Reliability of measurements with digital radiographs – a myth


Published online: Jun 20 2019

Bobin VARGHESE, Nagarajan MUTHUKUMAR, Muthukumar BALASUBRAMANIAM, Andrew SCALLY

From Hull Royal Infirmary, Kingston upon Hull, United Kingdom

Abstract

The purpose of this study was to assess the accuracy of digital radiographs and hence their effectiveness in templating. The methodology involved a retrospective study of post operative radiographs of patients with hemiarthroplasty of the hip. Three observers made observations blinded to each other’s measurements. A statistical analysis of the data highlights magnification varying from 6 to 31 percent. There is a statistically significant relationship between the size of the error (size measured on radiograph minus implant size, i.e. magnification) and the implant size (p = 0.005) but the percentage error (error/implant size x 100) is independent of implant size (p = 0.505). It is our impression that digital radiographs and templating on the digital radiographs should not be considered a precise process.