Summary Pisiform Fractures are rare carpal fractures associated with falls on an outstretched hand. Diagnosis is often made with orthogonal radiographs but may require CT for confirmation. Treatment is primarily nonoperative with painful nonunions requiring surgical excision. Epidemiology Incidence <1% of carpal fractures rare injury and often missed Etiology Pathophysiology mechanism of injury usually occurs by direct impact against a hard surface fall on outstretched hand Associated conditions 50% occur as isolated injuries 50% occur in association with other carpal fractures or distal radius fractures Anatomy Pisiform Bone osteology pea shaped, seasmoid bone location most ulnar and palmar carpal bone in proximal row located within the FCU tendon function contributes to the stability of the ulnar column by preventing triquetral subluxation Presentation Symptoms ulnar sided wrist pain after a fall grip weakness Physical exam inspection hypothenar tenderness and swelling rule out associated injury to other carpal bones and distal radius Imaging Radiographs recommended views PA lateral ER oblique carpal tunnel best seen with ER oblique or carpal tunnel view CT indications may be required to delineate fracture pattern and determine treatment plan MRI indications suspected carpal fracture with negative radiographs findings may show bone marrow edema within the pisiform indicating fracture Differential Hamate body fracture Hook of hamate fracture FCU tendonitis Diagnosis Radiographic diagnosis confirmed by history, physical exam, and radiographs Treatment Nonoperative early immobilization indications first line of treatment technique short arm cast with 30 degrees of wrist flexion and ulnar deviation for 6-8 weeks outcomes most often go on to heal without posttraumatic osteoarthritis Operative pisiformectomy indications severely displaced and symptomatic fractures painful nonunion outcomes studies show a pisiformectomy is a reliable way to relieve this pain and does not impair wrist function Complications Malunion Non-union Chronic ulnar sided pain Decreased grip strength