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Femoral Shape and Size Variability from segmented CT datasets for patient-specific THA planning

Femoral Shape and Size Variability from segmented CT datasets for patient-specific THA planning DE GRUYTER Current Directions in Biomedical Engineering 2020;6(3): 20203125 Christopher Fleischmann*, Irina Leher, David Scherb, Alexander Wolf, Jörg Miehling, Sandro Wartzack, Stefan Sesselmann Femoral Shape and Size Variability from segmented CT datasets for patient-specific THA planning Abstract: Biomechanical functionality of artificial hips rising [1]. THA ensures the mobility of patients and thus, strongly correlates with quality of life of patients after total increases their quality of life [2]. hip arthroplasty. As the numbers of total hip arthroplasty are Although THA was designated as one of the most growing due to increasing life expectancy, biomechanical successful operations of the 20th century, with a life rate of research is of utmost importance to improve the implants up to 95% after 10 years in patients older than 75 years, an used and the operative procedures applied. Multibody increasing number of revision surgeries is expected in nearer simulation is used to predict forces and moments inside the future [3, 4]. human body. Generic scaling is usually performed to adapt Revision THA is characterized by the fact that it does the human models used in multibody simulation to individual not improve pain and function as well as primary THA [5, 6]. patients. However, since the shape and size of the bones can Hence, meticulous planning of hip surgery parameters, vary considerably, this type of scaling often is not sufficient. such as the femoral centrum-collum-diaphyseal (CCD) angle In this work various CT datasets were used to quantify or the acetabular anteversion is of utmost importance to differences of individual femoral shapes, especially with ensure functionality in case of revision THA. However, joint regard to important biomechanical hip parameters, such as forces and moments as well as other important biomechanical the CCD angle or the femoral offset. Our results prove that factors are not considered in THA planning at all. multibody simulations should be modeled more patient- Multibody simulation (MBS) is essential to correctly specific to be able to calculate articular forces and moments estimate these parameters and hence, to improve surgical more precisely, and thus, to improve surgical planning. planning. MBS allow to simulate forces, moments and muscle activities in order to gain important information about Keywords: Total hip arthroplasty, Biomechanics, human biomechanics [7, 8]. Segmentation, Multibody simulation, Subject-specific Models of the human body consisting of rigid bodies modeling, Surgery planning, Orthopaedics (bones), muscles and joints are mostly used for MBS purpose. In order to adapt these models individually to https://doi.org/10.1515/cdbme-2020-3125 patients, height and weight can be adjusted. These adjustments are usually based on generic scaling. However, important patient-specific information is 1 Introduction usually lost or not simulated correctly. The purpose of this work is to quantify individual differences of important Due to demographic change in sense of a progressively landmarks of the femur bone for biomechanical simulation to ageing population, cases of osteoarthritis especially of the hip demonstrate the importance of an individualized adaption of and hence, the numbers of total hip arthroplasty (THA) are these landmarks to human models. Due to adjustments of models to individual femur physiology, the muscle attachment points of the MBS-model and in consequence the ______ calculated forces and moments of the hip joint will *Corresponding author: Christopher Fleischmann: Institute for Biomedical Engineering, Ostbayerische Technische Hochschule change [9]. Amberg-Weiden, Hetzenrichter Weg 15, 92637 Weiden, Germany, e-mail: c.fleischmann@oth-aw.de Irina Leher, Stefan Sesselmann: Institute for Biomedical Engineering, Ostbayerische Technische Hochschule Amberg- 2 Material and Methods Weiden, Hetzenrichter Weg 15, 92637 Weiden, Germany David Scherb, Alexander Wolf, Jörg Miehling, Sandro For this study, 7 CT-datasets were examined. Therefore, Wartzack: Engineering Design, Friedrich-Alexander-Universität the DICOM-images were imported to Materialise Mimics Erlangen-Nürnberg, Martensstraße 9, 91058 Erlangen, Germany Open Access. © 2020 Christopher Fleischmann et al., published by De Gruyter. This work is licensed under the Creative Commons Attribution 4.0 License. Christopher Fleischmann et al., Femoral Shape and Size Variability from segmented CT datasets for patient-specific THA planning — Table 1: Minimum, maximum and mean values of the CCD-angle Research (Materialise NV, Leuven, Belgium). First, and the femoral-offset for the 7 patients. important