The influence of timing on outcomes following anterior cruciate ligament reconstruction in skeletally immature patients: A meta-analysis

Background and Aims: Anterior cruciate ligament (ACL) injuries in skeletally immature patients present a clinical challenge because knee stability must be restored while avoiding physeal injury and subsequent growth disturbance. Early ACL reconstruction (ACLR) may reduce secondary intra-articular damage, whereas delayed reconstruction has traditionally been considered to minimize physeal risk. This meta-analysis evaluated the influence of surgical timing on meniscal injury, graft failure, and growth disturbance following ACLR in skeletally immature patients. Materials and Methods: A systematic review and meta-analysis were performed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and registered in PROSPERO (CRD420251034702). Studies comparing early and delayed ACLR, or reporting relevant outcomes after early ACLR in skeletally immature patients, were included. Random-effects models were used to estimate pooled risk ratios (RRs), pooled proportions, 95% confidence intervals (CIs), and prediction intervals. Heterogeneity was assessed using I 2 and τ 2 statistics. Results: Twelve studies were included across the assessed outcomes. Compared with delayed reconstruction, early ACLR was associated with a significantly lower risk of adverse outcomes (RR = 0.56, 95% CI: 0.34–0.92, p = 0.02). The pooled proportion of meniscal injury identified at the time of ACLR was 48% (95% CI: 42–55%), supporting the concern that delayed surgery may increase concomitant meniscal damage. Graft failure occurred in approximately 17% of cases (95% CI: 2–32%), with substantial heterogeneity (I 2 = 98%). Growth disturbance was infrequent, with a pooled proportion of 4% (95% CI: 0–11%). Moderate heterogeneity (I 2 = 65%) was observed in the comparison of early versus delayed ACLR. Conclusion: Early ACLR in skeletally immature patients appears to provide protective benefit against secondary meniscal injury with a low pooled risk of growth disturbance when physeal-respecting techniques are used. However, variability in graft failure rates indicates that surgical timing should be individualized according to skeletal maturity, activity level, graft choice, surgical technique, and rehabilitation compliance. Larger prospective studies with standardized timing definitions and long-term follow-up are needed.