Anatomical variation in the form of inter- and intra-individual laterality of the calcaneofibular ligament.

The lateral ligament complex of the ankle is involved in a large proportion of ankle sprains. The calcaneofibular ligament (CFL) is often involved in severe injuries. The purpose of this study was to evaluate the anatomical variation and laterality of the CFL to improve our understanding of the mechanisms of CFL-related injuries. This study utilized 110 paired ankles from 55 formalin-fixed Japanese cadavers (33 male and 22 female). The length and width of the CFL and the angle created by the CFL and long axis of the fibula (CF angle) were measured after exposing the CFL by careful dissection from the surrounding tissues. The results revealed that each parameter exhibited a wide range of values and showed unique patterns of frequency distribution, among which only the length was normally distributed. Among the parameters, only the CF angle showed no significant correlation with the other parameters. Analysis of laterality revealed that the mean left CF angle was significantly greater than the value on the opposite side (p < 0.05) and that the values of the bilateral CF angle showed no significant correlation at the individual level. The present results revealed not only detailed information regarding the CFL morphology, but also inter- and intra-individual laterality regarding the CFL traveling angle. It is likely that the differences in the quality and quantity of mechanical stress against each leg may have caused this morphologic laterality of the CFL.