geometrical parameters with influence on the biomechanical function such as the CCD angle or the femoral Min Max Mean (± SD) offset were determined in 2D anatomical planes (Fig 1a). Second, the bony structures of the CT data were segmented. CCD-angle [°] 118.3 139.5 130.1 (±7.2) Then the femur was separated from the pelvis (Fig 1b) and a Femoral-offset [mm] 29.7 46.8 37.8 (±6.8) 3D reconstruction of the femur was performed (Fig 1c). Four d-COR-PPTP [mm] 42.7 56.7 51.0 (±4.4) different landmarks were set to the 3D femur model on the d-PFHP-AFHP [mm] 34.0 49.4 43.9 (±5.2) femoral center of rotation (COR), the proximal posterior greater trochanter point (PPTP), posterior femoral head point (PFHP) and the anterior femoral head point (AFHP). Distances were then measured between the COR and PPTP 4 Discussion (d-COR-PPTP) and the PFHP and the AFHP (d-PFHP- AFHP). The results show large differences for all measured parameters. If these different shapes and sizes of the femur were considered in a patient-specific way in MBS, muscle and tendon attachment points would change and thus, lead to more precise moments and forces of the hip joint. As a result, more realistic results of MBS could lead to a better understanding of hip biomechanics and thus, help to improve surgical planning of THA. 5 Conclusion The large differences in the shape and size of bones and the need of patient-specific modelling have also been shown in Figure 1: Segmentation workflow: a) Imported DICOM-Files of the other studies [10]. Differences in size and shape of the femur CT-Scan b) Marking of bony structures and differntiation of lead to changes in the tendon and muscle attachment points pelvis (blue) and the femur (yellow); c) 3D reconstruction of and hence, to more precise results in MBS. the femur. Author Statement Research funding: The author state no funding involved. 3 Results Conflict of interest: Authors state no conflict of interest. The results of the measurements of the CCD angle and the References femoral offset are shown in Table 1. The minimum measured CCD angle was 118.3° and the maximum angle was 139.5°. [1] Pabinger C, Geissler A. Utilization rates of hip arthroplasty in The mean value of the measurements gave a CCD angle of OECD countries. Osteoarthritis Cartilage. 2014 130.1° ±7.2. Jun;22(6):734-41. [2] Mariconda M, Galasso O, Costa GG, Recano P, Cerbasi S. The femoral offset also showed significantly different Quality of life and functionality after total hip arthroplasty: a values. The lowest femoral offset was 29.7 mm and the long-term follow-up study. BMC Musculoskelet Disord. maximum 46.8 mm. The mean offset was 37.8 mm ±6.8 for 2011;12:222. Published 2011 Oct 6. the seven patients. [3] Learmonth ID, Young C, Rorabeck C. The operation of the century: total hip replacement. Lancet. 2007 Oct The mimimal distance of the d-COR-PPTP was 42.7 mm 27;370(9597):1508-19. Review. and the maximum 56.7 mm. The mean was 51.0 mm ±4.4. [4] Rajaee SS, Campbell JC, Mirocha J, Paiement GD. The distances for d-PFHP-AFHP were 34.0 mm (minimum), Increasing Burden of Total Hip Arthroplasty Revisions in 49.9 mm (maximum) with a mean value of 43.9 mm ±5.2. Patients Between 45 and 64 Years of Age. J Bone Joint Surg Am. 2018 Mar 21;100(6):449-458. Christopher Fleischmann et al., Femoral Shape and Size Variability from segmented CT datasets for patient-specific THA planning — [5] Evans JT, Evans JP, Walker RW, Blom AW, Whitehouse [8] Sesselmann, S., Miehling, J., Wartzack, S. & Forst, R. MR, Sayers A. How long does a hip replacement last? A (2016). Enhancement of Surgical Planning through Patient- systematic review and meta-analysis of case series and Specific Biomechanical Modeling and Simulation. – 37th national registry reports with more than 15 years of follow-up. SICOT Orthopaedic World Congress – Rome 2016. Lancet. 2019;393(10172):647–654. [9] Scherb, D., Wolf, A., Fleischmann, C., Sesselmann, S., [6] Vanhegan IS, Malik AK, Jayakumar P, Ul Islam S, Haddad Wartzack, S., Miehling, J.: Conceptual Approach to estimate FS. A financial analysis of revision hip arthroplasty: the the musculoskeletal follow-ups of endoprosthetic hip economic burden in relation to the national tariff. Bone Joint replacements. CAMS-Knee OpenSim Workshop – Zürich J. 2012;94:619–623. 2020. [7] Miehling J., Forst R., Wartzack S., Sesselmann S.: [10] Tkany L., Hofstätter B., Petersik A., Miehling J., Wartzack S., Biomechanischer Simulator zur prä-operativen Abschätzung Sesselmann S.: A new design process for anatomically und Optimierung der post-operativen Muskelfunktion am enhanced osteosynthesis plates. Journal of Orthopaedic Beispiel der Revisionsendoprothetik des Hüftgelenks. Research (2019). Deutscher Kongress für Orthopädie und Unfallchirurgie (DKOU2016, Berlin, 25. Oktober 2016 - 28. Oktober 2016) http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Current Directions in Biomedical Engineering de Gruyter

