Abstract
1. Eight patients with rheumatoid arthritis had an intra-articular nodule in one or both knees causing mechanical symptoms.
2. The nodule was on the lateral side of the knee and interfered with walking. It caused a click and painful instability of the knee at about 15 degrees of flexion.
3. Surgical excision of the nodule, which was attached to the synovial membrane, abolished the symptoms.