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Hidayat T, Ammarullah MI, Ismail R, Saputra E, Lamura MDP, K N C, Bayuseno AP, Jamari J. Investigation of contact behavior on a model of the dual-mobility artificial hip joint for Asians in different inner liner thicknesses. World J Orthop 2024; 15:321-336. [PMID: 38680676 PMCID: PMC11045469 DOI: 10.5312/wjo.v15.i4.321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2023] [Revised: 01/28/2024] [Accepted: 03/25/2024] [Indexed: 04/16/2024] Open
Abstract
BACKGROUND The four components that make up the current dual-mobility artificial hip joint design are the femoral head, the inner liner, the outer liner as a metal cover to prevent wear, and the acetabular cup. The acetabular cup and the outer liner were constructed of 316L stainless steel. At the same time, the inner liner was made of ultra-high-molecular-weight polyethylene (UHMWPE). As this new dual-mobility artificial hip joint has not been researched extensively, more tribological research is needed to predict wear. The thickness of the inner liner is a significant component to consider when calculating the contact pressure. AIM To make use of finite element analysis to gain a better understanding of the contact behavior in various inner liner thicknesses on a new model of a dual-mobility artificial hip joint, with the ultimate objective of determining the inner liner thickness that was most suitable for this particular type of dual-mobility artificial hip joint. METHODS In this study, the size of the femoral head was compared between two diameters (28 mm and 36 mm) and eight inner liner thicknesses ranging from 5 mm to 12 mm. Using the finite element method, the contact parameters, including the maximum contact pressure and contact area, have been evaluated in light of the Hertzian contact theory. The simulation was performed statically with dissipated energy and asymmetric behavior. The types of interaction were surface-to-surface contact and normal contact behavior. RESULTS The maximum contact pressures in the inner liner (UHMWPE) at a head diameter of 28 mm and 36 mm are between 3.7-13.5 MPa and 2.7-10.4 MPa, respectively. The maximum von Mises of the inner liner, outer liner, and acetabular cup are 2.4-11.4 MPa, 15.7-44.3 MPa, and 3.7-12.6 MPa, respectively, for 28 mm head. Then the maximum von Mises stresses of the 36 mm head are 1.9-8.9 MPa for the inner liner, 9.9-32.8 MPa for the outer liner, and 2.6-9.9 MPa for the acetabular cup. A head with a diameter of 28 mm should have an inner liner with a thickness of 12 mm. Whereas the head diameter was 36 mm, an inner liner thickness of 8 mm was suitable. CONCLUSION The contact pressures and von Mises stresses generated during this research can potentially be exploited in estimating the wear of dual-mobility artificial hip joints in general. Contact pressure and von Mises stress reduce with an increasing head diameter and inner liner's thickness. Present findings would become one of the references for orthopedic surgery for choosing suitable bearing geometric parameter of hip implant.
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Affiliation(s)
- Taufiq Hidayat
- Department of Mechanical Engineering, Universitas Muria Kudus, Kudus 59352, Central Java, Indonesia
- Department of Mechanical Engineering, Universitas Diponegoro, Semarang 50275, Central Java, Indonesia
| | - Muhammad Imam Ammarullah
- Department of Mechanical Engineering, Universitas Diponegoro, Semarang 50275, Central Java, Indonesia
- Undip Biomechanics Engineering & Research Centre, Universitas Diponegoro, Semarang 50275, Central Java, Indonesia
| | - Rifky Ismail
- Department of Mechanical Engineering, Universitas Diponegoro, Semarang 50275, Central Java, Indonesia
- Center for Biomechanics Biomaterials Biomechatronics and Biosignal Processing, Universitas Diponegoro, Semarang 50275, Central Java, Indonesia
| | - Eko Saputra
- Department of Mechanical Engineering, Politeknik Negeri Semarang, Semarang 50275, Central Java, Indonesia
| | - M Danny Pratama Lamura
- Department of Mechanical Engineering, Universitas Diponegoro, Semarang 50275, Central Java, Indonesia
- Undip Biomechanics Engineering & Research Centre, Universitas Diponegoro, Semarang 50275, Central Java, Indonesia
| | - Chethan K N
- Department of Aeronautical and Automobile Engineering, Manipal Institute of Technology, Manipal, Manipal Academy of Higher Education, Manipal 576104, Karnataka, India
| | | | - J Jamari
- Department of Mechanical Engineering, Universitas Diponegoro, Semarang 50275, Central Java, Indonesia
