Wrist kinetics after scaphoidectomy.

Background: The scaphoid cannot be excised without generating substantial carpal dysfunction. The extent and nature of such a destabilizing procedure, however, has never been properly studied in the laboratory.

Methods: We used a six-degrees-of-freedom motion tracking device to quantify the changes in carpal alignment produced by isometric simultaneous loading of five wrist motor tendons in 12 fresh normal cadaver arms, before and after excising the entire scaphoid.

Findings: In the intact wrist, tendon loading consistently extended and supinated the capitate while flexing the triquetrum. After scaphoidectomy, the opposite rotations were always found: the capitate collapsed into flexion and pronation, whereas the triquetrum migrated proximally, while extending and radial deviating. All these changes were statistically significant.

Interpretation: Unless it is supplemented by some sort of midcarpal stabilization, scaphoidectomy alone is much too aggressive as a procedure to be considered a treatment option for wrist osteoarthritis.

Level Of Evidence: Laboratory study. Not applicable.