Functional and Psychological Factors Assessed at 6 Months Postoperatively Associated With a Successful Return to Sport 2 Years After Anterior Cruciate Ligament Reconstruction

Background: The rate of patients failing to return to preinjury sport at the preinjury level after anterior cruciate ligament (ACL) reconstruction remains high (42%-63%), despite the use of the limb symmetry index (LSI) in knee strength and functional tests as part of return-to-sport (RTS) decision-making. Purpose: To assess the ability of knee isokinetic strength and functional and psychological evaluations at 6 months after ACL reconstruction to predict successful RTS 2 years postoperatively. Study Design: Case series; Level of evidence, 4. Methods: Overall, 364 competitive athletes who underwent primary unilateral ACL reconstruction performed a battery of tests (ie, isokinetic, concentric, and eccentric strength of knee muscles; single, triple, crossover, and side hop tests for both lower limbs; and the Anterior Cruciate Ligament–Return to Sport after Injury [ACL-RSI] questionnaire) at 6 months postoperatively. The patients were contacted 2 years postoperatively to answer an RTS survey. The LSI, normalized performances of the strength and hop tests, conventional (concentric hamstring/concentric quadriceps) and functional ratios (eccentric hamstring/concentric quadriceps), and ACL-RSI score were included in a logistic regression to develop a predictive model for successful RTS (ie, returning to the preinjury sport at the preinjury level). Results: In total, 179 patients were included in the analysis, with 53% achieving a successful RTS. The predictive model for successful RTS included the conventional ratio (odds ratio [OR], 0.68; 95% CI, 0.46 to 1.01; P = .053), side hop test performance (OR, 2.02; 95% CI, 1.01-4.03; P = .047), and normalized performance on the single hop test (OR, 0.21; 95% CI, 0.07-0.64; P = .006) for the involved knee; the eccentric quadriceps strength (OR, 1.76; 95% CI, 1.13-2.75; P = .013), conventional ratio (OR, 1.63; 95% CI, 1.09-2.43; P = .016), and normalized performance on the single (OR, 0.41; 95% CI, 0.15-1.14; P = .087) and triple hop tests (OR, 4.53; 95% CI, 1.70-12.06; P = .003) for the uninvolved limb; and the ACL-RSI score (OR, 2.73; 95% CI, 1.77-4.22; P = .001). Conclusion: Functional symmetry between the involved and uninvolved knee was not predictive of successful RTS, but certain functional performances of the involved and uninvolved limbs, as well as psychological readiness, were predictive.