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Shen Z, Zhang P, Cheng B, Liu F, He D. Computational modelling of the fossa component fixation associated with alloplastic total temporomandibular joint replacements. J Mech Behav Biomed Mater 2023; 147:106104. [PMID: 37729840 DOI: 10.1016/j.jmbbm.2023.106104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 08/29/2023] [Accepted: 09/03/2023] [Indexed: 09/22/2023]
Abstract
The alloplastic total temporomandibular joint (TMJ) replacement is a complex surgical approach to end-stage TMJ disorders. The fixation of TMJ prostheses remains a critical issue for implant design and performance. For the fossa component, it is generally considered to use fixation screws to achieve tripod stability. However, the fossa may still come loose, and the mechanism remains unknown. A computational framework, consisting of a musculoskeletal model for calculating muscle and TMJ forces, and a finite element model for the fossa fixation simulation, was developed. A polyethylene (PE) fossa with stock prosthesis design was analyzed to predict contact pressures at the fixation interfaces, and stresses/strains in the fossa implant and bone during the static loading of normal chewing bite and maximum-force bite. The predicted maximum von Mises stresses were 33 MPa and 44 MPa for the bone, 13 MPa and 28 MPa for the PE fossa, and 131 MPa and 244 MPa for the screws, for the normal and maximum bites, respectively; the peak minimum principal strain was in the range of -2514 ∼ -3545 με for the bone. The results show that the sufficient initial mechanical strength of the fossa component fixation can be established using the screws in combination with bone support. The functional loads applied through the prosthetic TMJ bearing can be largely transferred to supporting bone without causing high level stresses. Tightening fixation screws with a pretension of 100 N can reduce transverse load to the screws and help prevent screw loosening. Further research is recommended to accurately quantify the transverse load and its influence on screw loosening during dynamic loading, and the frictional properties at the bone-implant interface.
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Affiliation(s)
- Zhenhao Shen
- School of Mechanical Engineering, North University of China, PR China
| | - Pengyu Zhang
- School of Mechanical Engineering, North University of China, PR China
| | - Bo Cheng
- School of Mechanical Engineering, North University of China, PR China
| | - Feng Liu
- School of Mechanical Engineering, North University of China, PR China.
| | - Dongmei He
- Department of Oral Surgery, Shanghai Ninth People's Hospital, College of Stomatology, Shanghai Jiao Tong University School of Medicine & Shanghai Key Laboratory of Stomatology, PR China.
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2
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Grace TM, Solomon LB, Atkins GJ, Thewlis D, Taylor M. Assigning trabecular bone material properties in finite element models simulating the pelvis before and after the development of peri-prosthetic osteolytic lesions. J Mech Behav Biomed Mater 2022; 133:105311. [PMID: 35716527 DOI: 10.1016/j.jmbbm.2022.105311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 05/24/2022] [Accepted: 06/06/2022] [Indexed: 10/18/2022]
Abstract
Estimating strain distribution in the acetabulum before and after the development of peri-prosthetic osteolytic lesions secondary to total hip arthroplasty may assist with understanding the pathogenesis of this condition. This could be achieved by performing patient-specific finite element analysis of (1) total hip arthroplasty recipients with developed acetabular osteolytic lesions, and (2) models simulating the patient's pelvis and implant immediately after primary surgery. State of the art patient-specific total hip arthroplasty finite element analysis simulations obtain trabecular bone material properties from Hounsfield units within computed tomography (CT) scans of patients. However, this is not feasible when an implant is already in situ due to metal artefact disruption and, in turn, incorrectly reproduced Hounsfield units. Therefore, alternative methods of assigning trabecular bone material properties within such models were tested and strain results compared. It was found that assigning set material properties throughout the trabecular bone geometry was sufficient for the desired application. Simulating the primary implant and pelvis requires geometric and material based assumptions. Therefore, comparisons were made between strain values obtained from simulated primary models, from state of the art methods using material properties obtained from intact bone within a CT scan, and from models with osteolytic lesions. Strain values found using the finite element models simulating the pelvis before osteolytic lesion developed were considerably closer to those found using state of the art methods than those found for the bone loss models. These models could be used to determine relationships between strain distribution and factors such as bone loss.
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Affiliation(s)
- Thomas M Grace
- Centre for Orthopaedic & Trauma Research, Faculty of Health and Medical Sciences, The University of Adelaide, Adelaide, SA, Australia, 5005.
| | - Lucian B Solomon
- Centre for Orthopaedic & Trauma Research, Faculty of Health and Medical Sciences, The University of Adelaide, Adelaide, SA, Australia, 5005; Royal Adelaide Hospital, Adelaide, SA, Australia, 5000
| | - Gerald J Atkins
- Centre for Orthopaedic & Trauma Research, Faculty of Health and Medical Sciences, The University of Adelaide, Adelaide, SA, Australia, 5005
| | - Dominic Thewlis
- Centre for Orthopaedic & Trauma Research, Faculty of Health and Medical Sciences, The University of Adelaide, Adelaide, SA, Australia, 5005
| | - Mark Taylor
- Medical Device Research Institute, College of Science and Engineering, Flinders University, Bedford Park, SA, Australia, 5042
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Fischman D, Mahatma MM, Slullitel P, Farzi M, Grammatopoulos G, Poitras S, Wilkinson JM, Beaulé PE. Does a Monoblock Acetabular Component With a Ceramic Liner Cause More Pelvic Bone Loss Than a Conventional Modular Cementless Acetabular Component? A 2-Year Randomized Clinical Trial. J Arthroplasty 2022; 37:75-82. [PMID: 34649747 DOI: 10.1016/j.arth.2021.08.033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 08/19/2021] [Accepted: 08/30/2021] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND Ceramic-on-ceramic bearings permit the use of large femoral head size while maintaining a favorable effect on wear rates. However, because of increased device rigidity, periprosthetic bone quality could be negatively affected due to stress shielding. The purpose of this study is to assess pelvic periprosthetic bone remodeling around a monoblock ceramic-on-ceramic acetabular component compared to that around a conventional modular metal-on-polyethylene device. METHODS Participants were randomized to receive hip replacement using either a porous-coated, modular metal-on-polyethylene acetabular component (n = 46) or a hydroxyapatite and titanium-coated monoblock shell with an integrated ceramic-on-ceramic bearing (n = 40). Radiographic assessments were completed preoperatively and postoperatively, and measurements of bone mineral density (BMD) using dual-energy X-ray absorptiometry with region free analysis were performed postoperatively and over 2-years of follow-up. RESULTS There was no significant difference in BMD between the 2 groups at baseline or over the following 2 years. At follow-up, complete shell-to-bone contact without a radiolucent line was observed in 26 (67%) of the modular devices and in 37 (93%) of monoblock (P < .001). The modular device was an independent predictor of radiolucent lines (odds ratio 19.1, P = .007). No cases underwent revision surgery for acetabular loosening. CONCLUSION Both the porous-coated modular and hydroxyapatite-coated monoblock acetabular components showed successful clinical results at short-term follow-up with no difference in pixel-level BMD. Using a large head monoblock device does not appear to be associated with an adverse effect on the local bone environment when compared to a modular device. NCT: NCT01558752.