- Undip Biomechanics Engineering & Research Centre, Universitas Diponegoro, Semarang 50275, Central Java, Indonesia
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Bologna FA, Putame G, Audenino AL, Terzini M. Understanding the role of head size and neck length in micromotion generation at the taper junction in total hip arthroplasty. Sci Rep 2024; 14:6397. [PMID: 38493233 PMCID: PMC10944531 DOI: 10.1038/s41598-024-57017-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Accepted: 03/13/2024] [Indexed: 03/18/2024] Open
Abstract
Modular hip implants allow intra-operative adjustments for patient-specific customization and targeted replacement of damaged elements without full implant extraction. However, challenges arise from relative micromotions between components, potentially leading to implant failure due to cytotoxic metal debris. In this study magnitude and directions of micromotions at the taper junction were estimated, aiming to understand the effect of variations in head size and neck length. Starting from a reference configuration adhering to the 12/14 taper standard, six additional implant configurations were generated by varying the head size and/or neck length. A musculoskeletal multibody model of a prothesized lower limb was developed to estimate hip contact force and location during a normal walking task. Following the implant assembly, the multibody-derived loads were imposed as boundary conditions in a finite element analysis to compute the taper junction micromotions as the relative slip between the contacting surfaces. Results highlighted the L-size head as the most critical configuration, indicating a 2.81 μm relative slip at the mid-stance phase. The proposed approach enables the investigation of geometric variations in implants under accurate load conditions, providing valuable insights for designing less risky prostheses and informing clinical decision-making processes.
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Affiliation(s)
- Federico A Bologna
- PolitoBIOMed Lab, Politecnico di Torino, 10129, Turin, Italy
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, 10129, Turin, Italy
| | - Giovanni Putame
- PolitoBIOMed Lab, Politecnico di Torino, 10129, Turin, Italy
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, 10129, Turin, Italy
| | - Alberto L Audenino
- PolitoBIOMed Lab, Politecnico di Torino, 10129, Turin, Italy
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, 10129, Turin, Italy
| | - Mara Terzini
- PolitoBIOMed Lab, Politecnico di Torino, 10129, Turin, Italy.
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, 10129, Turin, Italy.
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Hidayat T, Ismail R, Tauviqirrahman M, Saputra E, Ammarullah MI, Lamura MDP, Bayuseno AP, Jamari. Running-in behavior of dual-mobility cup during the gait cycle: A finite element analysis. Proc Inst Mech Eng H 2024; 238:99-111. [PMID: 38156402 DOI: 10.1177/09544119231216023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2023]
Abstract
The running-in process is considered an essential aspect of the comprehensive wear process. The phenomenon of running-in occurs during the initial stages of wear in the prosthetic hip joint. Within the field of tribology, the running-in phenomenon of the hip joint pertains to the mechanism by which the contact surfaces of the artificial hip joint components are adjusted and a suitable lubricating film is formed. During the process of hip joint running-in, there is an interaction between the metal surface of the ball and the joint cup, which results in adjustments being made until a steady state is achieved. The achievement of desirable wear existence and reliable performance of artificial hip joint components are reliant upon the tribological running-in of the hip joint. Despite the establishment of current modeling approaches, there remains a significant lack of understanding concerning running-in wear, particularly the metal-on-polyethylene (MoP) articulations in dual-mobility cups (DMC). An essential aspect to consider is the running-in phase of the dual mobility component. The present study employed finite element analysis to investigate the running-in behavior of dual mobility cups, wherein femoral head components were matched with polyethylene liners of varying thicknesses. The analysis of the running-in phase was conducted during the normal gait cycle. The results of this investigation may be utilized to design a dual-mobility prosthetic hip joint that exhibits minimal running-in wear.
