pronation to ensure that the wire is within the bone in all planes. The wire should be advanced to the subchondral bone on the proximal side and measured.
The appropriate screw length is shorter than this distance by at least 4 mm; I often use a screw even shorter; a 20-mm screw is often an appropriate length for an adult male. The screw should be relatively long but should definitely not be too long. If it is too long, it can distract the fracture or protrude out of the bone distally or proximally. Once this length is determined, the guidewire is driven into the radius or out of the dorsal skin and clamped so that the wire will not come out during drilling. A second antirotation wire may be placed. The wire is overdrilled with a cannulated drill that is common to most headless compression screw systems. Although some of the systems tout a “self-drilling” screw, my preference is to overdrill up to the subchondral bone on the far end of the scaphoid as determined by fluoroscopy. After drilling, I believe it to be imperative to countersink the entrance hole. This is to decrease hoop stresses when tightening the screw, which can crack the distal fragment. After countersinking, a screw of appropriate size is placed, making sure that it is seated below the cartilage and flush with the subchondral bone. After the screw is placed and the guidewire removed, it is important to check all fluoroscopic views (AP, lateral, supinated and pronated oblique views) to ensure an excellent position of fracture reduction and hardware placement. If a tourniquet is used, it is deflated at this time. If an incision is used, it is closed with sutures or Steri-Strips. A well-padded short-arm splint is placed. Depending on fracture stability and patient compliance, a thermoplastic splint or short-arm cast is placed at 2 weeks until the bone is healed. Some surgeons allow light activities as tolerated and early range-of-motion exercises to restore wrist mobility prior to complete healing. Fracture healing at 6 to 10 weeks postoperatively is assessed clinically by lack of tenderness and by imaging with radiographs and/or CT scans.
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Place the guidewire as centrally as possible in the scaphoid.
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Consider using an antirotation wire.
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Common error is using a screw that is too long.
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Subtract at least 4 mm from the measured distance.
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A common screw length for an adult male is 20 mm.
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Do not ream past the far cortex.
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If feeling a lot of resistance (especially when reaming over wire), stop and look. The wire may be bent and break or the drill bit may break ( Figure 16.15 ).
FIGURE 16.15
Broken drill bit from attempting to drill over a bent guidewire.
(From Kosy JD, Standley DM: Retrieval of broken Acutrak drill bit. J Hand Surg Eur 35(8):683, 2010.)
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Beware of hoop stresses. Use countersinking to avoid excessive hoop stresses that can fracture the near fragment.
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Consider the use of joysticks to gain reduction.
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If needed, reduce and pin the lunate in neutral (out of DISI) ( Figure 16.16, A to C ).
FIGURE 16.16
A, Preoperative computed tomographic scan showing dorsal intercalated segmental instability (DISI). Postoperative posteroanterior view (B) and lateral view (C) after reduction of DISI and Kirschner wire placement from radius to lunate.
(Courtesy of Scott W. Wolfe, MD.)
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Consider supplemental fixation for more stability ( Figure 16.17 ).
FIGURE 16.17
Example of supplemental fixation for stability.
(Courtesy of Steve K. Lee, MD.)
Palmar Percutaneous Method of Scaphoid Fixation (Alternate Method)
In the palmar percutaneous method of scaphoid fixation, the patient is placed supine on an operating table and the hand is suspended vertically by the thumb using a finger trap ( Figure 16.18 ). This position extends the scaphoid and ulnarly deviates the wrist to improve access to the distal pole of the scaphoid. A fluoroscopic imaging unit is rotated parallel to the floor and positioned so that the wrist is in its central axis. Traction from a tower permits full rotation of the scaphoid in the imaging beam. In the majority of cases, longitudinal traction is enough to reduce the scaphoid fracture. If the fracture is not reduced, Kirschner wires can be inserted and used as joysticks to manipulate the fragments into position. The quality of the reduction can then be checked radiographically.
Having achieved an acceptable reduction, the most important step is to establish the entry point of the guidewire. The ulnar deviation of the wrist extends the scaphoid to make the tubercle more accessible. The entry point, the scaphoid tuberosity, is located using a 12- or 14-gauge intravenous needle introduced on the anteroradial aspect of the wrist, just radial and distal to the scaphoid tuberosity. The needle serves as a trocar to guide the wire and establish a central path along the scaphoid. The needle is inserted into the scaphotrapezial joint and tilted into a vertical position. The needle is levered on the trapezium, which brings the distal pole of the scaphoid more radially and facilitates screw insertion. The wrist is rotated in the fluoroscopic beam to confirm that the needle is aligned along the axis of the scaphoid in all planes, with the intent of directing the guidewire into the proximal pole to a point just radial to the scapholunate ligament. Leventhal and colleagues identified the ideal starting point to be approximately 2 mm dorsal and just radial to the apex of the scaphoid tubercle, in order to achieve maximum guidewire length within the scaphoid.
