Randomized controlled trials evaluating high tibial osteotomy for osteoarthritis are fragile: A systematic review

High tibial osteotomy (HTO) is a procedure meant to address knee malalignment and delay a total knee arthroplasty in patients with osteoarthritis. In this study we used the fragility index (FI), reverse fragility index (rFI), and fragility quotient (FQ) to determine the robustness of outcomes reported in RCTs assessing management of osteoarthritis with HTO.

PubMed, Embase, and MEDLINE were queried for RCTs January 1, 2010-October 1, 2023 relating to treatment of osteoarthritis with HTO. We then screened for RCTs with two arms assessing surgical management of osteoarthritis with HTO. The FI and rFI were defined as the number of outcome reversals required to alter statistical significance for significant and non-significant outcomes, respectively. The FQ was determined by dividing the FI by the sample size of each study. Subgroup analysis was performed based on the outcome category.

Of 256 articles screened, 21 RCTs were ultimately included in our analysis. The median FI for the 158 total outcomes was 4 (IQR 3-6) with an associated median FQ of 0.083 (IQR 0.043-0.121). For 20 statistically significant outcomes, the median FI was 3 (IQR 1-8.25) with an associated median FQ of 0.053 (IQR 0.022-0.013). For 138 nonsignificant outcomes the median rFI was 4 (IQR 3-6) with a median rFQ of 0.083 (IQR 0.05-0.120). There were 6 studies comparing outcomes in open wedge vs closed wedge tibial osteotomies. The median FI for these studies was 5 (IQR 3-6) and the median FQ was 0.065 (IQR 0.037-0.1). Complications were the most common outcome type reported with a median FI of 4 (IQR 3-6) across 100 outcomes. The most fragile outcome category was limb length discrepancy, with a median FI of 1.5 (IQR 1-3.25). This was followed by hardware complication (median FI 2), post-op ambulatory ability (median FI 3.5), and progression of OA (median FI 4). The most stable outcome categories were clinical score/clinical improvement (median FI 8) and re-operation/intervention (median FI 9.5).

The outcomes in RCTs evaluating HTOs demonstrate statistical fragility, with results comparable to other orthopedic RCTs. The reversal of minimal outcome events was sufficient to alter outcome significance. Reporting results which combine P-values with FI and FQ can provide additional insights into the stability of reported outcomes, providing increased transparency for clinicians.