Background: In vivo evaluation of ankle joint biomechanics is key to investigating the effect of injuries on the mechanics of the joint and evaluating the effectiveness of treatments. The objectives of this study were to 1) investigate the kinematics and contact strains of the ankle joint and 2) to investigate the correlation between the tibiotalar joint contact strains and the prevalence of osteochondral lesions of the talus distribution.
Methods: Eight healthy human ankle joints were subjected to compressive load and 3 T MRIs were obtained before and after applying load. The MR images in combination with digital volume correlation enabled non-invasive measurement of ankle joint kinematics and tibiotalar joint contact strains in three dimensions.
Findings: The total translation of the calcaneus was smaller (0.48 ± 0.15 mm, p < 0.05) than the distal tibia (0.93 ± 0.16 mm) and the talus (1.03 ± 0.26 mm). These movements can produce compressive and shear joint contact strains (approaching 9%), which can cause development of lesions on joints. 87.5% of peak tensile, compressive, and shear strains in the tibiotalar joint took place in the medial and lateral zones.
Interpretation: The findings suggested that ankle bones translate independently from each other, and in some cases in opposite directions. These findings help explain the distribution of osteochondral lesions of the talus which have previously been observed to be in medial and lateral regions of the talar dome in 90% of cases. They also provide a reason for the central region of talar dome being less susceptible to developing osteochondral lesions.
Keywords: Ankle; Digital volume correlation; Joint contact strains; Kinematics; Magnetic resonance imaging; Osteochondral lesions of the talus.
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