Different Lower Extremity Joint Energetic Pattern between Subjects with Copers and Ankle Instability

Abstract

Lateral ankle sprains are common sport-related injuries, which often lead to ankle instability (AI) or may not develop into AI (coper). Identification of coper energetic patterns may clarify underlying injury pathomechanics of AI. PURPOSE: To examine if AI and coper subjects demonstrate different joint power patterns during a forward-side jump when compared to controls. METHODS: 19 AI (22.9±2.0yrs, 175.3±10.7cm, 73.7±12.2kg; 4.1±2.8 sprains), 19 Coper (22.1±2.2yrs, 173.9±8.2cm, 72.9±12.9kg; 2.0±1.1 sprains) and 19 control subjects (21.6±2.5yrs, 172.9±7.7cm, 68.4±10.8kg) were categorized according to the FAAM and the MAII. They performed 5 forward-side jumps on the force plate. Joint power (W/kg) was measured during the landing (eccentric power: 0-50% of stance) and take-off (concentric power: 50-100% of stance) phases of a forward-side jump. Functional linear models (α=0.05) were used to evaluate difference in joint power between groups. Functions of each group as well as 95% confidence interval (CI) were plotted to determine significant differences. RESULTS: Figure 1. The AI group had less ankle eccentric power during landing phase while greater knee and hip eccentric power in the initial phase of landing compared to coper and control groups (p<.05). During take-off phase, AI demonstrated less ankle and knee concentric power whereas copers and controls demonstrated increased hip joint power (p<.05). CONCLUSIONS: The AI group increased proximal joint energy absorption to compensate for decreased distal joint power during landing compared to the coper and control groups. AI subjects also generated greater energy with the hip joint to compensate for less concentric ankle and knee joint power during the take-off phase.