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Emonde CK, Eggers ME, Wichmann M, Hurschler C, Ettinger M, Denkena B. Radiopacity Enhancements in Polymeric Implant Biomaterials: A Comprehensive Literature Review. ACS Biomater Sci Eng 2024; 10:1323-1334. [PMID: 38330191 PMCID: PMC10934286 DOI: 10.1021/acsbiomaterials.3c01667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Revised: 01/17/2024] [Accepted: 01/18/2024] [Indexed: 02/10/2024]
Abstract
Polymers as biomaterials possess favorable properties, which include corrosion resistance, light weight, biocompatibility, ease of processing, low cost, and an ability to be easily tailored to meet specific applications. However, their inherent low X-ray attenuation, resulting from the low atomic numbers of their constituent elements, i.e., hydrogen (1), carbon (6), nitrogen (7), and oxygen (8), makes them difficult to visualize radiographically. Imparting radiopacity to radiolucent polymeric implants is necessary to enable noninvasive evaluation of implantable medical devices using conventional imaging methods. Numerous studies have undertaken this by blending various polymers with contrast agents consisting of heavy elements. The selection of an appropriate contrast agent is important, primarily to ensure that it does not cause detrimental effects to the relevant mechanical and physical properties of the polymer depending upon the intended application. Furthermore, its biocompatibility with adjacent tissues and its excretion from the body require thorough evaluation. We aimed to summarize the current knowledge on contrast agents incorporated into synthetic polymers in the context of implantable medical devices. While a single review was found that discussed radiopacity in polymeric biomaterials, the publication is outdated and does not address contemporary polymers employed in implant applications. Our review provides an up-to-date overview of contrast agents incorporated into synthetic medical polymers, encompassing both temporary and permanent implants. We expect that our results will significantly inform and guide the strategic selection of contrast agents, considering the specific requirements of implantable polymeric medical devices.
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Affiliation(s)
- Crystal Kayaro Emonde
- Laboratory
for Biomechanics and Biomaterials (LBB), Hannover Medical School, Anna-von-Borries-Strasse 1-7, 30625 Hannover, Germany
| | - Max-Enno Eggers
- Institute
of Production Engineering and Machine Tools, Leibniz University Hannover, An der Universität 2, 30823 Garbsen, Hannover, Germany
| | - Marcel Wichmann
- Institute
of Production Engineering and Machine Tools, Leibniz University Hannover, An der Universität 2, 30823 Garbsen, Hannover, Germany
| | - Christof Hurschler
- Laboratory
for Biomechanics and Biomaterials (LBB), Hannover Medical School, Anna-von-Borries-Strasse 1-7, 30625 Hannover, Germany
| | - Max Ettinger
- Department
of Orthopedic Surgery − DIAKOVERE Annastift, Hannover Medical School, Anna-von-Borries-Strasse 1-7, 30625 Hannover, Germany
| | - Berend Denkena
- Institute
of Production Engineering and Machine Tools, Leibniz University Hannover, An der Universität 2, 30823 Garbsen, Hannover, Germany
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Linnemann SK, Friedrichs L, Niebuhr NM. Stress-Adaptive Stiffening Structures Inspired by Diatoms: A Parametric Solution for Lightweight Surfaces. Biomimetics (Basel) 2024; 9:46. [PMID: 38248620 PMCID: PMC10813791 DOI: 10.3390/biomimetics9010046] [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: 12/15/2023] [Revised: 01/04/2024] [Accepted: 01/09/2024] [Indexed: 01/23/2024] Open
Abstract
The intricate and highly complex morphologies of diatom frustules have long captured the attention of biomimetic researchers, initiating innovation in engineering solutions. This study investigates the potential of diatom-inspired surface stiffeners to determine whether the introduced innovative strategy is a viable alternative for addressing engineering challenges demanding enhanced stiffness. This interdisciplinary study focuses on the computer-aided generation of stress-adaptive lightweight structures aimed at optimizing bending stiffness. Through a comprehensive microscopical analysis, morphological characteristics of diatom frustules were identified and abstracted to be applied to a reference model using computer-aided methods and simulated to analyze their mechanical behavior under load-bearing conditions. Afterwards, the models are compared against a conventional engineering approach. The most promising biomimetic approach is successfully automated, extending its applicability to non-planar surfaces and diverse boundary conditions. It yields notable improvement in bending stiffness, which manifests in a decrease of displacement by approximately 93% in comparison to the reference model with an equivalent total mass. Nonetheless, for the specific load case considered, the engineering approach yields the least displacement. Although certain applications may favor conventional methods, the presented approach holds promise for scenarios subjected to varying stresses, necessitating lightweight and robust solutions.
