Technique Spotlight: Scaphoid Fractures—Volar vs. Dorsal, Open vs. Percutaneous; Bone Graft Options

Positioning and Equipment

The patient is placed in a supine position with a radiolucent hand table. Two techniques for positioning of the wrist are commonly used. In one approach, the arm is fully supinated with the volar wrist facing the ceiling. With this approach, a larger C-arm, with the image intensifier under the table, is preferred. Finger traps with 8–10 pounds of traction hang from the end of the hand table ( Fig. 71.1A ).

The other method for volar percutaneous scaphoid fixation is to have the elbow flexed 90 degrees with the arm strapped to the table. If an arthroscopy traction tower is used, the metal post can be a challenge to image around. Instead of a traction tower, the arm can be suspended using finger traps from an IV pole with weights hanging from the elbow. This may make imaging easier. With these techniques with the forearm positioned vertically, the mini C-arm is preferred to a standard fluoroscopy unit, as imaging occurs with the C-arm positioned horizontally. A headless compression screw of the surgeon’s selection is used for fixation.

Technique Description

Fracture location, morphology, and alignment are confirmed via fluoroscopy to be sure that percutaneous fixation remains an acceptable surgical option. If necessary, one to two K-wires can be placed percutaneously to reduce a minimally displaced fracture. One to two rolled towels are placed beneath the dorsal wrist and a single finger trap is placed on the thumb. Eight to 10 pounds of weight is hung off the end of the hand table, pulling the wrist into extension and ulnar deviation. A K-wire is used to mark out the trajectory for centralized screw placement using a surgical marker, in both the anteroposterior (AP) and lateral views. This, along with palpation of the distal pole of the scaphoid, will allow for identification of the appropriate starting position. A 14-gauge needle is then placed percutaneously and advanced to the appropriate starting position on the distal pole of the scaphoid ( Fig. 71.1B ). The bevel should face dorsally and the needle can be used to hinge the scaphoid into flexion, levering on the trapezium to push it slightly dorsally to allow a better guidewire trajectory. The guidewire for the implant is then placed in a retrograde fashion through the needle. Positioning is confirmed in multiple views to make sure there is no violation of an articular surface. Critical views are the ulnarly deviated scaphoid view to evaluate for screw length and position, the hypersupinated PA to evaluate the scaphocapitate joint, the lateral view to check for volar penetration and volar screw trajectory, and the pronated oblique for proximal and distal penetration. Once the guidewire is determined to be in perfect position, a small incision is made along the guidewire, only large enough to allow entry of the screw. The tip is confirmed to be at the level of proximal subchondral bone and measured for length. Typically, 4 mm will be subtracted from this measurement to account for cartilage thickness. For more distal fractures, the length of the screw chosen may be even shorter and still provide adequate fixation. The guidewire is then advanced into, or through, the proximal subchondral bone to prevent its accidental removal after drilling. The guidewire is overdrilled on power. Many systems have two diameter drills, one for the leading threads and one for the trailing threads. It is important to use the larger drill for the trailing threads to prevent hoop stresses and possible fracture around the trailing threads.

In some cases, a second, de-rotation wire may be beneficial ( Fig. 71.2 ). This is likely more important in unstable fractures or in those that have more displacement. It tends to be used less commonly in percutaneous fixation as those fractures that may require a second wire tend not to be amenable to percutaneous reduction. However, if displaced or unstable fractures are managed percutaneously, a de-rotation wire should be strongly considered.

Traction is released and the screw is inserted. As the screw is advanced, longitudinal pressure should be placed on the screw, adding to the compression. While the variable pitch threads do lead to compression, each thread can provide only a small compressive force and the force from the screwdriver can assist in maximizing compression at the fracture site. Final imaging should confirm fracture reduction and screw positioning.