Femoral Shape and Size Variability from segmented CT datasets for patient-specific THA planning

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© 2020 by Walter de Gruyter Berlin/Boston
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Abstract

DE GRUYTER Current Directions in Biomedical Engineering 2020;6(3): 20203125 Christopher Fleischmann*, Irina Leher, David Scherb, Alexander Wolf, Jörg Miehling, Sandro Wartzack, Stefan Sesselmann Femoral Shape and Size Variability from segmented CT datasets for patient-specific THA planning Abstract: Biomechanical functionality of artificial hips rising [1]. THA ensures the mobility of patients and thus, strongly correlates with quality of life of patients after total increases their quality of life [2]. hip arthroplasty. As the numbers of total hip arthroplasty are Although THA was designated as one of the most growing due to increasing life expectancy, biomechanical successful operations of the 20th century, with a life rate of research is of utmost importance to improve the implants up to 95% after 10 years in patients older than 75 years, an used and the operative procedures applied. Multibody increasing number of revision surgeries is expected in nearer simulation is used to predict forces and moments inside the future [3, 4]. human body. Generic scaling is usually performed to adapt Revision THA is characterized by the fact that it does the human models used in multibody simulation to individual not improve pain and function as well as primary THA [5, 6]. patients. However, since the shape and size of the bones can Hence, meticulous planning of hip surgery parameters, vary considerably, this type of scaling often is not sufficient. such as the femoral centrum-collum-diaphyseal (CCD) angle In this work various CT datasets were used to quantify or the acetabular anteversion is of utmost importance to differences of individual femoral shapes, especially with ensure functionality in case of revision THA. However, joint regard to important biomechanical hip parameters, such as forces and moments as well as other important biomechanical the CCD angle or the femoral offset. Our results prove that factors are not considered in THA planning at all. multibody simulations should be modeled more patient- Multibody simulation (MBS) is essential to correctly specific to be able to calculate articular forces and moments estimate these parameters and hence, to improve surgical more precisely, and thus, to improve surgical planning. planning. MBS allow to simulate forces, moments and muscle activities in order to gain important information about Keywords: Total hip arthroplasty, Biomechanics, human biomechanics [7, 8]. Segmentation, Multibody simulation, Subject-specific Models of the human body consisting of rigid bodies modeling, Surgery planning, Orthopaedics (bones), muscles and joints are mostly used for MBS purpose. In order to adapt these models individually to https://doi.org/10.1515/cdbme-2020-3125 patients, height and weight can be adjusted. These adjustments are usually based on generic scaling. However, important patient-specific information is 1 Introduction usually lost or not simulated correctly. The purpose of this work is to quantify individual differences of important Due to demographic change in sense of a progressively landmarks of the