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Bellare A, Carvalho BL. The role of lamellar morphology on the post-irradiation oxidative degradation of ultra-high molecular weight polyethylene. Polym Degrad Stab 2022. [DOI: 10.1016/j.polymdegradstab.2022.110174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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2
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Third body damage and wear in arthroplasty bearing materials: A review of laboratory methods. BIOMATERIALS AND BIOSYSTEMS 2021; 4:100028. [PMID: 36824573 PMCID: PMC9934499 DOI: 10.1016/j.bbiosy.2021.100028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 08/16/2021] [Accepted: 09/05/2021] [Indexed: 12/28/2022] Open
Abstract
Third body wear of arthroplasty bearing materials can occur when hard particles such as bone, bone cement or metal particles become trapped between the articulating surfaces. This can accelerate overall implant wear, potentially leading to early failure. With the development of novel bearing materials and coatings, there is a need to develop and standardise test methods which reflect third body damage seen on retrieved implants. Many different protocols and approaches have been developed to replicate third body wear in the laboratory but there is currently no consensus as to the optimal method for simulating this wear mode, hence the need to better understand existing methods. The aim of this study was to review published methods for experimental simulation of third body wear of arthroplasty bearing materials, to discuss the advantages and limitations of different approaches, the variables to be considered when designing a method and to highlight gaps in the current literature. The methods were divided into those which introduced abrasive particles into the articulating surfaces of the joint and those whereby third body damage is created directly to the articulating surfaces. However, it was found that there are a number of parameters, for example the influence of particle size on wear, which are not yet fully understood. The study concluded that the chosen method or combination of methods used should primarily be informed by the research question to be answered and risk analysis of the device.
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Bracco P, Bellare A, Bistolfi A, Affatato S. Ultra-High Molecular Weight Polyethylene: Influence of the Chemical, Physical and Mechanical Properties on the Wear Behavior. A Review. MATERIALS (BASEL, SWITZERLAND) 2017; 10:E791. [PMID: 28773153 PMCID: PMC5551834 DOI: 10.3390/ma10070791] [Citation(s) in RCA: 96] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/17/2017] [Revised: 07/06/2017] [Accepted: 07/08/2017] [Indexed: 01/03/2023]
Abstract
Ultra-high molecular weight polyethylene (UHMWPE) is the most common bearing material in total joint arthroplasty due to its unique combination of superior mechanical properties and wear resistance over other polymers. A great deal of research in recent decades has focused on further improving its performances, in order to provide durable implants in young and active patients. From "historical", gamma-air sterilized polyethylenes, to the so-called first and second generation of highly crosslinked materials, a variety of different formulations have progressively appeared in the market. This paper reviews the structure-properties relationship of these materials, with a particular emphasis on the in vitro and in vivo wear performances, through an analysis of the existing literature.
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Affiliation(s)
- Pierangiola Bracco
- Department of Chemistry and NIS (Nanostructured Interfaces and Surfaces) Center, University of Torino, 10125 Torino, Italy.
| | - Anuj Bellare
- Department of Orthopedic Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
| | | | - Saverio Affatato
- Medical Technology Laboratory, Rizzoli Orthopaedic Institute, 40136 Bologna, Italy.
