Influence of preoperative femoral orientation on radiographic measures of femoral head height in total hip replacement

John D. O'Connor, Janet C. Hill, David E. Beverland, Nicholas J. Dunne, Alex B. Lennon*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Background: In total hip arthroplasty the surgeon aims to restore the biomechanics of the joint. Femoral height has the greatest influence on restoring limb length and contributes equally to the restoration of femoral head centre. On X-ray, the level of femoral neck resection is most often referenced off the upper border of lesser trochanter. Less frequently, femoral head centre is referenced from the tip of the greater trochanter. The error in measurement of femoral height resulting from unknown femoral rotation is crucially important and can result in inappropriate surgical planning for implant selection and placement. It is unknown which reference produces lower error. Methods: A sample of femoral shapes was generated using a femoral statistical shape model. These were placed in a range of orientations in terms of external rotation and flexion, at intervals of 10°. Simulated X-rays were then produced and the distances from the tip of either greater or lesser trochanter to femoral head centre were measured. Findings: Although using greater trochanter as a reference demonstrated greater errors at the extremes, both techniques resulted in errors of 7–8 mm with 20° of both femoral external rotation and flexion. Interpretation: Moderate degrees of femoral external rotation combined with flexion can result in unsatisfactory errors when templating limb length. There should be greater focus and an agreed definition for femoral height. There is a clinical need for a method with a lower error in determining true femoral height and the level of neck resection.

Original languageEnglish
Article number105247
JournalClinical Biomechanics
Volume81
Early online date14 Dec 2020
DOIs
Publication statusPublished - 01 Jan 2021

Bibliographical note

Funding Information:
This work was funded by the Belfast Arthroplasty Research Trust ( http://www.bartni.org/ ).

Funding Information:
David Beverland has received funding from DePuy Synthes and Zimmer Biomet but not directly for this work.

Publisher Copyright:
© 2020 Elsevier Ltd

Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.

Keywords

  • Femoral height
  • Limb length
  • Preoperative planning
  • Total hip arthroplasty

ASJC Scopus subject areas

  • Biophysics
  • Orthopedics and Sports Medicine

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