Validated cemented socket model for optimising acetabular fixation

Research output: Contribution to conferencePaper

Abstract

Introduction

The THR is the second most successful and cost-effective surgical procedure of all time. Data shows that hip cup failure is a significant problem. The aim of this study is to improve methods of cemented cup fixation through validation experiments and FEA.

Methods

Five Sawbones composite pelves with cemented UHMWPE cups were tested. Each pelvis was instrumented with triaxial strain gauges at four locations of predicted high strain. Each sample (n = 5) was bolted at the sacroiliac joint in a uniaxial testing machine. A load of 500 N was applied in the direction of the peak force during normal walking, for five repetitions. The directional surface strains were used to evaluate the equivalent strain. Specimen specific finite element models were developed based on CT scan data using ScanIP. Each mesh consisted of an average of 2.5 million linear tetrahedral elements and was solved in ANSYS.

Results

The experimentally measured strains were compared against the finite element predictions. The mean linear gradients and SD of the mean at each gauge location were: 1.00 (16%), 0.78 (17%), 0.90 (13%) and 1.05 (4%).

Discussion

The agreement between the predicted and experimental equivalent strains was good, but varied across the population. This was caused by the variation in mechanical properties between specimens, and the sensitivity of the gauges to location (steep surface strain gradients). This is most evident with the second strain gauge (0.78, 17%), which is at a suboptimal location.

This specific methodology of conducting finite element analyses of the pelvis based on CT image data has been validated. The same methodology has been used to develop a patient specific FEA model, including a bone remodelling algorithm and muscle forces, based on the CT images from the Virtual Human Project. This model is currently being used to optimize the cemented fixation and will be verified experimentally using composite pelves. This research is aimed at informing clinical practice and enhancing long-term cemented fixation. Reducing the need for revision surgery will greatly improve patient quality of life, whilst also reducing the burden on the healthcare delivery system.
Original languageEnglish
Publication statusPublished - Sep 2017
Event25th Annual Meeting of the European Orthopaedic Research Society - Munich, Germany
Duration: 13 Sep 201715 Sep 2017
http://eors.info/meetings/next.html

Conference

Conference25th Annual Meeting of the European Orthopaedic Research Society
CountryGermany
CityMunich
Period13/09/1715/09/17
Internet address

Fingerprint

Pelvis
Delivery of Health Care
Sacroiliac Joint
Finite Element Analysis
Bone Remodeling
Reoperation
Walking
Hip
Quality of Life
Costs and Cost Analysis
Muscles
Research
Population

Cite this

Gosiewski, J., Gheduzzi, S., & Gill, H. (2017). Validated cemented socket model for optimising acetabular fixation. Paper presented at 25th Annual Meeting of the European Orthopaedic Research Society, Munich, Germany.

Validated cemented socket model for optimising acetabular fixation. / Gosiewski, Jan; Gheduzzi, Sabina; Gill, Harinderjit.

