James R. Mullen
The pisiform is a pea-shaped sesamoid bone within the tendon of the flexor carpi ulnaris (FCU).
Attaches to FCU proximally
Distally is attached to the pisohamate, pisometacarpal, and pisotriquetral ligaments
Origin of abductor digiti minimi
Transverse carpal ligament also has attachments to the pisiform.
The ulnar nerve and artery lie radial to the pisiform in Guyon’s canal.
Mechanism of injury
Direct impact against a hard surface
Forceful contraction of FCU
1% to 2% of all carpal fractures
Injury is often missed
50% occur in isolation
50% associated with other conditions
Fall on outstretched hand
Most commonly produces a transverse pisiform fracture
Impact with ground fractures the pisiform at pisotriquetral joint.
Forceful contraction of the FCU results in a transverse avulsion fracture.
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