Once the entry point and the direction of the guidewire are confirmed, the needle is impacted into the soft articular cartilage over the distal pole of the scaphoid so that the tip does not slip during insertion of the guidewire. The guidewire is passed down through the needle and drilled across the fracture; its direction is continually checked on the image intensifier and adjusted as necessary, with the goal of entering the radial aspect of the proximal pole. The position is checked in multiple fluoroscopy planes, and, if satisfactory, a longitudinal incision of 0.5 cm is made at the entry point of the wire and deepened down to the distal pole of the scaphoid using a small hemostat and blunt dissection. This is a relatively safe zone, with minimal risk to the adjacent neurovascular structures.
The length of the screw is determined using a depth gauge or by advancing a second guidewire of the same length up the distal cortex of the scaphoid and subtracting the difference between the two. The correct screw size is 4 to 5 mm shorter than the measured length, which will ensure that the screw head is fully buried below the cartilage and the subchondral bone on each end. In rare cases a second antirotation wire may be inserted parallel to the first prior to drilling and reaming. The wire is advanced into the radius or out of the dorsal skin and clamped, so as to avoid loss of wire position with drilling. The 12-gauge needle is removed and the cannulated drill is passed over the wire and advanced under imaging guidance, stopping 1 to 2 mm short of the far articular surface. At this point the hand is taken out of traction so that the screw will adequately compress the scaphoid. A countersink or a trailing drill is used, depending on the particular set. A self-tapping screw is advanced over the guidewire. The final position is checked with multiple fluoroscopic views to confirm complete containment within the scaphoid. A hyperpronated PA view profiles the dorsal-radial cortical margin of the scaphoid, where a perforation of the proximal cortical bone can occur. Compression of the fracture site is confirmed radiographically on the image intensifier. The wire is removed, the skin closed with a suture or Steri-Strips, and the wound covered with a sterile compressive dressing.
Postoperative Care.
A volar plaster splint is removed at 10 to 14 days postoperatively. The sutures are removed at this stage, and wrist radiographs are taken to confirm that screw position is satisfactory. Depending on the bone quality, fixation, and assumed patient compliance, a short-arm thumb spica cast or well-molded Orthoplast short-arm thumb spica splint is used for 4 additional weeks or until the wrist has healed. Hand therapy may be useful to regain hand motion; no heavy carrying or weight-bearing activity is permitted. A return to sedentary work is allowed as soon as the patient feels ready or when 75% of the contralateral range of movement is achieved. When radiographic and clinical union have been achieved, the splint is discontinued and all previous activities are resumed as tolerated. CT is used to confirm healing before return to heavy lifting or competitive athletics.
Potential complications include malposition of the screw, violation of the cortical surface, and hardware protrusion within the radioscaphoid or scaphocapitate joint proximally, breakage of a guidewire, and fracture of the scaphoid during screw placement. Another potential problem is a failure to completely bury the head of the screw within the scaphoid, which can lead to scaphotrapeziotrapezoidal (STT) arthrosis. This problem is avoided by selecting a screw length approximately 4 to 5 mm shorter than measured with the depth gauge. Fracture displacement can occur with guidewire malposition or in proximal pole or oblique fractures. Other risks include transient dysesthesia just distal to the scar. This is secondary to a neurapraxia of a sensory branch of the median nerve and usually resolves within 4 to 6 weeks. Volar fixation of a small proximal scaphoid fragment is contraindicated because of tenuous fixation and minimal compression. Nonunions or delayed unions using the volar approach have occurred with proximal pole fractures, and small proximal pole fractures should be treated using a dorsal approach.
Arthroscopy-Assisted Percutaneous Scaphoid Fixation
The goals of arthroscopy-assisted stabilization of scaphoid fractures are to reduce displaced fractures without an open incision and provide secure fixation that will permit early motion until solid union has been achieved. The early results of arthroscopy-assisted percutaneous screw fixation of displaced fractures of the scaphoid suggest that minimally invasive reduction and fracture union can be predictably obtained with good to excellent functional results in the correctly selected patient. Avoidance of open exposure limits the potential for wrist ligament injury, may help to preserve the blood supply, and minimizes postoperative stiffness. However, many scaphoid fractures are now treated with percutaneous or mini-open techniques that create little scarring and do not adversely affect postoperative motion.
Slade reviewed his results in arthroscopy-assisted fixation from a dorsal approach in 27 consecutive patients. There were 18 waist fractures and 9 fractures of the proximal pole. Seventeen patients were treated within 1 month of injury, and 10 patients were treated late. All fractures healed, as documented by CT.