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Affiliation(s)
- Taufiq Hidayat
- Department of Mechanical Engineering, Diponegoro University, Semarang, Central Java, Indonesia
- Department of Mechanical Engineering, Universitas Muria Kudus, Kudus, Central Java, Indonesia
| | - Rifky Ismail
- Department of Mechanical Engineering, Diponegoro University, Semarang, Central Java, Indonesia
- Center for Biomechanics Biomaterials Biomechatronics and Biosignal Processing (CBIOM3S) Diponegoro University, Semarang, Central Java, Indonesia
| | - Mohammad Tauviqirrahman
- Department of Mechanical Engineering, Diponegoro University, Semarang, Central Java, Indonesia
| | - Eko Saputra
- Department of Mechanical Engineering, Semarang State Polytechnic, Semarang, Central Java, Indonesia
| | - Muhammad Imam Ammarullah
- Biomechanics and Biomedics Engineering Research Centre, Universitas Pasundan, Bandung, West Java, Indonesia
| | - M Danny Pratama Lamura
- Department of Mechanical Engineering, Diponegoro University, Semarang, Central Java, Indonesia
- Undip Biomechanics Engineering & Research Centre (UBM-ERC), Diponegoro University, Semarang, Central Java, Indonesia
| | | | - Jamari
- Department of Mechanical Engineering, Diponegoro University, Semarang, Central Java, Indonesia
- Undip Biomechanics Engineering & Research Centre (UBM-ERC), Diponegoro University, Semarang, Central Java, Indonesia
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D’Isidoro F, Brockmann C, Friesenbichler B, Zumbrunn T, Leunig M, Ferguson SJ. Moving fluoroscopy-based analysis of THA kinematics during unrestricted activities of daily living. Front Bioeng Biotechnol 2023; 11:1095845. [PMID: 37168610 PMCID: PMC10164959 DOI: 10.3389/fbioe.2023.1095845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Accepted: 04/10/2023] [Indexed: 05/13/2023] Open
Abstract
Introduction: Knowledge of the accurate in-vivo kinematics of total hip arthroplasty (THA) during activities of daily living can potentially improve the in-vitro or computational wear and impingement prediction of hip implants. Fluoroscopy- based techniques provide more accurate kinematics compared to skin marker-based motion capture, which is affected by the soft tissue artefact. To date, stationary fluoroscopic machines allowed the measurement of only restricted movements, or only a portion of the whole motion cycle. Methods: In this study, a moving fluoroscopic robot was used to measure the hip joint motion of 15 THA subjects during whole cycles of unrestricted activities of daily living, i.e., overground gait, stair descent, chair rise and putting on socks. Results: The retrieved hip joint motions differed from the standard patterns applied for wear testing, demonstrating that current pre-clinical wear testing procedures do not reflect the experienced in-vivo daily motions of THA. Discussion: The measured patient-specific kinematics may be used as input to in vitro and computational simulations, in order to investigate how individual motion patterns affect the predicted wear or impingement.
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Affiliation(s)
| | | | | | | | | | - Stephen J. Ferguson
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
- *Correspondence: Stephen J. Ferguson,
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Adopted walking condition for computational simulation approach on bearing of hip joint prosthesis: review over the past 30 years. Heliyon 2022; 8:e12050. [PMID: 36506403 PMCID: PMC9730145 DOI: 10.1016/j.heliyon.2022.e12050] [Citation(s) in RCA: 40] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 07/23/2022] [Accepted: 11/24/2022] [Indexed: 12/11/2022] Open
Abstract
Bearing on artificial hip joint experiences friction, wear, and surface damage that impact on overall performance and leading to failure at a particular time due to continuous contact that endangers the user. Assessing bearing hip joint using clinical study, experimental testing, and mathematical formula approach is challenging because there are some obstacles from each approach. Computational simulation is an effective alternative approach that is affordable, relatively fast, and more accessible than other approaches in examining various complex conditions requiring extensive resources and several different parameters. In particular, different gait cycles affect the sliding distance and distribution of gait loading acting on the joints. Appropriate selection and addition of gait cycles in computation modelling are crucial for accurate and reliable prediction and analysis of bearing performance such as wear a failure of implants. However, a wide spread of gait cycles and loading data are being considered and studied by researchers as reported in literature. The current article describes a comprehensive literature review adopted walking condition that has been carried out to study bearing using computational simulation approach over the past 30 years. Many knowledge gaps related to adoption procedures, simplification, and future research have been identified to obtain bearing analysis results with more realistic computational simulation approach according to physiological human hip joints.
