Fracture anatomy of the calcaneus with axial loading. Cadaver experiments

Abstract

Summary The fracture anatomy of the calcaneus was investigated in 30 lower leg specimens. They were submitted to axial loads with metal weights on a vertical sledge. The fractured specimens were studied radiographically and by anatomic dissection. Intra-articular fractures of the calcaneus occurred in 25 specimens. Fracture lines could be divided into a relatively constant primary fracture in 22 specimens, which ran from the posterior subtalar joint surface to the tuber calcanei, and highly variable secondary fractures in 24 specimens. In order to facilitate classification of the fracture specimens, the calcaneus was divided into four segments: the sustentacular segment, the posterior subtalar joint segment, the segment of the anterior process, and the tuberosity segment. In addition, the following joints were identified: the posterior subtalar joint, the anterior subtalar joint, and the calcaneo-cuboid joint. Each specimen was classified by the number of segments (x) and the number of joints (y) affected, and accordingly labelled as x-segment, y-joint fracture. The addition of both numbers was used to grade the severity of the fracture. The minimum fracture grade was three; in five specimens the maximum of seven was reached. The mean fracture grade was 5.1, composed of 3.4 segments and 1.7 joints. This classification could easily be applied to all 25 experimental fracture specimens, as well as to 33 clinical cases.