Acute Scaphoid Fractures in Nonunions

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CHAPTER 27 Acute Scaphoid Fractures in Nonunions

The scaphoid is the most frequently fractured bone in the carpus and accounts for approximately 70% of all carpal fractures.¹ This fracture typically occurs in young men between the ages of 15 and 30 years.² A scaphoid fracture is a common athletic injury, occurring most often in contact sports, particularly in football and basketball players. It is estimated that 1 of 100 college football players will sustain a fracture of the scaphoid.³ Commonly, an injured athlete continues to compete and eventually presents to the treating physician after the season is over with a scaphoid nonunion.

Acute nondisplaced fractures of the scaphoid have traditionally been managed with cast immobilization.⁴^,⁵ Nondisplaced scaphoid fractures usually heal in 8 to 12 weeks when immobilized in long arm or short arm spica casts.⁴^–⁶ Although cast immobilization is successful in up to 85% to 90% of cases, it must be asked what the cost is to the patient, particularly the athlete, who may not be able to tolerate a lengthy course of immobilization during the season or while actively training.⁴^–⁶ Prolonged immobilization may lead to muscle atrophy, disuse osteopenia, joint contracture, and financial hardship. Until the fracture unites, the athlete may be inactive for 6 months or longer.

The duration of cast immobilization varies dramatically according to the fracture site. A fracture of the scaphoid tubercle may be healed within a period of 6 weeks, whereas a fracture of the waist of the scaphoid may require immobilization for 3 months or longer. A fracture of the proximal third of the scaphoid may take 5 months or longer to heal with a cast because of the vascularity of the scaphoid.⁷ This may result in loss of an athletic scholarship or loss of employment.

Displaced scaphoids have a reported nonunion rate of up to 50%.² Factors that decrease the prognosis for healing include the amount of displacement, associated carpal ligament instability, and delayed presentation (>4 to 6 weeks).¹ Traditionally, acute displaced fractures of the scaphoid and scaphoid nonunions have been managed by open reduction and internal fixation.¹^,²^,⁸^–¹⁶ Complications associated with open reduction fixation include avascular necrosis, carpal instability, donor site pain, infection, screw protrusion, and reflex sympathetic dystrophy resulting from the significant soft tissue dissection that is required.⁴^,¹⁷ The most commonly reported complication in one series was hypertrophic scarring.² Although jigs have been designed to assist an open reduction, they frequently are difficult to apply and may necessitate further extensive surgical dissection.¹⁸

Wrist arthroscopy has revolutionized the practice of orthopedics by allowing the surgeon to examine and treat intra-articular abnormalities of the wrist joint under bright light and magnification.¹⁹ The scaphoid is well visualized from the radiocarpal and midcarpal spaces. Whipple is credited with being the first surgeon to attempt arthroscopic management of scaphoid fractures.¹⁹ His preliminary work set the stage for the current concepts and treatment by arthroscopy of these common fractures.

Fractures of the scaphoid are best visualized with the arthroscope in the midcarpal space. Fractures of the proximal pole of the scaphoid are best seen with the arthroscope in the ulnar midcarpal portal, and fractures of the waist are best visualized with the arthroscope in the radial midcarpal portal. Arthroscopic reduction of scaphoid fractures allows direct visualization and reduction of the scaphoid as the guidewires and percutaneous screws are being inserted. Associated soft tissue injuries that may occur with a fracture of the scaphoid can be arthroscopically detected and managed at the same sitting.

The indications and techniques of arthroscopic management of acute scaphoid fractures and selected nonunions are reviewed in this chapter. Arthroscopic stabilization provides direct visualization of the fracture reduction, screw insertion, and limited surgical dissection, which may allow for a greater range of motion and earlier return to competition or employment.

