The statistical fragility of randomized controlled trials comparing hip arthroscopy to conservative management for the treatment of femoroacetabular impingement syndrome

Abstract The fragility index (FI) assesses the robustness or fragility of statistically significant results in randomized controlled trials (RCTs), but is limited to dichotomous outcomes. The continuous FI (CFI) extends this concept to continuous outcomes. This is particularly relevant when comparing hip arthroscopy (HA) and conservative management or physical therapy (PT) for the treatment of femoroacetabular impingement syndrome (FAIS), which commonly demonstrates significantly higher improvement in patient-reported outcomes among surgical intervention arms in comparison to conservative management. The study aimed to identify RCTs comparing outcomes after HA or conservative management for FAIS and characterize the fragility of statistically significant results. PubMed, Embase, Cochrane, and ClinicalTrials.gov were utilized for RCT search. The Cochrane risk-of-bias tool for randomized trials was used to assess the risk of bias. RCTs were included if (1) they contained a HA and conservative management or PT arm, and (2) reported ≥ one statistically significant outcome. CFI and FI were calculated for significant continuous and categorical outcomes, respectively. Five RCTs met inclusion criteria. Risk of bias was ‘low’ in 2 RCTs and ‘some concerns’ in 3 RCTs. The mean CFI was 15.84 (range, 8.8–28.4). The mean dichotomous FI was 3.5 (range, 1–6). Loss to follow-up exceeded calculated CFI or FI in 2 of the 5 RCTs. These findings may provide surgeons with greater confidence that HA can have superior clinical outcomes compared to PT, particularly when considering HA as a treatment option following unsuccessful conservative management. Meta-Analysis; Level of Evidence, 2.