Isolated Fracture of the Pisiform Bone

Abstract

Fracture of the pisiform bone without other carpal injury is apparently rather uncommon. The first report of a pisiform fracture, by Guibout (17) in 1847, was in a case complicated by fractures of the navicular, the capitate, and the radius, resulting from a fatal jump from a third-story window. The fracture was proved at necropsy. Jaeger (19), summarizing the literature in 1931, was able to find 11 cases, and reported one of his own. Since then there have been 5 additional reports (6, 8, 11, 12, 24), so that, including the present case, there are on record 18 examples of isolated pisiform fracture. In two instances the reports were in Russian journals which are not available to the author, so that verification of these (12,24) has not been made. Schnek (5), in an experience of six years in Bohler's clinic, found 13 pisiform fractures in 437 carpal injuries, but he does not indicate how many of these were isolated fracture of this bone. He states, by way of comparison, that during the same period 669 fractures of the radius and/or ulna were seen. Blumer (3) reports 2 cases of pisiform fracture in 79 carpal injuries from a series of 270,000 examinations for the Swiss compensation insurance system, but these were both accompanied by radial fracture. Destot (10) cites Morgues as giving the incidence as 1 in 61 carpal fractures, but he had not himself seen a case in 500 carpal injuries. Bunnell (7) quotes Snodgrass as reporting 1 case in 170 carpal fractures. Most published reports are, like the present, of single cases. Considering these facts, the incidence might be estimated not to exceed 1 case in 100 fractures of carpal bones exclusively. This apparent rarity, however, may not be truly representative, since the fracture is seldom suspected or looked for, and there is, moreover, a very reasonable reluctance on the part of most physicians to report single cases of a relatively unimportant condition. In addition to fracture, dislocation of the pisiform has been reported, apparently with about the same frequency of occurrence. The demonstration of the fracture depends on taking an 80° oblique view of the wrist with the dorsum turned back, although in the case here reported, as well as in Jaeger's illustrations, the fracture was readily visible on the palmar projection. The injury must be distinguished from the anomalous bones, the secondary pisiform, the os triangulare, and the separate styloid process of the ulna, but these as a rule lie between the pisiform and the ulna rather than in the pisiform region proper (4). The pisiform serves as the insertion for the flexor carpi ulnaris and the abductor digiti quinti, and as attachment for the transverse carpal ligament.