PATIENT EVALUATION

Diagnostic Imaging

Posteroanterior and lateral radiographs are mandatory to assess displacement, alignment, and angulation of a scaphoid fracture. Semisupinated and pronated views can demonstrate the proximal and distal poles of the scaphoid. It is often helpful to place the wrist in ulnar deviation, which extends the scaphoid in a posteroanterior view for detection of fracture displacement. A nondisplaced fracture of the scaphoid will not become apparent on radiographs for several weeks after injury. It is important to mobilize the patient who presents with snuffbox tenderness until the pain has resolved or until a diagnosis has been confirmed radiographically.

Computed tomography (CT) parallel to the longitudinal axis of the scaphoid is useful to evaluate displacement, angulation, and healing when further information is required to assess the fracture. The patient is placed prone with the arms extended overhead and the wrist radially deviated to obtain longitudinal access to the scaphoid. Coronal CT slices are obtained with supination of the forearm to a neutral position. CT evaluation is particularly helpful when nonoperative management of scaphoid fractures is selected, because it can be difficult to judge healing of the scaphoid by plain radiography. This is particularly important when returning an athlete back to contact sports. One advantage of operative fixation is that the screw acts as an internal splint to stabilize the fracture, and the exact timing of return to competition is less critical compared with nonoperative management.

TREATMENT

Indications

Arthroscopic fixation may be performed for acute nondisplaced fractures of the scaphoid and acute displaced fractures of the scaphoid that are reducible. For acute nondisplaced fractures, the risks and benefits of arthroscopic stabilization compared with cast immobilization must be discussed with the patient so that an informed decision can be made by the patient and associated family members. For acute fractures of the scaphoid that are reducible, the fracture may be reduced by manipulation of the wrist in a traction tower or by joysticks inserted into the proximal and distal poles of the scaphoid, with the reduction viewed with the arthroscope in the midcarpal space.

Arthroscopic stabilization of selected scaphoid nonunions may be performed. Slade and Geissler published their radiographic classification of scaphoid nonunions (Table 27-1).²⁰

Type I fractures are the result of a delayed presentation (4 to 12 weeks after injury).

In type II injuries, a fibrous union is present. A minimal fracture line may be seen on plain radiographs. The lunate is not rotated, and there is no humpback deformity.

In type III injuries, minimal sclerosis is seen at the fracture site. Sclerosis is less than 1 mm long, the lunate is not rotated, and no humpback deformity is seen.

In type IV injuries, cystic formation is present. The cystic formation is between 1 and 5 mm in diameter. No humpback deformity or rotation of the lunate is seen on plain radiographs.

In type V injuries, the cystic changes are larger than 5 mm in diameter, and rotation of the lunate has occurred, resulting in a humpback deformity as seen with plain radiography or CT. The lunate has rotated to a position of dorsal intercalated segment instability (DISI).

In type VI injuries, secondary degenerative changes are present, with spurring along the radial border of the scaphoid and peaking of the radial styloid (i.e., scaphoid nonunion advanced collapse [SNAC]).

TABLE 27-1 Slade-Geissler Classification of Scaphoid Nonunions

Type	Description
I	Delayed presentation at 4-12 wk
II	Fibrous union, minimal fracture line
III	Minimal sclerosis < 1 mm
IV	Cystic formation, 1-5 mm
V	Humpback deformity with > 5-mm cystic change
VI	Wrist arthrosis

Arthroscopic stabilization of selected scaphoid nonunions is indicated in fracture types I through IV. After a humpback deformity occurs, arthroscopic stabilization is not recommended, and open reduction is needed to correct the humpback deformity and the DISI rotation of the lunate.

