Classification of the subtalar articular surface and its matching situation: an anatomical study on Chinese subtalar joint.

According to Bunnins's classification, the type with separated facets predominated but the matching situation between STJ was not elaborated, which was closely linked to the stability of STJ and surgical strategy of calcaneus fracture. The calcaneus articular surfaces in a sample Chinese population were divided into five types. Type I was the most common type and Type V was the rarest. Type II have the highest stability, Type V may be the lowest stability and Type III was more prone to osteoarthritis. The STJ articular surfaces were basically matched, contributing to the coordinate movement of the STJ. The matching articular surfaces of STJ were more stable than the mismatching surfaces. To some extent that STJ facet number, shape, facet area, and matching situation are factors in STJ stability, and the anatomical variations of the STJ offer predictive value in determining the predisposition to STI.