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Affiliation(s)
| | | | - Nils M. Niebuhr
- Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany; (S.K.L.)
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Naghavi SA, Tamaddon M, Garcia-Souto P, Moazen M, Taylor S, Hua J, Liu C. A novel hybrid design and modelling of a customised graded Ti-6Al-4V porous hip implant to reduce stress-shielding: An experimental and numerical analysis. Front Bioeng Biotechnol 2023; 11:1092361. [PMID: 36777247 PMCID: PMC9910359 DOI: 10.3389/fbioe.2023.1092361] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 01/10/2023] [Indexed: 01/27/2023] Open
Abstract
Stress shielding secondary to bone resorption is one of the main causes of aseptic loosening, which limits the lifespan of hip prostheses and exacerbates revision surgery rates. In order to minimise post-hip replacement stress variations, this investigation proposes a low-stiffness, porous Ti6Al4V hip prosthesis, developed through selective laser melting (SLM). The stress shielding effect and potential bone resorption properties of the porous hip implant were investigated through both in vitro quasi-physiological experimental assays, together with finite element analysis. A solid hip implant was incorporated in this investigation for contrast, as a control group. The stiffness and fatigue properties of both the solid and the porous hip implants were measured through compression tests. The safety factor of the porous hip stem under both static and dynamic loading patterns was obtained through simulation. The porous hip implant was inserted into Sawbone/PMMA cement and was loaded to 2,300 N (compression). The proposed porous hip implant demonstrated a more natural stress distribution, with reduced stress shielding (by 70%) and loss in bone mass (by 60%), when compared to a fully solid hip implant. Solid and porous hip stems had a stiffness of 2.76 kN/mm and 2.15 kN/mm respectively. Considering all daily activities, the porous hip stem had a factor of safety greater than 2. At the 2,300 N load, maximum von Mises stresses on the hip stem were observed as 112 MPa on the medial neck and 290 MPa on the distal restriction point, whereby such values remained below the endurance limit of 3D printed Ti6Al4V (375 MPa). Overall, through the strut thickness optimisation process for a Ti6Al4V porous hip stem, stress shielding and bone resorption can be reduced, therefore proposing a potential replacement for the generic solid implant.
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Affiliation(s)
- Seyed Ataollah Naghavi
- Institute of Orthopaedics and Musculoskeletal Science, Division of Surgery and Interventional Science, Royal National Orthopaedic Hospital, University College London, Stanmore, United Kingdom
| | - Maryam Tamaddon
- Institute of Orthopaedics and Musculoskeletal Science, Division of Surgery and Interventional Science, Royal National Orthopaedic Hospital, University College London, Stanmore, United Kingdom
| | - Pilar Garcia-Souto
- Medical Physics and Biomedical Engineering, University College London, London, United Kingdom
| | - Mehran Moazen
- Department of Mechanical Engineering, University College London, London, United Kingdom
| | - Stephen Taylor
- Institute of Orthopaedics and Musculoskeletal Science, Division of Surgery and Interventional Science, Royal National Orthopaedic Hospital, University College London, Stanmore, United Kingdom
| | - Jia Hua
- School of Science and Technology, Middlesex University, London, United Kingdom
| | - Chaozong Liu
- Institute of Orthopaedics and Musculoskeletal Science, Division of Surgery and Interventional Science, Royal National Orthopaedic Hospital, University College London, Stanmore, United Kingdom,*Correspondence: Chaozong Liu,
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Naghavi SA, Lin C, Sun C, Tamaddon M, Basiouny M, Garcia-Souto P, Taylor S, Hua J, Li D, Wang L, Liu C. Stress Shielding and Bone Resorption of Press-Fit Polyether-Ether-Ketone (PEEK) Hip Prosthesis: A Sawbone Model Study. Polymers (Basel) 2022; 14:4600. [PMID: 36365594 PMCID: PMC9657056 DOI: 10.3390/polym14214600] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 10/22/2022] [Accepted: 10/25/2022] [Indexed: 09/23/2023] Open
Abstract