Arthroscopic Techniques

Various arthroscopically assisted and percutaneous techniques for fractures of the scaphoid have been described in the literature.²¹^–³² Haddad and Goddard²⁴ popularized the volar approach, and the dorsal approach was popularized by Slade and colleagues.²⁶ Geissler and Slade described a technique in which the starting point of the guidewire and the eventual screw insertion are determined arthroscopically, which limits guesswork concerning the insertion point.³²

Volar Percutaneous Approach

In the volar percutaneous technique that was popularized by Haddad and Goddard, the patient is placed supine with the thumb suspended in a Chinese finger trap.²⁴ Placing the thumb under suspension allows ulnar deviation of the wrist, which improves access to the distal pole of the scaphoid. Under fluoroscopic guidance, a longitudinal, 0.5-cm skin incision is made over the most distal radial aspect of the scaphoid. Blunt dissection is used to expose the distal pole of the scaphoid. The cutaneous nerves must be protected when using this technique.

A percutaneous guidewire is introduced into the scaphoid trapezial joint and advanced proximally and dorsally across the fracture site. The position of the guidewire is easily checked in the anteroposterior, oblique, and lateral planes by rotating the forearm under fluoroscopy. This provides an almost 360-degree view of the position of the guidewire within the scaphoid. The length of the guidewire within the scaphoid is determined by placing a second guidewire next to the initial one and measuring the difference between the two. A drill is inserted through the soft tissue protector, and the scaphoid is reamed. A headless cannulated screw is then placed over the guidewire. A second guidewire may be useful to prevent rotation of the fracture fragments while the screw is being inserted.

Haddad and Goddard reported their initial results in a pilot study of 15 patients with acute fractures of the scaphoid.²⁴ Union was achieved in all patients within an average of 57 days (range, 38 to 71 days). With this percutaneous technique, the range of motion after union was equal to that of the contralateral limb, and grip strength averaged 90% at 3 months. The patients were able to return to sedentary work within 4 days and to manual work within 5 weeks.

This technique is fairly simple and straightforward, and it requires minimal specialized equipment. The disadvantage is the possibility that the screw may be placed slightly oblique to the midwaist fracture line in the scaphoid.

Dorsal Percutaneous Approach

Slade and coworkers popularized the dorsal percutaneous approach.²⁶^,²⁷ This technique has become popular because it involves limited surgical dissection and allows arthroscopic evaluation and reduction of the scaphoid fracture. The patient is placed in the supine position on the table with the arm extended. Several towels are placed under the elbow to support the forearm parallel to the floor. The wrist is then flexed and pronated under fluoroscopy until the distal and proximal poles of the scaphoid are aligned to form a perfect cylinder. Continuous fluoroscopy is recommended as the wrist is flexed to obtain a true ring sign as the proximal and distal poles are aligned.

Under fluoroscopy, a 14-gauge needle is placed percutaneously in the center of the ring sign and parallel to the fluoroscopy beam. A guidewire is then inserted through the 14-gauge needle and driven across the central axis of the scaphoid from dorsal to volar until the end of the guidewire comes into contact with the distal scaphoid cortex. The position of the guidewire is then evaluated under fluoroscopy in the posteroanterior, oblique, and lateral planes while the wrist is maintained in flexion. The wrist must not be extended at this time, because doing so may bend the guidewire. A second guidewire is placed parallel to the first so that it touches the proximal pole of the scaphoid, and the difference in the lengths of the two guidewires is measured to determine the length of the screw. Use of a screw 4 mm shorter than what is measured is recommended.

The primary guidewire is advanced volarly through a portion of the trapezium and along the radial side of the thumb metacarpal until it exits the skin on the volar aspect of the hand. The wire continues to be advanced volarly until it is flush with the proximal pole of the scaphoid dorsally and the wrist is extended.

The wrist is suspended in a traction tower, and the radiocarpal and midcarpal spaces are arthroscopically evaluated. The radiocarpal space is evaluated for associated soft tissue injuries. The reduction of the scaphoid is best seen with the arthroscope in the midcarpal space. After the reduction of the scaphoid fracture is considered satisfactory, the primary guidewire is advanced back dorsally and proximally with the wrist flexed. A portion of the guidewire should be left extending out of the volar and dorsal aspects of the wrist; if the guidewire breaks, it is easy to remove. Blunt dissection is continued around the guidewire dorsally to minimize the risk of soft tissue injuries, particularly injury to the extensor tendons as the scaphoid is reamed and the screw is inserted over the guidewire. Through a soft tissue protector, the scaphoid is drilled over the guidewire, and a headless cannulated screw is inserted.

