Biomechanical study on lateral collateral ligament and joint capsule injuries in parachuting

Abstract

Objective To determine the load of causing parachutist's lateral collateral ligament and the joint capsule injuries by investigating the ankle inversion from plantar flexion to varus position under simulated landing state,and to analyze its stress features in order to provide theoretical reference to the development of Chinese Air Force Paratrooper boots and ankle brace.Methods Six human ankle specimens were fixed on the MTS-858 biomechanical testing machine by the self-made fixture.The axial compression range was 10 cm.The axial force was applied until the load curve appeared peak.The force and the time to peak were recorded,as well as the load time curve.Results In the simulation of ankle inversion from plantar flexion to varus position,the average peak force was 2207.18 N,and the average time to the peak was 9.76 s.The load curve showed such feature as gradual increase and sharp drop.The dissection showed that the lateral collateral ligament and the joint capsule had inactive ruptured injuries with irregular section as the peak force applied.X-ray examination indicated no osseous injuries in all specimens.Conclusions The ankle's lateral collateral ligament and joint capsule would show isometric and isotonic contraction features in the load-time curve as overcoming the ankle change from plantar flexion to varus position under simulated landing state.Those would provide theoretical reference in improving paratrooper boots and ankle brace in order to prevent ankle from lateral collateral ligament and the related soft tissue injuries. Key words: Aviation; Ankle joint; Lateral ligament, ankle; Joint capsule; Ankle injuries; Biomechanics