Relationship Between Neuromuscular Characters And Biomechanical Risk Factors Of Anterior Cruciate Ligament Injury

Objective: The purpose of this study was to determine if neuromuscular characters as well as sex could predict the anterior cruciate ligament(ACL)biomechanical risk factors during three jump-landing maneuvers,and to compare the neuromuscular characters and ACL biomechanical risk factors between sex and maneuvers.This study aims to provide better understanding on the reason of gender difference in the incidence of ACL injury and the injury mechanisms,and theoretical basis for the prevention and rehabilitation of ACL injury in human activity.Methods: 59 healthy subjects(28 males and 31 females).Neuromuscular function tests including isokinetic test of maximum muscle strength,active joint position sense measurement,Y-balance test and core endurance test.Infrared motion capture system and three-dimensional force plates,as well as EMG system in jump-landing maneuvers were used to collect the data of kinematics,kinetics and muscle activation of lower extremity.Independent-samples T test was performed to determine the effect of sex on neuromuscular characters.A two-way Mixed-design ANOVA was performed to determine the effect of sex and maneuvers on ACL biomechanical risk factors.Multiple linear regression analysis was performed to determine the neuromuscular characters as well as sex could predict ACL biomechanical risk factors during three jump-landing maneuvers.Results: 1)The relative maximum muscle strength of the trunk,pelvis and thigh as well as side core endurance test score were significantly greater in men.There are no gender differences in other neuromuscular character.2)The ground reaction force,knee valgus angle,the knee extension moment,vastus medialis activation in pre-activation phase and coavtivation of quadriceps-to-hamstrings were significantly greater in women.There were no gender differences in other ACL biomechanical risk factors.3)Significant differences were reported in the ground reaction force,knee flexion angle,knee valgus angle,the knee extension moment,vastus medialis activation and biceps femoris activation in pre-activation phase among maneuvers.There were no differences in other ACL biomechanical risk factors.4)Hip abductor strength and knee extension active joint position sense was found to be significant predictors of peak posterior ground reaction force.The ratios of trunk extensor to flexor strength and Y-balance test overall composite score were found to be significant predictors of peak vertical ground reaction force,hip external-ratation strength and anterior reach of Y-balance test were found to be significant predictors of knee angle,hip extensor strength,knee flexor strength,and knee extension active joint position sense were found to be significant predictors of knee valgus angle,trunk extensor strength,the ratios of trunk extensor to flexor strength,hip external-ratation strength,trunk lateral flexion active joint position sense,knee extension active joint position sense,anterior reach of Y-balance test and sex were found to be significant predictors of knee extension moment,trunk lateral flexion active joint position sense was found to be significant predictors of knee valgus moment.Conclusions:1)Sex could have effects on neuromuscular characters.Men group reported a higher level in strength of trunk,pelvis and thigh and side core stability.2)Sex could have effects on ACL biomechanical risk factors.The ground reaction force,knee valgus angle,the knee extension moment,vastus medialis activation in pre-activation phase and coavtivation of quadriceps-to-hamstrings was significantly greater during jump-landing maneuvers in women which may be the main reason for the higher incidence of ACL injury in women.3)Neuromuscular characters were found to be significant predictors of ACL biomechanical risk factors.Greater trunk extensor strength,hip extensor strength,hip external-ratation strength,hip abductor strength,knee flexor strength,as well as better dynamic postural control ability,trunk lateral flexion active joint position sense and knee extension active joint position sense could reduce the risk of ACL injury in jump-landing maneuvers.