The head of the proximal phalanx is bicondylar and the collateral ligaments arise from the center axis of joint rotation. Collateral ligaments are the primary stabilizers to lateral stress and dislocations are associated with disruption in lateral collateral ligament

The proximal interphalnageal joint receives static stability from the proper and accessory collateral ligaments and the volar plate. It is further supplemented by the dynamic stability of the dorsal plate and balanced tendon forces acting across the joint.

Some of the dislocation may be subtle and missed. These should be diagnosed on stress views.

Other patterns of dislocation are

• Dorsal dislocation
• Pure volar dislocation
• Rotatory volar dislocation

Dorsal dislocations are the one where the distal fragment moves towards dorsal side. It also causes volar plate injury. [Read more...]