A chaos-inspired biomechanical biomarker of ankle instability

A lateral ankle sprain (LAS) is one of the most common injuries in sports, and particularly in females who take part in indoor court sports, with 40% of cases developing into chronic ankle instability (CAI) [1]. CAI describes a predisposition for recurrent sprains, persistent pain, limited range of motion, weakness and frequently feeling the ankle is ‘giving way’. Currently CAI is diagnosed through patient reported outcome measures, such as the Cumberland ankle instability tool (CAIT), manual testing and imaging. There is no standard method for diagnosis, and none based on function. Insufficient methods to quantify CAI result in people returning to sport without adequate treatment, further damage to the ankle or retirement from sport altogether. Applying chaos theory to ankle kinematics, this study develops and assesses a novel biomechanical biomarker of ankle instability.