Lateral ankle instability, resulting from the inability of ankle ligaments to heal after injury, is believed to cause a change in the articular contact mechanics that may promote cartilage degeneration. Considering that lateral ligaments’ insufficiency has been related to rotational instability of the talus, and that few studies have addressed the contact mechanics under this condition, the aim of this work was to evaluate if a purely rotational ankle instability could cause non-physiological changes in contact pressures in the ankle joint cartilages using the finite element method. A finite element model of a healthy ankle joint, including bones, cartilages and nine ligaments, was developed. Pure internal talus rotations of 3.67°, 9.6° and 13.43°, measured experimentally for three ligamentous configurations, were applied. The ligamentous configurations consisted in a healthy condition, an injured condition in which the anterior talofibular ligament was cut, and an injured condition in which the anterior talofibular and calcaneofibular ligaments were cut. For all simulations, the contact areas and maximum contact pressures were evaluated for each cartilage. The results showed not only an increase of the maximum contact pressures in the ankle cartilages, but also novel contact regions at the anteromedial and posterolateral sections of the talar cartilage with increasing internal rotation. The anteromedial and posterolateral contact regions observed due to pathological internal rotations of the talus are a computational evidence that supports the link between a pure rotational instability and the pattern of pathological cartilaginous load seen in patients with long-term lateral chronic ankle instability.

The number of people running has risen exponentially in the last decade, increasing the need for better research on running-related injuries, shoe construction and performance enhancement. Considering the key role of the ankle, the second most injured joint after the knee and the only link of the body to the ground, for human motion, the aim of this study is to provide a general overview of generic foot multibody models and their application to the analysis of ankle biomechanics during running. Searches for studies published until February 2021 were performed in scientific databases. The selected studies contemplated original foot multibody models and their running applications. Multibody models of the foot included kinematic and dynamic approaches with the foot being modelled by 3 to 26 segments. Some models have been used to understand the ankle biomechanics regarding running, but most considered only simplified models of the foot. Moreover, their application in the understanding of running mechanics is still very shallow, focusing mainly on the study of joint angle variation and ground reaction forces. This narrative review shows that detailed multibody models of the ankle, which represent its high complexity, are still scarce. An understanding of the different parameters that influence sports performance and injury prevalence has yet to be achieved. Future research should address these topics to create intervention strategies on injury prevention and to maximise sports performance.