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.