Objective

A growing body of evidence demonstrates instability of reported outcomes within the orthopaedic literature. The purpose of this study was to utilize fragility analysis to assess the robustness of randomized controlled trials evaluating the management of articular cartilage defects of the knee. We hypothesize the cartilage restorative literature will be fragile with the reversal of only a few outcome events required to change statistical significance.

Design: Randomized controlled trials (RCTs) from prominent orthopaedic journals indexed on PubMed from 2000-2020 that reported dichotomous outcome measures relating to the management of articular cartilage defects of the knee were included. The Fragility Index (FI) for each outcome was calculated through the iterative reversal of a single outcome event until significance was reversed. The Fragility Quotient (FQ) was calculated by dividing each FI by study sample size. Additional statistical analysis was performed to provide median FI and FQ across subgroups.

Results

Nineteen RCTs containing 60 dichotomous outcomes were included for analysis. The FI and FQ of all outcomes was 4 (IQR 2-7) and 0.067 (IQR 0.034-0.096), respectively. The average number of patients lost to follow up (LTF) was 3.9 patients with 15.8% of the included studies reporting LTF greater than or equal to 4, the FI of all included outcomes.

Conclusions

The orthopaedic literature evaluating articular cartilage defects of the knee is fragile as the reversal of relatively few outcome events may alter the significance of statistical findings. We therefore recommend comprehensive fragility analysis and triple reporting of the P value, FI and FQ to aid in the interpretation and contextualization of clinical findings reported in the cartilage restoration literature.

Keywords: articular cartilage; knee; fragility index; fragility quotient; P value; cartilage restoration; statistical significance