Articular Contact Mechanics in Osteochondral Lesions of the Talus: A Weightbearing-CT study

Category: Sports; Ankle Introduction/Purpose: Osteochondral Lesions of the Talus (OLT) may progress into a cascade of cartilage degeneration. While edge-loading on the surrounding tibiotalar articular surfaces has been proposed as principal determinant of cartilage degeneration, the pathophysiological pathways have not yet been clarified. The present study aims to evaluate the patient-specific influence of OLTs on the mechanical behaviour of the surrounding cartilage of the talus and tibia. More specifically, this study aims to investigate whether the location of the OLTs influences their loading characteristics during the range of motion of the ankle joint. Methods: Patient-specific 3D models from 36 patients with an OLT, derived from weightbearing CT, were used to analyse the contact stress on the tibiotalar articulation using Discrete Element Analysis (DEA). A matched, virtual healthy control group was developed for each talus. Mean- , peak contact-stress and contact area were calculated during simulated ankle flexion. Results: The mean talar contact-stress was elevated in the OLT cases, with a notable correlation between ankle flexion and OLT location. Edge loading occurred predominantly in anteromedial lesions during dorsiflexion (2.9 MPa (IQR: 1.3) for OLT versus 2.4 MPa (IQR: 0.9) for the controls), while posteromedial lesions were mostly loaded during plantarflexion (3.5 MPa (IQR: 1.7) for the OLT versus 2.9 MPa (IQR: 1.1) for the controls). Conclusion: OLTs influence the whole-joint articular contact mechanics of the ankle, leading to increased stress on both the talus and the opposing tibia. More specifically, a clear pattern of edge-loading on the surrounding OLT cartilage was found. Anterior lesions had the highest stresses in neutral and dorsiflexion, while Posterior lesions experienced higher stress during plantarflexion. OLT versus Healthy Twin Contact Stress Contact stress plot, depicting the difference between OLT (upper) and the matched, healthy twin (lower) for increasing plantarflexion