[Fracture and dislocation fracture of the os pisiforme].

Four cases of pisiform fracture are presented. In one case the largest fragment of the pisiform bone with the articular surface was dislocated. After open reduction, osteosynthesis with K-wires was performed. Two patients had an isolated fracture without fragment dislocation. They had their lower arms immobilized with a plaster of Paris cast for 4 weeks. In the fourth case the fracture of the pisiform bone was associated with an intraarticular distal radial fracture and wrist dislocation. The typical traumatic cause of pisiform fracture is a fall onto the outstretched hand. Immobilization for 4 weeks results in functional recovery. In cases with dislocation of the pisotriquetral joint open reduction and osteosynthesis are necessary. Excision of the pisiform bone is not indicated in a fresh injury.