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Affiliation(s)
- Daniel Fischman
- Division of Orthopaedic Surgery, The Ottawa Hospital, Ottawa, Canada
| | - Mohit M Mahatma
- Department of Oncology and Metabolism, University of Sheffield, Sheffield, UK
| | - Pablo Slullitel
- Division of Orthopaedic Surgery, The Ottawa Hospital, Ottawa, Canada; Institute of Orthopaedics 'Carlos E. Ottolenghi', Italian Hospital of Buenos Aires, Buenos Aires, Argentina
| | - Mohsen Farzi
- Centre for Computational Imaging and Simulation Technologies in Bioscience, University of Leeds, Leeds, UK
| | | | - Stéphane Poitras
- School of Rehabilitation, Faculty of Health Sciences, University of Ottawa, Ottawa, Ontario, Canada
| | - J Mark Wilkinson
- Department of Oncology and Metabolism, University of Sheffield, Sheffield, UK
| | - Paul E Beaulé
- Division of Orthopaedic Surgery, The Ottawa Hospital, Ottawa, Canada
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4
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Tobar-Reyes J, Andueza-Castro L, Jiménez-Silva A, Bustamante-Plaza R, Carvajal-Herrera J. Micromotion analysis of immediately loaded implants with Titanium and Cobalt-Chrome superstructures. 3D finite element analysis. Clin Exp Dent Res 2021; 7:581-590. [PMID: 34042328 PMCID: PMC8404496 DOI: 10.1002/cre2.365] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2020] [Revised: 10/27/2020] [Accepted: 10/31/2020] [Indexed: 11/26/2022] Open
Abstract
Objective The aim of this study was to evaluate the amount of micromotion of dental implants under immediate loading supported by Titanium (Ti) and Cobalt‐Chrome (Co‐Cr) superstructures. Material and methods A model of tridimensional half‐edentulous maxilla with three dental implants was made using the Finite Element Analysis (FEA). Two standard and one zygomatic implants were connected to a superstructure with an elliptic section of 6x 3 mm (mm). Two study models were established. Model A: Titanium (Ti) alloy superstructure; Model B: Cobalt‐Chrome (Co‐Cr) alloy superstructure. To simulate an immediate‐loading situation, a friction coefficient of 0.71 was applied between the implant and the bone surface. An axial load of 252.04 [N] was applied on standard and zygomatic implants. Results The Micromotion of dental implants was similar in both superstructure situations. The amount of micromotion was slightly higher in B1 and B3 models (Co‐Cr alloy‐superstructure) compared with A1 and A3 models (Titanium alloy superstructure). The micromotion values in two groups were greater than 150 μm in the incisive region (standard implant) and molar region (zygomatic). In general, the micromotion was higher on the implant that received the load with respect to the other implants. The greater difference was observed when the load was applied on the standard implant A1 (Model A1 = 189.12 μm) compared with standard implant B1(Model B1 = 263.25 μm). Conclusions Within the limits of present study, all implants on different load application points showed micromotion; in general, the amount of micromotion was slightly higher in the implants connected with Co‐Cr alloy superstructure.
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Affiliation(s)
- Julio Tobar-Reyes
- Department of Oral Rehabilitation, Faculty of Dentistry, University of Chile, Santiago, Chile
| | - Luis Andueza-Castro
- Facultad de Diseño, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Antonio Jiménez-Silva
- Orthodontic and Orthopaedic Department, Faculty of Dentistry, Universidad Andrés Bello, Santiago, Chile
| | | | - Juan Carvajal-Herrera
- Department of Oral Rehabilitation, Faculty of Dentistry, University of Chile, Santiago, Chile
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Liu Y, Lim R, Chanchareonsook N, Walboomers XF, Jansen JA, Saffari SE, Goh BT. Third-generation modular mandible endoprosthesis in Macaca fascicularis. Int J Oral Maxillofac Surg 2020; 50:887-894. [PMID: 33272771 DOI: 10.1016/j.ijom.2020.09.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 07/29/2020] [Accepted: 09/24/2020] [Indexed: 10/22/2022]
Abstract
The aim of this study was to develop a third-generation modular mandible endoprosthesis that would experience less stress concentration at its stems compared to earlier generations, thereby minimizing micromotion and achieving long-term stability. In this three-piece modular design, different degrees of movement were incorporated between the endoprosthesis module interfaces. It was hypothesized that this unique feature would minimize stress concentration at the stems and hence promote osseointegration during the early phase of implantation. The endoprosthesis system was made of commercially pure grade 4 titanium, machined and surface-treated, then sterilized and implanted in segmental mandible defects of nine Macaca fascicularis. Clinical, radiological, histological, and histomorphometric evaluations were performed 4 months post-implantation. The endoprosthesis systems with a degree of movement incorporated, exhibited superior performance compared to the rigid system: 30.9-34.8 times higher percentage bone-implant contact (P< 0.0001) and 3.4-4.1 times higher percentage bone area (P<0.0001), with osseointegration noted at the posterior stems. However, fibrous tissue encapsulation was noted around the majority of the anterior stems in all groups. Although the degree of movement was favourable for improving bone healing and stability of the endoprosthesis system, more work needs to be done to investigate other strategies to further reduce loading on the endoprosthesis to achieve predictable osseointegration at the stems.
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Affiliation(s)
- Y Liu
- National Dental Research Institute Singapore, National Dental Centre Singapore, Singapore; Oral Health Academic Clinical Programme, Duke-NUS Medical School, Singapore.
| | - R Lim
- National Dental Research Institute Singapore, National Dental Centre Singapore, Singapore.
| | - N Chanchareonsook
- National Dental Research Institute Singapore, National Dental Centre Singapore, Singapore; Oral Health Academic Clinical Programme, Duke-NUS Medical School, Singapore; Department of Oral and Maxillofacial Surgery, National Dental Centre Singapore, Singapore.
| | - X F Walboomers
- Department of Dentistry - Biomaterials, Radboud University Medical Centre, Nijmegen, Netherlands.
| | - J A Jansen
- Department of Dentistry - Biomaterials, Radboud University Medical Centre, Nijmegen, Netherlands.
| | - S E Saffari
- Health Services and Systems Research, Duke-NUS Medical School, Singapore.
| | - B T Goh
- National Dental Research Institute Singapore, National Dental Centre Singapore, Singapore; Oral Health Academic Clinical Programme, Duke-NUS Medical School, Singapore; Department of Oral and Maxillofacial Surgery, National Dental Centre Singapore, Singapore.
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Dion C, Yamomo G, Howard J, Teeter M, Willing R, Lanting B. Revision total knee arthroplasty using a novel 3D printed titanium augment: A biomechanical cadaveric study. J Mech Behav Biomed Mater 2020; 110:103944. [DOI: 10.1016/j.jmbbm.2020.103944] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 05/27/2020] [Accepted: 06/21/2020] [Indexed: 10/23/2022]
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7
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Jeuken RM, Roth AK, Peters MJM, Welting TJM, van Rhijn LW, Koenen J, Peters RJRW, Thies JC, Emans PJ. In vitro and in vivo study on the osseointegration of BCP-coated versus uncoated nondegradable thermoplastic polyurethane focal knee resurfacing implants. J Biomed Mater Res B Appl Biomater 2020; 108:3370-3382. [PMID: 32614486 PMCID: PMC7586808 DOI: 10.1002/jbm.b.34672] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2019] [Revised: 04/18/2020] [Accepted: 06/03/2020] [Indexed: 11/10/2022]
Abstract
Focal knee resurfacing implants (FKRIs) are intended to treat cartilage defects in middle-aged patients. Most FKRIs are metal-based, which hampers follow-up of the joint using magnetic resonance imaging and potentially leads to damage of the opposing cartilage. The purpose of this study was to develop a nondegradable thermoplastic polyurethane (TPU) FKRI and investigate its osseointegration. Different surface roughness modifications and biphasic calcium phosphate (BCP) coating densities were first tested in vitro on TPU discs. The in vivo osseointegration of BCP-coated TPU implants was subsequently compared to uncoated TPU implants and the titanium bottom layer of metal control implants in a caprine model. Implants were implanted bilaterally in stifle joints and animals were followed for 12 weeks, after which the bone-to-implant contact area (BIC) was assessed. Additionally, 18F-sodium-fluoride (18F-NaF) positron emission tomography PET/CT-scans were obtained at 3 and 12 weeks to visualize the bone metabolism over time. The BIC was significantly higher for the BCP-coated TPU implants compared to the uncoated TPU implants (p = .03), and did not significantly differ from titanium (p = .68). Similar 18F-NaF tracer uptake patterns were observed between 3 and 12 weeks for the BCP-coated TPU and titanium implants, but not for the uncoated implants. TPU FKRIs with surface modifications could provide the answer to the drawbacks of metal FKRIs.