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Affatato S, De Mattia JS, Bracco P, Pavoni E, Taddei P. Wear performance of neat and vitamin E blended highly cross-linked PE under severe conditions: The combined effect of accelerated ageing and third body particles during wear test. J Mech Behav Biomed Mater 2016; 64:240-52. [PMID: 27522313 DOI: 10.1016/j.jmbbm.2016.08.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Revised: 07/28/2016] [Accepted: 08/01/2016] [Indexed: 12/28/2022]
Abstract
The objective of this study is to evaluate the effects of third-body particles on the in vitro wear behaviour of three different sets of polyethylene acetabular cups after prolonged testing in a hip simulator and accelerated ageing. Vitamin E-blended, cross-linked polyethylene (XLPE_VE), cross-linked polyethylene (XLPE) and conventional polyethylene (STD_PE) acetabular cups were simulator tested for two million cycles under severe conditions (i.e. by adding third-body particles to the bovine calf serum lubricant). Micro-Fourier Transform Infrared and micro-Raman spectroscopic analyses, differential scanning calorimetry, and crosslink density measurements were used to characterize the samples at a molecular level. The STD_PE cups had twice mass loss than the XLPE_VE components and four times than the XLPE samples; statistically significant differences were found between the mass losses of the three sets of cups. The observed wear trend was justified on the basis of the differences in cross-link density among the samples (XLPE>XLPE_VE>STD_PE). FTIR crystallinity profiles, bulk DSC crystallinity and surface micro-Raman crystallinity seemed to have a similar behaviour upon testing: all of them (as well as the all-trans and ortho-trans contents) revealed the most significant changes in XLPE and XLPE_VE samples. The more severe third-body wear testing conditions determined more noticeable changes in all spectroscopic markers with respect to previous tests. Unexpectedly, traces of bulk oxidation were found in both STD_PE (unirradiated) and XLPE (remelting-stabilized), which were expected to be stable to oxidation; on the contrary, XLPE_VE demonstrated a high oxidative stability in the present, highly demanding conditions.
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Affiliation(s)
- Saverio Affatato
- Medical Technology Laboratory, Rizzoli Orthopaedic Institute, Bologna, Italy.
| | | | - Pierangiola Bracco
- Chemistry Department and Nanostructured Interfaces and Surfaces (NIS) Centre, University of Turin, Via Giuria 7, 10125 Turin, Italy
| | - Eleonora Pavoni
- Dipartimento di Scienze Biomediche e Neuromotorie, Università di Bologna, Via Belmeloro 8/2, 40126 Bologna, Italy
| | - Paola Taddei
- Dipartimento di Scienze Biomediche e Neuromotorie, Università di Bologna, Via Belmeloro 8/2, 40126 Bologna, Italy
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Trommer R, Maru M, Oliveira Filho W, Nykanen V, Gouvea C, Archanjo B, Martins Ferreira E, Silva RF, Achete C. Multi-Scale Evaluation of Wear in UHMWPE-Metal Hip Implants Tested in a hip Joint Simulator. ACTA ACUST UNITED AC 2015. [DOI: 10.1016/j.biotri.2015.08.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Zietz C, Fabry C, Reinders J, Dammer R, Kretzer JP, Bader R, Sonntag R. Wear testing of total hip replacements under severe conditions. Expert Rev Med Devices 2015; 12:393-410. [PMID: 26048088 DOI: 10.1586/17434440.2015.1050378] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Controlled wear testing of total hip replacements in hip joint simulators is a well-established and powerful method, giving an extensive prediction of the long-term clinical performance. To understand the wear behavior of a bearing and its limits under in vivo conditions, testing scenarios should be designed as physiologically as possible. Currently, the ISO standard protocol 14242 is the most common preclinical testing procedure for total hip replacements, based on a simplified gait cycle for normal walking conditions. However, in recent years, wear patterns have increasingly been observed on retrievals that cannot be replicated by the current standard. The purpose of this study is to review the severe testing conditions that enable the generation of clinically relevant wear rates and phenomena. These conditions include changes in loading and activity, third-body wear, surface topography, edge wear and the role of aging of the bearing materials.
