Predictors of Return to Sports at 6 Months After Anterior Cruciate Ligament Reconstruction in Non-elite Athletes

Introduction: The return to sports (RTS) is a primary goal after anterior cruciate ligament reconstruction (ACLR) for most elite and non-elite athletes. The predictors and kinematic factors associated with the RTS are unclear. This study aimed to explore the predictors of RTS and the difference of knee kinematics between the RTS and non-RTS (nRTS) group in non-elite athletes. Methods This study was conducted with 41 non-elite athletes who underwent ACLR. The isokinetic test, single and triple hop tests, three-dimensional knee kinematics and the administration of two questionnaires [International Knee Documentation Committee (IKDC) and ACL-Return to Sport after Injury scale (ACL-RSI)] were conducted 6months after surgery. One year post-operatively, an interview and Tegner score were used to assign patients to RTS and nRTS groups. Multivariate logistic regression and receiver operating characteristic curve analyses were performed to identify the independent predictors of the RTS. Results Thirty (73%) patients were allocated to the RTS group and 11 (27%) were allocated to the nRTS group. Multivariate logistic regression showed that significant predictors of RTS (odds ratio/10-unit increase, P , cut-off value, sensitivity, specificity) were the single hop LSI (1.714, P  = 0.004; 84.4%, 0.867, 0.818), IKDC (1.486, P  = 0.015; 84.5, 0.867, 0.727), ACL-RSI (1.262, P  = 0.016; 53.8, 0.833, 0.818) and quadriceps LSI (1.137, P  = 0.012; 90.4%, 0.700, 0.818). Compared with the uninvolved limbs, the involved limbs in the nRTS group had larger external rotation angles at initial contact (IC; P  = 0.019) and maximum ( P  < 0.001), smaller flexion angle at IC ( P  = 0.01) and greater anteroposterior translation ( P  = 0.05) in stance phase. In the RTS group, only the flexion-extension range of motion differed significantly between limbs ( P  < 0.001). Conclusions Single hop test LSI, IKDC score, ACL-RSI score and quadricep strength at 6 months after ACLR were related to a greater likelihood of nRTS at 1 year after surgery in non-elite athletes. The nRTS group also displayed more asymmetrical gait behavior.