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Affiliation(s)
- Ralph M Jeuken
- Department of Orthopaedic Surgery, Research School CAPHRI, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Alex K Roth
- Department of Orthopaedic Surgery, Research School CAPHRI, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Marloes J M Peters
- Department of Orthopaedic Surgery, Research School CAPHRI, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Tim J M Welting
- Department of Orthopaedic Surgery, Research School CAPHRI, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Lodewijk W van Rhijn
- Department of Orthopaedic Surgery, Research School CAPHRI, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Jac Koenen
- DSM Biomedical BV, Geleen, The Netherlands
| | | | | | - Pieter J Emans
- Department of Orthopaedic Surgery, Research School CAPHRI, Maastricht University Medical Center, Maastricht, The Netherlands
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O'Rourke D, Taylor M. Patient and surgical variability in the primary stability of cementless acetabular cups: A finite element study. J Orthop Res 2020; 38:1515-1522. [PMID: 32086833 DOI: 10.1002/jor.24636] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 01/23/2020] [Accepted: 02/19/2020] [Indexed: 02/04/2023]
Abstract
Aseptic loosening is the most common indication for revision of cementless acetabular cups and often depends on the primary stability achieved following surgery. Cup designs must be capable of achieving primary stability for a wide variety of individuals and surgical conditions to be successful. Typically, preclinical finite element (FE) testing of cups involves assessing the performance in a single patient and under a limited set of idealized conditions. The aim of this study was to assess the effect of patient and surgical parameters on the primary stability of an acetabular cup design in a set of subject-specific FE models. Interference fit was varied in a representative set of 12 patient-specific models of the implanted hemipelvis. Linear mixed models showed a significant association with micromotion for interference fit (P < .0001), acetabular bone elastic modulus (P < .001), native acetabular diameter (P = .03), and the interference fit-elastic modulus interaction (P = .01). There were no significant associations between the polar gap and any of the parameters considered. The significant interference fit-elastic modulus interaction suggests that increasing the interference fit in patients with low bone quality leads to a greater reduction in micromotion than in patients with higher bone quality. However, the significant association between percentage bone yielding and interference fit (P < .0001) suggests a higher periacetabular fracture risk at higher interference fits. This work supports the development of preclinical testing of cup designs for the broad range patients and surgical conditions a cup may face following surgery.
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Affiliation(s)
- Dermot O'Rourke
- Medical Device Research Institute, College of Science and Engineering, Flinders University, Adelaide, South Australia, Australia
| | - Mark Taylor
- Medical Device Research Institute, College of Science and Engineering, Flinders University, Adelaide, South Australia, Australia
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Weißmann V, Ramskogler T, Schulze C, Bader R, Hansmann H. Influence of Synthetic Bone Substitutes on the Anchorage Behavior of Open-Porous Acetabular Cup. MATERIALS (BASEL, SWITZERLAND) 2019; 12:E1052. [PMID: 30935040 PMCID: PMC6479851 DOI: 10.3390/ma12071052] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 03/25/2019] [Accepted: 03/26/2019] [Indexed: 11/17/2022]
Abstract
BACKGROUND The development in implants such as acetabular cups using additive manufacturing techniques is playing an increasingly important role in the healthcare industry. METHOD This study compared the primary stability of four selectively laser-melted press-fit cups (Ti6Al4V) with open-porous, load-bearing structural elements on the surface. The aim was to assess whether the material of the artificial bone stock affects the primary stability of the acetabular cup. The surface structures consist of repeated open-porous, load-bearing elements orthogonal to the acetabular surface. Experimental pull-out and lever-out tests were performed on exact-fit and press-fit cups to evaluate the primary stability of the cups in different synthetic bone substitutes. The acetabular components were placed in three different commercially available synthetic materials (ROHACELL-IGF 110, SikaBlock M330, Sawbones Solid Rigid). Results & conclusions: Within the scope of the study, it was possible to show the differences in fixation strength between the tested acetabular cups depending on their design, the structural elements used, and the different bone substitute material. In addition, functional correlations could be found which provide a qualitative reference to the material density of the bone stock and the press-fit volume of the acetabular cups.
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Affiliation(s)
- Volker Weißmann
- Faculty of Engineering, University of Applied Sciences, Technology, Business and Design, Philipp-Müller-Str. 14, 23966 Wismar, Germany.
- Biomechanics and Implant Technology Research Laboratory, Department of Orthopedics, Rostock University Medicial Center, Doberaner Strasse 142, 18057 Rostock, Germany.
| | - Tim Ramskogler
- Department Industrial Engineering, Technical University of Applied Sciences, Hetzenrichter Weg 15, 92637 Weiden, Germany.
| | - Christian Schulze
- Biomechanics and Implant Technology Research Laboratory, Department of Orthopedics, Rostock University Medicial Center, Doberaner Strasse 142, 18057 Rostock, Germany.
| | - Rainer Bader
- Biomechanics and Implant Technology Research Laboratory, Department of Orthopedics, Rostock University Medicial Center, Doberaner Strasse 142, 18057 Rostock, Germany.
| | - Harald Hansmann
- Faculty of Engineering, University of Applied Sciences, Technology, Business and Design, Philipp-Müller-Str. 14, 23966 Wismar, Germany.
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Khokle RP, Esselle KP, Bokor DJ. Design, Modeling, and Evaluation of the Eddy Current Sensor Deeply Implanted in the Human Body. SENSORS (BASEL, SWITZERLAND) 2018; 18:E3888. [PMID: 30423900 PMCID: PMC6263918 DOI: 10.3390/s18113888] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 11/02/2018] [Accepted: 11/06/2018] [Indexed: 11/24/2022]
Abstract
Joint replacement surgeries have enabled motion for millions of people suffering from arthritis or grave injuries. However, over 10% of these surgeries are revision surgeries. We have first analyzed the data from the worldwide orthopedic registers and concluded that the micromotion of orthopedic implants is the major reason for revisions. Then, we propose the use of inductive eddy current sensors for in vivo micromotion detection of the order of tens of μ m. To design and evaluate its characteristics, we have developed efficient strategies for the accurate numerical simulation of eddy current sensors implanted in the human body. We present the response of the eddy current sensor as a function of its frequency and position based on the robust curve fit analysis. Sensitivity and Sensitivity Range parameters are defined for the present context and are evaluated. The proposed sensors are fabricated and tested in the bovine leg.
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Affiliation(s)
| | - Karu P Esselle
- School of Engineering, Macquarie University, Sydney, NSW 2109, Australia.
| | - Desmond J Bokor
- Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW 2109, Australia.
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11
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Experimental Characterization of the Primary Stability of Acetabular Press-Fit Cups with Open-Porous Load-Bearing Structures on the Surface Layer. METALS 2018. [DOI: 10.3390/met8100839] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Background: Nowadays, hip cups are being used in a wide range of design versions and in an increasing number of units. Their development is progressing steadily. In contrast to conventional methods of manufacturing acetabular cups, additive methods play an increasingly central role in the development progress. Method: A series of eight modified cups were developed on the basis of a standard press-fit cup with a pole flattening and in a reduced version. The surface structures consist of repetitive open-pore load-bearing textural elements aligned right-angled to the cup surface. We used three different types of unit cells (twisted, combined and combined open structures) for constructing of the surface structure. All cups were manufactured using selective laser melting (SLM) of titanium powder (Ti6Al4V). To evaluate the primary stability of the press fit cups in the artificial bone cavity, pull-out and lever-out tests were conducted. All tests were carried out under exact fit conditions. The closed-cell polyurethane (PU) foam, which was used as an artificial bone cavity, was characterized mechanically in order to preempt any potential impact on the test results. Results and conclusions: The pull-out forces as well as the lever moments of the examined cups differ significantly depending on the elementary cells used. The best results in pull-out forces and lever-out moments are shown by the press-fit cups with a combined structure. The results for the assessment of primary stability are related to the geometry used (unit cell), the dimensions of the unit cell, and the volume and porosity responsible for the press fit. Corresponding functional relationships could be identified. The findings show that the implementation of reduced cups in a press-fit design makes sense as part of the development work.
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12
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Zhao LM, Tian DM, Wei Y, Zhang JH, Di ZL, He ZY, Hu YC. Biomechanical Analysis of a Novel Intercalary Prosthesis for Humeral Diaphyseal Segmental Defect Reconstruction. Orthop Surg 2018; 10:23-31. [PMID: 29484857 DOI: 10.1111/os.12368] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 11/23/2017] [Indexed: 11/27/2022] Open
Abstract
OBJECTIVE To study the biomechanical properties of a novel modular intercalary prosthesis for humeral diaphyseal segmental defect reconstruction, to establish valid finite element humerus and prosthesis models, and to analyze the biomechanical differences in modular intercalary prostheses with or without plate fixation. METHODS Three groups were set up to compare the performance of the prosthesis: intact humerus, humerus-prosthesis and humerus-prosthesis-plate. The models of the three groups were transferred to finite element software. Boundary conditions, material properties, and mesh generation were set up for both the prosthesis and the humerus. In addition, 100 N or 2 N.m torsion was loaded to the elbow joint surface with the glenohumeral joint surface fixed. Humeral finite element models were established according to CT scans of the cadaveric bone; reverse engineering software Geomagic was used in this procedure. Components of prosthetic models were established using 3-D modeling software Solidworks. To verify the finite element models, the in vitro tests were simulated using a mechanical testing machine (Bionix; MTS Systems Corporation, USA). Starting with a 50 N preload, the specimen was subjected to 5 times tensile (300 N) and torsional (5 N.m) strength; interval time was 30 min to allow full recovery for the next specimen load. Axial tensile and torsional loads were applied to the elbow joint surface to simulate lifting heavy objects or twisting something, with the glenohumeral joint surface fixed. RESULTS Stress distribution on the humerus did not change its tendency notably after reconstruction by intercalary prosthesis whether with or without a plate. The special design which included a plate and prosthesis effectively diminished stress on the stem where aseptic loosening often takes place. Stress distribution major concentrate upon two stems without plate addition, maximum stress on proximal and distal stem respectively diminish 27.37% and 13.23% under tension, 10.66% and 11.16% under torsion after plate allied. CONCLUSION The novel intercalary prosthesis has excellent ability to reconstruct humeral diaphyseal defects. The accessory fixation system, which included a plate and prosthesis, improved the rigidity of anti-tension and anti-torsion, and diminished the risk of prosthetic loosening and dislocation. A finite element analysis is a kind of convenient and practicable method to be used as the confirmation of experimental biomechanics study.
