The talus (talus) is a tarsal bone that supports the tibia and rests on the tarsus. On the lower surface of the talus, three articular surfaces are found: anterior, middle, and posterior, through which it is connected to the calcaneus and for which anatomical variations have been described. According to the Modified Boyan Classification, several types of variations are described: types A, B, and C (5). When three separate, fully demarcated articular surfaces are observed, the bone is designated as type A. The distance between the anterior and middle is used for further typing, with A1 being ≤2 mm, A2 being 2 to 5 mm, and A3 being ≥5 mm. In the presence of only two articular surfaces, the talus is defined as type B. In B1 and B2, there is a fusion between the anterior and middle facets, respectively incomplete and complete, and in B3, the middle surface is fused with the posterior one. In cases where there is only one articular surface on the lower side of the talus, it is classified as type C.
In this study, 111 pieces of talus from the bone collection of the Department of Anatomy and Cell Biology at the Medical University of Varna were evaluated. The percentage distribution of the studied bones according to variations in facies articularis calcanea was: 89.20% for type B2; 5.40% for type B1; 4.50% for type A1; and 0.90% for type A2. No bones with one continuous articular surface (type C) were found, as were those with a distance between the anterior and middle facies articularis calcanea greater than 5 mm.
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