Pisiform Fractures

The pisiform is a sesamoid bone located within the flexor carpi ulnaris (FCU) tendon on the medial side of the wrist, articulating with the triquetrum at the pisiotriquetral joint. Pisiform fractures are uncommon injuries, typically caused by a direct blow to the hypothenar eminence or a fall onto the outstretched hand. They account for less than 2% of all carpal fractures and are frequently missed on standard PA and lateral wrist radiographs, requiring a carpal tunnel view or a supinated oblique view for detection — CT is the gold standard. The ulnar nerve and artery pass directly adjacent to the pisiform within Guyon's canal, making them vulnerable to injury or compression in high-energy pisiform fractures. Classification is descriptive: fractures may be transverse, comminuted, or involve the pisiotriquetral articular surface, with avulsions from the FCU also reported. Non-operative management with immobilisation in a short-arm cast with the wrist in slight flexion and ulnar deviation for 4–6 weeks is appropriate for most acute undisplaced fractures. Displaced or comminuted fractures, pisiotriquetral joint instability, or failure of conservative management are indications for surgical intervention, the most reliable of which is pisiform excision — a well-tolerated procedure with consistently good functional outcomes. Post-traumatic pisiotriquetral arthritis is the most important late complication and is the primary indication for late-presenting pisiform excision.