Stress shielding secondary to bone resorption is one of the main causes of aseptic loosening, which limits the lifespan of the hip prostheses and increases the rates of revision surgery. This study proposes a low stiffness polyether-ether-ketone (PEEK) hip prostheses, produced by fused deposition modelling to minimize the stress difference after the hip replacement. The stress shielding effect and the potential bone resorption of the PEEK implant was investigated through both experimental tests and FE simulation. A generic Ti6Al4V implant was incorporated in this study to allow fair comparison as control group. Attributed to the low stiffness, the proposed PEEK implant showed a more natural stress distribution, less stress shielding (by 104%), and loss in bone mass (by 72%) compared with the Ti6Al4V implant. The stiffness of the Ti6Al4V and the PEEK implant were measured through compression tests to be 2.76 kN/mm and 0.276 kN/mm. The factor of safety for the PEEK implant in both static and dynamic loading scenarios were obtained through simulation. Most of the regions in the PEEK implant were tested to be safe (FoS larger than 1) in terms of representing daily activities (2300 N), while the medial neck and distal restriction point of the implant attracts large von Mises stress 82 MPa and 76 MPa, respectively, and, thus, may possibly fail during intensive activities by yield and fatigue. Overall, considering the reduction in stress shielding and bone resorption in cortical bone, PEEK could be a promising material for the patient-specific femoral implants.
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Affiliation(s)
- Seyed Ataollah Naghavi
- Institute of Orthopaedics & Musculoskeletal Science, Division of Surgery & Interventional Science, University College London, Royal National Orthopaedic Hospital, Stanmore, London HA7 4LP, UK
| | - Churun Lin
- Department of Mechanical Engineering, University College London, London WC1E 7JE, UK
| | - Changning Sun
- Institute of Orthopaedics & Musculoskeletal Science, Division of Surgery & Interventional Science, University College London, Royal National Orthopaedic Hospital, Stanmore, London HA7 4LP, UK
- State Key Laboratory for Manufacturing Systems Engineering, School of Mechanical Engineering, Xi’an Jiaotong University, Xi’an 710049, China
- National Medical Products Administration (NMPA), Key Laboratory for Research and Evaluation of Additive Manufacturing Medical Devices, Xi’an Jiaotong University, Xi’an 710054, China
| | - Maryam Tamaddon
- Institute of Orthopaedics & Musculoskeletal Science, Division of Surgery & Interventional Science, University College London, Royal National Orthopaedic Hospital, Stanmore, London HA7 4LP, UK
| | - Mariam Basiouny
- Institute of Orthopaedics & Musculoskeletal Science, Division of Surgery & Interventional Science, University College London, Royal National Orthopaedic Hospital, Stanmore, London HA7 4LP, UK
| | - Pilar Garcia-Souto
- Medical Physics & Biomedical Engineering, University College London, London WC1E 6BT, UK
| | - Stephen Taylor
- Institute of Orthopaedics & Musculoskeletal Science, Division of Surgery & Interventional Science, University College London, Royal National Orthopaedic Hospital, Stanmore, London HA7 4LP, UK
| | - Jia Hua
- School of Science and Technology, Middlesex University, London NW4 4BT, UK
| | - Dichen Li
- State Key Laboratory for Manufacturing Systems Engineering, School of Mechanical Engineering, Xi’an Jiaotong University, Xi’an 710049, China
- National Medical Products Administration (NMPA), Key Laboratory for Research and Evaluation of Additive Manufacturing Medical Devices, Xi’an Jiaotong University, Xi’an 710054, China
| | - Ling Wang
- State Key Laboratory for Manufacturing Systems Engineering, School of Mechanical Engineering, Xi’an Jiaotong University, Xi’an 710049, China
- National Medical Products Administration (NMPA), Key Laboratory for Research and Evaluation of Additive Manufacturing Medical Devices, Xi’an Jiaotong University, Xi’an 710054, China
| | - Chaozong Liu
- Institute of Orthopaedics & Musculoskeletal Science, Division of Surgery & Interventional Science, University College London, Royal National Orthopaedic Hospital, Stanmore, London HA7 4LP, UK
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Janssen SJ, van Oost I, Breugem SJM, van Geenen RCI. A structured evaluation of the symptomatic medial Oxford unicompartmental knee arthroplasty (UKA). EFORT Open Rev 2021; 6:850-860. [PMID: 34760285 PMCID: PMC8559574 DOI: 10.1302/2058-5241.6.200105] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Unicompartmental knee arthroplasty (UKA) has several advantages over total knee arthroplasty; however, in many reports, the risk of revision remains higher after UKA.Many reasons for failure of UKA exist.Successful treatment starts with accurate assessment of the symptomatic UKA as a specific mode of failure requires a specific solution.A structured and comprehensive evaluation aids assessment of the symptomatic UKA.This review provides an overview of the causes for a symptomatic medial UKA, its risk factors, diagnostic modalities that can be used, and briefly discusses treatment options. Cite this article: EFORT Open Rev 2021;6:850-860. DOI: 10.1302/2058-5241.6.200105.
