Ankle and hip isometric strength program for ankle instability weakness : Pilot randomized controlled trial

Background : Chronic ankle instability (CAI) represents 40% of lateral ankle sprains one year after the initial injury. Muscle weaknesses, range of motion, postural control, jumping deficits and feeling of instability could potentially participate to CAI development. This study aims to determine the effectiveness of an ankle and hip isometric strength program on deficits among CAI population.
Methods : In this pilot randomized controlled trial, 29 volunteers with a CAI were assessed with a hand-held dynamometer for isometric ankle strength (plantar flexion, dorsiflexion, eversion and inversion) and isometric hip strength (abduction, external rotation and clamshell). Postural control (Single leg stance and Y-balance test (YBT), jumping ability (side hop test and the figure of 8 test), range of motion (weight bearing lunge test : WBLT), feeling of instability (questionnaires) were also assessed. The outcomes were reported at the baseline (T1), after five weeks (T2) and after eight weeks (T3). Volunteers were randomly split into three groups : ankle strength group (n=10), hip strength groups (n=9) and a control group (n=10). Ankle and hip strength groups realized an isometric strength program of 12 sessions, three times a week of approximately five minutes, respectively focus on the ankle and on hips. No intervention was realized in the control group.
Results :Plantar flexion and dorsiflexion strength were significantly improved (58-80%) in the ankle strength group (respectively, p < 0.001, p <0.01) compared to hip strength and control group. Similarly, clamshell strength was significantly improved (112%) in the hip strong group (p < 0.05) compared to the ankle strength and control group. The eversion and inversion were improved (36-46%) in the ankle strength group as well as external hip rotation and abduction were improved (49%-51%) in the hip strength group but those results were not significant (p > 0.05). Feeling of instability significantly decrease in the ankle strength group compared to the hip strength and the control group (p<0.05). The range of motion was also significantly increased (11%) in the ankle strength group.