The dorsal approach has the advantage that the screw can be inserted down the central axis of the scaphoid. This allows compression directly across the fracture site, compared with the more oblique orientation of the screw when the volar technique is used. The concern with the dorsal percutaneous approach is that the wrist is hyperflexed; this may displace the scaphoid fracture to create a humpback deformity if it is unstable. The reduction of the scaphoid should be evaluated with the arthroscope in the midcarpal space when this technique is used to ensure that the fracture is not hyperflexed.

Geissler Technique for Arthroscopic Reduction

The advantage of using my arthroscopic technique for reduction of acute scaphoid fractures and certain scaphoid nonunions ³³ is that the starting point for the guidewire is viewed directly through the arthroscope, and there is no guesswork concerning the insertion point and the location of the headless cannulated screw. I think this is a simpler approach than the dorsal percutaneous approach with the ring sign. The wrist is not hyperflexed, which could distract the scaphoid fracture and cause a humpback deformity.

Using the Geissler technique, the wrist is initially suspended in a wrist traction tower (Acumed, Hillsboro, OR) (Fig. 27-1). The arthroscope is initially placed in the 3-4 portal to evaluate any associated soft tissue injuries that may occur with a scaphoid fracture. After evaluation and treatment of the soft tissue injuries, the arthroscope is transferred into the 6-R portal. The wrist is flexed approximately 30 degrees in the traction tower. A 14-gauge needle is inserted through the 3-4 portal, and the junction of the scapholunate interosseous ligament as it inserts onto the proximal pole of the scaphoid is palpated. The junction of the scapholunate interosseous ligament onto the scaphoid along the middle third is the ideal starting point for the screw (Fig. 27-2). A 14-gauge needle is advanced and impaled into the proximal pole of the scaphoid at the insertion of the scapholunate interosseous ligament (Figs. 27-3 and 27-4). Occasionally, some dorsal synovitis blocks visualization of the starting point and may need to be débrided.

FIGURE 27-1 The wrist is suspended in 30 degrees of flexion in the Acumed wrist traction tower.

FIGURE 27-2 After arthroscopic evaluation of the wrist with the arthroscope in the diagnostic 3-4 portal, the it is switched to the 6-R portal, and the junction of the scapholunate interosseous ligament to the proximal pole of the scaphoid is palpated with a probe.

FIGURE 27-3 A 14-gauge needle is inserted through the 3-4 portal at the junction of the scapholunate interosseous ligament to the proximal pole of the scaphoid.

FIGURE 27-4 Arthroscopic confirmation of the 14-gauge needle is obtained as it impales the proximal pole of the scaphoid at the junction of the scapholunate interosseous ligament.

The traction tower is then flexed, and the starting point of the needle is evaluated under fluoroscopy (Figs. 27-5 and 27-6). With this technique, the starting point is consistently determined to be at the most proximal pole of the scaphoid. The needle is simply aimed toward the thumb under fluoroscopy, and a guidewire is advanced through the needle down the central axis of the scaphoid to abut the distal pole. The position of the guidewire is checked in the posteroanterior, oblique, and lateral planes under fluoroscopy by rotating the forearm in the traction tower (Figs. 27-7 and 27-8). The fluoroscopic image is not hindered by the support beam of the tower, which is off to the side rather than in the central axis. A second guidewire is advanced against the proximal pole of the scaphoid, and the length of the screw is determined by the difference of the two guidewires. A screw at least 4 mm shorter than this measurement is recommended.

FIGURE 27-5 The Acumed wrist traction tower is flexed, and fluoroscopic confirmation of the ideal starting point is obtained.