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Marian M, Berman D, Nečas D, Emani N, Ruggiero A, Rosenkranz A. Roadmap for 2D materials in biotribological/biomedical applications – A review. Adv Colloid Interface Sci 2022; 307:102747. [DOI: 10.1016/j.cis.2022.102747] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 07/26/2022] [Accepted: 07/28/2022] [Indexed: 01/01/2023]
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Dalli D, Buhagiar J, Mollicone P, Schembri Wismayer P. A novel hip joint prosthesis with uni-directional articulations for reduced wear. J Mech Behav Biomed Mater 2022; 127:105072. [PMID: 35033983 DOI: 10.1016/j.jmbbm.2021.105072] [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: 10/11/2021] [Revised: 12/26/2021] [Accepted: 12/29/2021] [Indexed: 10/19/2022]
Abstract
A novel polymer-on-metal hip joint prosthesis design that makes use of uni-directional articulations was developed and tested in this work. The new implant was tested using two polymer variants, virgin ultra-high molecular weight polyethylene (UHMWPE), and Vitamin E-infused highly crosslinked polyethylene (VEHXPE). The degrees of freedom of the ball-and-socket are reproduced by three cylindrical orthogonally-aligned articulations. This unconventional design leverages on the molecular orientation hardening mechanisms of the polyethylene and increased contact area to minimize wear. An experimental hip joint simulator was used to compare the gravimetric wear of the conventional ball-on-socket and the new implant. The new prosthesis including UHMWPE components produced a 78% reduction in wear, whereas the new prosthesis with VEHXPE components produced a 100% reduction in wear, as no measurable wear was detected. Machining marks on the acetabular cups of the new prosthesis were retained for both polyethylene variants, further demonstrating the low levels of wear exhibited by the new implants. Both polyethylene materials produced particles in the range of 0.1-1.0 μm, which are the most biologically active. Nonetheless, the extremely low wear rates are likely to induce minimal osteolysis effects. Furthermore, the novel design also offers an increase of more than 24% in the range of motion in flexion/extension when compared to a dual-mobility hip implant. A prototype of the prosthesis was implanted into a Thiel-embalmed human cadaver during a mock-surgery, which demonstrated high resistance to dislocation and the possibility of performing a figure of four position.
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Affiliation(s)
- Donald Dalli
- Department of Metallurgy and Materials Engineering, Faculty of Engineering, University of Malta, Msida, MSD 2080, Malta
| | - Joseph Buhagiar
- Department of Metallurgy and Materials Engineering, Faculty of Engineering, University of Malta, Msida, MSD 2080, Malta.
| | - Pierluigi Mollicone
- Department of Mechanical Engineering, Faculty of Engineering, University of Malta, Msida, MSD 2080, Malta
| | - Pierre Schembri Wismayer
- Department of Anatomy, Faculty of Medicine and Surgery, University of Malta, Msida, MSD 2080, Malta
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Toh SMS, Ashkanfar A, English R, Rothwell G. Computational method for bearing surface wear prediction in total hip replacements. J Mech Behav Biomed Mater 2021; 119:104507. [PMID: 33862425 DOI: 10.1016/j.jmbbm.2021.104507] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 03/22/2021] [Accepted: 04/01/2021] [Indexed: 11/30/2022]
Abstract
Total hip replacement (THR) is a revolutionary treatment when a hip joint becomes severely damaged. Wear is known as one of the main reasons for THR failure. Current experimental techniques to investigate the wear at the bearing surfaces of THRs are time-consuming, complicated and expensive. In this study, an in-house fretting wear algorithm has been further developed to investigate the wear damage that occurs on bearing surfaces of THRs and its consequence on the longevity of the implants. A 3D finite element model has been created with a 36 mm diameter Cobalt-Chromium femoral head and a 4 mm thick cross-linked polyethylene bearing liner. A gait loading cycle was used to simulate walking for up to 5 million cycles (Mc). The wear algorithm extracts relative displacements and contact shear stresses from the finite element package to predict the linear and volumetric wear rates. This method is shown to have modelled the evolution of wear effectively and found it to be similar to those from experimental analyses. The linear and volumetric wear per million cycles predicted in this study were 0.0375mm/Mc and 33.6mm3/Mc which are comparable to those measured in-vivo THRs. The wear patterns obtained from this study are also comparable to the wear patterns shown on available conventional polyethylene liners. This method can be used to further aid in the design and clinical technique to reduce wear rate in THRs.
