712 MEP019 – The developed double spiral elastomeric ACL strap prevents knee-in effectively during the 3D one-legged landing motion

AbstractBackground Knee-in, mainly caused by adduction and internal rotation of the hip joint, is one of the mechanisms of occurrence in ACL injuries. The double spiral elastomeric strap, which has been designed to prevent ACL injuries, has shown an inhibitory effect on knee-in during one-legged landing, but its kinetic action is unknow.Objective This study examined the effect of the double spiral elastomeric strap on postural control during one-legged landing motion. Design Quasi-experimental study.Setting/Patients Eleven female university students with knees-in.Interventions Five one-legged landings from a 30cm platform were performed with and without the double spiral elastomeric strap from the waist to the proximal lower leg, made of thermoplastic styrene elastomer, respectively.Main Outcome Measurements The three-dimensional motion analyzer (Vicon Nexus)and force plate(AMTI) were used to measure the knee valgus angles and external knee valgus moment at 80ms after landing. Paired t-test was used for statistics, with a significance level of 5%.Results The knee valgus angle (the double spiral elastomeric strap/without a strap, unit: °, knee valgus is indicated as +) at 80ms after landing was -11.6±1.3/5.2±1.2, and the double spiral elastomeric strap was significantly reduced compared to without a strap. The external knee valgus moment (with the double spiral elastomeric strap/without a strap. unit: Nm/kg/m, knee valgus is expressed as +) was -0.11±0.01/0.05±0.01. The double spiral elastomeric strap significantly reduced the external knee valgus moment after landing compared to the without a strap.Conclusions The devised double spiral elastomeric strap suppressed the knee valgus angle and external knee valgus moment of the caused knee-in after landing and induced a safe landing posture for prevention of ACL injuries.