Clinical Study Of Flexion And Extension Muscle Strength And Motor Function Of The Knee Joint After Anterior Cruciate Ligament Reconstruction

Objective:To observe the degree of quadriceps and hamstring strength recovery and related the findings to functional performance of anterior cruciate ligament reconstruction using semitendonosus and gracilis(STG)as a autograft.So as to better guide the rehabilitation of patients with anterior cruciate ligament reconstruction.Methods:150 patients with anterior cruciate ligament injuries participated in this study.Extension and flexion torques were measured for the injured and healthy limbs at speeds of 60°per second approximately 3,6,9 and 12 months after anterior cruciate ligament reconstruction,and calculate the quadriceps strength symmetry index(Q-LSI),Hamstring/Quadriceps(H/Q)ratio;Functional assessment include the single hop test,the 6-m timed hop test,crossover hop test and the side-to-side hop test,and were measured respectively at 6 and 12 months after anterior cruciate ligament reconstruction.The changes of muscle strength and motor function with time were analyzed and evaluated.Results:Of the 150 patients,only 118 patients completed all tests,32 patients(21.3 3%)lost to follow up.The average quadriceps strength at 3,6,9 and 12 months after anterior cruciate ligament reconstruction was 64.01±4.45%,77.97±5.04%,84.25±5.14% and 86.98±5.28%,respectively.The average hamstring strength at 3,6,9,and 12 months after anterior cruciate ligament reconstruction was 81.58±3.12%,91.06±3.72%,96.48±3.87% and 97.59±3.77%,respectively.After repeated measurement test confirmed that the flexor extensor strength gradual recovery with time(F=27.231,P=0.000;muscle strength recovers quickly during the 3 to 6 months(P<0.05);quadriceps strength of involved is still significantly lower than the uninvolved limb after ACLR 12 months(P<0.05),And hamstring muscle is not significant difference of the uninvolved limb after ACLR 12 months(P>0.05).At 3,6,9 and 12 months,H/Q ratios were significantly higher than uninjured limb(P<0.05);ACLR 6th month after operation the single hop test,crossover hop test,the side-to-side hop test and the 6-m timed hop test were lower than uninjured limb 90%;12th month after operation,the single hop test and the 6-m timed hop test were more than uninjured limb 90%,but crossover hop test and the side-to-side hop test were still lower than uninjured limb 90%.Conclusions:(1)At twelfth months after anterior cruciate ligament reconstruction,the flexor muscle strength of the knee was basically restored to normal after anterior cruciate ligament reconstruction.(2)At 12 months after anterior cruciate ligament reconstruction,the extensor strength of the knee does not return to normal after anterior cruciate ligament reconstruction.(3)The best time to recover the flexor and extensor muscle strength of the affected limb after anterior cruciate ligament reconstruction is 3 to 6 months after operation.(4)At 12 after anterior cruciate ligament reconstruction,the hamstring/quadriceps(H/Q)strength ratios and sports ability of the patients were not completely restored to normal.