Arthroscopy-assisted fixation of scaphoid fractures also allows for simultaneous detection of associated intracarpal soft tissue injuries. Braithwaite originally reported on four patients with a fracture of the scaphoid with complete scapholunate dissociation. As in fractures of the distal radius, associated soft tissue lesions may occur with scaphoid fractures, and arthroscopic evaluation allows detection and management. It is not known whether early arthroscopic detection and management of the associated injuries improve the final outcome. For operative details of arthroscopic-assisted percutaneous treatment of scaphoid fractures and scaphoid nonunions, the reader is referred to Chapter 17 .
Delayed (Subacute) Presentation of Waist Fracture
Surgery is generally indicated for delayed presentation of a scaphoid fracture 4 to 6 weeks or more following injury. Patients with delayed presentation of scaphoid fractures have a higher likelihood of nonunion with closed treatment and require 4 to 6 months to heal in plaster.
Managing Scaphoid Fractures in Athletes
Scaphoid fractures are common in competitive and recreational athletes, and such patients are reluctant to submit to the long period of immobilization and restricted activity that plaster requires. These factors may influence our treatment decisions. The treating physician may permit participation in athletic activity with a playing cast. Some organizations permit casts that are protected with foam padding. Whether the forces generated by firm gripping are detrimental to healing probably depends on the fracture’s inherent stability. One study reported a faster return to play with internal fixation compared with a playing cast alone. A potential problem with plaster immobilization is compliance. Young people often will modify or remove the cast and are increasingly noncompliant with follow-up over time. The pressure to return to sports may lead the patient and coach to seek ways of shortening the period off of the field. The player’s ability to return to sports before the fracture is healed depends on the sport and its requirements. Options to be weighed will be surgery, a playing cast, and playing restrictions. The goal will be the successful union of the scaphoid fracture regardless of the patient’s athletic responsibilities. Clearly, educating the patient, family, trainer, and coach is essential.
Complex Scaphoid Injuries
Combined Fractures of the Scaphoid and Distal Radius
Combined fractures of the distal radius and scaphoid are uncommon but present a challenging treatment dilemma. Scaphoid fractures may not be recognized when associated with a comminuted distal radius fracture and when untreated can result in carpal collapse, cystic degeneration, and eventual carpal degenerative arthritis. Although an isolated stable scaphoid fracture might be safely managed with plaster immobilization, the 12 to 16 weeks of immobilization required for healing are not appropriate for the treatment of the distal radius fracture. Prolonged immobilization may result in arthrofibrosis and atrophy of the forearm and hand, making the recovery of full hand function difficult.
A review of the published reports on combined scaphoid and distal radius fractures demonstrates that treatments have evolved over the past decade. Trumble and colleagues reported on six patients treated with internal fixation for ipsilateral combined fractures of the scaphoid and radius. All patients sustained a high-energy injury from a fall from a substantial height. All of the fractures united, with the radial fractures healing in an average of 6 weeks and the scaphoid fractures healing in an average of 13 weeks. Internal fixation of the scaphoid in these combined injuries allowed for earlier and more aggressive therapy to maximize wrist and forearm motion. Treatment in my hands is usually open reduction and internal fixation (ORIF) of the distal radius fracture and the mini-open approach and fixation of the scaphoid fracture.
Transscaphoid Perilunate Fracture-Dislocations
Open and Arthroscopic Treatment.
Acute fracture-dislocations of the carpus are uncommon. Perilunate fracture-dislocations represent approximately 5% of wrist fractures and are about twice as common as pure ligamentous dislocations. Transscaphoid perilunate fracture-dislocation is the most common type of complex carpal dislocation.
Treatment of these injuries can be challenging owing to the extensive soft tissue, cartilaginous, and bony damage. Furthermore, obtaining universally excellent long-term results can be elusive. Various operative treatment options have been recommended, including dorsal, volar, percutaneous, and arthroscopic approaches.
These injuries are usually due to a high-energy impact, as may occur in motor vehicle accidents, a fall from a height, or contact sports. The mechanism of injury characteristically involves forceful wrist extension, ulnar deviation, and intercarpal supination. The injuries have been classified as greater and lesser arc injuries. Greater arc injuries have associated fractures and lesser arc injuries do not; lesser arc injuries are purely ligamentous. Bone or ligament failure usually begins with the radial styloid and or scaphoid fracture or palmar capsuloligamentous disruption starting radially and propagating ulnarly. In the greater arc injury, the energy takes a transosseous route through the scaphoid, with usual disruption of the lunotriquetral interosseous (LTIO) ligament and fracture of the ulnar styloid. The proximal fragment of the scaphoid and the lunate remain with the radius, while the distal fragment of the scaphoid dislocates dorsal to the lunate with the attached distal carpal row. In 10% of dislocations, the distal scaphoid fragment and the distal carpal row dislocate palmarly to the lunate. Variations of perilunate fracture-dislocations include fractures of the capitate, triquetrum, radial styloid, and ulnar styloid. A specific variation of the perilunate fracture-dislocation is scaphocapitate syndrome . In this injury, the injury force passes through the neck of the capitate, fracturing both the scaphoid and the capitate. The proximal portion of the capitate may rotate 90 to 180 degrees, with the articular surface of the head of the capitate directed distally. The injury to the capitate can be missed on plain radiographs. If scaphocapitate syndrome is suspected, a CT scan will better elucidate the pathoanatomic situation. ORIF is indicated in scaphocapitate syndrome through a dorsal approach. Both the capitate and scaphoid should be reduced and fixed with proximal to distal headless compression screws. Briseno and Yao reported on a lunate fracture along with perilunate injury and stressed the importance of looking for this injury and treating it appropriately. Even with treatment, the simultaneous lunate fracture portends a worse prognosis.
