Biomechanical Study of Risk Factors for Anterior Cruciate Ligament Injury During Unanticipated Drop Jumps
Objective From a biomechanical point of view,the effect of the presence or absence of anticipation during a drop jump on the risk of anterior cruciate ligament(ACL)injuries during their landing was compared between different sexes.Methods The biome-chanics of the drop jump was tested in 20 subjects(10 males and 10 females)with and without anticipation using an optical motion capture system,a force platform,and wireless surface electromyography,and the results were analysed by a two-way(gender x antic-ipation)analysis of variance(ANOVA).Results 1)Under the anticipated conditions,knee joint at the time of first peak of parallel backward ground reaction force(PBGRF)was subjected to varus moment while was subjected to valgus moment in unanticipated con-dition.2)The first peak of PBGRF and the knee valgus angle at that time during unanticipated landing was significantly larger than an-ticipated landing,and the knee flexion angle was significantly smaller than anticipated landing(p＜0.05).3)The peak vertical ground reaction force(VGRF)and knee extension moment at the first peak of PBGRF of females were significantly larger than those of males(p＜0.05).4)Among females,the co-activation rate of quadriceps/hamstring during unanticipated condition were significantly greater than anticipated landing(p＜0.05),and under unanticipated landing,the co-activation rate of quadriceps/hamstring of females was sig-nificantly higher than that of males.Conclusion 1)The risk of ACL injury in the no-anticipation condition was increased in both sexes by changes in moments,increased ground reaction forces,increased knee valgus angle,and decreased knee flexion angle.2)The risk of injury was increased in females by the lack of braking and cushioning in the early stages of the landing,as well as by the weakening of muscle activation equilibrium in the female lower limb in the no-anticipation condition.
万方数据
维普
