The PIP volar plate is a fibrocartilaginous structure preventing hyperextension, with a solid distal insertion on the middle phalanx and a thin membranous proximal portion (the checkrein ligaments) that can avulse during hyperextension injury. Volar plate avulsion from the middle phalanx produces the classic dorsal PIP dislocation. Chronic volar plate laxity produces the swan neck deformity from FDS weakness or post-traumatic hyperextension.
| Origin | Middle phalanx palmar base |
|---|---|
| Insertion | Proximal phalanx head — the proximal edge is membranous (the checkrein ligaments) |
| Actions | Prevents PIP joint hyperextension; the primary restraint against dorsal PIP dislocation |
|---|
Volar plate avulsion fractures involving the middle phalanx volar lip are managed by extension block splinting for small fragments, or ORIF/hemi-hamate reconstruction for fractures involving more than 30-40% of the articular surface. The extension block splint position (preventing the terminal 20-30 degrees of extension) protects the volar plate while allowing early motion. Dynamic external fixation for comminuted volar lip fractures maintains joint congruence during healing.
Middle phalanx volar lip fracture from hyperextension managed with extension block splinting or hemi-hamate reconstruction for large fragments.
