Anatomic placement of the Herbert-Whipple screw in scaphoid fractures: a cadaver study.

An anthropometric cadaver study was performed to determine the optimal placement of a Herbert-Whipple screw in the scaphoid. Twenty pairs of cadaver wrists were examined and anthropometric analysis of the scaphoids using plain radiography, computed tomography, and en bloc resection was performed. Scaphoid vascularity was evaluated using India ink injection. Radiographic and actual measurements of height and width confirmed symmetry in paired scaphoids. Anatomic evaluation defined a safe zone for screw placement. K-wire placement defined the extent of this zone. The entry point of this zone was found by moving dorsally and distally 15% of the lateral radiographic length of the contralateral scaphoid from the volar aspect of the scaphoid tuberosity. Moving 10% of this same length from the membranous central portion of the scapholunate ligament defined the target site. Computed tomography confirmed proper position of the screw to maximize bony purchase and avoid articular penetration while maintaining dorsal vascular integrity.