Calculation of the 3-D femoral component's orientation in total hip arthroplasty using a trigonometric algorithm

Journal article (2022)

Authors

J. H.J. van Erp Clinical Orthopedic Research Center Midden-Nederland, University Medical Center Utrecht, Diakonessehuis Utrecht
T. P.C. Schlösser University Medical Center Utrecht
Ariënne W. Baijense Clinical Orthopedic Research Center Midden-Nederland
T. E. Snijders Clinical Orthopedic Research Center Midden-Nederland, Diakonessehuis Utrecht
Rob P. Stevenson Universiteit van Amsterdam
W. P. Gielis University Medical Center Utrecht
René M. Castelein University Medical Center Utrecht
H. Weinans University Medical Center Utrecht, Biomaterials & Tissue Biomechanics - Mechanical, Maritime and Materials Engineering
A. de Gast Clinical Orthopedic Research Center Midden-Nederland
Research Group
Biomaterials & Tissue Biomechanics (Mechanical, Maritime and Materials Engineering) (TU Delft)
Copyright: © 2022 Joost H.J. van Erp, Tom P.C. Schlösser, Ariënne W. Baijense, Thom E. Snijders, Rob Stevenson, Willem Paul Gielis, René M. Castelein, Harrie Weinans, Arthur de Gast
DOI: https://doi.org/10.1038/s41598-022-07331-z
More Info
expand_more

Published Date

2022

Language

English

Faculty

Mechanical, Maritime and Materials Engineering

Department

Biomechanical Engineering

Research Group

Biomaterials & Tissue Biomechanics

Abstract

Femoral component orientation plays a key role in implant stability and therefore the success rate of total hip arthroplasty. To date, this topic has been studied using various definitions and a variety of imaging modalities and protocols. The aim of this study is a proof of concept that a new algorithm can be used to describe the femoral component's 3D orientation on the three orthogonal anatomical planes and relative to its mechanical axis using input from two orthogonal planes. CT scans of 18 patients with a total of 22 hip arthroplasties were collected. From these, orthogonal coronal and sagittal projections of the complete femur were acquired in the scanning position (MIPs) and relative to the femoral mechanical axis (corrected MIPs). On these images, the orientation of the neck of the femoral component in space and relative to the femoral axis, respectively, was measured by coronal inclination (CIF), sagittal inclination (SIF) and transverse version (TVF). With the algorithm, TVF was also calculated based on CIF and SIF. Differences between measured and calculated TVF and intra- and inter-observer reliability were evaluated using intra-class correlation coefficients (ICC). The error of non-orthogonal imaging (85° angle between the sagittal and coronal reconstructions) was tested on a third series of MIPs. The ICC between the calculated TVF and manually measured TVF, in space and relative to the femoral axis, was 0.98 for both with median absolute differences of 1.3 and 1.5°. For non-orthogonal images this was 0.70 with a median absolute difference of 5°. ICCs for intra-observer and inter-observer reliability for the calculated TVF values were 0.98 and 0.88, respectively. With this algorithm the transverse orientation of the neck of the femoral component can be assessed in space and relative to the mechanical femoral axis by combining its sagittal and coronal orientation. As long as the imaging visualizes two orthogonal planes, the orientation of an implant can be assessed in 3-D, regardless of the imaging modality.