[Traumatic chondrosis dissecans of the ulnar head (case report)].

A thirty-five-year old woman suffered from a sprain of her wrist joint. Painful blocking and snapping during supination appeared. No pathology was seen in the X-rays and the arthrogram. At surgery the expected dislocation of the extensor carpi ulnaris tendon was not discovered but rather a handle-like dissection of the cartilage of the ulnar head was squeezed into the inferior radioulnar joint by supination. The patient recovered soon after resection of the dissected cartilage. In retrospect the injury could have been diagnosed by arthrography of the inferior radioulnar joint.