Magnification of digital hip radiographs differs between clinical workplaces

PLoS One. 2017 Nov 30;12(11):e0188743. doi: 10.1371/journal.pone.0188743. eCollection 2017.

Abstract

Preoperative planning for total hip arthroplasty includes templating on anteroposterior radiographs. It is necessary to consider radiographic magnification in order to scale templates accurately. Studies dealing with hip templating report different values of radiographic magnification. It is not clear if the observed difference in magnification between the studies is caused by variability in studied groups, methodology or instrumentation. We hypothesize that there is a difference in magnification between clinical workplaces. Within this study, radiographic magnification was estimated on 337 radiographs of patients after total hip surgery from five orthopaedic departments in the Czech Republic. Magnification was determined for each patient as a ratio between diameter of implanted femoral head measured on radiogram and its true size. One-way ANOVA revealed significant differences in magnification between workplaces (F(4,332) = 132, p≤0.001). These results suggest that radiographic magnification depends on the workplace where it is taken or more precisely on radiographic device. It indicates potential limits in generalizability of results of studies dealing with preoperative planning accuracy to other institutions.

MeSH terms

  • Arthroplasty, Replacement, Hip*
  • Female
  • Hip / diagnostic imaging*
  • Humans
  • Male
  • Radiographic Image Interpretation, Computer-Assisted / methods*

Grants and funding

This work was supported by Czech Health Research Council, Project No. 15-31269A (URL: https://www.rvvi.cz/cep?s=jednoduche-vyhledavani&ss=detail&n=0&h=NV15-31269A) (authors: MD PR JH); and student grant project University Palacký, Project No. IGA_LF UPOL_2017_021 (URL: http://www.psup.cz/iga-grantove-projekty/) (author: JG).