Which statement regarding rheumatoid arthritis hand deformities is true?

• A. Radial drift at MCP joints is common
• B. Ulnar drift at MCP joints is common
• C. No joint involvement in RA affects the MCP
• D. Trigger finger does not occur with RA

Answer: (B)

Rheumatoid arthritis commonly affects the small joints of the hand, and inflammation at the metacarpophalangeal (MCP) joints weakens the ligaments and the extensor mechanism around them. This disruption allows the tendons to migrate toward the ulnar side, pulling the fingers with it and producing ulnar drift at the MCP joints. This ulnar deviation is a hallmark RA hand deformity, reflecting the imbalance created by synovitis and destruction of stabilizing structures around the MCPs. It’s important to note that radial drift is not the typical pattern, the MCP joints are often involved in RA, and trigger finger can occur due to Tenosynovitis of the flexor tendons. So the statement that ulnar drift at the MCP joints is common best captures the common RA hand deformity.