Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2023 Aug;31(8):3412-3419.
doi: 10.1007/s00167-023-07420-0. Epub 2023 Apr 24.

The reverse fragility index: RCTs reporting non-significant differences in failure rates between hamstring and bone-patellar tendon-bone autografts have fragile results

Verdinand C B Ruelos #  1 , Raisa Masood #  2 , Richard N Puzzitiello  2 , Michael A Moverman  2 , Nicholas R Pagani  2 , Mariano E Menendez  3 , Matthew J Salzler  4
Affiliations

The reverse fragility index: RCTs reporting non-significant differences in failure rates between hamstring and bone-patellar tendon-bone autografts have fragile results

Verdinand C B Ruelos et al. Knee Surg Sports Traumatol Arthrosc. 2023 Aug.

Abstract

Purpose: The reverse fragility index (RFI) is a novel metric to appraise the results of studies reporting statistically non-significant results. The purpose of this study was to determine the statistical robustness of randomized controlled trials (RCTs) reporting non-significant differences in anterior cruciate ligament reconstruction (ACLR) graft failure rates, defined as re-rupture/revision ACLR rate, between hamstring tendon (HT) and bone-patellar tendon-bone (BTB) autografts by calculating RFIs.

Methods: A systematic review was performed to identify RCTs that compared HT to BTB grafts for ACLR through January 2022. Studies reporting non-significant differences in graft re-rupture and revision ACLR rate (n.s.) were included. The RFI, defined as the fewest number of event reversals needed to change the non-significant graft re-rupture/revision outcome to statistically significant (P < 0.05), was recorded for each study. In addition, the number of studies in which the loss to follow-up exceeded the RFI was recorded.

Results: Among the 16 included RCTs, the median (interquartile range [IQR]) sample size was 71 (64-114), and the median (IQR) total number of graft re-rupture/revision ACLR events was 4 (4-6). The median (IQR) graft re-rupture/revision ACLR rate was 4.3% (3.0-6.4) overall, 4.1% (2.6-6.7) in the BTB group, and 5.4% (3.0-6.3) in the HT group. The median (IQR) RFI was 3 (3-4), signifying that a reversal of the outcome in 3 patients in one arm was needed to flip the studies' result from non-significant to statistically significant (P < 0.05). The median (IQR) number of participants lost to follow-up was 11 (3-13), and 13 (81.3%) of the included studies had a loss to follow-up greater than the studies' RFI.

Conclusion: The results of RCTs reporting statistically non-significant re-rupture/revision ACLR rates between HT and BTB autografts would become significant if the outcome were reversed in a small number of patients-a number that was less than the loss to follow-up in the majority of studies. Thus, the neutrality of these studies is fragile, and a true statistically significant difference in re-rupture/revision rates may have been undetected.

Level of evidence: Level I.

Keywords: ACL reconstruction; Graft selection; Reverse fragility index; Sports.

PubMed Disclaimer

References

    1. Ahmed W, Fowler RA, McCredie VA (2016) Does sample size matter when interpreting the fragility index? Crit Care Med 44(11):e1142–e1143 - PubMed - DOI
    1. Aune AK, Holm I, Risberg MA, Jensen HK, Steen H (2001) Four-strand hamstring tendon autograft compared with patellar tendon-bone autograft for anterior cruciate ligament reconstruction. A randomized study with two-year follow-up. Am J Sports Med 29(6):722–728 - PubMed - DOI
    1. Barenius B, Nordlander M, Ponzer S, Tidermark J, Eriksson K (2010) Quality of life and clinical outcome after anterior cruciate ligament reconstruction using patellar tendon graft or quadrupled semitendinosus graft: an 8-year follow-up of a randomized controlled trial. Am J Sports Med 38(8):1533–1541 - PubMed - DOI
    1. Biau DJ, Tournoux C, Katsahian S, Schranz PJ, Nizard RS (2006) Bone-patellar tendon-bone autografts versus hamstring autografts for reconstruction of anterior cruciate ligament: meta-analysis. BMJ 332(7548):995–1001 - PubMed - PMC - DOI
    1. Björnsson H, Samuelsson K, Sundemo D, Desai N, Sernert N, Rostgård-Christensen L, Karlsson J, Kartus J (2016) A randomized controlled trial with mean 16-year follow-up comparing hamstring and patellar tendon autografts in anterior cruciate ligament reconstruction. Am J Sports Med 44(9):2304–2313 - PubMed - DOI

Publication types

MeSH terms

LinkOut - more resources