Herzberg and Forissier investigated the medium-term results (mean follow-up, 8 years) of a series of 14 transscaphoid dorsal perilunate fracture-dislocations treated operatively at an average of 6 days following injury. Eleven underwent ORIF through a dorsal approach. Combined palmar and dorsal approaches were used in three cases: in two cases, ORIF, and in one case, proximal row carpectomy. All internally fixed scaphoids healed, and no carpal AVN or collapse was observed. Carpal alignment was satisfactory in most cases. Posttraumatic radiologic midcarpal arthritis or radiocarpal arthritis, or both, was almost always observed.
Nearly every combination of radiocarpal and intercarpal dislocation has been described, but few fit neatly into a particular pattern or classification scheme. These injuries may be subtle, and diagnosis is still frequently delayed; the dislocation is missed by primary providers in up to 25% of cases. Prompt recognition, accurate reduction, and stable internal fixation all contribute to improved outcomes. Internal fixation techniques depend on the pathologic condition of the carpus. Although arthroscopic techniques and fluoroscopically aided percutaneous techniques have been described, my preference for treatment is an open procedure. The wrist is approached dorsally primarily for treatment of the scaphoid fracture or the scapholunate tear if it is a lesser arc injury. In 3% of cases, a complete SLIL tear accompanies a scaphoid fracture-dislocation. An extended carpal tunnel approach is added if one of two situations is present: (1) The preoperative history and examination are consistent with acute carpal tunnel syndrome. If left untreated, median nerve compression can lead to long-term nerve deficits, hand stiffness, and, potentially, a complex regional pain syndrome. (2) A perilunate fracture-dislocation is irreducible from the dorsal approach. The lunate is visualized in the space of Poirier between the RSC ligament and long radiolunate ligament. Using a Freer elevator or similar instrument from the volar approach and manual wrist manipulation, the lunate can be negotiated into reduction.
For associated lunotriquetral ligament injury, the lunotriquetral joint is reduced and held with two Kirschner wires. One technique that is very valuable and surgically efficient is to place one or two double-ended Kirschner wires from within the lunotriquetral joint out the ulnar side of the wrist through the triquetrum before the lunate is reduced. A similar technique can be used in the scaphoid when the SLIL is torn. It is important to protect the soft tissues (radial artery, superficial radial nerve, tendons, veins) on the radial side of the wrist. The lunate is reduced and the wires are driven back into the lunate from inside the triquetrum and scaphoid, respectively. If extended carpal tunnel release has been performed, the stronger palmar component of the lunotriquetral ligament can be sutured with nonabsorbable braided suture from the palmar side.
Occasionally the dorsal radioulnar ligament origin is avulsed off of the dorsal ulnar corner of the radius. The distal radioulnar joint will be unstable and the dorsal ulnar corner of the radius will be devoid of soft tissue during the exposure. It is important to repair the ligament with bone suture anchor. Repairs are generally protected with cast immobilization for 8 to 12 weeks, followed by removal of Kirschner wires and then gentle active mobilization of the wrist over the next 4 to 8 weeks ( Figure 16.19, A to H ).
- 1.
It is imperative during reduction to restore Gilula’s lines in coronal plane and attain neutral radiolunate and capitolunate alignment in the sagittal plane.
- 2.
Consider starting K wires from within the scapholunate joint and going out radially and ulnarly. Reduce the joint, then drive wires back in to fix the scapholunate joint and lunotriquetral joints, respectively.
- 3.
Bury K wires because they should stay for approximately 10 to 12 weeks.
- 4.
Beware of concomitant wrist injuries, such as dorsal radioulnar ligament injury.
Complications of Scaphoid Fracture Treatment
The most common complications reported in the literature are delayed union, nonunion, arthritis, reduced wrist motion, and loss of strength. Prolonged cast immobilization leads to muscle atrophy, possible joint contracture, disuse osteopenia, and potential financial hardship. Closed treatment of scaphoid waist fractures may require cast immobilization for 3 months or longer, and fractures of the proximal third of the scaphoid in particular may take 6 months or longer to heal. Surgical repair of scaphoid nonunion is successful in 50% to 95% of patients, depending on the vascular status and presence of arthritis or carpal collapse; successfully repaired scaphoid nonunions may require up to 6 additional months for healing and rehabilitation.
