Ankle joint evertor–invertor muscle torque ratio decrease due to recurrent lateral ligament sprains

Objective. To determine an ankle inversion–eversion movement range part where evertor/invertor muscles torque ratio is altered after recurrent ankle lateral ligament sprains. Design. The ankle evertor/invertor muscles torque ratios were determined in the different range parts of angular positions by the muscle isokinetic movements. Background. It is important to determine the movement range part where the evertor muscle weakness after the ankle lateral ligament sprains is more expressed and a repeated trauma of the lateral ligaments is more probable. Methods. Twenty-eight male handball players participated in the tests using an ankle isokinetic inversion–eversion movement investigation dynamometer system. Thirty-three ankle joints were uninjured, but 23 underwent recurrent lateral ligament sprains. Results. The ankle evertor/invertor muscles torque ratio for the sprained ankles was significantly lower in comparison with the uninjured joints in inversion positions at 50° and 60° of the range of movements in all applied velocities, except the slowest movement (30°/s). Conclusions. The recurrent ankle lateral ligament sprains reduced the evertor/invertor muscles torque ratio in the inversion positions of the range of movements and therefore the evertor muscle weakness was more expressed in the beginning of the eversion movement