Are Comparable Short-term Outcomes Between Hamstring and Quadriceps Tendon Autografts for ACL Reconstruction Statistically Robust? A Reverse Continuous Fragility Index Analysis of Randomized Controlled Trials

Abstract

Background: Randomized controlled trials (RCTs) and meta-analyses have generally reported comparable short-term outcomes between hamstring tendon (HT) and quadriceps tendon (QT) autografts for anterior cruciate ligament reconstruction (ACLR). However, the statistical robustness of these nonsignificant continuous outcomes remains unclear. Purpose/Hypothesis: To evaluate the robustness of nonsignificant continuous outcomes in RCTs comparing HT and QT autografts for ACLR using the reverse continuous fragility index (rCFI). It was hypothesized that these outcomes would demonstrate statistical robustness. Study Design: Systematic review; Level of evidence, 1. Methods: A systematic search of PubMed, Embase, and the Cochrane Library was performed according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines from database inception to April 2026. Level 1 RCTs comparing HT and QT autografts for primary adult ACLR were included if they reported ≥1 nonsignificant continuous outcome with sufficient summary statistics for rCFI calculation. The primary analysis evaluated nonsignificant primary continuous outcomes at the longest available follow-up. rCFI values were calculated using pseudoindividual data sets generated from published summary statistics and were compared with loss to follow-up. Reverse continuous fragility quotients were also calculated. Sensitivity analysis using 20 simulation seeds assessed estimate stability. Results: Eight RCTs including 562 allocated patients were included. At the follow-up time point used for primary analysis, 482 patients were available, with an overall loss to follow-up of 80 patients. Six studies reported nonsignificant primary continuous outcomes eligible for rCFI analysis. The mean rCFI was 17.4 ± 7.3, and the mean reverse continuous fragility quotient was 0.296 ± 0.069. All eligible primary outcomes had rCFI values greater than the corresponding loss to follow-up, and sensitivity analysis showed stable findings. Among 21 eligible secondary outcomes, 19 had rCFI values greater than loss to follow-up. Conclusion: Nonsignificant primary continuous outcomes in RCTs comparing HT and QT autografts for ACLR demonstrated statistical robustness. These findings support the stability of randomized evidence showing comparable short-term continuous outcomes between HT and QT autografts.