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Affiliation(s)
- Li-Ming Zhao
- Department of Joint Surgery, Ningbo Sixth Hospital, Ningbo, Zhejiang, China
| | - Dong-Mu Tian
- Beijing Weigao Yahua Artificial Joint Development Company, Beijing, China
| | - Yue Wei
- Shandong Weigao Orthopaedic Device Company Limited, Weihai, China
| | - Jun-Hui Zhang
- Department of Joint Surgery, Ningbo Sixth Hospital, Ningbo, Zhejiang, China
| | - Zheng-Lin Di
- Department of Joint Surgery, Ningbo Sixth Hospital, Ningbo, Zhejiang, China
| | - Zhi-Yong He
- Department of Joint Surgery, Ningbo Sixth Hospital, Ningbo, Zhejiang, China
| | - Yong-Cheng Hu
- Department of Orthopaedic Oncology, Tianjin Hospital, Tianjin, China
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Michel A, Nguyen VH, Bosc R, Vayron R, Hernigou P, Naili S, Haiat G. Finite element model of the impaction of a press-fitted acetabular cup. Med Biol Eng Comput 2016; 55:781-791. [PMID: 27491803 DOI: 10.1007/s11517-016-1545-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 07/03/2016] [Indexed: 01/07/2023]
Abstract
Press-fit surgical procedures aim at providing primary stability to acetabular cup (AC) implants. Impact analysis constitutes a powerful approach to retrieve the AC implant insertion properties. The aim of this numerical study was to investigate the dynamic interaction occurring between the hammer, the ancillary and bone tissue during the impact and to assess the potential of impact analysis to retrieve AC implant insertion conditions. A dynamic two-dimensional axisymmetric model was developed to simulate the impaction of the AC implant into bone tissue assuming friction at the bone-implant interface and large deformations. Different values of interference fit (from 0.5 to 2 mm) and impact velocities (from 1 to 2 m.s-1) were considered. For each configuration, the variation of the force applied between the hammer and the ancillary was analyzed and an indicator I was determined based on the impact momentum of the signal. The simulated results are compared to the experiments. The value of the polar gap decreases with the impact velocity and increases with the interference fit. The bone-implant contact area was significantly correlated with the resonance frequency (R 2 = 0.94) and the indicator (R 2 = 0.95). The results show the potential of impact analyses to retrieve the bone-implant contact properties.
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Affiliation(s)
- Adrien Michel
- Université Paris Est, Laboratoire de Modélisation et de Simulation Multi-Echelle, UMR CNRS 8208, 61 avenue du Général de Gaulle, 94010, Créteil, France
| | - Vu-Hieu Nguyen
- Université Paris Est, Laboratoire de Modélisation et de Simulation Multi-Echelle, UMR CNRS 8208, 61 avenue du Général de Gaulle, 94010, Créteil, France
| | - Romain Bosc
- Service de Chirurgie Plastique et Reconstructive, Hôpital Henri Mondor AP-HP, CHU Paris 12, Université Paris-Est, 51 avenue du Maréchal de Lattre de Tassigny, 94000, Créteil, France
| | - Romain Vayron
- Université Paris Est, Laboratoire de Modélisation et de Simulation Multi-Echelle, UMR CNRS 8208, 61 avenue du Général de Gaulle, 94010, Créteil, France
| | - Philippe Hernigou
- Service de Chirurgie Orthopédique, Hôpital Henri Mondor AP-HP, CHU Paris 12, Université Paris-Est, 51 avenue du Maréchal de Lattre de Tassigny, 94000, Créteil, France
| | - Salah Naili
- Université Paris Est, Laboratoire de Modélisation et de Simulation Multi-Echelle, UMR CNRS 8208, 61 avenue du Général de Gaulle, 94010, Créteil, France
| | - Guillaume Haiat
- CNRS, Laboratoire de Modélisation et de Simulation Multi‑Echelle, UMR CNRS 8208, 61 avenue du Général de Gaulle, 94010, Créteil, France.
- École de technologie supérieure, 1100 Notre-Dame Street West, Montreal, QC, H3C 1K3, Canada.
- Research Center, Hôpital du Sacré-Cœur de Montréal, 5400, Gouin Boul. West, Montreal, QC, H4J 1C5, Canada.
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14
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Mukherjee K, Gupta S. The effects of musculoskeletal loading regimes on numerical evaluations of acetabular component. Proc Inst Mech Eng H 2016; 230:918-29. [DOI: 10.1177/0954411916661368] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 07/05/2016] [Indexed: 11/17/2022]
Abstract
The importance of clinical studies notwithstanding, the failure assessment of implant–bone structure has alternatively been carried out using finite element analysis. However, the accuracy of the finite element predicted results is dependent on the applied loading and boundary conditions. Nevertheless, most finite element–based evaluations on acetabular component used a few selective load cases instead of the eight load cases representing the entire gait cycle. These in silico evaluations often suffer from limitations regarding the use of simplified musculoskeletal loading regimes. This study attempts to analyse the influence of three different loading regimes representing a gait cycle, on numerical evaluations of acetabular component. Patient-specific computer tomography scan-based models of intact and resurfaced pelvises were used. One such loading regime consisted of the second load case that corresponded to peak hip joint reaction force. Whereas the other loading regime consisted of the second and fifth load cases, which corresponded to peak hip joint reaction force and peak muscle forces, respectively. The third loading regime included all the eight load cases. Considerable deviations in peri-acetabular strains, standard error ranging between 115 and 400 µε, were observed for different loading regimes. The predicted bone strains were lower when selective loading regimes were used. Despite minor quantitative variations in bone density changes (less than 0.15 g cm−3), the final bone density pattern after bone remodelling was found to be similar for all the loading regimes. Underestimations in implant–bone micromotions (40–50 µm) were observed for selective loading regimes after bone remodelling. However, at immediate post-operative condition, such underestimations were found to be less (less than 5 µm). The predicted results highlight the importance of inclusion of eight load cases representing the gait cycle for in silico evaluations of resurfaced pelvis.
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Affiliation(s)
- Kaushik Mukherjee
- Department of Mechanical Engineering, Indian Institute of Technology Kharagpur, Kharagpur, India
| | - Sanjay Gupta
- Department of Mechanical Engineering, Indian Institute of Technology Kharagpur, Kharagpur, India
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15
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The contact mechanics and occurrence of edge loading in modular metal-on-polyethylene total hip replacement during daily activities. Med Eng Phys 2016; 38:518-25. [DOI: 10.1016/j.medengphy.2016.03.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 01/05/2016] [Accepted: 03/06/2016] [Indexed: 12/12/2022]
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16
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Mircheski I, Gradišar M. 3D finite element analysis of porous Ti-based alloy prostheses. Comput Methods Biomech Biomed Engin 2016; 19:1531-40. [PMID: 27015664 DOI: 10.1080/10255842.2016.1167881] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
In this paper, novel designs of porous acetabular cups are created and tested with 3D finite element analysis (FEA). The aim is to develop a porous acetabular cup with low effective radial stiffness of the structure, which will be near to the architectural and mechanical behavior of the natural bone. For the realization of this research, a 3D-scanner technology was used for obtaining a 3D-CAD model of the pelvis bone, a 3D-CAD software for creating a porous acetabular cup, and a 3D-FEA software for virtual testing of a novel design of the porous acetabular cup. The results obtained from this research reveal that a porous acetabular cup from Ti-based alloys with 60 ± 5% porosity has the mechanical behavior and effective radial stiffness (Young's modulus in radial direction) that meet and exceed the required properties of the natural bone. The virtual testing with 3D-FEA of a novel design with porous structure during the very early stage of the design and the development of orthopedic implants, enables obtaining a new or improved biomedical implant for a relatively short time and reduced price.