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Affiliation(s)
- Shawn Ming Song Toh
- School of Engineering, Liverpool John Moores University, Byrom Street, Liverpool, L3 3AF, UK.
| | - Ariyan Ashkanfar
- School of Engineering, Liverpool John Moores University, Byrom Street, Liverpool, L3 3AF, UK
| | - Russell English
- School of Engineering, Liverpool John Moores University, Byrom Street, Liverpool, L3 3AF, UK
| | - Glynn Rothwell
- School of Engineering, Liverpool John Moores University, Byrom Street, Liverpool, L3 3AF, UK
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A Perspective on Biotribology in Arthroplasty: From In Vitro toward the Accurate In Silico Wear Prediction. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10186312] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Nowadays hip arthroplasty is recognized as one of the most successful orthopedic surgical procedures, even if it involves challenges to overcome, such that lately, younger and more active patients are in need of total arthroplasty. Wear is still one of the main issues affecting joint prostheses endurance, and often causes loosening accompanied by implant failures. Actual in vitro wear tests executed by mechanical simulators have a long duration, are very expensive, and do not take into account all the possible daily activities of the patients; thus, the challenge to obtain a complete in silico tribological and dynamical model of (bio) tribo-systems could give the possibility to overcome the actual testing procedures and could contribute as a tool for a more accurate tribological design of human prostheses. This prospective paper is intended to underline actual research trends toward the challenge of having accurate numerical algorithms to be used both in preclinical testing and in the optimizations of the prostheses design. With this aim we depicted the possible in silico approach in artificial joints’ wear assessment over time, accounting for contact mechanics, numerical stress–strain analysis, musculoskeletal multibody, and synovial lubrication modelling (boundary/mixed, hydrodynamic, and elastohydrodynamic).
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Li G, Peng Y, Zhou C, Jin Z, Bedair H. The effect of structural parameters of total hip arthroplasty on polyethylene liner wear behavior: A theoretical model analysis. J Orthop Res 2020; 38:1587-1595. [PMID: 31876311 DOI: 10.1002/jor.24577] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 12/21/2019] [Indexed: 02/04/2023]
Abstract
Using large femoral heads in total hip arthroplasty (THA) has been widely advocated to improve the function and longevity of the components. However, increasing the head size has been shown to accelerate polyethylene liner wear. Few studies have investigated the effect of other important structural parameters (such as polyethylene liner thickness, metal cup size, head-liner conformity, loading conditions, etc.) on the biomechanical functions of the THAs. In this study, an analytical model was used to evaluate the polyethylene liner wear characteristics of the THAs (defined using a biomechanical wear factor) with various structural parameters of the THAs and loading conditions. For all the THA systems examined in this study, under the same loading conditions, a larger head leads to increasing contact areas, lower contact stresses, and higher biomechanical wear factors. When the head size is fixed, a decrease in the polyethylene liner thickness or a decrease in the head-liner conformity leads to higher peak contact stresses and smaller contact areas and consequently, lower biomechanical wear factors. This study provides a parametric analysis tool for the optimal design/selection of the THA systems and for prediction of early effects of various structural parameters on the biomechanical function (such as contact stresses) and longevity (such as polyethylene liner wear) of the THA systems.
