The Timing of Return to Sports after Anterior Cruciate Ligament Reconstruction in Elite Athletes: A Study Based on Isokinetic Knee Muscle Strength and Multiple Hop Tests / 中国运动医学杂志

ABSTRACT

Objective To compare the knee function recovery at different times of returning to sport after anterior cruciate ligament reconstruction(ACLR) among elite athletes using knee isokinetic muscle strength test and various hop test.Methods Forty-one elite athletes(14 males,27 females,mean age 22.6 ± 4.1 years) undergoing ACLR between January 2013 and September 2014 were chosen from the database of the National Institute of Sports Medicine and Shanghai Huashan Hospital.Rehabilitation was performed using the same protocol by professional physiotherapists and trainers,who recorded the time of returning to sport of each athlete.One week prior to the scheduled return,bilateral knee isokinetic muscle strength test(test valuepeak torque;angle velocity60°/s,180°/s;motionflexion,extension) and four hop tests(single hop for distance,side-to-side hop,up-down hop and 8 hop) were applied with the limb symmetry index(LSI) calculated.The athletes were then grouped by their returntime referring to surgery into the premature group(6～8 months),timely return group(9～12 months) and delayed group(over 12 months).The tests results were recorded and compared among the three groups.Results Fourteen athletes were selected into the premature group,with 19 in the timely group and 8 in the delayed group.The average LSI of 60°/s flexion peak torque of the premature group (87.4％ ± 7.5％) was significantly lower than the timely group(95.8％ ± 6.6％) and the delayed group(96.0％ ± 2.4％) (P＜0.01).Significant differences were observed between the premature group and delayed group regarding the 60° extension peak torque(85.8％ ± 9.4％ and 94.8％ ± 4.8％,P＜0.05),180°/s flexion peak torque(90.7％ ± 8.7％ and 101.4％ ± 6.8％,P＜0.05),and 180°/s extension peak torque (90.6％ ± 5.2％ and 97.8％ ± 5.6％,P＜0.05).The average LSL of the premature group at single hop for distance,side-to-side hop and up-down hop(93.A％ ± 8.5％,84.7％ ± 7.3％ and 112.5％ ± 5.7％) was significantly lower than that of the timely group(95.7％ ± 6.0％,104.2％ ± 4.3％ and 105.3％ ± 7.9％) and the delayed group regarding(98.1％ ± 1.9％,104.7％ ± 4.0％ and 106.3％ ± 7.4％) (P＜0.01 for all).The relative peak torque of 60°/s extension of the premature group(2.48 ± 0.58 Nm/kg) was significantly lower than the delayed group(3.21 ± 0.51 Nm/kg) (P＜0.01).Conclusions For elite athletes,returning to sport within 9 months after ACLR results in insufficient restoration of the knee function.Delayed return to sport doesn't improve the outcomes of hop tests,but can enhance the maximum extension torque peak,which needs further study.