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Metacarpal Extra-articular Base Frx

- See: Extra-articular Thumb Metacarpal Fractures

- Discussion:
    - interosseous muscles & intrinsically strong carpometacarpal capsular and interosseous ligaments provide intrinsic stability to extra-articular fractures at the metacarpal bases;
    - mechanism of frx of little CMC:
          - stability of CMC joint derives from articulation w/ carpal bones,
          - convex bases metacarpals are displaced dorsally losing stability of articulation and causing extrinsic tendon power to be unbalanced;
          - ECU is a deforming force since it inserts onto base of 5th metacarpal;
          - overpull of ECU along w/ interposition of capsule may complicate reduction;
          - most common presentation is the dorsal avulsion frx of metacarpal base;
     - associated frx: CMC joints dislocation is associated w/ this injury;

- X-Rays:
     - isolated metacarpal views are not possible;
     - 30 deg pronated lateral: for index and long metacarpals;
     - 30 supinated lateral: for ring and little metacarpals;


- Non operative treatment:
     - extra-articular fractrues may be impacted and clinically stable when they occur from direct trauma;
           - these may be treated w/ splints;

- Operative treatment:
     - unstable fractures may result from violent trauma and may require & internal fixation w/ K wires;
     - more stable fixation can be gained w/ 2.0 mm or 2.7 mm condylar plate;
     - note associatted soft tissue injuries, may preclude plate fixation



       

Clinical results of intraarticular fractures of the base of the fifth metacarpal treated by closed reduction and cast immobilization.
Intra-articular fractures at the base of the fifth metacarpal. A clinical and radiographical study of 64 cases.
The surgical treatment of fractures of the base of the fifth metacarpal bone
Management of Intra-Articular Metacarpal Base Fractures of the Second Through Fifth Metacarpals
Fracture-subluxation of base of fifth metacarpal
The ‘mirrored’ Bennett fracture of the base of the fifth metacarpal