Rehabilitation for Chronic Ankle Instability Does Not Influence Post-Impact Kinematics During a Dynamic Landing Task

Abstract

PURPOSE: To compare the influence of two rehabilitation protocols on lower extremity kinematics after landing in subjects with chronic ankle instability (CAI). METHODS: Twenty-nine physically active subjects (10 males, 19 females; age: 20.24±2.11 yr; height: 174.26±8.29 cm; mass: 75.91±11.46 kg) with unilateral CAI reported to the laboratory for two testing sessions 6 weeks apart during which they performed a single-limb jump landing task using the injured and non-injured limb. Subjects jumped off two feet to a height equal to 50% of maximum vertical jumping height and landed onto a forceplate using one limb. Subjects were asked to land on the designated limb, stabilize as quickly as possible in a single-limb stance, and remain as motionless as possible for 5 seconds. Five jump-landings were performed on each test limb. During the task, hip flexion, knee flexion and ankle plantar flexion were captured with an electromagnetic tracking device. The subjects were randomly assigned to one of three groups: Ankle Rehabilitation (AR), Knee Rehabilitation (KR) or Control (NR). During the 6 weeks between the pre- and post-testing sessions, subjects in the AR and KR groups reported to the laboratory three times/week for supervised rehabilitation sessions designed to target function of the ankle (AR) or the knee (KR). Subjects in the NR group did not participate in any rehabilitation program during the six week period. All subjects reported to the lab at the end of the 6-week period and repeated the jumplanding procedures as performed in the pre-testing session. The peak kinematic values for hip flexion, knee flexion and ankle plantar flexion during the post-ground impact phase of the task served as the dependant variables. For each dependant variable, a separate Time by Limb by Group repeated measures ANOVA was performed. RESULTS: There were no significant interactions for hip flexion (F1,27=0.52, p=.60), knee flexion (F1,27=0.03, p=0.98) or ankle dorsiflexion (F1,27=3.09, p=.063). Additionally, there were no significant main effects among any of the variables. CONCLUSIONS: Rehabilitation designed for the ankle and knee did not influence kinematics of the ankle, knee and hip while stabilizing from a jump in subjects with CAI. It is possible that the selected variables may not be sensitive to the influence of rehabilitation.