Remnant-preserving techniques in anterior cruciate ligament reconstruction: a systematic review and meta-analysis

Background Anterior cruciate ligament reconstruction (ACLR) is a widely performed procedure to restore knee function and stability. Remnant-preserving techniques have been proposed to improve postoperative outcomes by retaining the proprioceptive and biological benefits of the ACL remnant. Remnant preservation is hypothesized to enhance graft integration and proprioceptive restoration. This systematic review and meta-analysis aimed to evaluate the surgical and functional outcomes of remnant-preserving ACLR compared to standard ACLR. Methods A systematic search of PubMed, Embase, Web of Science, and the Cochrane Library was conducted on November 6, 2024, adhering to PRISMA guidelines. Eligible studies included randomized controlled trials (RCTs) and cohort studies that compared remnant-preserving ACLR with standard ACLR. Outcomes assessed included functional scores (Lysholm and IKDC), knee stability (KT-1000/2000 measurements), and complication rates. Quality assessment was performed using the Newcastle-Ottawa Scale for cohort studies and the Cochrane Risk of Bias tool for RCTs. Statistical analyses utilized fixed- or random-effects models based on heterogeneity. Results The meta-analysis included 10 studies, comprising 6 RCTs and 4 cohort studies. Remnant-preserving ACLR demonstrated significant improvements in Lysholm scores (WMD = 0.85; 95% CI, 0.29-1.42; P < 0.05) and knee stability (RCTs: WMD = -0.45; 95% CI, -0.62 to -0.27; P < 0.01; cohort studies: WMD = -0.42; 95% CI, -0.62 to -0.23; P < 0.01). No significant difference was observed in IKDC scores (WMD = -0.21; 95% CI, -1.68 to 1.26; P > 0.05) or complication rates (RR = 1.16; 95% CI, 0.77-1.76; P > 0.05). Publication bias was not detected. Conclusions Remnant-preserving ACLR provides superior functional outcomes and knee stability compared to standard ACLR without increasing complication rates. These findings support the adoption of remnant-preserving techniques in clinical practice. Further research is needed to assess long-term outcomes and refine patient selection criteria.