Other complications are reported. Filan and Herbert in 1996 reported on 431 patients treated with ORIF using the Herbert bone screw. They reported that 56 patients had hypertrophic scarring and 20 patients complained of postoperative pain and swelling at the donor site of a bone graft. Four superficial infections and one deep wound infection resolved satisfactorily with conservative treatment. Four patients had early signs of reflex sympathetic dystrophy after surgery. In two patients these signs resolved spontaneously, but two patients developed carpal tunnel syndrome, which required surgical decompression. Only two wrists showed instability of the scaphoid after surgery. One had sustained a tear of the scapholunate ligament at the time of injury; the other appeared to have a late rupture of this ligament. AVN developed after surgery in 20 scaphoids, all of which required further operations. In one case, a very small necrotic fragment of the proximal pole was excised and the scaphoid stabilized by dorsal capsulorrhaphy. Five wrists had a midcarpal fusion. The necrotic proximal pole was excised in 14 cases and was replaced with a stabilized silicone implant in 13 and an osteochondral autograft in one.
In another early report of headless screw fixation, Dias and colleagues investigated 88 patients with minimally displaced or nondisplaced bicortical fractures of the waist of the scaphoid in a prospective, randomized controlled study comparing plaster immobilization in a below-elbow plaster cast with early internal fixation with use of a Herbert or Herbert-Whipple screw. Complications occurred in 13 patients (30%) who had been managed operatively, and nonunion occurred in 10 of 44 patients (23%) of those treated in a cast. Most operative complications were minor, and included superficial wound infection (in one patient), sensitive scar (in three patients), hypertrophic scar (in four patients), sensitive and hypertrophic scar (in three patients), hypoesthesia in the region of the palmar cutaneous branch of the median nerve (in one patient), and mild early complex regional pain syndrome (in one patient). Technical difficulty was experienced in seven patients (16%) during surgery. In four of them, there was initial misplacement of either the drill or the screw. In one patient, the scaphoid tuberosity split during screw insertion.
Bushnell reported his complications with repair of scaphoid fractures using a dorsal percutaneous approach and cannulated headless screw fixation in 24 cases performed over 5 years. All cases involved nondisplaced (<1 mm) fractures of the scaphoid waist. The overall complication rate was 29%; there were five major complications (21%) and two minor complications (8%). Major complications consisted of one case of nonunion, three cases of hardware problems, and one case of postoperative fracture of the proximal pole of the scaphoid. Minor complications included intraoperative equipment breakage, with one case involving a screw and one case involving a guidewire.
Complications of internal fixation are usually due to screw placement and length. Controversy exists as to whether the screw should be placed centrally in the scaphoid or perpendicular to the fracture. Eccentric screws decrease fixation strength and risk penetration out of the scaphoid.
Use of Fluoroscopy and Surgical Navigation to Reduce Screw Malposition
The development of small cannulated screws has permitted minimally invasive percutaneous fixation of acute scaphoid fractures. There are known mechanical advantages to increased screw length and central screw placement. As cited above, there are potential deleterious effects of eccentric screw placement, including articular protrusion, proximal pole fracture, and nonunion. Tumilty and Squire reported that the curvilinear surface of the proximal pole of the scaphoid may lead to errors in calculation of screw length and penetration into the joint. In this cadaveric study of six specimens, two screws were found to be penetrating subchondral bone. The plain x-ray films were accurate in only five of the six specimens, while 360-degree fluoroscopic views were accurate in all six. Fluoroscopy during placement of a scaphoid screw may decrease the rate of subchondral penetration.
Recently, investigators have evaluated CT-generated models to assist in the development of a targeting system for implantation of screws into a reduced scaphoid fracture. Several investigative teams have demonstrated that a computer-assisted navigation of volar percutaneous scaphoid screw placement improved accuracy and required less time, less use of fluoroscopy, and diminished radiation exposure when compared with traditional percutaneous techniques. Hoffman and colleagues showed in a cadaveric model that compared with the standard fluoroscopic technique, an electromagnetic navigation technique had a higher accuracy rate and lower rates of complications and required less operative time and radiation exposure time.
Cost of Surgical or Nonsurgical Treatment
The treatment of stable scaphoid waist fractures by surgery has raised the issue of cost. Would the health care system be better served by plaster immobilization of these stable fractures, not considering the costs of re-treating fractures that failed to heal (6% to 23% nonunion rate)? Arora and colleagues compared two groups of stable scaphoid fractures, one treated with plaster immobilization and the other with internal screw fixation. They concluded that internal screw fixation of nondisplaced scaphoid fractures had a shorter time to bony union and that the patients returned to work an average of 7 weeks earlier than patients with cast immobilization. Although it is assumed that operative treatment is more expensive, in this study the overall cost was not found to be higher.
