Emergent Care / Stabilization: Immobilize the affected wrist.

Causes / typical injury mechanism: Pisiform fracture is most commonly caused by direct trauma to the volar ulnar wrist (ie, a fall, baseball / cricket bat).

Classic history and presentation: Presents with ulnar-sided wrist pain immediately after a fall onto an outstretched hand or direct trauma to the volar ulnar wrist.

Prevalence: 0.2%-2% of all carpal fractures.

• Age – Unusual in children aged under 12 years as it is the last bone to ossify at approximately age 12.
• No sex or gender predilection.

Risk factors:

• A fall onto an outstretched hand
• Bat and ball games

Pathophysiology: The sesamoid bone in the proximal carpal row, which lies within the flexor carpi ulnaris (FCU) tendon, fractures as a result of direct trauma.

Grade / classification system: There are 4 types of pisiform fracture based on the radiologic fracture pattern:

1. Transverse – Associated with sudden FCU contracture while the pisiform is locked (ie, fall onto an outstretched hand).
2. Parasagittal – Fracture of the ulnar rim of the pisiform that does not involve the FCU tendon.
3. Comminuted – Associated with ulnar neurovascular bundle injuries.
4. Impaction – Result of triquetral fracture.