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.

踝关节外侧不稳定，由于踝关节韧带在受伤后无法愈合，被认为会导致关节接触力学发生变化，从而促进软骨退化。考虑到外侧韧带的功能不全与距骨的旋转不稳定有关，并且很少有研究解决这种情况下的接触力学问题，这项工作的目的是评估纯粹的踝关节旋转不稳定是否会导致非生理变化使用有限元方法测量踝关节软骨中的接触压力。开发了一个健康踝关节的有限元模型，包括骨骼、软骨和九个韧带。应用了 3.67°、9.6° 和 13.43° 的纯内距骨旋转，对三种韧带结构进行了实验测量。韧带结构包括健康状态、距腓前韧带被切断的损伤状态和距腓前韧带和跟腓前韧带被切断的损伤状态。对于所有模拟，评估每个软骨的接触面积和最大接触压力。结果表明，不仅踝关节软骨的最大接触压力增加，而且随着内旋的增加，距软骨前内侧和后外侧部分的新接触区域也增加。