Two cases of unusual snapping at the elbow are described. In both, the medial head of the triceps was found to be separated from the main muscle belly. During flexion of the elbow, the medial head dislocated over the medial epicondyle, producing a characteristic snapping phenomenon. Both cases were of long standing and had been asymptomatic for years. The first clinical symptoms were those of an ulnar neuropathy. In order to restore the normal position of the medial head of the triceps, its tendon was detached from the olecranon, passed under the central tendon and interlaced to it. The ulnar nerve was left in the epicondylar groove in one case and transposed anteriorly in the other. At the end of the procedure flexion of the elbow was unobstructed and the snapping phenomenon had disappeared.

1. A review of seventeen patients who underwent silicone arthroplasty of the trapezio-metacarpal joint by prosthetic replacement of the base of the first metacarpal is reported.

2. Eighteen operations were performed and observed for periods varying from two to five years.

3. The technique of operation and the criteria for the assessment of results are discussed.