Structures at Risk During Volar Percutaneous Fixation of Scaphoid Fractures: A Cadaver Study

BACKGROUND: Fracture of the scaphoid bone can be treated with cast immobilization or surgery. Historically, surgery was reserved for displaced fractures. However, because weeks of cast immobilization may result in stiffness, loss of strength, loss of bone density and an inability to work or participate in recreational activities for a prolonged period, operative treatment of non-displaced fractures has become increasingly common. Several surgical techniques for fixation have been described, but their risks and benefits have not yet been clearly elucidated. In a study in cadavers, we investigated whether one approach--volar percutaneous fixation--might pose a risk of injury to surrounding structures.

METHODS: In 15 cadaver upper limbs with the wrist structures intact, a K-wire was inserted in a volar percutaneous manner under fluoroscopic guidance, distal to proximal and through the scaphoid waist into the center-center position. The volar aspect of the wrist and hand were then dissected around the K-wire, with isolation of surrounding structures. The distance between the K-wire and several individual structures was then measured with use of a digital caliper.

RESULTS: The K-wire was at least 4 mm from the superficial radial nerve, the first dorsal extensor compartment, the recurrent motor branch of the median nerve, and the radial artery (RA) in all specimens. However, the K-wire had penetrated die flexor carpi radialis (FCR) tendon in four specimens and was directly adjacent to it in another four. In one specimen, the K-wire was directly adjacent to the superficial volar branch of die RA.

CONCLUSIONS: The K-wire may penetrate the FCR tendon and the superficial volar branch of the radial artery during volar percutaneous scaphoid fixation. The possible long-term clinical implications of this finding require investigation.

CLINICAL RELEVANCE: Our findings indicate that modification of the volar percutaneous approach to scaphoid fixation may be advisable to avoid damage to adjacent structures. We suggest use of a "mini-open" percutaneous procedure.