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Affiliation(s)
- Carmen Zietz
- Department of Orthopaedics, Biomechanics and Implant Technology Research Laboratory, University Medicine Rostock, Rostock, Germany
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Medel FJ, Kurtz SM, Sharkey P, Parvizi J, Klein G, Hartzband M, Kraay M, Rimnac CM. In vivo oxidation contributes to delamination but not pitting in polyethylene components for total knee arthroplasty. J Arthroplasty 2011; 26:802-10. [PMID: 20875942 PMCID: PMC3385511 DOI: 10.1016/j.arth.2010.07.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2010] [Accepted: 07/18/2010] [Indexed: 02/01/2023] Open
Abstract
The aim of this study was to better understand how in vivo oxidation contributes to fatigue damage in total knee arthroplasty (TKA). A total of 119 tibial inserts were consecutively collected after revision surgery. Of the 119 polyethylene retrievals, 29 were gamma sterilized in air (historical), whereas the remaining 90 were gamma sterilized in nitrogen (conventional). Surface damage assessment and characterization of oxidation were performed on all the retrievals. Delamination was significantly more prevalent and extensive in the longer-term, highly oxidized, historical tibial inserts. Pitting damage, in contrast, seemed to be equally prevalent between both retrieval groups and was not correlated with in vivo oxidation. Our findings support our hypothesis that in vivo oxidation is a contributing factor to delamination, but not pitting, in TKA. Despite the lower oxidation displayed by conventional retrievals, this study provides strong evidence that delamination secondary to in vivo oxidation may occur during the second decade of implantation.
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Affiliation(s)
| | - Francisco J. Medel
- Implant Research Center, School of Biomedical Engineering, Science, and Health Systems, Drexel University, Philadelphia, PA 19104,Corresponding Author: Francisco J Medel, Ph.D., Implant Research Center, 3401 Market St., Suite 300, Philadelphia, PA 19104, Tel: 215-594-8858, Fax: 215-594-8899,
| | - Steven M. Kurtz
- Implant Research Center, School of Biomedical Engineering, Science, and Health Systems, Drexel University, Philadelphia, PA 19104,Exponent, Inc., 3401 Market Street, Philadelphia, PA 19104
| | - Peter Sharkey
- Rothman Institute, 925 Chestnut Street, Philadelphia, PA 19107
| | - Javad Parvizi
- Rothman Institute, 925 Chestnut Street, Philadelphia, PA 19107
| | - Gregg Klein
- Hartzband Center for Hip and Knee Replacement and Hackensack University Medical Center, Hackensack, NJ
| | - Mark Hartzband
- Hartzband Center for Hip and Knee Replacement and Hackensack University Medical Center, Hackensack, NJ
| | - Matthew Kraay
- Department of Orthopaedic Surgery, University Hospitals of Cleveland, 11100 Euclid Avenue, Cleveland, OH 44106
| | - Clare M. Rimnac
- Musculoskeletal Mechanics and Materials Laboratories, Departments of Mechanical and Aerospace Engineering and Orthopaedics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106-7222
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Hauser J, Esenwein SA, Awakowicz P, Steinau HU, Köller M, Halfmann H. Sterilization of heat-sensitive silicone implant material by low-pressure gas plasma. Biomed Instrum Technol 2011; 45:75-79. [PMID: 21322816 DOI: 10.2345/0899-8205-45.1.75] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
BACKGROUND In recent years, plasma treatment of medical devices and implant materials has gained more and more acceptance. Inactivation of microorganisms by exposure to ultraviolet (UV) radiation produced by plasma discharges and sterilization of medical implants and instruments is one possible application of this technique. The aim of this study was to evaluate the effectiveness of this sterilization technique on silicone implant material. METHODS Bacillus atrophaeus spores (10(6) colony-forming units [CFUs]) were sprayed on the surfaces of 12 silicone implant material samples. Four plasma sets with different gas mixtures (argon [Ar], argon-oxygen [Ar:O(2)], argon-hydrogen [Ar:H(2)] and argon-nitrogen [Ar:N(2)]) were tested for their antimicrobial properties. Post-sterilization mechanical testing of the implant material was performed in order to evaluate possible plasma-induced structural damage. RESULTS The inductively coupled low-pressure plasma technique can achieve fast and efficient sterilization of silicone implant material without adverse materials effects. All four gas mixtures led to a significant spore reduction, and no structural damage to the implant material could be observed.
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Affiliation(s)
- Joerg Hauser
- Department of Plastic Surgery, Bergmannsheil University Hospital, Bochum, Germany.
