Summary

The quadriceps tendon is becoming a popular graft choice for anterior cruciate ligament reconstruction, however randomized controlled trials comparing this graft option with others are statistically fragile.

Abstract

Purpose

Fragility index is described as the minimum number of patients whose status would have to change from a non-event to an event required to turn a statistically significant result into a nonsignificant result and is a metric to assess the robustness of randomized controlled trials (RCTs). There has been a significant increase in interest in the use of the quadriceps tendon (QT) autograft in anterior cruciate ligament reconstruction (ACLR) in the form of RCTs. Therefore, this systematic review aimed to determine the statistical fragility of randomized controlled trials (RCTs) which compare the use of quadriceps tendon (QT) autografts to either hamstring tendon (HT) or bone-patellar tendon-bone (BPTB) autografts in anterior cruciate ligament reconstruction (ACLR).

Methods

A search was conducted across PubMed, MEDLINE, and EMBASE databases for RCTs comparing QT autografts to HT or BPTB autografts in ACLR from inception to April 21st, 2024.The authors adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and Revised Assessment of Multiple Systematic Reviews (R-AMSTAR) guidelines and Cochrane Handbook for Systematic Reviews of Interventions. Studies that reported ≥1 statistically significant continuous outcome, statistically significant dichotomous outcome, and/or non-significant dichotomous outcome were included for analysis. The fragility index (FI), continuous fragility index (CFI), and reverse fragility index (RFI) were calculated for significant dichotomous outcomes, significant continuous outcomes, and non-significant dichotomous outcomes, respectively.

Results

A total of 11 RCTs comprising 716 patients were included. The mean sample size was 65.8 patients. The median FI amongst nine outcomes from four studies was 1.0 (Interquartile range [IQR], 0.5; 95% confidence interval [CI], 0.6–1.4; range 0.5–1.5). The number of patients lost to follow-up at the final follow-up period was more than the study-specific FI in three (75%) studies. The median CFI amongst thirty outcomes from six studies was 4.9 (IQR, 10.1, 95% CI, 3.9–8.2; range 0–18.2). The number of patients lost to follow-up at the final follow-up period was more than the study-specific CFI in four (66.7%) studies. The median RFI amongst ten outcomes from five studies was 5.0 (IQR, 3.5; 95% CI, 3.4–6.6; range 1.0–9.0). The number of patients lost to follow-up at the final follow-up period was more than the study-specific RFI in four (80%) studies.

Conclusion

This systematic review revealed that regardless of the metric used, RCTs comparing QT autografts to HT or BPTB autograft options in ACLR are statistically fragile. While the indices of statistical fragility evaluated in this study are important metrics of robustness to consider, their application in research and clinical practice needs to be further elucidated.