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Affiliation(s)
- Guoan Li
- Department of Orthopaedic Surgery, Orthopaedic Bioengineering Research Center, Newton-Wellesley Hospital, Harvard Medical School, Newton, Massachusetts
| | - Yun Peng
- Department of Orthopaedic Surgery, Orthopaedic Bioengineering Research Center, Newton-Wellesley Hospital, Harvard Medical School, Newton, Massachusetts
| | - Chaochao Zhou
- Department of Orthopaedic Surgery, Orthopaedic Bioengineering Research Center, Newton-Wellesley Hospital, Harvard Medical School, Newton, Massachusetts.,Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Zhongmin Jin
- Tribology Research Institute, School of Mechanical Engineering, Southwest Jiaotong University, Chengdu, Sichuan, China.,Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK
| | - Hany Bedair
- Department of Orthopaedic Surgery, Orthopaedic Bioengineering Research Center, Newton-Wellesley Hospital, Harvard Medical School, Newton, Massachusetts.,Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
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Ikhsan, Prabowo AR, Sohn JM, Triyono J. Finite Element Analysis of Different Artificial Hip Stem Designs Based on Fenestration under Static Loading. ACTA ACUST UNITED AC 2020. [DOI: 10.1016/j.prostr.2020.07.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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12
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Design, Optimization, and Evaluation of Additively Manufactured Vintiles Cellular Structure for Acetabular Cup Implant. Processes (Basel) 2019. [DOI: 10.3390/pr8010025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Cellular materials with very highly regulated micro-architectures are promising applicant materials for orthopedic medical uses while requiring implants or substituting for bone due to their ability to promote increased cell proliferation and osseointegration. This study focuses on the design of an acetabular cup (AC) cellular implant which was built using a vintiles cellular structure with an internal porosity of 56–87.9% and internal pore dimensions in the range of 600–1200 μm. The AC implant was then optimized for improving mechanical performance to reduce stress shielding by adjusting the porosity to produce stiffness (elastic modulus) to match with the bone, and allowing for bone cell ingrowth. The optimized and non-optimized AC cellular implant was fabricated using the SLM additive manufacturing process. Simulation (finite element analysis, FEA) was carried out and all cellular implants are finally tested under static loading conditions. The result showed that on the finite element model of an optimized implant, cellular has shown 69% higher stiffness than non-optimized. It has been confirmed by experimental work shown that the optimized cellular implant has a 71% higher ultimate compressive strength than the non-optimized counterpart. Finally, we developed an AC implant with mechanical performance adequately close to that of human bone.
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Ruggiero A, D'Amato R, Affatato S. Comparison of Meshing Strategies in THR Finite Element Modelling. MATERIALS 2019; 12:ma12142332. [PMID: 31340439 PMCID: PMC6679155 DOI: 10.3390/ma12142332] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 06/24/2019] [Accepted: 07/20/2019] [Indexed: 12/26/2022]
Abstract
In biomechanics and orthopedics, finite element modelling allows simulating complex problems, and in the last few years, it has been widely used in many applications, also in the field of biomechanics and biotribology. As is known, one crucial point of FEM (finite element model) is the discretization of the physical domain, and this procedure is called meshing. A well-designed mesh is necessary in order to achieve accurate results with an acceptable computational effort. The aim of this work is to test a finite element model to simulate the dry frictionless contact conditions of a hip joint prosthesis (a femoral head against an acetabular cup) in a soft bearing configuration by comparing the performances of 12 common meshing strategies. In the simulations, total deformation of the internal surface of the cup, contact pressure, and the equivalent von Mises stress are evaluated by using loads and kinematic conditions during a typical gait, obtained from a previous work using a musculoskeletal multibody model. Moreover, accounting for appropriate mesh quality metrics, the results are discussed, underlining the best choice we identified after the large amount of numerical simulations performed.
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Affiliation(s)
- Alessandro Ruggiero
- Department of Industrial Engineering, University of Salerno, Via Giovanni Paolo II, nr. 132, 84084 Fisciano, Italy.
| | - Roberto D'Amato
- Escuela Técnica Superior de Ingeniería y Diseño Industrial, Universidad Politécnica de Madrid, Roda de Valencia, 3, 28012 Madrid, Spain
| | - Saverio Affatato
- Laboratorio di Tecnologia Medica, IRCCS Istituto Ortopedico Rizzoli, Via di Barbiano, 1/10, 40136 Bologna, Italy
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