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Affatato S, Traina F, Mazzega-Fabbro C, Sergo V, Viceconti M. Is ceramic-on-ceramic squeaking phenomenon reproducible in vitro? A long-term simulator study under severe conditions. J Biomed Mater Res B Appl Biomater 2009; 91:264-71. [PMID: 19422051 DOI: 10.1002/jbm.b.31398] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Clinical and in vitro studies on ceramic hip prostheses correlate cup implant position with hip noise, ceramic wear, or ceramic liner damage. A ceramic cup malposition could lead to edge load, ceramic head wear, and squeaking. A noise of a ceramic hip could also be correlate with implant instability and liner damage. Aim of this study was to investigate the long-term wear behavior of 12 commercial alumina-on-alumina bearings under severe conditions: different angles of inclination (23 degrees, 45 degrees, and 63 degrees) and the addition of third body particles (titanium and alumina powder) to address the effective role of cup position and ceramic particles on wear and hip noise. The study was performed using a 12-stations hip joint wear simulator (Shore Western, Monrovia) under bovine calf serum used as lubricant. Wear was evaluated by gravimetric method and the piezo-spectroscopic technique was used to evaluate the residual stress of the ceramic components and correlate this to the weight loss. After eight million cycles, we found that the inclination of the cup (63 degrees in this study) was the most disadvantaged and it was correlated with a hip noise. Gravimetric measurements showed higher wear than the other configurations and these results were in agreement with the Photoluminescence investigation. In particular, the results obtained in this work revealed a residual stress state greater not only with respect to the other angles of inclination but also to two retrieved alumina acetabular cups with a 10 years follow-up.
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Affiliation(s)
- S Affatato
- Laboratorio di Tecnologia Medica, Istituto Ortopedico Rizzoli, Bologna, Italy.
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Hauser J, Halfmann H, Awakowicz P, Köller M, Esenwein SA. [A double inductively coupled low-pressure plasma for sterilization of medical implant materials]. ACTA ACUST UNITED AC 2008; 53:199-203. [PMID: 18643713 DOI: 10.1515/bmt.2008.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The potential of plasma treatment in medicine is only slowly gaining acceptance. Inactivation of germs through exposure to UV radiation produced by plasma discharges and sterilization of medical implant devices and instruments is one possible application of this technique. In addition, due to the manifold possibilities of coating through plasma processes, quick sterilization-coating combinations of medical implant devices are possible. To analyze the effectiveness of this sterilization process on different material surfaces, three different alloys (X2CrNiMo18-15-3, Ti6Al7Nb and Ti6Al4V) and one thermoplastic material (ultra-high molecular weight polyethylene, UHMWPE), commonly used in medical implant devices, were examined in the presented study. After spraying Bacillus atrophaeus spores (10(6) CFU) on the surfaces of four different implant materials tested in this study (X2CrNiMo18-15-3, UHMWPE, Ti6Al7Nb and Ti6Al4V), it was demonstrated in each of four gas mixtures used (Ar, Ar:O2, Ar:H2 and Ar:N2) that due to the application of inductively coupled low-pressure plasma technique, plain medical implant materials can be sterilized rapidly, and can be protective and efficient.
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Affiliation(s)
- Jörg Hauser
- Klinik für Plastische Chirurgie, Berufsgenossenschaftliches Universitätsklinikum Bergmannsheil, Bochum, Deutschland.
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11
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Ilizaliturri Sánchez VM, Mangino Pariente G, Camacho Galindo J. [Surgical treatment of hip osteoarthritis: update in total hip arthroplasty]. ACTA ACUST UNITED AC 2007; 3 Suppl 3:S57-62. [PMID: 21794483 DOI: 10.1016/s1699-258x(07)73657-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Total hip replacement is one of the most successful procedures in orthopaedic surgery. There are two different technologies for implant fixation in total hip replacement: cemented and cementless, both can be combined, which is called Hybrid arthroplasty. Long term implant stability results in long term function. The most important factor that limits longevity of well-fixed implants is the wear of the articular surfaces. Wear of the polyethylene from the acetabulum generates particles that access the implant bone or the implant-cement-bone interface. This produces an inflammatory reaction, osteolysis and implant loosening. Polyethylene of higher resistance to wear and prosthetic articulations without polyethylene (hard on hard bearings), have been introduced to improve wear particle generation. Minimally invasive surgical techniques minimize surgical trauma to sort tissue around the hip joint, facilitating a better and more rapid recovery.
