Individuals with Chronic Ankle Instability Exhibit Altered Ground Reaction Force Patterns during Walking

Abstract

Lateral ankle sprains frequently occur and often lead to chronic ankle instability (CAI). CAI has been shown to alter neuromuscular function and walking mechanics which impact ground reaction force (GRF). PURPOSE: To examine patterns of ground reaction forces across the stance phase of gait in those with and without CAI. METHODS: 100 CAI patients (M=49, F=51; 22±2 yrs, 174±10 cm, 71±14 kg, 82±9% FAAM ADL, 62±13% FAAM Sports, 4.5±2.6 ankle sprains) and 100 controls (M=56, F=44; 22±3 yrs, 172±13 cm, 72±18 kg, 100% FAAM ADL & Sports, no previous sprains) performed five walking trials. Three dimensional GRFs (anterior-posterior, medial-lateral, and vertical) were measured during the stance phase of gait (0-25%: initial stance, 25-50%: loading response, 50-75%: midstance, and 75-100%: terminal stance). Functional linear models were used to compare difference in GRFs between the groups during walking (α=.05). If functions and associated 95% confidence intervals did not cross zero, group differences existed. RESULTS: Figure 1. CAI subjects demonstrated greater vertical GRF during 0-10% and 67-95% of stance. Patients with CAI also increased posterior and anterior GRFs during 10-20% and 70-95% of stance respectively. Lateral GRF was greater in CAI subjects during 65-75% of stance compared to controls. CONCLUSION: CAI subjects may compensate for ankle instability with a more rigid walking strategy by increasing anterior-posteior, lateral and vertical GRFs during the stance phase of gait. The greater GRF of the CAI group indicates altered gait mechanics which could increase loads on lower extremity joints and potentially increase re-injury risk.Figure