Finger Dislocation

Finger dislocations are common sporting hand injuries, and the proximal interphalangeal (PIP) joint is the joint most often dislocated, usually dorsally after a hyperextension force.

Most are simple: they reduce easily and do well with a short period of protection and early movement. A smaller group needs specialist care: open, irreducible or unstable dislocations, fracture-dislocations, and the closely related tendon avulsions, jersey finger and mallet finger (which has its own page).

The principles are prompt reduction, X-rays after every reduction, and early protected movement, because prolonged immobilisation causes lasting stiffness.

Finger joint stability comes from the joint surfaces, the volar plate (which resists hyperextension), the collateral ligaments and the tendons crossing each joint.

The main patterns:

• •Dorsal PIP dislocation: hyperextension tears the volar plate, often with a small avulsion fragment from the volar base of the middle phalanx; usually stable after reduction
• •Volar PIP dislocation: rare; injures the central slip of the extensor mechanism and, if missed, leads to a boutonniere deformity
• •Jersey finger: forced extension of a flexed DIP joint avulses flexor digitorum profundus (FDP), most often in the ring finger. In Leddy type I the tendon retracts into the palm and its blood supply through the vincula is lost
• •Mallet finger: forced flexion of the DIP joint disrupts the terminal extensor

A complex metacarpophalangeal (MCP) dislocation, of the thumb or of a finger (classically the index), cannot be reduced closed because the volar plate is trapped between the metacarpal head and the proximal phalanx. Skin dimpling in the palm is the sign.

Other patterns include collateral ligament sprains and DIP dislocations, which are uncommon.