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Affiliation(s)
- Ile Mircheski
- a Faculty of Mechanical Engineering , "Ss. Cyril and Methodius" University in Skopje , Skopje , Republic of Macedonia
| | - Marko Gradišar
- b HELI PRO Production and Sales of Ortopaedic Implants , Lesce , Slovenia
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17
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Qiu C, Wang L, Li D, Jin Z. The influence of metallic shell deformation on the contact mechanics of a ceramic-on-ceramic total hip arthroplasty. Proc Inst Mech Eng H 2015; 230:4-12. [PMID: 26511269 DOI: 10.1177/0954411915614514] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2015] [Accepted: 09/14/2015] [Indexed: 11/17/2022]
Abstract
Total hip arthroplasty of ceramic-on-ceramic bearing combinations is increasingly used clinically. The majority of these implants are used with cementless fixation that a metal-backing shell is press-fitted into the pelvic bone. This usually results in the deformation of the metallic shell, which may also influence the ceramic liner deformation and consequently the contact mechanics between the liner and the femoral head under loading. The explicit dynamic finite element method was applied to model the implantation of a cementless ceramic-on-ceramic with a titanium shell and subsequently to investigate the effect of the metallic shell deformation on the contact mechanics. A total of three impacts were found to be necessary to seat the titanium alloy shell into the pelvic bone cavity with a 1 mm diameter interference and a 1.3 kg impactor at 4500 mm s(-1) velocity. The maximum deformation of the metallic shell was found to be 160 µm in the antero-superior and postero-inferior direction and 97 µm in the antero-inferior and postero-superior direction after the press-fit. The corresponding values were slightly reduced to 67 and 45 µm after the ceramic liner was inserted and then modified to 74 and 43 µm under loading, respectively. The maximum deformation and the maximum principal stress of the ceramic liner were 31 µm and 144 MPa (tensile stress), respectively, after it was inserted into the shell and further increased to 52 µm and 245 MPa under loading. This research highlights the importance of the press-fit of the metallic shell on the contact mechanics of the ceramic liner for ceramic-on-ceramic total hip arthroplasties and potential clinical performances.
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Affiliation(s)
- Changdong Qiu
- State Key Laboratory for Manufacturing Systems Engineering, School of Mechanical Engineering, Xi'an Jiaotong University, Xi'an, China
| | - Ling Wang
- State Key Laboratory for Manufacturing Systems Engineering, School of Mechanical Engineering, Xi'an Jiaotong University, Xi'an, China
| | - Dichen Li
- State Key Laboratory for Manufacturing Systems Engineering, School of Mechanical Engineering, Xi'an Jiaotong University, Xi'an, China
| | - Zhongmin Jin
- State Key Laboratory for Manufacturing Systems Engineering, School of Mechanical Engineering, Xi'an Jiaotong University, Xi'an, China Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK
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18
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Hua X, Li J, Wang L, Wilcox R, Fisher J, Jin Z. The effect of cup outer sizes on the contact mechanics and cement fixation of cemented total hip replacements. Med Eng Phys 2015; 37:1008-14. [PMID: 26343226 DOI: 10.1016/j.medengphy.2015.08.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Revised: 07/27/2015] [Accepted: 08/03/2015] [Indexed: 10/23/2022]
Abstract
One important loosening mechanism of the cemented total hip arthroplasty is the mechanical overload at the bone-cement interface and consequent failure of the cement fixation. Clinical studies have revealed that the outer diameter of the acetabular component is a key factor in influencing aseptic loosening of the hip arthroplasty. The aim of the present study was to investigate the influence of the cup outer diameter on the contact mechanics and cement fixation of a cemented total hip replacement (THR) with different wear penetration depths and under different cup inclination angles using finite element (FE) method. A three-dimensional FE model was developed based on a typical Charnley hip prosthesis. Two acetabular cup designs with outer diameters of 40 and 43 mm were modelled and the effect of cup outer diameter, penetration depth and cup inclination angle on the contact mechanics and cement fixation stresses in the cemented THR were studied. The results showed that for all penetration depths and cup inclination angles considered, the contact mechanics in terms of peak von Mises stress in the acetabular cup and peak contact pressure at the bearing surface for the two cup designs were similar (within 5%). However, the peak von Mises stress, the peak maximum principal stress and peak shear stress in the cement mantle at the bone-cement interface for the 43 mm diameter cup design were predicted to be lower compared to those for the 40 mm diameter cup design. The differences were predicted to be 15-19%, 15-22% and 18-20% respectively for different cup penetration depths and inclination angles, which compares to the clinical difference of aseptic loosening incidence of about 20% between the two cup designs.
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Affiliation(s)
- Xijin Hua
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds LS2 9JT, United Kingdom.
| | - Junyan Li
- School of Science and Technology, Middlesex University, London HA0 1EH, UK
| | - Ling Wang
- School of Mechanical Engineering, Xi'an Jiaotong University, Xi'an 710049, Shanxi, China
| | - Ruth Wilcox
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - John Fisher
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Zhongmin Jin
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds LS2 9JT, United Kingdom; School of Mechanical Engineering, Xi'an Jiaotong University, Xi'an 710049, Shanxi, China
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19
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Damm NB, Morlock MM, Bishop NE. Friction coefficient and effective interference at the implant-bone interface. J Biomech 2015; 48:3517-21. [PMID: 26228713 DOI: 10.1016/j.jbiomech.2015.07.012] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Revised: 07/02/2015] [Accepted: 07/11/2015] [Indexed: 11/16/2022]
Abstract
Although the contact pressure increases during implantation of a wedge-shaped implant, friction coefficients tend to be measured under constant contact pressure, as endorsed in standard procedures. Abrasion and plastic deformation of the bone during implantation are rarely reported, although they define the effective interference, by reducing the nominal interference between implant and bone cavity. In this study radial forces were analysed during simulated implantation and explantation of angled porous and polished implant surfaces against trabecular bone specimens, to determine the corresponding friction coefficients. Permanent deformation was also analysed to determine the effective interference after implantation. For the most porous surface tested, the friction coefficient initially increased with increasing normal contact stress during implantation and then decreased at higher contact stresses. For a less porous surface, the friction coefficient increased continually with normal contact stress during implantation but did not reach the peak magnitude measured for the rougher surface. Friction coefficients for the polished surface were independent of normal contact stress and much lower than for the porous surfaces. Friction coefficients were slightly lower for pull-out than for push-in for the porous surfaces but not for the polished surface. The effective interference was as little as 30% of the nominal interference for the porous surfaces. The determined variation in friction coefficient with radial contact force, as well as the loss of interference during implantation will enable a more accurate representation of implant press-fitting for simulations.
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Affiliation(s)
- Niklas B Damm
- Institute of Biomechanics, TUHH Hamburg University of Technology, Denickestraße 15, 21073 Hamburg, Germany.
| | - Michael M Morlock
- Institute of Biomechanics, TUHH Hamburg University of Technology, Denickestraße 15, 21073 Hamburg, Germany
| | - Nicholas E Bishop
- Institute of Biomechanics, TUHH Hamburg University of Technology, Denickestraße 15, 21073 Hamburg, Germany
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20
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Wang L, Yang W, Peng X, Li D, Dong S, Zhang S, Zhu J, Jin Z. Effect of progressive wear on the contact mechanics of hip replacements--does the realistic surface profile matter? J Biomech 2015; 48:1112-8. [PMID: 25680298 DOI: 10.1016/j.jbiomech.2015.01.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Revised: 12/23/2014] [Accepted: 01/15/2015] [Indexed: 12/28/2022]
Abstract
The contact mechanics of artificial metal-on-polyethylene hip joints are believed to affect the lubrication, wear and friction of the articulating surfaces and may lead to the joint loosening. Finite element analysis has been widely used for contact mechanics studies and good agreements have been achieved with current experimental data; however, most studies were carried out with idealist spherical geometries of the hip prostheses rather than the realistic worn surfaces, either for simplification reason or lacking of worn surface profile. In this study, the worn surfaces of the samples from various stages of hip simulator testing (0 to 5 million cycles) were reconstructed as solid models and were applied in the contact mechanics study. The simulator testing results suggested that the center of the head has various departure value from that of the cup and the value of the departure varies with progressively increased wear. This finding was adopted into the finite element study for better evaluation accuracy. Results indicated that the realistic model provided different evaluation from that of the ideal spherical model. Moreover, with the progressively increased wear, large increase of the contact pressure (from 12 to 31 MPa) was predicted on the articulating surface, and the predicted maximum von Mises stress was increased from 7.47 to 13.26 MPa, indicating the marked effect of the worn surface profiles on the contact mechanics of the joint. This study seeks to emphasize the importance of realistic worn surface profile of the acetabular cup especially following large wear volume.
