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Varna Medical Forum

Anatomical variations in facies articularis calcanea on the talus in the Bulgarian population

Meglena Angelova, Desislava Marinova


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.


talus, subtalar joint, variations

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Drake RL, Vogl W, Mitchell AWM, Gray H, Tibbitts RM. Gray’s anatomy for students: Online access + interactive extras: Elsevier, Churchill Livingstone. 2005

Jung MH, Choi BY, Lee JY, Han CS, Lee JS, Yang YC, Cho BP. Types of subtalar joint facets. Surgical and Radiologic Anatomy: SRA. 2015;37(6): 629–638.

Khan IA, Varacallo M. Anatomy, Bony Pelvis and Lower Limb, Foot Talus.. In StatPearls. StatPearls Publishing.2023

Phunchago N, Uabundit N, Chaisiwamongkol K, Chaichun A, Iamsaard S. Types and Morphometric Study of Calcaneal Articular Facets on Human Tali of Thai Population. International Journal of Morphology, 2018;36(3), 975–978.

Prasad SA, Rajasekhar SSSN. Morphometric analysis of talus and calcaneus. Surgical and Radiologic Anatomy: SRA. 2019;41(1), 9–24.

Uygur M, Atamaz F, Celik S, Pinar Y. The types of talar articular facets and morphometric measurements of the human calcaneus bone on Turkish race. Archives of Orthopaedic and Trauma Surgery. 2009;129(7), 909–914.



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