What is a boutonniere deformity in rheumatoid arthritis (RA)?

Updated: Feb 07, 2020
  • Author: Howard R Smith, MD; Chief Editor: Herbert S Diamond, MD  more...
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The boutonniere deformity (see the image below) describes nonreducible flexion at the PIP joint along with hyperextension of the distal interphalangeal (DIP) joint of the finger.

Boutonniere deformity. Boutonniere deformity.

This deformity occurs as a result of synovitis stretching or rupturing the PIP joint through the central extensor tendon, with concomitant volar displacement of the lateral bands. When the lateral bands have subluxed far enough to pass the transverse axis of the joint, they become flexors of the PIP joint. Hyperextension of the DIP joint occurs as the tendons shorten with time. A compensatory and reducible hyperextension may occur at the MCP joint. Consequences of boutonniere deformity are loss of thumb mobility and pincher grasp.

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