femur bone for biomechanical simulation to ageing population, cases of osteoarthritis especially of the hip demonstrate the importance of an individualized adaption of and hence, the numbers of total hip arthroplasty (THA) are these landmarks to human models. Due to adjustments of models to individual femur physiology, the muscle attachment points of the MBS-model and in consequence the ______ calculated forces and moments of the hip joint will *Corresponding author: Christopher Fleischmann: Institute for Biomedical Engineering, Ostbayerische Technische Hochschule change [9]. Amberg-Weiden, Hetzenrichter Weg 15, 92637 Weiden, Germany, e-mail: c.fleischmann@oth-aw.de Irina Leher, Stefan Sesselmann: Institute for Biomedical Engineering, Ostbayerische Technische Hochschule Amberg- 2 Material and Methods Weiden, Hetzenrichter Weg 15, 92637 Weiden, Germany David Scherb, Alexander Wolf, Jörg Miehling, Sandro For this study, 7 CT-datasets were examined. Therefore, Wartzack: Engineering Design, Friedrich-Alexander-Universität the DICOM-images were imported to Materialise Mimics Erlangen-Nürnberg, Martensstraße 9, 91058 Erlangen, Germany Open Access. © 2020 Christopher Fleischmann et al., published by De Gruyter. This work is licensed under the Creative Commons Attribution 4.0 License. Christopher Fleischmann et al., Femoral Shape and Size Variability from segmented CT datasets for patient-specific THA planning — Table 1: Minimum, maximum and mean values of the CCD-angle Research (Materialise NV, Leuven, Belgium). First, and the femoral-offset for the 7 patients. important geometrical parameters with influence on the biomechanical function such as the CCD angle or the femoral Min Max Mean (± SD) offset were determined in 2D anatomical planes (Fig 1a). Second, the bony structures of the CT data were segmented. CCD-angle [°] 118.3 139.5 130.1 (±7.2) Then the femur was separated from the pelvis (Fig 1b) and a Femoral-offset [mm] 29.7 46.8 37.8 (±6.8) 3D reconstruction of the femur was performed (Fig 1c). Four d-COR-PPTP [mm] 42.7 56.7 51.0 (±4.4) different landmarks were set to the 3D femur model on the d-PFHP-AFHP [mm] 34.0 49.4 43.9 (±5.2) femoral center of rotation (COR), the proximal posterior greater trochanter point (PPTP), posterior femoral head point (PFHP) and the anterior femoral head point (AFHP). Distances were then measured between the COR and PPTP 4 Discussion (d-COR-PPTP) and the PFHP and the AFHP (d-PFHP- AFHP). The results show large differences for all measured parameters. If these different shapes and sizes of the femur were considered in a patient-specific way in MBS, muscle and tendon attachment points would change and thus, lead to more precise moments and forces of the hip joint. As a result, more realistic results of MBS could lead to a better understanding of hip biomechanics and thus, help to improve surgical planning of THA. 5 Conclusion The large differences in the shape and size of bones and the need of patient-specific modelling have also been shown in Figure 1: Segmentation workflow: a) Imported DICOM-Files of the other studies [10]. Differences in size and shape of the femur CT-Scan b) Marking of bony structures and differntiation of lead to changes in the tendon and muscle attachment points pelvis (blue) and the femur (yellow); c) 3D reconstruction of and hence, to more precise results in MBS. the femur. Author Statement Research funding: The author state no funding involved. 