Ankylosis of the Finger in Erosive Osteoarthritis

A 57-year-old woman presented with long-standing pain of both hands. She had been receiving treatment for hypertension and dyslipidemia for two years. A physical examination revealed tenderness and swelling of the proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints of both hands (Picture 1, 2). There were no findings that would suggest spondyloarthritis, such as back pain or psoriasis. Her C-reactive protein levels were normal (0.28 mg/dL, normal <0.3). The findings for rheumatoid factor, anti-cyclic citrullinated peptide antibody, and anti-nuclear antibody were all negative. Posteroanterior radiographs of both hands showed narrowing of the joint space and subchondral sclerosis of multiple joints in both hands, saw-tooth erosion of the PIP joint in the right ring finger (short arrow in Picture 3), and ankylosis of the PIP joint in the left ring finger (long arrow in Picture 3). Unlike in primary osteoarthritis, ankylosis of DIP and PIP joints can be seen in erosive osteoarthritis because of its inflammatory component (1, 2).