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- See:
    - Phalangeal Injury
    - Finger Swan Neck Deformity

- Discussion:
    - this deformity is more common in OA than in RA;
    - deformity results from CMC joint dz (where as boutonniere deformity is mainly at MCP joint);
    - result is erosion of articular surfaces & stretching of joint capsule;
    - causes dorsal & radial subluxation of CMC joint;
          - causes adduction contracture of metacarpal;
          - hyperextension of MP joint & flexion deformity of IP joint;

- Treatment:
    - conservative management includes splinting;
    - hemiarthroplasty of CMC joint may be used for early disease;
    - arthrodesis of MCP joint;
          - volar capsulodesis in a position of flexion;
          - complete replacement of trapezium in RA patient has high rate of dislocation;

- Swan Neck Staging:
    - stage I:
          - minimal CMC deformity w/o MP involvement
          - consider splinting and CMC hemiarthroplasty
    - stage II:
          - CMC disease and correctable MP deformity
          - CMC hemi arthroplasty
          - MP tenodesis or fusion
    - stage III:
          - CMC dislocation w/ fixed MP deformity & fixed metacarpal adduction;
          - CMC hemiarthroplasty, MP fusion, and 1st web space release