The PIP joint collateral ligaments are the primary lateral stabilisers of the finger's most important joint. The PIP joint has no intrinsic bony stability (unlike the DIP and MCP joints which have greater inherent stability). PIP collateral ligament injuries are the most common finger ligament injuries, occurring from lateral stress during ball sports. The distinction between partial (treat with early motion) and complete (consider repair) injuries guides management.
| Origin | Proximal phalanx head condyles (radial and ulnar) |
|---|---|
| Insertion | Middle phalangeal base (proper collateral) and palmar plate (accessory collateral) |
| Actions | PIP joint lateral stability; the primary restraint against radial and ulnar deviation at the PIP joint |
|---|
PIP collateral ligament injuries are graded: Grade I (sprain, <20% torn), Grade II (partial, >20% but stable), Grade III (complete, unstable). The finger must be tested in both extension and flexion — complete tears produce instability throughout the range. Buddy taping for 3-4 weeks and early active motion achieves excellent results for Grade I-II injuries.
Lateral stress finger injury at the PIP joint managed with buddy taping and early active motion — surgical repair for complete unstable Grade III tears.