Davis and colleagues conducted a cost/utility analysis to weigh ORIF against cast immobilization in the treatment of acute nondisplaced midwaist scaphoid fractures. The authors used a model to calculate the outcomes and costs of ORIF and of cast immobilization, assuming the societal perspective. Medical costs were estimated using Medicare reimbursement rates, and costs of lost productivity were estimated by average wages obtained from the U.S. Bureau of Labor Statistics. ORIF offered greater quality-adjusted life-years than casting. ORIF was less costly than casting ($7940 versus $13,851 per patient) because of a longer period of lost productivity with casting. When considering only direct costs, the incremental cost/utility ratio for ORIF ranged from $5438 per quality-adjusted life-year for the 25- to 34-year-old age group to $11,420 for the 55- to 64-year-old age group, and $29,850 for the age group 65 years and older. They concluded that, unlike casting, ORIF is more cost-effective relative to other widely accepted interventions.
Bone Growth Stimulators
The currently used bone stimulators that have been discussed in the context of scaphoid fractures fall into two major categories: external stimulation of ultrasound or pulsed electromagnetic field (PEMF) therapy. The external stimulators mimic stress to the bones, augmenting bone formation. Ultrasound (Exogen, Bioventus, Durham, NC) is used for only 20 minutes per day and PEMF for 8 to 12 hours per day; understandably, patient compliance with PEMF use is difficult to achieve. Randomized controlled data for ultrasound treatment in acute scaphoid fractures support its use. Mayr reported on 30 patients in a randomized study who had a cast with or without ultrasound for 20 minutes per day. His results showed that fractures that underwent ultrasound treatment healed in 43.2 ± 10.9 days, versus 62 ± 19.2 days in the control group ( p < .01). Using criteria of trabecular bridging as evidence of healing, 81.2% ± 10.4% of the ultrasound-stimulated fractures were healed at 6 weeks, versus 54.6% ± 29% in the control group ( p < .05). PEMF has been used to attempt to accelerate scaphoid healing. However, there are no reliable randomized controlled data for PEMF in scaphoid fractures. My preference is to use ultrasound for difficult scaphoid fractures.
Biologic Stimulation of Scaphoid Nonunions
Bone morphogenetic proteins play critical roles in both bone development and fracture healing. Urist first showed that extracts from demineralized bone matrix were capable of inducing new bone formation when implanted in an intramuscular site. The osteoinductive properties of bone morphogenetic proteins for inducing bone formation in ectopic sites and producing healing of critical-sized segmental bone defects in experimental animal studies are attributable to their ability to stimulate the chemotaxis and differentiation of mesenchymal stem cells into chondroblasts or osteoblasts, or both. With the difficulty in treating proximal pole scaphoid nonunions, it is natural that these biologic enhancements would be investigated.
In a case reported by Jones and colleagues, a chronic nonunion of a proximal pole fracture of the scaphoid was treated by curettage of the nonunion, single Kirschner wire fixation, and implantation of 50 mg of human bone morphogenetic protein followed by 12 weeks of cast immobilization without any conventional corticocancellous bone grafting or rigid screw fixation. Radiographs showed signs of bony healing by 12 weeks, and an MRI 6 years after surgery showed no signs of AVN. The authors discussed the potential future applications of human bone morphogenetic protein in hand surgery.
Bilic and colleagues reported on 17 patients with scaphoid nonunion at the proximal pole treated with and without bone graft osteogenic protein-1 (OP-1) or bone morphogenetic protein 7 (BMP-7). OP-1 improved the performance of both autologous and allograft bone implants and reduced radiographic healing time to 4 weeks compared with 9 weeks without OP-1. CT scans and scintigraphy showed that in patients treated with OP-1, sclerotic bone was replaced by well-vascularized bone. Allograft and autologous grafts treated with OP-1 healed at a similar rate. At present, there is insufficient evidence to derive recommendations concerning the role of biologics in scaphoid fracture or nonunion treatment, and their use is not common.
Scaphoid Fracture in Children
Fractures of the immature scaphoid are uncommon and can be challenging to diagnose. These fractures most commonly involve the distal scaphoid and are effectively treated with cast immobilization. Fortunately most acute pediatric scaphoid fractures heal with nonoperative treatment, and surgery in children is indicated only if there is nonunion.
