Background: 

Despite the most recent American Academy of Orthopaedic Surgeons clinical practice guideline making a “strong” recommendation against the use of intraoperative navigation in total knee arthroplasty (TKA), its use is increasing. We utilized the concept of the reverse fragility index (RFI) to assess the strength of neutrality of the randomized controlled trials (RCTs) comparing the long-term survivorship of computer-navigated and conventional TKA.

Methods: 

A systematic review was performed including all RCTs through August 3, 2021, comparing the long-term outcomes of computer-navigated and conventional TKA. Randomized trials with mean follow-up of >8 years and survivorship with revision as the end point were included. The RFI quantifies the strength of a study’s neutrality by calculating the minimum number of events necessary to flip the result from nonsignificant to significant. The RFI at a threshold of p < 0.05 was calculated for each study reporting nonsignificant results. The reverse fragility quotient (RFQ) was calculated by dividing the RFI by the study sample size.

Results: 

Ten clinical trials with 2,518 patients and 38 all-cause revisions were analyzed. All 10 studies reported nonsignificant results. The median RFI at the p < 0.05 threshold was 4, meaning that a median of 4 events would be needed to change the results from nonsignificant to significant. The median RFQ was 0.029, indicating that the nonsignificance of the results was contingent on only 2.9 events per 100 participants. The median loss to follow-up was 27 patients. In all studies, the number of patients lost to follow-up was greater than the RFI.

Conclusions: 

The equipoise in long-term survivorship between computer-navigated and conventional TKA rests on fragile studies, as their statistical nonsignificance could be reversed by changing the outcome status of only a handful of patients––a number that was always smaller than the number lost to follow-up. Routine reporting of the RFI in trials with nonsignificant findings may provide readers with a measure of confidence in the neutrality of the results.

Level of Evidence: 

Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

中文翻译：

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反向脆弱性指数：解读当前关于计算机导航与传统 TKA 长期生存的文献：随机对照试验的系统回顾和横断面研究

背景： 

尽管最新的美国骨科医师学会临床实践指南提出“强烈”建议反对在全膝关节置换术 (TKA) 中使用术中导航，但其使用仍在增加。我们利用反向脆弱性指数 (RFI) 的概念来评估随机对照试验 (RCT) 的中立强度，这些试验比较了计算机导航和传统 TKA 的长期生存率。

方法： 

对截至 2021 年 8 月 3 日的所有 RCT 进行了系统回顾，比较了计算机导航和传统 TKA 的长期结果。随机试验平均随访 > 8 年，以翻修为终点的生存率被纳入。RFI 通过计算将结果从不重要变为重要所需的最小事件数来量化研究中立性的强度。为报告非显着结果的每项研究计算阈值为 p < 0.05 的 RFI。通过将 RFI 除以研究样本量来计算反向脆弱性商数 (RFQ)。

结果： 

分析了 2,518 名患者的 10 项临床试验和 38 项全因修正。所有 10 项研究均报告了无显着性的结果。p < 0.05 阈值的 RFI 中位数为 4，这意味着需要 4 个事件的中位数才能将结果从不显着变为显着。RFQ 中位数为 0.029，表明结果的不显着性取决于每 100 名参与者中仅 2.9 起事件。中位失访患者为 27 名患者。在所有研究中，失访患者数量均大于 RFI。

结论： 

计算机导航和传统 TKA 之间长期生存率的平衡取决于脆弱的研究，因为它们的统计意义可以通过仅改变少数患者的结果状态来逆转——这个数字总是小于失去的人数跟进。在发现不显着的试验中定期报告 RFI 可能会让读者对结果的中立性有一定程度的信心。

证据等级： 

预后二级。有关证据等级的完整描述，请参阅作者须知。