Observational Study
Copyright ©The Author(s) 2017. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Orthop. Oct 18, 2017; 8(10): 785-789
Published online Oct 18, 2017. doi: 10.5312/wjo.v8.i10.785
Digital blinding of radiographs to mask allocation in a randomized control trial
Gerard P Slobogean, Lukasz Soswa, Giuliana Rotunno, Peter J O’Brien, Kelly A Lefaivre
Gerard P Slobogean, Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201, United States
Lukasz Soswa, Peter J O’Brien, Kelly A Lefaivre, Department of Orthopaedics, University of British Columbia, Vancouver V5Z 1M9, Canada
Giuliana Rotunno, University of Maryland School of Medicine, Baltimore, MD 21201, United States
Author contributions: Slobogean GP, O’Brien PJ, Lefaivre KA contributed to study conception and design; Slobogean G, Soswa L, Rotunno G and Lefaivre KA contributed to data acquisition, data analysis and interpretation, and writing of article; Slobogean GP, Soswa L, Rotunno G, O’Brien PJ and Lefaivre KA contributed to editing, reviewing and final approval of article.
Institutional review board statement: This study was approved by the University of British Columbia Institutional Review Board (H13-00098).
Informed consent statement: All subjects gave their informed consent prior to the study enrolment.
Conflict-of-interest statement: The authors certify that they, or a member of their immediate families, have no funding or commercial associations.
Data sharing statement: No additional data are available for this study. All data are included in the paper itself.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Gerard P Slobogean, MD, MPH, FRCSC, Department of Orthopaedics, University of Maryland School of Medicine, 6th Floor, Suite 300, 110 S. Paca St., Baltimore, MD 21201, United States. gslobogean@umoa.umm.edu
Telephone: +1-410-3286040 Fax: +1-410-3280534
Received: June 15, 2016
Peer-review started: June 17, 2016
First decision: July 29, 2016
Revised: September 1, 2016
Accepted: November 1, 2016
Article in press: November 2, 2016
Published online: October 18, 2017
Abstract
AIM

To demonstrate the effectiveness of a digital radiographic altering technique in concealing treatment allocation to blind outcome assessment of distal femur fracture fixation.

METHODS

Digital postoperative anteroposterior and lateral radiographs from a sample of 33 randomly-selected patients with extra-articular distal femur fractures treated by surgical fixation at a Level 1 trauma center were included. Using commercially available digital altering software, we devised a technique to blind the radiographs by overlaying black boxes over the implant hardware while preserving an exposed fracture site for assessment of fracture healing. Three fellowship-trained surgeons evaluated a set of blinded radiographs twice and a control set of unblinded radiographs once. Each set of radiographs were reviewed independently and in a randomly-assigned order. The degrees of agreement and disagreement among evaluators in identifying implant type while reviewing both blinded and unblinded radiographs were assessed using the Bang Blinding Index and James Blinding Index. The degree of agreement in fracture union was assessed using kappa statistics.

RESULTS

The assessment of blinded radiographs with both the Bang Blinding Index (BBI) and James Blinding Index (JBI) demonstrated a low degree of evaluator success at identifying implant type (Mean BBI, far cortical locking: -0.03, SD: 0.04; Mean BBI, standard screw: 0, SD: 0; JBI: 0.98, SD: 0), suggesting near perfect blinding. The assessment of unblinded radiographs with both blinding indices demonstrated a high degree of evaluator success at identifying implant type (Mean BBI, far cortical locking: 0.89, SD: 0.19; Mean BBI, standard screw: 0.87, SD: 0.04; JBI: 0.26, SD: 0.12), as expected. There was moderate agreement with regard to assessment of fracture union among the evaluators in both the blinded (Kappa: 0.38, 95%CI: 0.25-0.52) and unblinded (Kappa: 0.35, 95%CI: 0.25-0.45) arms of the study. There was no statistically significant difference in fracture union agreement between the blinded and unblinded groups.

CONCLUSION

The digital blinding technique successfully masked the surgeons to the type of implant used for surgical treatment of distal femur fractures but did not interfere with the surgeons’ ability to reliably evaluate radiographic healing at the fracture site.

Keywords: Methods, Randomized controlled trials, Patient outcome assessment, Fracture healing, Femoral fractures

Core tip: The purpose of this study was to demonstrate the effectiveness of a digital blinding protocol to conceal treatment allocation and permit blinded assessment of radiographic healing of various distal femur fractures. Digital postoperative radiographs from a randomly-selected sample were blinded using digital altering software and evaluated by three fellowship-trained surgeons. This study demonstrates the success with which an uncomplicated and reproducible technique can blind radiographs of distal femur fractures. The blinding protocol successfully masked the surgeons to the type of fixation devices implanted but did not interfere with reliable evaluation of radiographic union.