Results and analyses of preoperative isokinetic and balance tests in patients with chronic lateral ankle instability who underwent surgical treatments

Category: Sports Introduction/Purpose: To (1) describe muscle strength and postural stability in patients with chronic lateral ankle instability, and (2) analyze the correlation between weakness of muscle strength and deficits of postural stability Methods: Results of preoperative isokinetic and balance tests in 203 patients whose contralateral ankle was normal were retrospectively reviewed. Isokinetic peak torque values of eversion and inversion at 2 angular velocities (30°/s, 120°/s) were measured in injured and normal ankles. In balance test, the percent differences of 3 actual scores (Overall, Anterior-Posterior, and Medial-Lateral) between injured and normal ankles were calculated. Additional statistical analyses were performed to describe weakness of muscle strength, deficits of postural stability, and their correlation. Results: There were significant differences in 4 peak torque values and 4 relative peak torque values (peak torque/body weight) between injured and normal ankles. Eight values were significantly lower in injured ankles. Weakness was severe during inversion and at 30°/s. In balance test, 49 subjects (24.1%) had significant deficits in postural stability; the results in 109 subjects (53.7%) were favorable. There was no strong association between weakness of muscle strength and deficits of postural stability. Conclusion: Considering correlation between weakness of muscle strength and deficits of postural stability, strength measurement alone is insufficient in evaluating preoperative functional ability, and other functional test such as postural stability test is required. In addition, the results of this study may provide further evidence for rehabilitation program consisting of proprioceptive training as well as muscle strengthening.