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Affiliation(s)
- Ling Wang
- State Key Laboratory for Manufacturing Systems Engineering, Xi׳an Jiaotong University, Xi׳an 710054, China
| | - Wenjian Yang
- State Key Laboratory for Manufacturing Systems Engineering, Xi׳an Jiaotong University, Xi׳an 710054, China
| | - Xifeng Peng
- State Key Laboratory for Manufacturing Systems Engineering, Xi׳an Jiaotong University, Xi׳an 710054, China
| | - Dichen Li
- State Key Laboratory for Manufacturing Systems Engineering, Xi׳an Jiaotong University, Xi׳an 710054, China
| | - Shuangpeng Dong
- Tianjin Medical Devices Supervision and Testing Center, Tianjin 30084, China
| | - Shu Zhang
- Tianjin Medical Devices Supervision and Testing Center, Tianjin 30084, China
| | - Jinyu Zhu
- Department of Orthopaedics, Xi Jing Hospital, The Fourth Military Medical University, Xi׳an 710032, Shaanxi, China.
| | - Zhongmin Jin
- State Key Laboratory for Manufacturing Systems Engineering, Xi׳an Jiaotong University, Xi׳an 710054, China; School of Mechanical Engineering, University of Leeds, LS2 9JT, UK.
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21
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Cementless hydroxyapatite coated hip prostheses. BIOMED RESEARCH INTERNATIONAL 2015; 2015:386461. [PMID: 25802848 PMCID: PMC4352755 DOI: 10.1155/2015/386461] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Revised: 12/16/2014] [Accepted: 12/30/2014] [Indexed: 12/13/2022]
Abstract
More than twenty years ago, hydroxyapatite (HA), calcium phosphate ceramics, was introduced as a coating for cementless hip prostheses. The choice of this ceramic is due to its composition being similar to organic apatite bone crystals. This ceramic is biocompatible, bioactive, and osteoconductive. These qualities facilitate the primary stability and osseointegration of implants. Our surgical experience includes the implantation of more than 4,000 cementless hydroxyapatite coated hip prostheses since 1990. The models implanted are coated with HA in the acetabulum and in the metaphyseal area of the stem. The results corresponding to survival and stability of implants were very satisfactory in the long-term. From our experience, HA-coated hip implants are a reliable alternative which can achieve long term survival, provided that certain requirements are met: good design selection, sound choice of bearing surfaces based on patient life expectancy, meticulous surgical technique, and indications based on adequate bone quality.
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22
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Four decades of finite element analysis of orthopaedic devices: where are we now and what are the opportunities? J Biomech 2014; 48:767-78. [PMID: 25560273 DOI: 10.1016/j.jbiomech.2014.12.019] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/26/2014] [Indexed: 11/23/2022]
Abstract
Finite element has been used for more than four decades to study and evaluate the mechanical behaviour total joint replacements. In Huiskes seminal paper "Failed innovation in total hip replacement: diagnosis and proposals for a cure", finite element modelling was one of the potential cures to avoid poorly performing designs reaching the market place. The size and sophistication of models has increased significantly since that paper and a range of techniques are available from predicting the initial mechanical environment through to advanced adaptive simulations including bone adaptation, tissue differentiation, damage accumulation and wear. However, are we any closer to FE becoming an effective screening tool for new devices? This review contains a critical analysis of currently available finite element modelling techniques including (i) development of the basic model, the application of appropriate material properties, loading and boundary conditions, (ii) describing the initial mechanical environment of the bone-implant system, (iii) capturing the time dependent behaviour in adaptive simulations, (iv) the design and implementation of computer based experiments and (v) determining suitable performance metrics. The development of the underlying tools and techniques appears to have plateaued and further advances appear to be limited either by a lack of data to populate the models or the need to better understand the fundamentals of the mechanical and biological processes. There has been progress in the design of computer based experiments. Historically, FE has been used in a similar way to in vitro tests, by running only a limited set of analyses, typically of a single bone segment or joint under idealised conditions. The power of finite element is the ability to run multiple simulations and explore the performance of a device under a variety of conditions. There has been increasing usage of design of experiments, probabilistic techniques and more recently population based modelling to account for patient and surgical variability. In order to have effective screening methods, we need to continue to develop these approaches to examine the behaviour and performance of total joint replacements and benchmark them for devices with known clinical performance. Finite element will increasingly be used in the design, development and pre-clinical testing of total joint replacements. However, simulations must include holistic, closely corroborated, multi-domain analyses which account for real world variability.
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Liu F, Williams S, Fisher J. Effect of microseparation on contact mechanics in metal-on-metal hip replacements-A finite element analysis. J Biomed Mater Res B Appl Biomater 2014; 103:1312-9. [PMID: 25370809 PMCID: PMC4737106 DOI: 10.1002/jbm.b.33313] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Revised: 08/26/2014] [Accepted: 10/10/2014] [Indexed: 11/19/2022]
Abstract
Some early failures of metal‐on‐metal (MoM) hip replacements associated with elevated wear have caused concerns for the use of this bearing combination. Simulator studies have shown that microseparation and its associated rim contact and edge loading may produce the most severe wear in MoM bearings. It is generally recognized that this high wear can be attributed to the high contact stress of the head on the rim of the cup. In this study, an improved finite element contact model that incorporates an elastic‐perfectly plastic material property for cobalt‐chrome alloy of the metal bearing was developed in an attempt to provide an accurate prediction of the stress and strain for the rim contact. The effects of the microseparation displacement (0.1−2 mm), cup inclination angle (25−65°) and cup rim radius (0.5−4 mm) on the contact stress/strain were investigated. The results show that a translational displacement >0.1 mm under a load >0.5 kN can produce a highly concentrated contact stress at the surface of the cup rim which can lead to plastic deformation. This study also suggests that the magnitude of translational displacement was the major factor that determined the severity of the contact conditions and level of stress and strain under microseparation conditions. Future studies will address the effect of surgical translational and rotational malposition and component design on the magnitude of microseparation, contact stress and strain and severity of wear. © 2014 The Authors. Journal of Biomedical Materials Research Part B: Applied Biomaterials Published by Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 103B: 1312–1319, 2015.
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Affiliation(s)
- Feng Liu
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, West Yorkshire, UK
| | - Sophie Williams
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, West Yorkshire, UK
| | - John Fisher
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, West Yorkshire, UK
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24
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Hua X, Li J, Wang L, Jin Z, Wilcox R, Fisher J. Contact mechanics of modular metal-on-polyethylene total hip replacement under adverse edge loading conditions. J Biomech 2014; 47:3303-9. [PMID: 25218504 PMCID: PMC4199141 DOI: 10.1016/j.jbiomech.2014.08.015] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Revised: 08/06/2014] [Accepted: 08/18/2014] [Indexed: 11/15/2022]
Abstract
Edge loading can negatively impact the biomechanics and long-term performance of hip replacements. Although edge loading has been widely investigated for hard-on-hard articulations, limited work has been conducted for hard-on-soft combinations. The aim of the present study was to investigate edge loading and its effect on the contact mechanics of a modular metal-on-polyethylene (MoP) total hip replacement (THR). A three-dimensional finite element model was developed based on a modular MoP bearing. Different cup inclination angles and head lateral microseparation were modelled and their effect on the contact mechanics of the modular MoP hip replacement were examined. The results showed that lateral microseparation caused loading of the head on the rim of the cup, which produced substantial increases in the maximum von Mises stress in the polyethylene liner and the maximum contact pressure on both the articulating surface and backside surface of the liner. Plastic deformation of the liner was observed under both standard conditions and microseparation conditions, however, the maximum equivalent plastic strain in the liner under microseparation conditions of 2000 µm was predicted to be approximately six times that under standard conditions. The study has indicated that correct positioning the components to avoid edge loading is likely to be important clinically even for hard-on-soft bearings for THR.
