The PIP volar plate is the strongest stabiliser against PIP hyperextension, with a firm distal insertion on the middle phalanx and flexible check-rein ligaments proximally that allow full extension. Dorsal PIP dislocations avulse the volar plate from the middle phalanx, producing an avulsion fracture (the volar plate avulsion fragment). The hyperextension injury of the 'coach's finger' typically avulses the volar plate distally.
| Origin | Palmar base of the middle phalanx (the thick distal insertion) |
|---|---|
| Insertion | Check-rein ligaments to the palmar proximal phalanx neck (the proximal attachment — allows PIP extension via the check-rein slots) |
| Actions | Prevents PIP joint hyperextension; the primary restraint against dorsal displacement of the middle phalanx |
|---|
Dorsal PIP dislocation is reduced by longitudinal traction with palmar pressure on the dislocated middle phalanx. Post-reduction extension block splinting at 30 degrees of flexion for 3 weeks prevents re-displacement while allowing early active motion within the safe zone. Volar plate avulsion fractures involving more than 40% of the articular surface require surgical fixation.
Dorsal PIP dislocation avulsing the volar plate producing hyperextension deformity managed with closed reduction and extension block splinting.
