Positional dislocation of the pisiform.

Positional dislocation of the pisiform repeatedly occurred in the right wrist of a 19-year-old man following a motorcycle accident. The pisiform repeatedly dislocated distal to the triquetrum when the wrist was extended to 45 degrees or more, and the pisiform was reduced to proper joint congruity after wrist flexion of 55 degrees or more. The patient had a background of generalized joint laxity. Resection of the pisiform resulted in a pain-free, fully functional wrist.