Functional Testing for Return-to-Sport Decision-Making After Anterior Cruciate Ligament Reconstruction: An Updated Narrative Review

Abstract

Return-to-sport (RTS) decision-making after anterior cruciate ligament reconstruction (ACLR) has moved away from time alone toward criterion-based models, yet the optimal composition of a functional testing battery remains debated. Functional tests are still essential because they quantify residual deficits in strength, power, neuromuscular control, balance, and confidence; however, contemporary evidence shows that no single test has adequate validity to clear an athlete independently. This updated narrative review synthesizes landmark cohort studies together with recent reviews, guidelines, and meta-analyses on functional RTS assessment after primary ACLR. The current literature indicates that hop tests remain clinically valuable, especially the single-leg hop for distance, crossover hop, 6-m timed hop, and single-leg vertical hop, but isolated pass/fail thresholds show inconsistent ability to predict second injury or successful RTS. Quadriceps strength remains indispensable, although limb symmetry index (LSI) should not be interpreted without consideration of absolute strength, time since surgery, graft type, sex, and possible deconditioning of the contralateral limb. Movement-quality assessments during landing, single-leg squat, or change-of-direction tasks may reveal high-risk patterns that distance-based tests miss. Psychological readiness, most commonly assessed with the ACL-Return to Sport after Injury scale, is another core domain because fear of reinjury and low confidence often persist despite acceptable physical scores. Importantly, recent evidence shows that RTS testing is commonly administered around 7 months post-operatively, which is earlier than timelines associated with lower reinjury risk in pivoting sports. A contemporary RTS strategy should therefore rely on a domain-based battery combining clinical status, strength testing, at least two hop or jump tasks, movement-quality assessment, patient-reported outcomes, and psychological readiness. For unrestricted return to level I pivoting sports, final clearance is best delayed until at least 9 months after surgery and only after satisfactory performance is demonstrated across domains.