Subtalar Joint Instability and Calcaneal Spurs Associated with the Configuration of the Articular Facets of Adult Human Calcaneum in Indian Population.

Abstract

Morphological variations of articular facets of calcaneum may predispose people to joint instability, ligamentous laxity and development of arthritic changes in the subtalar joint. Knowledge of such variations is essential for treatment and diagnostic procedures in orthopaedic surgeries. The aim of this study was to determine patterns of articular facets of calcanei and to establish its correlation with calcaneal spurs. The study was conducted on 580 adult calcanei of Indian origin at Maulana Azad Medical College and pattern of articular facets were observed and classified according to five patterns described in literature. A digital vernier calliper was used to measure separation between anterior and middle facet. Degree of intersecting angle between anterior and medial facets was calculated using UTHSCSA Image Tool software. The calcaneal spurs were observed by visual inspection. Out of 580 calcanei, 66.55% had fused anterior and middle facets (Pattern I), 27.59% had all three facets separate (Pattern II), 5.52% had absence of anterior facet (Pattern III), 0.17% had all three facets fused (Pattern IV) and 0.17% had fused middle and posterior facets (Pattern V). A significant side variation was present in Pattern III with predominance on left side. Mean angle of intersection was 147.700 in Pattern I and 133.340 in Pattern II calcaneum. Calcaneal spurs were found in 61.38% out of which it was associated with Pattern I in 43.62%, Pattern II in 14.66% and Pattern III in 2.76%. Individuals with Pattern I and III calcaneum were found to be at a greater risk of subtalar joint instability than individuals with Pattern II. Angle of intersection was obtuse in Pattern I which resulted in ligament laxity and unstable joint. Pattern I was more common in Indian population and this fact necessitates modifications of the western surgical techniques to suit the Indian scenario. An association between the presence of spur and facet configuration was found to be significant.