Causes / typical injury mechanism: The most common mechanism is a fall onto an outstretched hand.

Classic history and presentation: Metacarpophalangeal (MCP) joint dislocation typically presents with characteristic MCP joint extension and associated proximal interphalangeal (PIP) and distal interphalangeal (DIP) joint flexion.

Prevalence:

• Age – Most commonly seen in children and adults between the ages of 20 and 30 years.
• Sex / gender – Predominantly male.
• Finger – The index finger is most commonly affected. The thumb is the second most commonly affected.

Grade / classification system: The injury is classified according to direction of displacement of the proximal phalanx (volar or dorsal) as well as whether it will require surgical treatment (complex) or can be managed nonoperatively (simple).