Influence of Isokinetic Muscle Strength Training Combined With Early Functional Exercise on Joint Function After Knee Cruciate Ligament Reconstruction

AIM: The purpose of this study was to evaluate and analyze the influence of isokinetic muscle strength training combined with early functional exercise on joint function after knee cruciate ligament reconstruction.METHODS: A total of 294 patients undergoing knee cruciate ligament reconstruction from January 2023 to June 2025 were retrospectively selected. Based on different exercise methods, 155 patients who received early functional exercise for 24 weeks were included in a control group (CG), and the other 139 patients receiving isokinetic muscle strength training (starting from the 4th week after surgery) combined with early functional exercise were enrolled as an experimental group (EG). After propensity score matching (PSM), 252 patients were retained for analysis, including 126 cases in the EG and 126 cases in the CG. The primary clinical outcomes encompassed International Knee Documentation Committee Subjective Knee Form (IKDCSKF) and Knee Injury and Osteoarthritis Outcome Score (KOOS) before training (T0) and at 8 weeks (T1), 12 weeks (T2) and 24 weeks (T3) after surgery, and the secondary outcomes included joint range of motion (ROM) and isokinetic muscle strength test results involving extensor peak torque (EPT), flexor peak torque (FPT) and hamstrings/quadriceps (H/Q).RESULTS: Repeated measures analysis of variance (ANOVA) revealed significant group × time interaction effects for both IKDCSKF and KOOS scores (both p < 0.001), indicating different improvement trajectories between the two groups. Significant time effects and group effects were also observed for both outcomes (both p < 0.001). Post hoc analysis with Bonferroni correction demonstrated that the EG group had significantly higher IKDCSKF and KOOS scores than the CG group at T1, T2, and T3 (p < 0.05 or p < 0.001), with more pronounced differences observed at T2 and T3 (all p < 0.001). At T3, EG had higher ROM, EPT, FPT and H/Q than CG (p < 0.001, p < 0.001, p < 0.001, p = 0.001). No significant difference was found in the proportion of patients with normal H/Q between the two groups (χ2 = 0.06, p = 0.798). The β (95% CI) for EG on IKDCSKF score was 4.35 (2.82~5.87), and the β (95% CI) on KOOS score was 5.22 (3.91~6.53).CONCLUSIONS: Isokinetic muscle strength training combined with early functional exercise was associated with greater improvement in joint function and knee flexor and extensor muscle strength in patients undergoing knee cruciate ligament reconstruction. In addition, the intervention protocol may be independently associated with the patient’s joint function.