The effects of ankle compliance and flexibility on ankle sprains

Purpose: The goal of this study was to examine the influence of changes in subtalar joint flexibility and compliance on ankle sprain occurrence. Methods: Muscle model driven simulations of 10 subjects performing the landing phase of a side-shuffle movement were performed. The passive flexibility or compliance of the subtalar joint was varied, and each subject-specific simulation was exposed to a set of perturbed floor conditions. Results: Increases in flexibility and compliance both led to an increase in the occurrence of excessive supination, while changes in flexibility had a greater influence. Changes in flexibility or compliance caused only small changes in the occurrence of excessive supination torques. Conclusion: These results suggest that increased mechanical laxity does not directly cause an increase in sprain occurrence during side-shuffle movements.