56 THE JOURNAL OF BONE AND JOINT SURGERY SNAPPING ELBOW DUE TO DISLOCATION OF THE MEDIAL HEAD OF THE TRICEPS A REPORT OF TWO CASES

Two cases ofunusual snapping at the elbow are described. In both, the medial head ofthe triceps was found to be separated from the main muscle belly. During flexion ofthe 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. The term snapping elbow has been related almost exclusively to a slipping of the ulnar nerve out of its groove on flexion of the elbow to more than 90 degrees. Friction neuritis of the ulnar nerve has been reported in some patients. In 1970 Rolfsen described an exceptional case of snapping elbow produced by intermittent dislocation of the medial head of the triceps over th