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Affiliation(s)
- Xijin Hua
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK.
| | - Junyan Li
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK
| | - Ling Wang
- State Key Laboratory for Manufacturing System Engineering, Xi'an Jiaotong University, Xi'an, Shanxi, China
| | - Zhongmin Jin
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK; State Key Laboratory for Manufacturing System Engineering, Xi'an Jiaotong University, Xi'an, Shanxi, China
| | - Ruth Wilcox
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK
| | - John Fisher
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK
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25
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Hua X, Wang L, Al-Hajjar M, Jin Z, Wilcox RK, Fisher J. Experimental validation of finite element modelling of a modular metal-on-polyethylene total hip replacement. Proc Inst Mech Eng H 2014; 228:682-92. [PMID: 24963036 DOI: 10.1177/0954411914541830] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Finite element models are becoming increasingly useful tools to conduct parametric analysis, design optimisation and pre-clinical testing for hip joint replacements. However, the verification of the finite element model is critically important. The purposes of this study were to develop a three-dimensional anatomic finite element model for a modular metal-on-polyethylene total hip replacement for predicting its contact mechanics and to conduct experimental validation for a simple finite element model which was simplified from the anatomic finite element model. An anatomic modular metal-on-polyethylene total hip replacement model (anatomic model) was first developed and then simplified with reasonable accuracy to a simple modular total hip replacement model (simplified model) for validation. The contact areas on the articulating surface of three polyethylene liners of modular metal-on-polyethylene total hip replacement bearings with different clearances were measured experimentally in the Leeds ProSim hip joint simulator under a series of loading conditions and different cup inclination angles. The contact areas predicted from the simplified model were then compared with that measured experimentally under the same conditions. The results showed that the simplification made for the anatomic model did not change the predictions of contact mechanics of the modular metal-on-polyethylene total hip replacement substantially (less than 12% for contact stresses and contact areas). Good agreements of contact areas between the finite element predictions from the simplified model and experimental measurements were obtained, with maximum difference of 14% across all conditions considered. This indicated that the simplification and assumptions made in the anatomic model were reasonable and the finite element predictions from the simplified model were valid.
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Affiliation(s)
- Xijin Hua
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK
| | - Ling Wang
- State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an, Shanxi, China
| | - Mazen Al-Hajjar
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK
| | - Zhongmin Jin
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an, Shanxi, China
| | - Ruth K Wilcox
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK
| | - John Fisher
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK
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Bishop NE, Höhn JC, Rothstock S, Damm NB, Morlock MM. The influence of bone damage on press-fit mechanics. J Biomech 2014; 47:1472-8. [PMID: 24503049 DOI: 10.1016/j.jbiomech.2014.01.029] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Revised: 01/11/2014] [Accepted: 01/15/2014] [Indexed: 11/25/2022]
Abstract
Press-fitting is used to anchor uncemented implants in bone. It relies in part on friction resistance to relative motion at the implant-bone interface to allow bone ingrowth and long-term stability. Frictional shear capacity is related to the interference fit of the implant and the roughness of its surface. It was hypothesised here that a rough implant could generate trabecular bone damage during implantation, which would reduce its stability. A device was constructed to simulate implantation by displacement of angled platens with varying surface finishes (polished, beaded and flaked) onto the surface of an embedded trabecular bone cube, to different nominal interferences. Push-in (implantation) and Pull-out forces were measured and micro-CT scans were made before and after testing to assess permanent bone deformation. Depth of permanent trabecular bone deformation ('damage'), Pull-out force and Radial force all increased with implantation displacement and with implantation force, for all surface roughnesses. The proposed hypothesis was rejected, since primary stability did not decrease with trabecular bone damage. In fact, Pull-out force linearly increased with push-in force, independently of trabecular bone damage or implant surface. This similar behaviour for the different surfaces might be explained by the compaction of bone into the surfaces during push-in so that Pull-out resistance is governed by bone-on-bone, rather than implant surface-on-bone friction. The data suggest that maximum stability is achieved for the maximum implantation force possible (regardless of trabecular bone damage or surface roughness), but this must be limited to prevent periprosthetic cortical bone fracture, patient damage and component malpositioning.
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Affiliation(s)
- Nicholas E Bishop
- Biomechanics Section, TUHH Hamburg University of Technology, Denickestrasse 15, 21073 Hamburg, Germany.
| | - Jan-Christian Höhn
- Biomechanics Section, TUHH Hamburg University of Technology, Denickestrasse 15, 21073 Hamburg, Germany
| | - Stephan Rothstock
- Biomechanics Section, TUHH Hamburg University of Technology, Denickestrasse 15, 21073 Hamburg, Germany
| | - Niklas B Damm
- Biomechanics Section, TUHH Hamburg University of Technology, Denickestrasse 15, 21073 Hamburg, Germany
| | - Michael M Morlock
- Biomechanics Section, TUHH Hamburg University of Technology, Denickestrasse 15, 21073 Hamburg, Germany
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27
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Liu F, Williams S, Jin Z, Fisher J. Effect of head contact on the rim of the cup on the offset loading and torque in hip joint replacement. Proc Inst Mech Eng H 2013; 227:1147-54. [PMID: 23886972 DOI: 10.1177/0954411913496016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Head contact on the rim of the cup causes stress concentration and consequently increased wear. The head contact on the rim of the cup may in addition cause an offset load and torque on the cup. The head-rim contact resulting from microseparation or subluxation has been investigated. An analytical model has been developed to calculate the offset loading and resultant torque on the cup as a function of the translational displacement of the head under simplified loading condition of the hip joint at heel strike during a walking cycle. The magnitude of the torque on the cup was found to increase with the increasing translational displacement, larger diameter heads, eccentric cups, and the coefficient of friction of the contact. The effects of cup inclination, cup rim radius, and cup coverage angle on the magnitude of the torque were found to be relatively small with a maximum variation in the torque magnitude being lower than 20%. This study has shown an increased torque due to the head loading on the rim of the cup, and this may contribute to the incidence of cup loosening. Particularly, metal-on-metal hip joints with larger head diameters may produce the highest offset loading torque.
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Affiliation(s)
- Feng Liu
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK
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28
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Meng Q, Liu F, Fisher J, Jin Z. Effect of simplifications of bone and components inclination on the elastohydrodynamic lubrication modeling of metal-on-metal hip resurfacing prosthesis. Proc Inst Mech Eng H 2013; 227:523-34. [PMID: 23637262 DOI: 10.1177/0954411912472845] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
It is important to study the lubrication mechanism of metal-on-metal hip resurfacing prosthesis in order to understand its overall tribological performance, thereby minimize the wear particles. Previous elastohydrodynamic lubrication studies of metal-on-metal hip resurfacing prosthesis neglected the effects of the orientations of the cup and head. Simplified pelvic and femoral bone models were also adopted for the previous studies. These simplifications may lead to unrealistic predictions. For the first time, an elastohydrodynamic lubrication model was developed and solved for a full metal-on-metal hip resurfacing arthroplasty. The effects of the orientations of components and the realistic bones on the lubrication performance of metal-on-metal hip resurfacing prosthesis were investigated by comparing the full model with simplified models. It was found that the orientation of the head played a very important role in the prediction of pressure distributions and film profiles of the metal-on-metal hip resurfacing prosthesis. The inclination of the hemispherical cup up to 45° had no appreciable effect on the lubrication performance of the metal-on-metal hip resurfacing prosthesis. Moreover, the combined effect of material properties and structures of bones was negligible. Future studies should focus on higher inclination angles, smaller coverage angle and microseparation related to the occurrences of edge loading.
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Affiliation(s)
- Qingen Meng
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK
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29
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Winter W, Klein D, Karl M. Effect of Model Parameters on Finite Element Analysis of Micromotions in Implant Dentistry. J ORAL IMPLANTOL 2013; 39:23-9. [DOI: 10.1563/aaid-joi-d-11-00221] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Micromotion between dental implant and bony socket may occur in immediate-loading scenarios. Excessive micromotion surpassing an estimated threshold of approximately 150 μm may result in fibrous encapsulation instead of osseointegration of the implant. As finite element analysis (FEA) has been applied in this field, it was the aim of this study to evaluate the effect of implant-related variables and modeling parameters on simulating micromotion phenomena. Three-dimensional FEA models representing a dental implant within a bony socket were constructed and used for evaluating micromotion (global displacement) and stress transfer (von Mises equivalent stress) at the implant-bone interface when static loads were applied. A parametric study was conducted altering implant geometry (cylinder, screw), direction of loading (axial, horizontal), healing status (immediate implant, osseointegrated implant), and contact type between implant and bone (friction free, friction, rigid). Adding threads to a cylindrically shaped implant as well as changing the contact type between implant and bone from friction free to rigid led to a reduction of implant displacement. On the other hand, reducing the elastic modulus of bone for simulating an immediate implant caused a substantial increase in displacement of the implant. Altering the direction of loading from axial to horizontal caused a change in loading patterns from uniform loading surrounding the whole implant to localized loading in the cervical area. Implant-related and bone-related factors determine the degree of micromotion of a dental implant during the healing phase, which should be considered when choosing a loading protocol.