FIGURE 27-6 From the starting point, the needle is aimed toward the thumb, and a guidewire is advanced down the central axis of the scaphoid.

FIGURE 27-7 The fluoroscopic posteroanterior view confirms the ideal starting point of the guidewire and placement of the wire down the central axis of the scaphoid.

FIGURE 27-8 The fluoroscopic oblique view confirms ideal placement of the guidewire down the central axis of the scaphoid.

The reduction of the scaphoid is evaluated with the arthroscope in the radial and ulnar midcarpal portals. If reduction is unsatisfactory, the guidewire is advanced volarly across the wrist but still within the distal pole of the scaphoid. An additional Kirschner wire may be placed in the proximal pole of the scaphoid. These wires may be used as joysticks to further reduce the fracture anatomically under direct view with the arthroscope in the midcarpal portal. It helps to manipulate the wrist in the traction tower, usually with the wrist in extension, which further reduces the fracture. After the fracture is judged to be satisfactory, the guidewire is advanced proximally into the proximal pole of the scaphoid. The scaphoid is then reamed with the cannulated drill (Fig. 27-9).

FIGURE 27-9 After the length of the screw has been determined, the guidewire is advanced out the volar aspect of the wrist, and the scaphoid is reamed with a cannulated drill.

In cases of acute fractures or stable fibrous nonunions, demineralized bone matrix (DBM) is not used, and a headless cannulated screw is inserted over the guidewire (Fig. 27-10). The position of the screw is checked in the posteroanterior, oblique, and lateral planes under fluoroscopy with the wrist stabilized by the traction tower (Figs. 27-11 and 27-12). The wrist is again evaluated from the radiocarpal and midcarpal spaces. It is important to check from the radiocarpal space that the headless screw is inserted into the scaphoid and is not protruding, which may injure the articular cartilage of the scaphoid facet and the distal radius. The final reduction of the scaphoid fracture may be viewed with the arthroscope in the midcarpal space (Figs. 27-13 and 27-14).

FIGURE 27-10 The headless cannulated screw is inserted over the guidewire and down the central axis of the scaphoid.

FIGURE 27-11 On the posteroanterior view, fluoroscopy shows ideal placement of the screw and reduction of the scaphoid.

FIGURE 27-12 On the oblique view, fluoroscopy shows ideal placement of the headless cannulated screw.

FIGURE 27-13 The arthroscopic view in the radial midcarpal space confirms good compression of the scaphoid fracture and anatomic reduction with no rotation.

FIGURE 27-14 The arthroscopic view from the 3-4 portal confirms screw placement in the scaphoid.

Scaphoid Nonunions

Geissler and Slade described their use of Slade’s dorsal percutaneous fixation technique in 15 patients with stable fibrous nonunion of the scaphoid.³² Their series included 12 horizontal oblique fractures, 1 transverse fracture, and 2 proximal pole fractures. The average time between presentation and surgery was 8 months. All patients underwent percutaneous dorsal fixation with a headless cannulated screw and no accessory bone grafting procedure, and all fractures healed in an average time of 3 months. Eight of the 15 patients underwent CT evaluation to further document healing. The patients had excellent range of motion at their final follow-up visit because of minimal surgical dissection. Twelve of the 15 patients had excellent results according to the modified Mayo wrist scale. Dorsal percutaneous fixation without bone grafting is recommended for patients with a stable fibrous nonunion who have no signs of humpback deformity and do not have extensive sclerosis of the fracture site. The scaphoid nonunion classification scheme proposed by Slade and Geissler was used to include patients with type I through III scaphoid nonunions in the study, with a 100% success rate.

