Management of the Scaphoid during Four-Corner Fusion - A Cadaveric Study

Purpose: To examine the effects of scaphoid retention, inclusion, and excision on wrist motion and radiolunate contact characteristics in a cadaveric model after simulated 4-corner fusion with rigid internal fixation. Methods: Seven fresh-frozen cadaveric upper extremities were examined. For all surgical manipulations the motion was measured and contact characteristics were assessed using ultra-low prescale pressure-sensitive film. Results: Compared with the intact specimen, simple 4-corner fusion with scaphoid retention led to a significant decrease in extension, radial deviation, and ulnar deviation, but no change in radiolunate contact characteristics. After 4-corner fusion there was no significant difference in motion or radiolunate contact characteristics between scaphoid retention and scaphoid inclusion. After 4-corner fusion scaphoid excision allowed significantly greater radial deviation compared with scaphoid retention and scaphoid inclusion. Compared with the intact specimen 4-corner fusion with scaphoid excision also led to a significant increase in radiolunate contact area and mean contact pressure. Conclusions: When performing 4-corner arthrodesis in the absence of radioscaphoid arthritis, scaphoid excision may improve motion at the cost of increased mean radiolunate contact pressure.