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Affiliation(s)
- Werner Winter
- Department of Mechanical Engineering, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Daniel Klein
- Department of Mechanical Engineering, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Matthias Karl
- Department of Prosthodontics, School of Dental Medicine, University of Erlangen-Nuremberg, Erlangen, Germany
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30
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The effect of cup orientation and coverage on contact mechanics and range of motion of metal-on-metal hip resurfacing arthroplasty. Proc Inst Mech Eng H 2012. [DOI: 10.1177/0954411912456926] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Implant malpositioning has been identified as a factor associated with clinical failures of metal-on-metal hip resurfacings (MoMHRs). This study investigated the effect of cup orientation and cup coverage on the contact mechanics (incidence of edge-loading) and range of motion (ROM) of MoMHR. Three generic MoMHRs with differing amounts of cup coverage were considered at various orientations. Contact area and contact pressure at the bearing surface were predicted for each design using finite element (FE) method. The ROM was determined based on the geometry overlap. Edge contact was found at lower angles of inclination (65°) for lower coverage cup designs; however, they also provided the greatest ROM. Conversely, cups with greater coverage did not exhibit edge contact until the cup was more steeply positioned (75°), however ROM was reduced. This study enables both sets of variable to be considered in the design of metal-on-metal bearings in hip.
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31
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Hua X, Wroblewski BM, Jin Z, Wang L. The effect of cup inclination and wear on the contact mechanics and cement fixation for ultra high molecular weight polyethylene total hip replacements. Med Eng Phys 2012; 34:318-25. [DOI: 10.1016/j.medengphy.2011.07.026] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Revised: 06/14/2011] [Accepted: 07/24/2011] [Indexed: 10/17/2022]
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32
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Pawaskar SS, Ingham E, Fisher J, Jin Z. Fluid load support and contact mechanics of hemiarthroplasty in the natural hip joint. Med Eng Phys 2010; 33:96-105. [PMID: 20951626 DOI: 10.1016/j.medengphy.2010.09.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2010] [Revised: 08/12/2010] [Accepted: 09/16/2010] [Indexed: 10/18/2022]
Abstract
The articular cartilage covering the ends of the bones of diarthrodial synovial joints is thought to have evolved so that the loads are transferred under different and complex conditions, with a very high degree of efficiency and without compromising the structural integrity of the tissue for the life of an individual. These loading conditions stem from different activities such as walking, and standing. The integrity of cartilage may however become compromised due to congenital disease, arthritis or trauma. Hemiarthroplasty is a potentially conservative treatment when only the femoral cartilage is affected as in case of femoral neck fractures. In hemiarthroplasty, a metallic femoral prosthesis is used to articulate against the natural acetabular cartilage. It has also been hypothesized that biphasic lubrication is the predominant mechanism protecting the cartilage through a very high fluid load support which lowers friction. This may be altered due to hemiarthroplasty and have a direct effect on the frictional shear stresses and potentially cartilage degradation and wear. This study modelled nine activities of daily living and investigated the contact mechanics of a hip joint with a hemiarthroplasty, focussing particularly on the role of the fluid phase. It was shown that in most of the activities studied the peak contact stresses and peak fluid pressures were in the superior dome or lateral roof of the acetabulum. Total fluid load support was very high (~90%) in most of the activities which would shield the solid phase from being subjected to very high contact stresses. This was dependent not only on the load magnitude but also the direction and hence on the location of the contact area with respect to the cartilage coverage. Lower fluid load support was found when the contact area was nearer the edges where the fluid drained easily.
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Affiliation(s)
- Sainath Shrikant Pawaskar
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds LS2 9JT, UK.
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33
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Li X, Li D, Lian Q, Guo H, Jin Z. The Effect of Stem Structure on Stress Distribution of a Custom-Made Hip Prosthesis. Proc Inst Mech Eng H 2010; 224:1275-84. [DOI: 10.1243/09544119jeim768] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A custom-made hip is essential for the initial stability and longevity which correspond to an optimal stress distribution, since a standard hip cannot always satisfy every patient's need. In order to find out the designing principles of a custom-made hip, a patient's personal features on which the design was based were acquired. In this study, an integrated finite element model of the hip (including ilium, acetabular cup, femoral head, femoral stem, and femur) was created based on the computed tomography (CT) images of this patient. A series model with different stem length, cross-section, and collodiaphyseal angle were analysed under both static and quasi-static loading conditions. Comparing the stress distribution on each part of the hip prosthesis with that of the natural hip before replacement, the optimal stem structure for this patient was found. In addition, the changes of interspace between acetabular cup and femoral head were measured according to dynamic CT images on the healthy side of this patient during a gait cycle. Results correspond to the trail of the maximum contact stress sites, which were mainly located on the superolateral surface of the acetabular cup. This custom-design method can also be adopted for other patients.
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Affiliation(s)
- X Li
- State Key Lab for Manufacturing System Engineering, Xi'an Jiaotong University, Xi'an, ShaanXi, People's Republic of China
| | - D Li
- State Key Lab for Manufacturing System Engineering, Xi'an Jiaotong University, Xi'an, ShaanXi, People's Republic of China
| | - Q Lian
- State Key Lab for Manufacturing System Engineering, Xi'an Jiaotong University, Xi'an, ShaanXi, People's Republic of China
| | - H Guo
- State Key Lab for Manufacturing System Engineering, Xi'an Jiaotong University, Xi'an, ShaanXi, People's Republic of China
| | - Z Jin
- State Key Lab for Manufacturing System Engineering, Xi'an Jiaotong University, Xi'an, ShaanXi, People's Republic of China
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK
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34
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Schmidig G, Patel A, Liepins I, Thakore M, Markel DC. The effects of acetabular shell deformation and liner thickness on frictional torque in ultrahigh-molecular-weight polyethylene acetabular bearings. J Arthroplasty 2010; 25:644-53. [PMID: 19493649 DOI: 10.1016/j.arth.2009.03.020] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2008] [Accepted: 03/22/2009] [Indexed: 02/01/2023] Open
Abstract
The purposes of this study were to determine if there were differences in the frictional torque generated between spherical acetabular shells and acetabular shells deformed as a result of implantation and to evaluate how changes in polyethylene insert thickness and head diameter affected these frictional torque data. An established bench top model was used for mechanical testing. A total of 70 samples were tested. Acetabular shells were impacted into polyurethane foam that was designed to create spherical or deformed shell models. We found that deformed acetabular shells produced higher frictional torque than spherical shells. Also, larger femoral head sizes produced greater frictional torque than smaller femoral head sizes. For the deformed models, the thicker polyethylene inserts produced greater frictional torque than the thinner polyethylene inserts.
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35
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Dabirrahmani D, Hogg M, Kohan L, Gillies M. Primary and long-term stability of a short-stem hip implant. Proc Inst Mech Eng H 2010; 224:1109-19. [DOI: 10.1243/09544119jeim704] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The new generation short-stem hip implants are designed to encourage physiological-like loading, to minimize stress—strain shielding and therefore implant loosening in the long term. As yet there are no long-term clinical studies available to prove the benefits of these short-stem implants. Owing to this lack of clinical data, numerical simulation may be used as a predictor of longer term behaviour. This finite element study predicted both the primary stability and long-term stability of a short-stem implant. The primary implant stability was evaluated in terms of interface micromotion. This study found primary stability to fall within the critical threshold for osseointegration to occur. Longer term stability was evaluated using a strain-adaptive bone remodelling algorithm to predict the long-term behaviour of the bone in terms of bone mineral density (BMD) changes. No BMD loss was observed in the classical Gruen zones 1 and 7 and bone remodelling patterns were comparable with hip resurfacing results in the literature.
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Affiliation(s)
| | - M Hogg
- Medical Device Research Australia, Sydney, Australia
| | - L Kohan
- Joint Orthopaedics Centre, Sydney, Australia
| | - M Gillies
- Medical Device Research Australia, Sydney, Australia
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36
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Rothstock S, Uhlenbrock A, Bishop N, Morlock M. Primary stability of uncemented femoral resurfacing implants for varying interface parameters and material formulations during walking and stair climbing. J Biomech 2010; 43:521-6. [DOI: 10.1016/j.jbiomech.2009.09.052] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2009] [Revised: 09/22/2009] [Accepted: 09/22/2009] [Indexed: 11/26/2022]
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