Boutonniere deformity of the Thumb MP joint

- See: Phalangeal Boutonnere Injuries

- Discussion:
    - most common thumb deformity in RA;
    - results from arthritic involvement of MP joint and elongation or erosion of the attachement of the EPB tendon to the base of proximal phalanx (leading to flexion deformity);
    - EPL tendon & adductor expansions become displaced ulnarly, & lateral thenar expansions are displaced radially;
    - active MP extension is decreased w/ MCP flexion deformity;
          - w/ attempted extension of MCP joint there is hyperextension of IP joint;
          - MP flexion deformity results from displaced EPL which bypasses MCP joint & applies its power instead to distal phalanx;
    - collateral ligaments become elongated MCP joint dislocates;
    - CMC & IP joint may show hyperextension deformity;

- Classification:
    - stage I:
          - consists of mild of MCP swelling, subluxation & joint synovitis;
          - MP and IP joints will correct passively & are not accompanied by deformity;
          - EPL displaces volarly & ulnarly;
          - collateral ligaments stretch;
          - subluxation of proximal phalanx on metacarpal;
          - altered pull of intrinsics & EPL leads to IP hyperextension;
          - MP joint is fixed in full extension w/ K wire for about 4 weeks;
   - stage II:
          - MP fixed deformity, IP correctable
          - consider MP fusion, which usally provides excellent results and halts Boutonnere deformity;
          - relative contraindiction for MP fusion, is concomitant CMC arthritis;
   - stage III:
          - involves fixed MP and IP deformities;
          - consider IP fusion and MP arthroplasty;
          - consider IP and MP fusion (if the CMC joint is mobile);
   - management of stiff IP and mobile-flexion deformity of the MCP joint:
          - consider fusion of the IP joint and transfer of the EPL to the base of the proximal phalanx;
   - EPL management:
          - reconstruction of EPL tendons is required;
          - if EPL tendon is contracted, then  tendon is lengthened;
          - EPL tendon may also be tenodesed to base of proximal phalanx;
          - following pin removal, a dynamic digital splint is used for additional two weeks to maintain extension

Boutonniere rheumatoid thumb deformity.

Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Friday, September 21, 2012 12:51 pm