Pisiform–Hamate Coalition With Entrapment Neuropathy of the Deep Palmar Branch of the Ulnar Nerve

Pisiform and hamate coalition, a rare congenital anomaly, is most often identified as an asymptomatic incidental finding on radiographs. Some patients have symptomatic coalition with ulnar-sided wrist pain or ulnar nerve neuropathy from ulnar nerve compression. Sports activities such as cycling and weight lifting can cause compression of the ulnar nerve in the hand. This report describes a case of a pisiform and hamate coalition in a 36-year-old man who reported decreased right-hand dexterity and right ulnar-sided wrist pain. The patient, an amateur weight lifter, developed right claw hand through repeated bench press training. Intraoperative findings revealed compression of the deep palmar branch of the ulnar nerve between the tendinous arch of the hypothenar muscles and pisiform and hamate coalition. Surgical resection of the tendinous arch and the enlarged hook of hamate relieved the claw hand deformity.