For patients who have cystic scaphoid nonunions without a humpback deformity, percutaneous cancellous bone grafting or injection of DMB may be used. Applying Geissler’s technique, the scaphoid is reamed through a soft tissue protector.³³ A bone biopsy needle is filled with DBM putty. The needle is placed over the guidewire from dorsal to proximal and inserted through the drill hole directly into the nonunion site. The guidewire is then retracted distally out of the proximal pole of the scaphoid while still remaining in the distal pole of the scaphoid. DBM is injected through the bone biopsy needle directly into the central hole of the scaphoid at the nonunion site. The guidewire is advanced back through the bone biopsy needle from volar to dorsal. In this manner, the guidewire passes back through the original reamed hole of the proximal pole of the scaphoid and out dorsally, protruding from the skin. The needle is then removed, and a headless cannulated screw is inserted over the guidewire across the scaphoid nonunion. The radiocarpal and midcarpal spaces are re-evaluated arthroscopically to confirm reduction and placement of the screw.

I described a technique of arthroscopic reduction of cystic scaphoid nonunions without humpback deformity using DBM putty.³³ In this technique, 1 mL of DBM (Accell, Irving, CA) is injected percutaneously into the nonunion site of the scaphoid. According to the Slade and Geissler classification, the series was composed of type IV cystic scaphoid nonunions. In 14 of the 15 patients, the scaphoid nonunion healed after use of this technique. Arthroscopic evaluation of the wrist from the radiocarpal and midcarpal spaces showed no extravasation of the DBM into the joint.

PEARLS& PITFALLS

• Clear arthroscopic visualization of the proximal pole of the scaphoid is mandatory. Any dorsal synovitis that may obscure visualization should be shaved.

• The starting point for the guidewire is the junction of the scapholunate interosseous ligament at the proximal pole of the scaphoid.

• Reduction of the scaphoid fracture should be visualized with the arthroscope in the midcarpal space.

• The position of the guidewire must be checked in posteroanterior, oblique, and lateral planes before reaming and insertion of the headless screw.

• A second guidewire may help to protect against rotation of the fracture fragments as the headless cannulated screw is being inserted.

• The position of the screw inserted in the scaphoid must be checked with the arthroscope in the radiocarpal space to ensure that it is not prominent.

• Final reduction of the scaphoid after screw insertion should be checked with the arthroscope in the midcarpal space.

CONCLUSIONS

Fractures of the scaphoid are a common athletic injury, especially in young men.³⁴^,³⁵ Although most nondisplaced fractures of the scaphoid heal with cast immobilization, nonunion rates of 10% to 15% have been reported. Union rates of 100% for acute fractures of the scaphoid managed by percutaneous arthroscopically assisted fixation have been consistently reported in the literature.

Although cast immobilization is effective, it has certain disadvantages, including muscle atrophy, joint contracture, and stiffness. For this reason, arthroscopic fixation of acute scaphoid fractures, particularly in athletes, is recommended after the advantages and disadvantages of the procedure have been discussed with the patient and the family. This approach can allow the patient to return quickly to the workforce or to competition. Arthroscopic fixation of scaphoid fractures allows limited surgical dissection, which may result in improved range of motion, and enables detection and management of associated soft tissue injuries, which may result from the scaphoid fracture.

Arthroscopically assisted fixation has been beneficial in treating type I through type IV scaphoid nonunions by the classification scheme of Slade and Geissler.³⁶ In patients with a stable fibrous nonunion, stabilization with a screw alone has been effective. In patients with cystic changes, arthroscopic stabilization and percutaneous injection of DBM into the nonunion site has been successful.³³ Percutaneous bone grafting may be another option.

Compared with previously described percutaneous fluoroscopic techniques, arthroscopic fixation limits the guesswork concerning the exact location of the starting point of the screw. The guidewire starting point is at the most proximal pole of the scaphoid, at the junction of the scapholunate interosseous ligament. It is reproducible, as confirmed under fluoroscopy. The wrist is not hyperflexed, because such movement may flex the fracture fragment into a humpback deformity. Dorsal insertion of the screw enables central placement down the axis of the scaphoid. Early arthroscopic evaluation allows detection and management of associated soft tissue injuries (Figs. 27-15 to 27-18).