Chronic hypertrophy of the ulna in the professional rodeo cowboy.

Radiographs were taken of the forearm of 56 rodeo contestants who performed regularly in active competition. All of the professional bareback riders revealed a significant hypertrophy in the ulna. This hypertrophy is considered to be a chronic circumferential periostitis, secondary to contact of the subcutaneous ulna with the anterior iliac crest, and to the heavily resined chaps worn by the rodeo cowboy. There is no significant treatment with exception of padding, etc. The clinical complaints of "soreness" disappear with the cessation of the contact between the subcutaneous ulna and iliac crest.