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Metacarpal Neck Frx


- See: metacarpal frx menu

- Discussion:
    - frxs through neck & shaft of metacarpals usually angulate w/ apex dorsal, displacing the metacarpal head into the palm;
    - ring and little neck frx: (see boxer's frx);
            - corresponding CMC joints are mobile (in contrast to 1st & 2nd CMC) w/ flexion extension arc of between 20-30 deg in little finger and 10-15 deg in 4th metacarpal;
            - will tolerate up to 20 deg dorsal angulation;
            - amount of acceptable angulation will be greater when frx occurs more distally in the neck;
    - index and long metacarpal neck frx:
            - minimal angulation can be accepted because there is no compensatory motion at the CMC joints;
            - any residual angulation of these bones will cause problems;
            - in these joints angulation of 10-15 deg should be corrected;


- Exam:
    - look for malrotation of injured ray;
    - look for loss of ability to hyperextend the MCP joint;


- Closed Reduction:
    - easy to reduce by difficult to maintain;
    - MCP & PIP joints are both flexed 90 deg to gain control of distal fragment & then exert dorsally directed force on metacarpal to push metacarpal head dorsally (& metacarpal shaft volarly) to achieve reduction;
            - immobilization in this position is not allowed, however, as flexion contracture will develop;
    - more proximal frxs (ie, shaft frx) are more likely to produce noticable dorsal angulation & clawing, and therefore less angulation can be accepted in midshaft fractures than in neck frx