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van Erp JHJ, Schlösser TPC, Baijense AW, Snijders TE, Stevenson R, Gielis WP, Castelein RM, Weinans H, de Gast A. Calculation of the 3-D femoral component's orientation in total hip arthroplasty using a trigonometric algorithm. Sci Rep 2022; 12:3499. [PMID: 35241700 PMCID: PMC8894411 DOI: 10.1038/s41598-022-07331-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 02/11/2022] [Indexed: 11/09/2022] Open
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.
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Affiliation(s)
- Joost H J van Erp
- Clinical Orthopedic Research Center-mN, Zeist, The Netherlands. .,Department of Orthopedic Surgery, Diakonessenhuis, Utrecht, The Netherlands. .,Department of Orthopedic Surgery, University Medical Center Utrecht, Utrecht, The Netherlands.
| | - Tom P C Schlösser
- Department of Orthopedic Surgery, University Medical Center Utrecht, Utrecht, The Netherlands
| | | | - Thom E Snijders
- Clinical Orthopedic Research Center-mN, Zeist, The Netherlands.,Department of Orthopedic Surgery, Diakonessenhuis, Utrecht, The Netherlands
| | - Rob Stevenson
- Korteweg-de Vries Institute for Mathematics, University of Amsterdam, Amsterdam, The Netherlands
| | - Willem Paul Gielis
- Department of Orthopedic Surgery, University Medical Center Utrecht, Utrecht, The Netherlands
| | - René M Castelein
- Department of Orthopedic Surgery, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Harrie Weinans
- Department of Orthopedic Surgery, University Medical Center Utrecht, Utrecht, The Netherlands.,Department of Biomechanical Engineering, TU Delft, Delft, The Netherlands
| | - Arthur de Gast
- Clinical Orthopedic Research Center-mN, Zeist, The Netherlands
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