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Affatato S, Bersaglia G, Junqiang Y, Traina F, Toni A, Viceconti M. The predictive Power of Surface Profile Parameters on the Amount of Wear Measured In Vitro on Metal-On-Polyethylene Artificial Hip Joints. Proc Inst Mech Eng H 2006; 220:457-64. [PMID: 16808078 DOI: 10.1243/09544119jeim95] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Various studies report a weak correlation between the average surface roughness Ra of metallic ballheads and the observed wear rate of the polyethylene cups coupled to them. The aim of this study is to verify, with controlled in vitro experiments, whether other parameters such as the total roughness Rt, and the skewness Rsk are better predictors of the polyethylene wear when the metallic heads present a surface conditioning that varies substantially from specimen to specimen, as is usually the case with retrieved specimens. Twelve CoCrMo (cobalt-chromium-molybdenum) ballheads were intentionally damaged in order to reproduce a wide spectrum of surface conditioning and were then subjected to the standard wear test against polyethylene cups, using a hip joint wear simulator. After 2 × 106 cycles the weight lost by the cups was assessed with a gravimetric procedure, and the surface roughness of the metallic ballheads was qualified in terms of Ra, Rt, and Rsk. The various parameters were correlated to the weight loss using a linear regression analysis. The skewness Rsk showed a coefficient linear regression R2 = 0.80, while the average roughness Ra, used in most previous studies, presented an R2 = 0.56. It was concluded that when specimens with substantially different surface conditioning are compared, as in retrievals analysis, it is also important to report the skewness Rsk so that qualify the surface roughness of the specimens can be qualified.
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Affiliation(s)
- S Affatato
- Laboratorio di Tecnologia Medica, Istituti Ortopedici Rizzoli, Bologna, Italy.
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Mirghany M, Jin ZM. Prediction of scratch resistance of cobalt chromium alloy bearing surface, articulating against ultra-high molecular weight polyethylene, due to third-body wear particles. Proc Inst Mech Eng H 2005; 218:41-50. [PMID: 14982345 DOI: 10.1243/095441104322807749] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The entrapment of abrasive particles within the articulation between a cobalt chromium alloy (CoCrMo) femoral component and an ultra-high molecular weight polyethylene (UHMWPE) cup of artificial hip joints or tibial inserts of artificial knee joints usually scratches the metallic bearing surface and consequently increases the surface roughness. This has been recognized as one of the main causes of excessive polyethylene wear, leading to osteolysis and loosening of the prosthetic components. The purpose of this study was to use the finite element method to investigate the resistance of the cobalt chromium alloy bearing surface to plastic deformation, as a first approximation to causing scratches, due to various entrapped debris such as bone, CoCrMo and ZrO2 (contained in radiopaque polymethyl methacrylate cement). A simple axisymmetric micro contact mechanics model was developed, where a spherical third-body wear particle was indented between the two bearing surfaces, modelled as two solid cylinders of a given diameter, under the contact pressure determined from macro-models representing either hip or knee implants. The deformation of both the wear particle and the bearing surfaces was modelled and was treated as elastic-plastic. The indented peak-to-valley height on the CoCrMo bearing surface from the finite element model was found to be in good agreement with that reported in a previous study when the third-body wear particle was assumed to be rigid. Under the physiological contact pressure experienced in both hip and knee implants, ZrO2 wear particles were found to be fully embedded within the UHMWPE bearing surface, and the maximum von Mises stresses within the CoCrMo bearing surface reached the corresponding yield strength. Consequently, the CoCrMo bearing surface was deformed plastically and the corresponding peak-to-valley height (surface roughness) was found to increase with both the hardness and the size of the wear particle. Even in the case of CoCrMo wear particles, with similar mechanical properties to those of the CoCrMo bearing surface, a significant plastic deformation of the bearing surface was also noted; this highlighted the importance of considering the deformation of the wear particles. These findings support the hypotheses made by clinical studies on the contribution of entrapped debris to increased surface roughness of CoCrMo femoral bearing surfaces.
