Knee Biomechanical Characteristics Of Side-cutting For Rugby Players And The Research On ACL Rehabilitation Theroy

Objective:The purpose of the study is to identify the biomechanics characteristics of rugby player for side-cutting, to analysis the injury mechanism of the knee for rugby players. It focuses on analysis of the mechanism of ACL injury. The study tries to find the biomechanical cause for the higher ACL injury incidence of female rugby players;Methods:There are 36 subjects paticipatedt in the study, including 24 female athletes,12 male athletes, including 14 female elite athletes ofnational team,12 elite male players of national team,10 ordinary female athletes. Normal female group (NF) with 10 athletes, elite female group (EF)with 14 athletes, and 12 elite male group (EM), EF group is individed as control group (CON) and rehalibation group(REF) for 7 athletes. The instrumentations include Qualisys motion capture system, and 8 channel NORAXON wireless EMG system.Results:Landing time:hip flexion, knee valgus angle of the EF group are significantly greater than that EM group (P<0.05). Hip flexion angle for group NF is higher than that in group EF, the knee valgus angle of the EM is higher than that of group EF (P<0.05). REF group hip varus moment, flexion angles greater than the group CON, hip flexion moment and knee valgus angleof the group REF for are smaller than that of group CON (P<0.05). Peak time:Hip flexion and knee flexion angle of the EF group are less than EM group (P< 0.05), hip varus, hip internal rotation and knee valgus angle are significantly greater than the EM group (P< 0.05). For the group NF, peak flexion angle of the hip joint was significantly lower than the group EF (P<0.05). Hip flexion angle and knee varus moment of the group REF are less than the group CON (P< 0.05). There was significant difference inthe contribution rate between the group EM and the group EF (P<0.05). The EMG activity of group EF is higher than that of group NF (P<0.01). The EMG activity for the rectus muscle and the lateral rectus muscle of the REF group are lower than that of the group CON (P<0.05). CI:H/Q and LG/LH co-contraction index of the EM group were higher than that of EF group. H/Q co-contraction index of the EF group is lower than that of NF group (P< 0.05). Quadriceps RMS ratio: EM group Quadriceps RMS mean ratio is significantly higher than that of EF group (P< 0.05). the RMS ratio of the group REF compared with group CON has been significantly improved (P<0.05). Peak FACL and sagital Peak FACL of the EF group is higher than that of the EM group.Peak FACL and sagital Peak FACL of the EF group is higher than that of the REF group (P<0.05)Conclusions:1) The biomechanics characteristics of lower limb have significant gender difference and competitive level difference for the rugby players.2) The flexion Angle of hip and knee are the important risk factors for the ACL injury.3) ACL injury risk of female rugby athlete is higher than male rugby athlete. During the stance, Peak FACL and sagital Peak FACL of the female player is higher than that of the male player.4) Different levels of female rugby athlete for ACL injury risk is not clear.5) the earlier stance stage of the side cutting (< 30%), the ACL injury incidence is high heavily.6) PEP injury prevention programs can improve effectively lower limb biomechanical indexes of the female rugby athlete.