Prophylactic Ankle Stabilizers Affect Ankle and Knee Joint Kinematics During Landing

Abstract

PURPOSE: Ankle joint dorsiflexion contributes to energy absorption when landing, but wearing ankle stabilizers has been shown to restrict passive and active measures of dosiflexion. Recent changes in stabilizer design and materials have been intended to improve support to the lateral ankle joint without restricting sagittal plane motion. This study compared the effects of various ankle stabilizers on ankle and knee joint kinematics during soft and stiff landings. METHODS: Subjects (N=11) performed two-legged landings off a 0.32-m platform onto a force platform while recorded with an optotrak system (200 Hz). Five soft and five stiff landings landings were performed in five bilateral ankle stabilizer conditions (no stabilizer; standard taping; neoprene shell with support; reinforced lace up boot; hinged lace up boot), a total of fifty trials per subject. Stabilizer and style conditions were randomized across subjects. Each subject‘s five-trial mean value of selected ankle and knee kinematic variables for each landing style/stabilizer condition was entered into a two-way repeated measures ANOVA (a=0.05). RESULTS: As previously reported in the literature, joint ROMs were less in stiff landings than soft landings. Compared with the no stabilizer condition, the ROM at the ankle and knee were reduced in most stabilizer conditions, reflecting a more extended landing position at both ground contact and maximum joint flexion when using an ankle stabilizer. Stabilizer effects at the ankle joint were of similar magnitude to soft vs stiff differences, but of a smaller magnitude at the knee joint. CONCLUSIONS: In spite of design and material changes to the stabilizers, the results indicate that some ankle stabilizers still adversely affect ankle joint kinematics during landing, possibly inducing changes in the knee joint kinematics. ACKNOWLEDGEMENTS: Ankle stabilizers were supplied at no-cost by the manufacturers. The financial support of IAHPERD through a Jump Rope for Heart grant is gratefully appreciated.