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Affiliation(s)
- Stein J Janssen
- Department of Orthopaedic Surgery, Academic Medical Center, Amsterdam Movement Sciences, Amsterdam, The Netherlands
| | - Iris van Oost
- Department of Orthopaedic Surgery, FORCE (Foundation for Orthopaedic Research Care Education), Amphia Hospital, Breda, The Netherlands
| | - Stefan J M Breugem
- Department of Orthopaedic Surgery, Bergman Clinics, Naarden, The Netherlands
| | - Rutger C I van Geenen
- Department of Orthopaedic Surgery, FORCE (Foundation for Orthopaedic Research Care Education), Amphia Hospital, Breda, The Netherlands
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Low polyethylene creep and wear following mobile-bearing unicompartmental knee replacement. Knee Surg Sports Traumatol Arthrosc 2021; 29:3433-3442. [PMID: 32940731 PMCID: PMC8458199 DOI: 10.1007/s00167-020-06243-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 08/14/2020] [Indexed: 11/03/2022]
Abstract
PURPOSE The Oxford unicompartmental knee replacement (UKR) has a fully congruent mobile bearing to minimise wear. However, with younger higher demand patients, wear remains a concern. The aim of this study was to quantify the wear rate of Phase 3 Oxford UKR bearings over the course of 5 years and to identify the factors that influence it. METHODS 40 medial Oxford UKRs recruited for a randomised study of cemented and cementless fixation were studied with Radiostereometric analysis (RSA) at 1 week, 3 months, 6 months, 1 year, 2 years, and 5 years post-operatively and bearing thickness was calculated. Penetration, defined as the change in thickness compared to the 1-week measurement, was determined. Creep (early penetration) and wear (late penetration at a constant rate) were calculated. The influence of demographic factors, Oxford Knee Score (OKS), Tegner score, fixation and bearing overhang (determined by RSA) on wear was analysed. RESULTS After 6 months the penetration rate was constant, indicating that wear alone was occurring. The wear rate was 0.07 mm/year (SD 0.03). The creep was 0.06 mm with about 95% occurring during the first 3 months. There was no significant relationship between fixation (cemented/cementless), age, component size, OKS and Tegner score with wear rate. Increasing BMI was associated with decreasing wear (p = 0.042). 37/40 bearings overhung the tibia to some extent and 23/40 overhung the tibia medially. An increase in the area of overhang (p = 0.036), amount of medial overhang (p = 0.028) and distance between the bearing and tibial wall (p = 0.019) were associated with increased wear. Bearings that did not overhang (0.06 mm/year) had less wear (p = 0.025) than those that did (0.08 mm/year). There was no relationship (p = 0.6) between the femoral contact area and wear. CONCLUSION During the first three to six months after implantation, the bearing becomes 0.06 mm thinner due to creep. The combined wear rate of the upper and lower surfaces of the bearing is constant (0.07 mm/year). The wear is lower if the bearing does not overhang the tibia so surgeons should aim for the bearing to be close to the tibial wall. The orientation of the femoral component does not influence wear. LEVEL OF EVIDENCE Retrospective Study, Level III.