3 Results Conflict of interest: Authors state no conflict of interest. The results of the measurements of the CCD angle and the References femoral offset are shown in Table 1. The minimum measured CCD angle was 118.3° and the maximum angle was 139.5°. [1] Pabinger C, Geissler A. Utilization rates of hip arthroplasty in The mean value of the measurements gave a CCD angle of OECD countries. Osteoarthritis Cartilage. 2014 130.1° ±7.2. Jun;22(6):734-41. [2] Mariconda M, Galasso O, Costa GG, Recano P, Cerbasi S. The femoral offset also showed significantly different Quality of life and functionality after total hip arthroplasty: a values. The lowest femoral offset was 29.7 mm and the long-term follow-up study. BMC Musculoskelet Disord. maximum 46.8 mm. The mean offset was 37.8 mm ±6.8 for 2011;12:222. Published 2011 Oct 6. the seven patients. [3] Learmonth ID, Young C, Rorabeck C. The operation of the century: total hip replacement. Lancet. 2007 Oct The mimimal distance of the d-COR-PPTP was 42.7 mm 27;370(9597):1508-19. Review. and the maximum 56.7 mm. The mean was 51.0 mm ±4.4. [4] Rajaee SS, Campbell JC, Mirocha J, Paiement GD. The distances for d-PFHP-AFHP were 34.0 mm (minimum), Increasing Burden of Total Hip Arthroplasty Revisions in 49.9 mm (maximum) with a mean value of 43.9 mm ±5.2. Patients Between 45 and 64 Years of Age. J Bone Joint Surg Am. 2018 Mar 21;100(6):449-458. Christopher Fleischmann et al., Femoral Shape and Size Variability from segmented CT datasets for patient-specific THA planning — [5] Evans JT, Evans JP, Walker RW, Blom AW, Whitehouse [8] Sesselmann, S., Miehling, J., Wartzack, S. & Forst, R. MR, Sayers A. How long does a hip replacement last? A (2016). Enhancement of Surgical Planning through Patient- systematic review and meta-analysis of case series and Specific Biomechanical Modeling and Simulation. – 37th national registry reports with more than 15 years of follow-up. SICOT Orthopaedic World Congress – Rome 2016. Lancet. 2019;393(10172):647–654. [9] Scherb, D., Wolf, A., Fleischmann, C., Sesselmann, S., [6] Vanhegan IS, Malik AK, Jayakumar P, Ul Islam S, Haddad Wartzack, S., Miehling, J.: Conceptual Approach to estimate FS. A financial analysis of revision hip arthroplasty: the the musculoskeletal follow-ups of endoprosthetic hip economic burden in relation to the national tariff. Bone Joint replacements. CAMS-Knee OpenSim Workshop – Zürich J. 2012;94:619–623. 2020. [7] Miehling J., Forst R., Wartzack S., Sesselmann S.: [10] Tkany L., Hofstätter B., Petersik A., Miehling J., Wartzack S., Biomechanischer Simulator zur prä-operativen Abschätzung Sesselmann S.: A new design process for anatomically und Optimierung der post-operativen Muskelfunktion am enhanced osteosynthesis plates. Journal of Orthopaedic Beispiel der Revisionsendoprothetik des Hüftgelenks. Research (2019). Deutscher Kongress für Orthopädie und Unfallchirurgie (DKOU2016, Berlin, 25. Oktober 2016 - 28. Oktober 2016)

Journal

Current Directions in Biomedical Engineering – de Gruyter

Published: Sep 1, 2020

Keywords: Total hip arthroplasty; Biomechanics; Segmentation; Multibody simulation; Subject-specific modeling; Surgery planning; Orthopaedics

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