Acute non-infectious arthritis of the hip in rheumatoid arthritis: synovial membrane findings.

A case of acute hip pain in rheumatoid arthritis is presented, with synovial membrane findings. A patient with classical rheumatoid arthritis suffered three unusual bouts of sudden, severe but transient hip pain. The hips were clinically normal between these episodes. The clinical picture on two of these occasions strongly suggested septic arthritis. Although the synovial fluid was highly inflammatory, cultures were negative. The synovial membrane showed mild lining cell hyperplasia, vascular congestion, and scattered inflammatory cells, predominantly lymphocytes. These findings were not compatible with either pyogenic infection or longstanding rheumatoid arthritis. The clinical and pathological features of acute non-infectious arthritis of the hip appear to delineate a distinct syndrome.