Distal interphalangeal joint involvement in rheumatoid arthritis.

Sixty-two patients with seropositive rheumatoid arthritis (RA) were evaluated radiographically for distal interphalangeal (DIP) joint involvement and were compared with 50 age- and sex-matched control subjects. The frequency of DIP erosions was 37% in the patients versus 14% in the controls; these erosions were mild and were not related to disease duration. Erosions elsewhere in the hand and wrist were of all degrees of severity and were related in part to disease duration. Osteophytes occurred frequently in both the RA group (71%) and the control group (60%). However, joint space narrowing occurred more frequently in RA patients (77%) than in the controls (46%) (P less than 0.009). The findings from this study suggest that in RA patients, DIP erosions occur frequently, do not occur in isolation, and are not simply a marker for severe global erosive disease in the hand and wrist. The high frequency of osteophytosis and joint space narrowing in both groups probably represents the overlap of osteoarthritis and RA that occurs in many patients.