Hypoplasia of the elbow joint is often seen as one of the dysfunctions resulting from birth palsy, but there have been very few reports of the shortening of the radius relative to the ulna.
The case was a nine years old boy, and the range of motion of his left elbow joint was limited from 15 degrees to 130 degrees. On flexion, the olecranon showed ulnar subluxation accompanied with an audible click and pain.
Plain radiography showed that the radius had shortened relative to the ulna. On arthrography of the elbow joint, we were able to find that the humeroradial joint had opened widely and there was valgus deformity of the radial head, but no intra-articular interposition. Stress tests showed valgus instability of 30 degrees.
Considering the shortening and deformity of the radius as the cause of this dysfunction, we surgically corrected the valgus deformity and callotasis of the radius. The pain and stability of his elbow joint improved.
The humeroradial joint serves as a very important as a stabilizer of the radial side of the elbow joint, and its dysfunction may lead to degenerative arthritis. Immediate correction of this dysfunction is therefore essential.
