Anatomical insights into medial-sided talar dome osteochondral lesions: a comparative analysis of unilateral and bilateral cases and healthy controls using MRI measurements.

Background: The etiology of medial-sided talar osteochondral lesions (OCLs) remains insufficiently understood.

Purpose: To identify anatomical risk factors contributing to the development of unilateral or bilateral OCL of the talus on the medial side, utilizing morphological parameters derived from magnetic resonance imaging (MRI).

Material and methods: In this retrospective study, 24 ankle MRI scans from 12 patients exhibiting bilateral OCLs of the talar dome on the medial side, 24 ankle MRIs from 24 patients with unilateral medial-sided OCLs, and 24 healthy controls matched for age, sex, and side within each group were analyzed. Six distinct MRI parameters were measured: the anterior opening angle of the talus (AOT); tibial axis-medial malleolus angle (TMM); plafond-malleolar angle (PMA); anterior talofibular ligament-posterior talofibular ligament (ATFL-PTFL) angle; the ratio of the distal tibial articular surface to the length of the trochlea tali arc (TAS/TAL); and the depth of the incisura fibularis (IncDep).

Results: The AOT, ATFL-PTFL angle, and TMM of individuals in both the bilateral and unilateral groups were significantly higher when compared to the healthy controls. In addition, TMM measurements in the unilateral group were significantly higher than in the bilateral group.

Conclusion: AOT and TMM appeared to be the primary predisposing factors in the development of both unilateral and bilateral OCLs. Furthermore, TMM shows a greater increase in unilateral OCL cases compared to bilateral OCL cases. The fact that TMM is not significantly high in known unilateral OCL cases can be a stimulus for investigating the other ankle for OCL.