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Campbell D, Lewis P, Mooney L. Catastrophic failure of biconcave unicompartmental polyethylene bearings. Knee 2020; 27:987-992. [PMID: 32081624 DOI: 10.1016/j.knee.2020.02.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Revised: 01/27/2020] [Accepted: 02/09/2020] [Indexed: 02/02/2023]
Abstract
BACKGROUND A biconcave polyethylene (PE) bearing was developed for mobile-bearing unicompartmental knee arthroplasties (UKA) to reduce PE dislocation. METHODS A modification of the BalanSys Unicompartmental knee system with a biconcave PE and convex tibial component was used in 32 prostheses in 28 patients. Clinical outcomes and five cases of PE fracture are reported and extensively analyzed ex vivo. RESULTS Visual Analogue Score of pain and satisfaction, and Knee Society Scores improved for all patients. The passive range of motion was 130°. No PE bearings dislocated. Five bearings fractured with oxidation, cracking and delamination at the thinnest central region of the PE. The combination of increased stress and decreased poly thickness was associated with increased creep. PE oxidation caused embrittlement and contributed to fractures in the thin waist of the implant. CONCLUSIONS The unforeseen consequence of a novel design of a UKA that resulted in a specific mechanical and tribological mode of failure is reported. We conclude the PE failed due to a biconcave design that increased stress on the implant at its region of risk combined with a decrease of the polyethylene thickness by 1 mm in the central area.
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Affiliation(s)
- David Campbell
- Wakefield Orthopaedic Clinic, Adelaide, Australia; University of Adelaide, Adelaide, Australia.
| | - Peter Lewis
- Wakefield Orthopaedic Clinic, Adelaide, Australia
| | - Luke Mooney
- Wakefield Orthopaedic Clinic, Adelaide, Australia
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Pegg EC, Gill HS, Zaribaf FP. Characterisation of the physical, chemical and mechanical properties of a radiopaque polyethylene. J Biomater Appl 2020; 35:215-223. [PMID: 32419587 DOI: 10.1177/0885328220922809] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Ultra-high molecular weight polyethylene has a low X-ray attenuation, hence, the performance of the polyethylene implants used for joint replacements cannot be directly investigated using X-ray-based imaging techniques. In this study, the X-ray attenuation of polyethylene was increased by diffusing an FDA-approved oil-based contrast agent (Lipiodol ultra fluid) into the surface of the samples, and the suitability of this novel radiopaque ultra-high molecular weight polyethylene for clinical applications was examined. Different levels of radiopacity were created by controlling the diffusion parameters, and the level of radiopacity was quantified from computed tomography scans and reported in Hounsfield units. The physical, chemical and tensile properties of the radiopaque ultra-high molecular weight polyethylene were examined and compared to untreated and thermally treated controls. The results of this study confirmed that for the samples treated at 115°C or less the diffusion of the contrast agent did not significantly alter the crystallinity (p = 0.7) or melting point (p = 0.4) of the polyethylene. Concomitantly, the tensile properties were not significantly different from the control samples (p > 0.05 for all properties). In conclusion, the radiopaque ultra-high molecular weight polyethylene treated for less than 18 h at a temperature of 115°C or below is a promising candidate for joint replacement applications as it can be identified in a standard X-ray while retaining the tensile properties of clinically used radiolucent ultra-high molecular weight polyethylene.
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Affiliation(s)
- Elise C Pegg
- Department of Mechanical Engineering, University of Bath, Bath, UK
| | | | - Fedra P Zaribaf
- Department of Mechanical Engineering, University of Bath, Bath, UK
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Mohammad HR, Campi S, Kennedy JA, Judge A, Murray DW, Mellon SJ. Long-term in vivo wear of different bearing types used for the Oxford Unicompartmental Knee Replacement. Bone Joint Res 2019; 8:535-543. [PMID: 31832173 PMCID: PMC6888733 DOI: 10.1302/2046-3758.811.bjr-2019-0163.r1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Objectives The aim of this study was to determine the polyethylene wear rate of Phase 3 Oxford Unicompartmental Knee Replacement bearings and to investigate the effects of resin type and manufacturing process. Methods A total of 63 patients with at least ten years’ follow-up with three bearing types (1900 resin machined, 1050 resin machined, and 1050 resin moulded) were recruited. Patients underwent full weight-bearing model-based radiostereometric analysis to determine the bearing thickness. The linear wear rate was estimated from the change in thickness divided by the duration of implantation. Results The wear rate for 1900 resin machined (n = 19), 1050 machined (n = 21), and 1050 moulded bearings (n = 23) were 60 µm/year (sd 42), 76 µm/year (sd 32), and 57 µm/year (sd 30), respectively. There was no significant difference between 1900 machined and 1050 machined (p = 0.20), but 1050 moulded had significantly less wear than the 1050 machined (p = 0.05). Increasing femoral (p < 0.001) and tibial (p < 0.001) component size were associated with increasing wear. Conclusion Wear rate is similar with 1050 and 1900 resin, but lower with moulded bearings than machined bearings. The currently used Phase 3 bearings wear rate is low (1050 moulded, 57 µm/year), but higher than the previously reported Phase 2 bearings (1900 moulded, 20 µm/year). This is unlikely to be due to the change in polyethylene but may relate to the minimally invasive approach used with the Phase 3. This approach, as well as improving function and thus increasing activity levels, may increase the risk of surgical errors, such as impingement or bearing overhang, which can increase wear. Surgeons should aim to use 4 mm thick bearings rather than 3 mm thick bearings in young patients, unless they are small and need conservative bone resections. Cite this article: Bone Joint Res 2019;8:535–543.
