Remnant Preservation in Anterior Cruciate Ligament Reconstruction Versus Non-Preservation Methods: A Systematic Review and Meta-Analysis.

To manage anterior cruciate ligament (ACL) injury, both remnant-preserving anterior cruciate ligament reconstruction (ACLR) and standard ACLR without remnant preservation are applied. This study aims to systematically evaluate clinical outcomes of remnant-preserving versus standard ACLR techniques by analyzing randomized controlled trials (RCTs). The PubMed, Embase, and Cochrane Library databases were used to identify studies published from January 2000 to November 2024. Based on the PICOS framework, we systematically reviewed RCTs in which patients with ACL injuries compared ACLR with remnant preservation versus standard ACLR in terms of International Knee Documentation Committee (IKDC) score, Lysholm score, Lachman test, pivot shift test, KT1000/2000 arthrometer side-to-side difference (SSD), synovial coverage, proprioception evaluation, cyclops lesion, and range of motion (ROM). Data were pooled using the random-effects model or fixed-effects model, based on the heterogeneity. The quality of the included literature was assessed based on the Cochrane Risk of Bias tool (ROB 2.0), and the GRADE criteria were applied to rate evidence quality for key outcomes. Review Manager 5.4 and Stata 15 were used for the statistical analyses. The relative risk (RR) was used for dichotomous data, and the mean difference (MD) was used for continuous variable data. Both types of indicators were expressed as 95% confidence intervals (CIs). The minimal clinically important difference (MCID) was adopted to determine whether patients improved enough clinically to notice a difference. Subgroup analyses were conducted for outcomes failing to reach MCID thresholds in order to examine potential modifiers of different follow-up durations and remnant preservation techniques. A total of 10 studies were included in the qualitative review and meta-analysis. Although there were statistically significant differences between the remnant preservation group and the standard technique group in favor of the remnant preservation technique with respect to postoperative Lysholm score (MD 1.44; 95% CI, 0.60-2.29; I = 23%; p < 0.01) (GRADE: Moderate), SSD (MD -0.57; 95% CI, -0.98 to -0.15; I = 86%; p < 0.01) (GRADE: Low) and proprioception recovery (MD -0.57; 95% CI, -0.83 to -0.31; I = 0%; p < 0.01) (GRADE: Low), these observed differences are so small that they are unlikely to be clinically relevant. No differences were found in other clinical outcomes between the two groups. The follow-up duration and remnant preservation techniques were not identified as the key factors influencing the differences between remnant preservation ACLR and standard ACLR. No clinically meaningful benefit in postoperative knee stability or function; remnant preservation may be considered primarily when technical feasibility is high and remnant quality is optimal. This is achieved without increasing the risk of cyclops lesions and deficiency of ROM.