Peroneal reflex contribution to the development of functional instability of the ankle joint

Sprain of the lateral ligament complex of the ankle joint is one of the most common athletic injuries. Following initial injury a large percentage of individuals develop complaints of repetitive ankle sprain, such that they feel that the ankle “gives way” or feels unstable. These complaints of “giving way” and the occurrence of repeated inversion injury have been termed functional instability of the ankle joint.Previously it was proposed that functional instability developed as a result of articular deafferentation, whereby damage to mechanoreceptors in the ankle joint supporting ligaments and capsule at the time of initial injury resulted in reduced afferent feedback to the evertor musculature of the ankle joint. Consequently it was hypothesized that the evertor musculature could not reflexively stabilize the ankle joint if it was subjected to a sudden inversion perturbation. The aim of this paper was to review the literature relating to the reflex response times of the evertor musculature of the ankle joint to sudden unexpected inversion perturbation, and thus, discuss the role of reflex activity in the peroneal muscles to the development of functional instability of the ankle joint. There is conflicting evidence regarding the extent to which ligament mechanoreceptors induce reflex stabilization of the ankle joint in response to rapid inversion movements. Even if such reflex mechanisms do exist it is unlikely that they would be fast enough to provide adequate joint protection during dynamic activity, suggesting that their actual functional relevance is limited.