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Affiliation(s)
- Hasan R Mohammad
- Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK; Oxford University Hospitals. Nuffield Orthopaedic Centre, Oxford, UK
| | - Stefano Campi
- Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK; Oxford University Hospitals. Nuffield Orthopaedic Centre, Oxford, UK
| | - James A Kennedy
- Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK; Oxford University Hospitals. Nuffield Orthopaedic Centre, Oxford, UK
| | - Andrew Judge
- Musculoskeletal Research Unit, University of Bristol, Bristol, UK; Director MSc Orthopaedic Surgery, University of Bristol; Honorary Professor, Centre for Statistics in Medicine, University of Oxford, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK
| | - David W Murray
- Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK; Oxford University Hospitals. Nuffield Orthopaedic Centre, Oxford, UK
| | - Stephen J Mellon
- Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK
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MacLeod AR, Rose H, Gill HS. A Validated Open-Source Multisolver Fourth-Generation Composite Femur Model. J Biomech Eng 2017; 138:2552969. [PMID: 27618586 DOI: 10.1115/1.4034653] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2015] [Indexed: 11/08/2022]
Abstract
Synthetic biomechanical test specimens are frequently used for preclinical evaluation of implant performance, often in combination with numerical modeling, such as finite-element (FE) analysis. Commercial and freely available FE packages are widely used with three FE packages in particular gaining popularity: abaqus (Dassault Systèmes, Johnston, RI), ansys (ANSYS, Inc., Canonsburg, PA), and febio (University of Utah, Salt Lake City, UT). To the best of our knowledge, no study has yet made a comparison of these three commonly used solvers. Additionally, despite the femur being the most extensively studied bone in the body, no freely available validated model exists. The primary aim of the study was primarily to conduct a comparison of mesh convergence and strain prediction between the three solvers (abaqus, ansys, and febio) and to provide validated open-source models of a fourth-generation composite femur for use with all the three FE packages. Second, we evaluated the geometric variability around the femoral neck region of the composite femurs. Experimental testing was conducted using fourth-generation Sawbones® composite femurs instrumented with strain gauges at four locations. A generic FE model and four specimen-specific FE models were created from CT scans. The study found that the three solvers produced excellent agreement, with strain predictions being within an average of 3.0% for all the solvers (r2 > 0.99) and 1.4% for the two commercial codes. The average of the root mean squared error against the experimental results was 134.5% (r2 = 0.29) for the generic model and 13.8% (r2 = 0.96) for the specimen-specific models. It was found that composite femurs had variations in cortical thickness around the neck of the femur of up to 48.4%. For the first time, an experimentally validated, finite-element model of the femur is presented for use in three solvers. This model is freely available online along with all the supporting validation data.
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Affiliation(s)
- Alisdair R MacLeod
- Centre for Biomechanics, Department of Mechanical Engineering, University of Bath, Bath BA2 7AY, UK e-mail:
| | - Hannah Rose
- Centre for Biomechanics, Department of Mechanical Engineering, University of Bath, Bath BA2 7AY, UK e-mail:
| | - Harinderjit S Gill
- Centre for Biomechanics, Department of Mechanical Engineering, University of Bath, Bath BA2 7AY, UK e-mail:
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Mentink MJA, Van Duren BH, Murray DW, Gill HS. A novel flexible capacitive load sensor for use in a mobile unicompartmental knee replacement bearing: An in vitro proof of concept study. Med Eng Phys 2017; 46:44-53. [DOI: 10.1016/j.medengphy.2017.05.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Revised: 04/10/2017] [Accepted: 05/16/2017] [Indexed: 11/25/2022]
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