2017. Paper presented at 25th Annual Meeting of the European Orthopaedic Research Society, Munich, Germany.

Research output: Contribution to conferencePaper

Gosiewski, J, Gheduzzi, S & Gill, H 2017, 'Validated cemented socket model for optimising acetabular fixation' Paper presented at 25th Annual Meeting of the European Orthopaedic Research Society, Munich, Germany, 13/09/17 - 15/09/17, .
Gosiewski J, Gheduzzi S, Gill H. Validated cemented socket model for optimising acetabular fixation. 2017. Paper presented at 25th Annual Meeting of the European Orthopaedic Research Society, Munich, Germany.
Gosiewski, Jan ; Gheduzzi, Sabina ; Gill, Harinderjit. / Validated cemented socket model for optimising acetabular fixation. Paper presented at 25th Annual Meeting of the European Orthopaedic Research Society, Munich, Germany.
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abstract = "IntroductionThe THR is the second most successful and cost-effective surgical procedure of all time. Data shows that hip cup failure is a significant problem. The aim of this study is to improve methods of cemented cup fixation through validation experiments and FEA.MethodsFive Sawbones composite pelves with cemented UHMWPE cups were tested. Each pelvis was instrumented with triaxial strain gauges at four locations of predicted high strain. Each sample (n = 5) was bolted at the sacroiliac joint in a uniaxial testing machine. A load of 500 N was applied in the direction of the peak force during normal walking, for five repetitions. The directional surface strains were used to evaluate the equivalent strain. Specimen specific finite element models were developed based on CT scan data using ScanIP. Each mesh consisted of an average of 2.5 million linear tetrahedral elements and was solved in ANSYS.ResultsThe experimentally measured strains were compared against the finite element predictions. The mean linear gradients and SD of the mean at each gauge location were: 1.00 (16{\%}), 0.78 (17{\%}), 0.90 (13{\%}) and 1.05 (4{\%}).DiscussionThe agreement between the predicted and experimental equivalent strains was good, but varied across the population. This was caused by the variation in mechanical properties between specimens, and the sensitivity of the gauges to location (steep surface strain gradients). This is most evident with the second strain gauge (0.78, 17{\%}), which is at a suboptimal location.This specific methodology of conducting finite element analyses of the pelvis based on CT image data has been validated. The same methodology has been used to develop a patient specific FEA model, including a bone remodelling algorithm and muscle forces, based on the CT images from the Virtual Human Project. This model is currently being used to optimize the cemented fixation and will be verified experimentally using composite pelves. This research is aimed at informing clinical practice and enhancing long-term cemented fixation. Reducing the need for revision surgery will greatly improve patient quality of life, whilst also reducing the burden on the healthcare delivery system.",
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N2 - IntroductionThe THR is the second most successful and cost-effective surgical procedure of all time. Data shows that hip cup failure is a significant problem. The aim of this study is to improve methods of cemented cup fixation through validation experiments and FEA.MethodsFive Sawbones composite pelves with cemented UHMWPE cups were tested. Each pelvis was instrumented with triaxial strain gauges at four locations of predicted high strain. Each sample (n = 5) was bolted at the sacroiliac joint in a uniaxial testing machine. A load of 500 N was applied in the direction of the peak force during normal walking, for five repetitions. The directional surface strains were used to evaluate the equivalent strain. Specimen specific finite element models were developed based on CT scan data using ScanIP. Each mesh consisted of an average of 2.5 million linear tetrahedral elements and was solved in ANSYS.ResultsThe experimentally measured strains were compared against the finite element predictions. The mean linear gradients and SD of the mean at each gauge location were: 1.00 (16%), 0.78 (17%), 0.90 (13%) and 1.05 (4%).DiscussionThe agreement between the predicted and experimental equivalent strains was good, but varied across the population. This was caused by the variation in mechanical properties between specimens, and the sensitivity of the gauges to location (steep surface strain gradients). This is most evident with the second strain gauge (0.78, 17%), which is at a suboptimal location.This specific methodology of conducting finite element analyses of the pelvis based on CT image data has been validated. The same methodology has been used to develop a patient specific FEA model, including a bone remodelling algorithm and muscle forces, based on the CT images from the Virtual Human Project. This model is currently being used to optimize the cemented fixation and will be verified experimentally using composite pelves. This research is aimed at informing clinical practice and enhancing long-term cemented fixation. Reducing the need for revision surgery will greatly improve patient quality of life, whilst also reducing the burden on the healthcare delivery system.

AB - IntroductionThe THR is the second most successful and cost-effective surgical procedure of all time. Data shows that hip cup failure is a significant problem. The aim of this study is to improve methods of cemented cup fixation through validation experiments and FEA.MethodsFive Sawbones composite pelves with cemented UHMWPE cups were tested. Each pelvis was instrumented with triaxial strain gauges at four locations of predicted high strain. Each sample (n = 5) was bolted at the sacroiliac joint in a uniaxial testing machine. A load of 500 N was applied in the direction of the peak force during normal walking, for five repetitions. The directional surface strains were used to evaluate the equivalent strain. Specimen specific finite element models were developed based on CT scan data using ScanIP. Each mesh consisted of an average of 2.5 million linear tetrahedral elements and was solved in ANSYS.ResultsThe experimentally measured strains were compared against the finite element predictions. The mean linear gradients and SD of the mean at each gauge location were: 1.00 (16%), 0.78 (17%), 0.90 (13%) and 1.05 (4%).DiscussionThe agreement between the predicted and experimental equivalent strains was good, but varied across the population. This was caused by the variation in mechanical properties between specimens, and the sensitivity of the gauges to location (steep surface strain gradients). This is most evident with the second strain gauge (0.78, 17%), which is at a suboptimal location.This specific methodology of conducting finite element analyses of the pelvis based on CT image data has been validated. The same methodology has been used to develop a patient specific FEA model, including a bone remodelling algorithm and muscle forces, based on the CT images from the Virtual Human Project. This model is currently being used to optimize the cemented fixation and will be verified experimentally using composite pelves. This research is aimed at informing clinical practice and enhancing long-term cemented fixation. Reducing the need for revision surgery will greatly improve patient quality of life, whilst also reducing the burden on the healthcare delivery system.

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