A case report of patella cubiti.

Report of a patella cubiti in a patient with juvenile rheumatoid arthritis. The genesis of this patella is unknown up to now. The following hypotheses are discussed: 1. Persistent separation of the non fused epiphyseal bone centre with consecutive independent development. 2. Avulsion of the epiphysis due to muscle tension. 3. Epiphysitis as cause of the new formed patella.