A New Classification of Talocalcaneal Coalitions Based On Computed Tomography For Operative Planning

Abstract

Background Current classifications emphasize the morphology of the coalition, however, subtalar joint facets involved should also be emphasized.Objective The objective of this study was to develop a new classification system based on the articular facets involved to cover all coalitions and guide operative planning.Methods Patients were diagnosed with talocalcaneal coalition using a CT scan, between January 2009 and February 2021. We classified the coalition into four main types according to the shape and nature of the coalition: I, inferiorly overgrown talus or superiorly overgrown calcaneus; II, both talus and calcaneus overgrew; III, coalition with an accessory ossicle; (I-III types are non-osseous coalition) IV, complete osseous coalition. Then each type was further divided into three subtypes according to the articular facets involved. A, the coalition involving the anterior facets; M, the coalition involving the middle facets, and P, the coalition involving the posterior facets.Results There were 106 patients (108 feet) included in this study. Overall, 8 feet (7.5%) were classified as type I, 75 feet (69.4%) as type II, 7 feet (6.5%) as type III, and 18 feet (16.7%) as type IV. Twenty-nine coalitions (26.9%) involved the posterior facets only (subtype-P), 74 coalitions (68.5%) involved both the middle and posterior facets (subtype-MP), and five coalitions (4.6%) simultaneously involved the anterior, middle, and posterior facets (subtype-AMP). Type II-MP coalition was the most common.Conclusion A new classification system of the talocalcaneal coalition to facilitate operative planning was developed.

Prevalence and characteristics of tarsal coalition in East Asians: what are the differences compared to Caucasians?

“…But, most of these results were obtained in Caucasian studies. According to some East Asian studies which used computed tomography (CT) or MRI for diagnosis, TC coalition has a higher proportion than CN coalition, and TC coalition most commonly involves the posterior subtalar facet [30][31][32][33][34] . It appears that the anatomical distributions of tarsal coalition might differ between races.…”