The diagnosis of acute scaphoid fracture may be missed or delayed because of minimal symptoms. This is particularly true in athletic adolescents, who may return to sports prematurely after a seemingly minor injury to the wrist. The presentation of scaphoid fractures in adolescents has changed over the years and today more closely resembles the adult pattern. Malunion or nonunion may occur in patients with a missed diagnosis or delayed presentation and occasionally in patients treated promptly with immobilization. Surgical intervention should be considered for fracture nonunions in patients who are at or near skeletal maturity or in those in whom nonsurgical treatment has failed. Mintzer and Waters presented the outcome of 13 pediatric scaphoid fracture nonunions in 12 children treated over an 18-year period. The average elapsed time between fracture and surgery was 16.7 months. Four of the nonunions were treated with inlay bone graft from a palmar approach, and nine were treated with Herbert screw fixation and iliac crest bone grafting. The average time of follow-up was 6.9 years (range, 2 to 19 years). All cases went on to clinical and radiographic union. Patients had no statistically significant difference in range of motion or strength between the operative and nonoperative wrists. The length of time for postoperative immobilization in the Herbert screw group was significantly less than that in the inlay bone graft group. Though scaphoid nonunions in children can heal with prolonged cast immobilization, the authors recommended that the treatment of scaphoid fracture nonunions in the skeletally immature patient be rigid fixation with a compression screw and iliac crest bone graft.
Masquijo and Willis presented their series of 23 pediatric (average age, 15 years) scaphoid nonunions fixed with iliac crest bone graft and screws, with a 95.6% union rate.
Weber reported on six children with nonunited scaphoid fractures treated conservatively. The mean age was 12.8 years (range, 9.7 to 16.3 years), and the mean follow-up time was 67 months. Five had no previous treatment, and the time to diagnosis averaged 4.6 months (range, 3 to 7 months) after injury. Treatment consisted of cast immobilization until clinical and radiologic union. Fractures united in all six children after a mean period of immobilization of 5 months (range, 3 to 7 months). All patients returned to regular activities. Although prolonged treatment with cast immobilization resulted in union of the fracture and an excellent subjective wrist score in all patients, this delay may not be well tolerated by the child or family.
Management of Scaphoid Nonunion
The ability to successfully treat scaphoid nonunions in part defines the abilities of a hand/upper extremity surgeon. Unfortunately, missed scaphoid fractures are relatively common, because oftentimes the patient, trainer, or urgent care personnel will dismiss a wrist injury as a “sprain.” The traditional definition of scaphoid nonunion is failure of union following cast immobilization or surgical treatment of 6 months’ duration. When most patients with scaphoid nonunion present, however, they have not had any form of treatment, months to years have elapsed since the injury, and secondary deformities and carpal collapse have occurred. If scaphoid nonunion is left untreated, the natural history is carpal collapse and degenerative arthritis. In a long-term follow-up study of more than 30 years of scaphoid fractures treated with short-arm thumb spica casts, 10% had nonunion. Osteoarthritis with associated pain and weakness was present in 56% of patients. Only 2% of the healed group had osteoarthritis.
To minimize the incidence of arthritis, the goal of treatment is to attain a healed scaphoid with anatomic alignment. Advanced imaging, including CT and MRI, aids in the evaluation of scaphoid alignment, bone loss, scaphoid humpback deformity, carpal collapse, and osteonecrosis. Generally, scaphoid nonunions from waist fractures with severe collapse and humpback deformity must be approached volarly with interposition of bone graft and internal fixation. For proximal pole nonunions, a dorsal approach allows access for curetting the nonunion site, bone grafting, and internal fixation of headless compression screw(s) from proximal to distal. The indications and best method of vascularized bone grafting are controversial.
Evaluation of Scaphoid Nonunion
When evaluating patients with scaphoid nonunion, the following issues regarding the fracture must be considered:
- 1.
Where is the nonunion? At the waist or at the proximal pole?
- 2.
Is the nonunion displaced?
- 3.
Is there a humpback deformity?
- 4.
Is there comminution, cyst formation, or cavitation?
- 5.
Is DISI present?
- 6.
Was there previous surgery?
- 7.
Does the proximal pole look dysvascular?
- 8.
Is there arthritis (SNAC wrist)? If so, at what stage?
- 9.
Is the scaphoid deformed or salvageable?
Fracture Site.
The more proximal the fracture, the more likely the proximal bone will be dysvascular. This may have implications for the choice of bone graft or other treatment.
Amount of Scaphoid Deformity and Carpal Malalignment.
If there is humpback deformity and carpal malalignment, they may have to be corrected at the time of bone grafting and fixation.
Stability of Nonunion; Amount of Bone Loss.
If the nonunion is stable and well aligned and bone loss is minimal, limited opening in the nonunion site, curetting as necessary, and cancellous bone grafting may be appropriate, followed by internal fixation by a headless compression screw. Slade and colleagues had previously reported on successful percutaneous bone grafting and fixation for nonunions. I have not performed this and prefer an open technique, which also allows for confirmation of stability of the fracture and an intact cartilaginous envelope. Imaging, even CT scanning, does not necessarily predict the stability well (Mark Cohen, MD, personal communication).
Previous Treatment.
