Early implementation of hamstring isokinetic eccentric exercise and its effects on knee function,biomechanics,and graft morphology in patients after anterior cruciate ligament reconstruction

Zhou Jingjing; Deng Haipeng; Cui Haidong; Zhou Jingjie; Jiao Daiyan; Zhang Jianping; Yu Min

doi:10.11986/j.issn.1673-873X.2025.06.13

Abstract：Objective To investigate the effects of early hamstring isokinetic eccentric exercise(IEE)on knee joint function,graft morphology,and biomechanics in patients after anterior cruciate ligament reconstruction(ACLR).Methods From January 2022 to March 2024,44 patients undergoing postoperative rehabilitation after ACLR at the Department of Rehabili-tation,Haian People's Hospital were enrolled and randomly assigned to a study group(n=22)and a control group(n=22).The control group received standard early postoperative care including exercise therapy;the study group received the same basic treatment and,beginning at 6 weeks postoperatively,an additional 12-week course of IEE.Assessments were performed at 6 weeks and 18 weeks postoperatively.The International Knee Documentation Committee(IKDC)Subjective Knee Evaluation Form was used to assess ACL injury/deficit;the Lysholm Knee Scoring Scale(LKS)was used to evaluate knee function and morphology.Peak torque(PT)and total work(TW)were measured for quadriceps concentric contraction and hamstring eccentric contraction.The coefficient of variation(CV)of knee joint torque during contractions of the quadri-ceps and hamstrings was measured when electromyographic activity reached 60％of maximum.Tibial anterior translation under a 20-lb load was measured to evaluate graft laxity in the affected limb.Results At 6 weeks postoperatively,no signif-icant differences between groups in IKDC or LKS scores were noted(P＞0.05).At 18 weeks postoperatively,IKDC and LKS scores in both groups had increased significantly compared with 6 weeks,and the study group's scores were significant-ly higher than those of the control group(P＜0.05).At 6 weeks,there were no significant between-group differences in quadriceps concentric PT and TW or hamstring eccentric PT and TW(P＞0.05).At 18 weeks,quadriceps concentric PT and TW and hamstring eccentric PT and TW in both groups had increased significantly relative to 6 weeks,and the study group's values were significantly greater than the control group's(P＜0.05).At 6 weeks,there were no significant differ-ences between groups in the CV of knee torque during quadriceps and hamstring contractions(P＞0.05).At 18 weeks,CVs for knee torque during quadriceps and hamstring contractions(except for quadriceps CV in the control group)had de-creased significantly compared with earlier values,and the study group's CVs were significantly lower than the control group's(P＜0.05).At 6 weeks,graft laxity did not differ significantly between groups(P＞0.05);at 18 weeks,graft lax-ity in the study group had increased significantly compared with earlier measurement(P＜0.05).Conclusion Early imple-mentation of IEE after ACLR can safely and effectively strengthen patients' knee function and enhance the stability of the knee extensor activity during extension.