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Affiliation(s)
- M Mirghany
- Medical Engineering, School of Engineering, Design and Technology, University of Bradford, Bradford, UK
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14
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Affatato S, Bersaglia G, Rocchi M, Taddei P, Fagnano C, Toni A. Wear behaviour of cross-linked polyethylene assessed in vitro under severe conditions. Biomaterials 2005; 26:3259-67. [PMID: 15603821 DOI: 10.1016/j.biomaterials.2004.07.070] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2004] [Accepted: 07/30/2004] [Indexed: 12/28/2022]
Abstract
The polyethylene (PE) for hip implants presents serious clinical problems; the production of debris may induce adverse tissue reactions that may lead to extensive bone loss around the implant and consequently osteolysis and implant loosening. Several attempts have been made to improve the wear properties of ultra-high molecular weight polyethylene (UHMWPE). More recently the attention of various researchers has been focused on cross-linked polyethylene (XLPE), due to its improved wear resistance with respect to conventional UHMWPE. This study was aimed at comparing the wear performances of clinically available acetabular liners (Zimmer Inc.) made of electron beam XLPE and conventional UHMWPE. To evaluate the influence of the material properties on wear, conventional UHMWPE and XLPE acetabular cups were tested against deliberately scratched CoCrMo femoral heads (Ra = 0.12-0.14 microm) in a hip joint wear simulator run for 3 million cycles with bovine calf serum as lubricant. Gravimetric measurements revealed significant differences between the wear behaviours of the two sets of acetabular cups: XLPE exhibited a wear rate about 40 times lower than conventional UHMWPE. Raman spectroscopy coupled to partial least-squares analysis was used to evaluate the possible crystallinity changes induced by mechanical stress (and thus the material wear resistance): only the UHMWPE cup which showed the highest weight loss displayed significant crystallinity changes. These results were correlated to the thickness of the plasticity-induced damage layer. The wear debris produced during the tests were isolated according to a validated protocol and imaged by scanning electron microscopy . The wear particles produced by XLPE were smaller than those produced by UHMWPE; the latter were observed as fibrillar and agglomerated particles. The mean equivalent circle diameter was 0.71 and 0.26 microm for UHMWPE and XLPE, respectively.
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Affiliation(s)
- Saverio Affatato
- Laboratorio di Tecnologia Medica, Istituti Ortopedici Rizzoli, Via di Barbiano 1/10, Bologna 40136, Italy.
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15
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Bowden AE, Kurtz SM, Edidin AA. Validation of a micro-CT technique for measuring volumetric wear in retrieved acetabular liners. J Biomed Mater Res B Appl Biomater 2005; 75:205-9. [PMID: 16037962 DOI: 10.1002/jbm.b.30318] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
In this study, a novel micro-CT-based technique for evaluating wear in retrieved acetabular liners was introduced and validated. Six UHMWPE acetabular components ranging in implantation time from 2.7 to 14.4 years were collected and evaluated with the use of a high-resolution micro-CT scanner. The components were scanned with a uniform volumetric resolution of 74 microns (16-bit precision) with the use of a 1,024 x 1,024 in-plane image matrix. Manual rigid 3D image registration of the interior hemispherical portion of the acetabular cup with geometric primitives by trained observers allowed for isolation, visualization, and measurement of the wear volume. Results for these six components indicated an average wear rate of 65 mm(3)/year. Overall scanner error was quantified gravimetrically and associated with a maximum uncertainty of 0.6%. Intra-- and interobserver uncertainty analysis showed the method to be both accurate and repeatable.
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Affiliation(s)
- A E Bowden
- Implant Research Center, Drexel University. abowden@exponent,com
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