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Fracture Dislocation: at the PIP Joint


- See: Diff Dx

- Discussion:
    - when the volar lip fracture of the middle phalanx involves 20% or more of the articular surface, the remainder of the middle phalanx
         subluxes dorsally;
    - this unstable injury requires more sophisticated treatment than the simple volar plate avulsion;
- Radiographs:
    - can misleadingly suggest that very simple frx has occured w/ only small fragment of the bone involved;
    - this fragment, however, is often the major attachment of a collateral ligament, the volar plate, or a tendon;
         - this small frx may render joint grossly or potentially unstable;
    - when volar triangular frx frag of middle phalanx involves > 1/4 of articular surface, dorsal dislocation of middle phalanx may occur
         late because the volar plate and a significant portion of the collateral ligaments are attached to the small fragment;
    - since many of these acticular fractures were actually dislocations at the time of injury, the x-ray film may not indicate the true degree of 
         original displacement;
    - this injury often involves volar plate & collateral ligaments;
    - dislocations of digital joints may stretch the collateral ligaments w/o completely disrupting them, while still rupturing the volar capsule or 
         volar plate