Rationale and Basic Science Pertinent to the Procedure

Classically, it was considered that consolidation of scaphoid fractures could be achieved without surgery. For many years since, however, open reduction and internal fixation has been the recommended and well-accepted treatment for displaced and unstable intra-articular fractures.

The complex morphology and the small size of the scaphoid bone resulted in the development of numerous sophisticated techniques to achieve an anatomical and stable fixation. In 1984, Herbert and Fischer¹ reported their experience using a cannulated screw, which originally was not developed for fixation of scaphoid fractures. In the early 1990s, the first article was published² describing inserting cannulated screws with a minimally invasive technique. The main principle was to preserve the surrounding ligaments of the carpal bones to avoid a destabilization of the reduction and to protect the fragile vascularization of the scaphoid bone.³

Meanwhile, patients and their referring physicians became more and more demanding. The surgical indication was expanded because of the inconvenience of conservative treatment with its unpredictable economic consequences owing to the long duration of immobilization.

Whipple^4,5 first presented a method with percutaneous screw fixation using a modified Herbert screw combined with image intensifier control and arthroscopic examination of the wrist. This method allowed the surgeon to control the reduction and to assess potential associated lesions.

In the treatment of scaphoid fractures by surgical reduction and internal fixation, some rules have to be respected, as follows: verify the exact fracture reduction, avoid an intra-articular penetration of the screw, maintain the fixation under compression, and allow an early return to activities of daily living. We report our more recent experience of 38 scaphoid fractures treated with an arthroscopically assisted percutaneous screw fixation technique using a cannulated Herbert screw.

Indications

The disabling long cast immobilization in this mostly young and active patient population and the risk of nonunion or malunion favor surgical reduction and internal fixation of scaphoid fractures. The aim is stable fracture fixation allowing early mobilization without compromising consolidation. It is important to neutralize the fracture forces, while compressing the fracture. The minimally invasive technique, and hence limited operative trauma, allows early functional rehabilitation. Arthroscopy helps to reduce the fragments; to control the quality of the reduction; and to assess the position of the screw, especially with regard to the radiocarpal joint.

The ideal candidate for surgery is a patient motivated to return to sports or business activities as soon as possible (e.g., a professional swimmer on the French national team who sustained a scaphoid fracture and was determined to qualify for the Olympic Games at Athens 2004 15 days later). The typical patient is young (mean age in our series 31.5 years), understands the aim of the treatment, and understands its risks and benefits. The delay between fracture and surgery should be as short as possible and not more than 1 month. One should delay immediate surgery if the conditions are not optimal (e.g., cutaneous lesions). In these situations, the wrist should be immobilized until the conditions are perfect.

Contraindications

In uncooperative patients who do not understand the risks and benefits, this method is contraindicated. In comminuted fractures, it is not realistic to achieve an anatomical reduction with this technique. Advanced age, cutaneous lesions, suboptimal operative conditions (e.g., incomplete surgical equipment), and severe associated lesions (e.g., severe scapholunate dissociation) are relative contraindications that can delay the intervention or preclude this type of surgery.

Operative Technique

Under ambulatory conditions, the operation is performed with locoregional anesthesia. The patient is placed in the supine position on a special arm table with a tourniquet on the arm applied as proximal as possible. During the critical parts of the operation, the forearm can be extended using a pad underneath the wrist. Another possibility is to put the wrist under traction with a traction device, which is placed outside the arm table still allowing positioning the image intensifier. A retrograde (from distal to proximal) screw fixation is aimed. First, the fracture is visualized under arthroscopy using standard portals, leaving the forearm free on the table. Next, a 1-mm pin is placed through a small (5-mm) incision to the distal tuberosity of the scaphoid in a retrograde fashion (Fig. 44-1). Then the wrist is put under traction allowing arthroscopic control to verify the exact reduction of the scaphoid.

FIGURE 44-1 Percutaneous retrograde pinning of the scaphoid through a small approach centered on the distal tuberosity.

The arthroscope is introduced through a radial midcarpal portal through which the fracture can be assessed easily. If necessary, a débridement of the articulation can be done with the shaver while cleaning the medial surface of the scaphoid. If the fracture is displaced, reduction of the fragments is possible with a little retractor introduced through the STT midcarpal portal. Under arthroscopic control, the fracture fixation pin is slightly pulled back beyond the fracture line, then the fracture is reduced, and the pin is replaced into the proximal fragment (Figs. 44-2, 44-3, and 44-4). As soon as a satisfactory reduction is achieved, the hand is removed from the traction device, and the wrist is positioned on a pad on the arm table.

FIGURE 44-2 Mediocarpal arthroscopic view of a displaced scaphoid fracture.

FIGURE 44-3 Mediocarpal arthroscopic view of the same fracture during reduction with a probe after the pin was pulled back distally to the fracture line.

FIGURE 44-4 Mediocarpal arthroscopic view of the same fracture after reduction and stabilization.

Under fluoroscopic control, the hole for the screw is tapped. If a resorbable screw is chosen, a double-sized trephine, drilling proximal with a 3-mm part and distal with a 3.5-mm part at the same time, is used. The two different screw threads are separately prepared mechanically to avoid the phenomenon of blockage in torsion with a resorbable screw. This avoids the risk of implant fracture (Fig. 44-5). The screw is inserted over the guidewire. Again under arthroscopic control, the radiocarpal compartment is visualized through the 3,4 portal; this allows the surgeon to verify the absence of an intra-articular penetration of the screw head at the level of the proximal pole (Fig. 44-6).

FIGURE 44-5 A, Tapping of the proximal part of the scaphoid. B, Tapping of the distal part of the scaphoid.

FIGURE 44-6 Screw fixation under arthroscopic control.