Any previous surgical or other treatments should be taken into account because they would make further treatment more complex. We have had success with removal of the screw from the original surgery (usually, a volarly placed screw), cavitation of sclerotic or dysvascular bone, hybrid corticocancellous Russe autogenous bone grafting, and placement of a new screw from the opposite pole, usually from proximal to distal because the distal fragment has a hole from the previous screw.
Vascularity of Fragments.
There is general agreement that vascularity is important. Green showed that 92% of scaphoid fractures with good vascularity healed when treated by Russe bone grafting. Union took place in 71% of patients when there was diminished vascularity in the scaphoid, but healing did not take place in any patients when the proximal pole was avascular.
There is a lack of agreement on how to best determine vascularity. X-rays are not adequate to assess AVN, and MRI and intraoperative punctate bleeding do not always correlate (see previous section on Magnetic Resonance Imaging ).
According to Green, vascularity was best determined by punctate bleeding. The use of punctate bleeding intraoperatively to determine AVN has recently been challenged. Even if the fragment is deemed to be dysvascular, there is lack of agreement about the optimal and necessary treatment, as will be discussed.
Possibly to better determine vascularity, curettings of the proximal and distal poles of the scaphoid should be evaluated by a pathologist who is experienced in bone histologic findings.
Salvageability of the Fragment.
The fragment must not be collapsed or deformed beyond repair. In some cases the proximal pole has fragmented and collapsed and is not usable; this may occasionally happen with the distal pole, as well.
Presence and Location of Arthritis.
If there is arthritis of the radiocarpal, midcarpal, or distal radioulnar joint, the treatment may have to be tailored accordingly For instance, if early arthritis (SNAC I) is confined to the radial styloid, radial styloidectomy and scaphoid bone grafting could be considered. With advanced arthritis, nonoperative management is considered if symptoms are not severe. With increasing pain, other options may include partial denervation or salvage procedures such as scaphoid excision and four-bone fusion, proximal row carpectomy, total wrist fusion, hemiwrist arthroplasty, and total wrist arthroplasty.
Patient parameters to consider when evaluating scaphoid nonunions include:
- 1.
Length of time nonunion has been present
- 2.
Age of patient
- 3.
Amount of pain or dysfunction
- 4.
Activity level
- 5.
Systemic comorbidities present
Length of Time Nonunion Has Been Present.
The longer the nonunion has been present, the more likely it is that there will be secondary issues such as arthritis, scaphoid deformity, and carpal instability. In a study by Mack and colleagues, older nonunion was associated with more severe arthritis.
Age of the Patient.
Although scaphoid fractures are usually a problem of young males, in the case of nonunion in an older patient, treatment might be tailored depending on individual needs and activity levels.
Amount of Pain or Dysfunction.
In the case of nonunion with arthritis where a salvage procedure of scaphoid excision and four-bone fusion or proximal carpectomy might be an option, if the level of pain and dysfunction is tolerable, nonoperative treatment might be employed; the patient should be told that a salvage procedure may be needed later.
Activity Level.
Elderly, inactive, or infirm patients may choose to accept the pain and limited range of motion of a scaphoid nonunion. There is no mandate for operative repair because salvage operations may always be considered if escalating arthritic pain causes increasing impairment.
Presence of Comorbidities.
Scaphoid nonunion surgery can be complex and complicated, and the best efforts may be thwarted by heavy tobacco use, poor compliance, uncontrolled diabetes or inflammatory arthritis, steroid dependency, or other factors.
Operative Treatment of Scaphoid Nonunion ( Table 16.4 )
Type I: Delayed or Fibrous Union, No Deformity.
Scaphoid nonunions without substantial bone loss require only rigid fixation to heal if there is adequate perfusion. These include fractures with a delayed presentation, fibrous unions, and nonunions with minimal sclerosis (<1 mm). Stable scaphoid fractures presenting for treatment after 1 month have already developed bone resorption at the fracture site from shearing. Early bony resorption is not typically detected by standard radiographs. Scaphoid fractures with delayed presentation (>4 weeks) have a poorer union rate with casting alone. Selected stable scaphoid delayed unions without deformity or substantial bone loss can be successfully treated with reduction and internal rigid fixation without bone grafting using techniques described for acute fractures above.
| Type of Fracture | Treatment |
|---|---|
| Mini-open rigid fixation with headless compression screw |
Fibrous nonunion, waist Sclerotic nonunion, waist | Open repair and autogenous bone grafting Dorsal or volar |
| Humpback nonunion | Volar approach Russe or Matti-Russe corticocancellous autograft Intercalated wedge autograft Hybrid Russe autograft |
| Dorsal approach Open bone grafting and fixation with headless screw Percutaneous bone grafting with headless screw Lock midcarpal joint with Kirscher wire(s) or miniscrew(s) |
| Nonvascularized vs. vascularized bone graft: dorsal or palmar approach Osteoarticular graft |
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