[Ulnar nerve compression at the elbow caused by synovial cyst of rheumatoid origin].

The authors report on a case of a fifty year old white woman affected by a rheumatoïd arthritis of 3 year duration who develops a progressive ulnar nerve compression by a synovial cyst of the right elbow joint. Surgical procedure confirms the articular and rheumatoïd origin of the synovial cyst and obtains complete healing of the motor and sensory deficit without recurrence of the synovial cyst. Synovial cysts are rare at the elbow joint where they cause as an exception a compression of the ulnar nerve, the authors having found only five cases in the literature.