What club-deformity is classically associated with rheumatoid arthritis on examination?

• A. Hard, fixed nodules at the distal interphalangeal joints
• B. Hyperextension of the distal interphalangeal joint with flexion of the proximal interphalangeal joint
• C. Inability to extend the distal interphalangeal joint
• D. Unstable first metacarpophalangeal joint in the neutral position

Answer: (B)

Rheumatoid arthritis commonly disrupts the finger extensor mechanism, producing a characteristic deformity known as boutonnière deformity. This occurs when inflammation weakens or destroys the central slip of the extensor tendon over the proximal interphalangeal joint. As a result, the PIP joint stays flexed while the distal joints extend, so the finger posture shows flexion at the PIP with hyperextension (or extension) at the DIP. On exam, this deformity stands out as the finger resting with the PIP flexed and the DIP extended, reflecting the altered balance of the extensor mechanism caused by RA.

Other options don’t fit RA’s typical pattern as neatly: Heberden nodes at the DIP are more characteristic of osteoarthritis; inability to extend the DIP isn’t the classic RA presentation; and instability of the thumb’s first MCP is common in RA too but describes a different joint involvement rather than the PIP/DIP deformity pattern described here.