- 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.
Terrono A, Millender L, Nalebuff E: J Hand Surg Am 15:999-1003, 1990
