Longitudinal Quadriceps Strength Recovery After Anterior Cruciate Ligament Reconstruction With Hamstring Autograft: Patients Stratified by Preoperative Quadriceps Strength Deficit

Context:Some studies have discussed postoperative quadriceps strength recovery after anterior cruciate ligament reconstruction (ACLR). However, the effect of preoperative quadriceps strength deficit on longitudinal postoperative quadriceps strength recovery after ACLR with hamstring autograft is unknown.Objective:To reveal the longitudinal postoperative quadriceps strength recovery after ACLR with hamstring autograft among patient groups stratified by preoperative quadriceps strength deficit.Design:Retrospective cohort study.Setting:Single center.Patients:In total, 420 patients (222 men and 218 women; age at the time of surgery 23.1 [8.9] y) who underwent ipsilateral ACLR with hamstring autograft and completed knee function tests preoperatively and 3, 6, and 12 months postoperatively were included in this study.Intervention:The authors measured quadriceps strength at 60°/s, tested 1-leg hop performance (distance and anxiety), and calculated the quadriceps strength index (QSI) and limb symmetry index for 1-leg hop distance. Patients were divided into the following 4 groups according to their preoperative QSI: >80% (Excellent group), 80% to 60% (Good group), 60% to 40% (Moderate group), and ≤40% (Poor group).Main Outcome Measures:Postoperative QSI at 3, 6, and 12 months and 1-leg hop performance at 12 months after the surgery.Results:The Excellent group had the highest postoperative QSI at all periods. Based on the 1-leg hop performance, the Poor group had the lowest limb symmetry index and significantly greater anxiety during jump performance in comparison with the Excellent and Good groups.Conclusion:The present study shows a longitudinal recovery process and the average postoperative quadriceps strength after ACLR with hamstring autograft in patient groups stratified by preoperative QSI. The results indicate that the difference in preoperative QSI affects not only the longitudinal postoperative QSI recovery but also high-level 1-leg hop performance after ACLR using hamstring autograft.