Isokinetic Evaluation in a Large Cohort of Normal Ankles

CATEGORY: Ankle; Sports; Other INTRODUCTION/PURPOSE: The isokinetic test has been used diffusely as a way to evaluate the functional results after the rehabilitation of musculoskeletal injuries. In the ankle, in particular, most studies are related to lateral ligament injuries and Achilles tendon's injuries. However, different protocols are used and a lack of normative values is observed in the literature. The aim of this work is to perform a global isokinetic evaluation on healthy ankles in order to propose reference values for future patients. METHODS: We evaluated 100 participants (200 ankles) using the Biodex 3 System for the eversion, inversion, dorsiflexion and plantar flexion movements of the ankle. The sample consisted of individuals aged 20-60 years, with an active life and practice of recreational physical activity (non-athlete) and without previous injuries. Five repetitions for strength (N / m) and work (J) at a speed of 30o / sec and 10 repetitions for power (W) at a speed of 120o / sec were performed in our protocol. Agonist / antagonist ratio and the Muscle Deficiency Index, which globally assesses the balance between the sides for each movement, were also evaluated, as well as the demographic variables. Different statistical analyzes were performed for each parameter. RESULTS: The mean age was 38.5 years and BMI 25.8 (CI 2.7 and 0.8 respectively) in 69 men and 31 women. In 78% of participants, the dominant ankle was the right one. The non-dominant side was consistently stronger (higher peak torque) in all movements (p<0.001 - Wilcoxon Test). The mean values obtained for force in each movement were 29.9N/m for eversion, 34.8N/m (CI 1.6) for inversion, 48.6N/m (2.0) for dorsiflexion and 140.2 N/m for plantar flexion. Such parameters for men and women were also obtained (p<0.001) and there was no correlation between age or BMI with the maximum torque (N/m) through Spearman's Correlation. The ratio of eversors / inverters was 88.8% (CI 3.1) and that of dorsiflexors / plantar flexors was 36.1% (1.3). Limb symmetry Index were >= 90% between sides in all four moviments (91,99% for eversion, 98,57% for inversion, 96,96% for dorsiflexion and 94,72% for plantarflexion). CONCLUSION: The non-dominant side was stronger in this evaluation of the two hundred healthy ankles. However, this difference was within the expected range for the limb symmetry index and for the MDI, showing that limb dominance is not relevant for the isokinetic assessment of the ankle. In the studied sample, the demographic variables (except gender) did not show any correlation with the evaluated parameters, especially with the maximum torque. Normative values of torque forces and agonist/antagonist balances were proposed. The results have implications for rehabilitation protocols and criteria for returning to sports.