Comparing Clinical Outcomes and Knee Stability in Remnant-Preserving ACL Reconstruction Versus Standard ACL Reconstruction: A Systematic Review and Meta-analysis.

Background: Anterior cruciate ligament reconstruction (ACLR) is one of the most frequently performed procedures in sports medicine, and undesirable outcomes still may range from 3-18%. One technique that has been explored to improve outcomes is preservation of the ACL remnant tibial stump, as opposed to stump debridement, at the time of reconstruction.

Purpose: To review current high-level evidence and compare remnant-preserving anterior cruciate ligament reconstruction (ACLR) versus standard ACLR in terms of clinical outcomes and measures of knee stability.

Hypothesis: ACLR with remnant preservation would result in improved clinical outcomes and knee stability measures.

Study design: Systematic review; Level of evidence, 2.

Methods: A systematic review of randomized controlled trials (RCTs) and cohort studies comparing remnant-preserving ACLR with standard ACLR with a minimum level of evidence of 2 was performed. Extracted data were summarized as general information, surgical characteristics, postoperative clinical outcomes, knee stability, graft evaluation, tunnel assessment, and postoperative complications. When feasible, a meta-analysis was performed.

Results: Seven RCTs and 5 cohort studies met the inclusion criteria. In total, 518 patients underwent remnant-preserving ACLR and 604 patients underwent standard ACLR. Ten studies performed the reconstruction with hamstring tendon (HT) autografts, 1 study with HT and bone-patellar tendon-bone autografts, and 1 study with HT and tibialis anterior allografts. On meta-analysis, remnant-preserving ACLR provided comparable outcomes with respect to International Knee Documentation Committee grades or Tegner scores. Even though there was a significant improvement in Lysholm scores (mean difference, -1.9; 95% CI, -2.89 to -0.91; P = .0002) with the remnant-preserving technique, this did not exceed previously reported minimal clinically important difference values. Remnant-preserving ACLR demonstrated superior knee stability in terms of patients achieving negative pivot shift when compared with the control group (88.89% vs 79.92%; P = .006). Although there was a significant improvement in the side-to-side difference in anterior tibial translation favoring remnant preservation (P = .004), the mean difference was 0.51 mm.

Conclusion: Remnant-preserving ACLR, primarily with HT autografts, results in comparable clinical outcome scores and significantly improved knee stability relative to standard ACLR without remnant preservation without increasing the complication rate. Further studies will help clarify if remnant-preserving ACLR also has benefits in terms of enhancing graft integration and maturation, improving proprioception, limiting tunnel enlargement, and reducing complications.