Osteoid osteoma of the hamate: an unusual cause of ulnar-sided wrist pain.

Ulnar-sided wrist pain is a common complaint that presents a diagnostic challenge. Determining the cause of ulnar-sided wrist pain is difficult, largely due to the complexity of the anatomic and biomechanical properties of the ulnar side of the wrist. Osteoid osteoma is a benign skeletal neoplasm of unknown etiology that is composed of osteoid and woven bone. Its incidence is 11% of benign tumors and 3% of all primary bone tumors, with 6% to 13% of all cases occurring in the hand. Osteoid osteoma of the hamate can produce ulnar-sided wrist pain in the dorsal or volar aspect of the wrist, depending on the location of the tumor in the bone. In its classical and most frequent form, the osteoma may settle in the cortex or the spongiosa. A third rare form appears subperiosteally. Occasionally it destroys the articular cartilage by erosion or penetration. Most of the tumors will produce dorsal pain. A tumor located in the hook will produce volar pain. This article describes a case of ulnar-sided wrist pain due to a rare case of osteoid osteoma of the hamate. We recommend marking the nidus with a needle intraoperatively with the aid of radiography. Copyright 2010, SLACK Incorporated.