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Shahemi NH, Liza S, Sawae Y, Morita T, Shinmori H, Yaakob Y. Effects of surface wettability and thermal conductivity on the wear performance of ultrahigh molecular weight polyethylene/graphite and ultrahigh molecular weight polyethylene/graphene oxide composites. POLYM ADVAN TECHNOL 2022. [DOI: 10.1002/pat.5651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Nur Hidayah Shahemi
- TriPreM i‐Kohza, Department of Mechanical Precision Engineering, Malaysia‐Japan International Institute Technology Universiti Teknologi Malaysia Kuala Lumpur Malaysia
| | - Shahira Liza
- TriPreM i‐Kohza, Department of Mechanical Precision Engineering, Malaysia‐Japan International Institute Technology Universiti Teknologi Malaysia Kuala Lumpur Malaysia
| | - Yoshinori Sawae
- Machine Elements and Design Engineering Laboratory, Department of Mechanical Engineering, Faculty of Engineering Kyushu University Fukuoka Japan
| | - Takehiro Morita
- Machine Elements and Design Engineering Laboratory, Department of Mechanical Engineering, Faculty of Engineering Kyushu University Fukuoka Japan
| | - Hironori Shinmori
- Machine Elements and Design Engineering Laboratory, Department of Mechanical Engineering, Faculty of Engineering Kyushu University Fukuoka Japan
| | - Yazid Yaakob
- Department of Physics, Faculty of Science Universiti Putra Malaysia Serdang Malaysia
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2
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Synthesis of a Lubricant to Mimic the Biorheological Behavior of Osteoarthritic and Revision Synovial Fluid. LUBRICANTS 2021. [DOI: 10.3390/lubricants9090087] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The rheological properties of synovial fluid (SF) are essential for the friction behavior and wear performance of total joint replacements. Standardized in vitro wear tests for endoprosthesis recommend diluted calf serum, which exhibits substantial different rheological properties compared to SF. Therefore, the in vitro test conditions do not mimic the in vivo conditions. SF samples from osteoarthritis knee patients and patients undergoing knee endoprosthesis revision surgery were compared biochemically and rheologically. The flow properties of SF samples were compared to synthetic fluid constituents, such as bovine serum albumin (BSA) and hyaluronic acid (HA). Interestingly, HA was identified as a significant contributor to shear-thinning. Using the acquired data and mathematical modelling, the flow behavior of human SF was modelled reliably by an adapted adjustment of biorelevant fluid components. Friction tests in a hard/soft bearing (ceramic/UHMWPE) demonstrated that, in contrast to serum, the synthetic model fluids generate a more realistic friction condition. The developed model for an SF mimicking lubricant is recommended for in vitro wear tests of endoprostheses. Furthermore, the results highlight that simulator tests should be performed with a modified lubricant considering an addition of HA for clinically relevant lubrication conditions.
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Damm P, Bender A, Waldheim V, Winkler T, Duda GN. Surgical cup placement affects the heating up of total joint hip replacements. Sci Rep 2021; 11:15851. [PMID: 34349160 PMCID: PMC8338953 DOI: 10.1038/s41598-021-95387-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 07/07/2021] [Indexed: 11/16/2022] Open
Abstract
The long-term success of highly effective total hip arthroplasty (THA) is mainly restricted by aseptic loosening, which is widely associated with friction between the head and cup liner. However, knowledge of the in vivo joint friction and resulting temperature increase is limited. Employing a novel combination of in vivo and in silico technologies, we analyzed the hypothesis that the intraoperatively defined implant orientation defines the individual joint roofing, friction and its associated temperature increase. A total of 38,000 in vivo activity trials from a special group of 10 subjects with instrumented THA implants with an identical material combination were analyzed and showed a significant link between implant orientation, joint kinematics, joint roofing and friction-induced temperature increase but surprisingly not with acting joint contact force magnitude. This combined in vivo and in silico analysis revealed that cup placement in relation to the stem is key to the in vivo joint friction and heating-up of THA. Thus, intraoperative placement, and not only articulating materials, should be the focus of further improvements, especially for young and more active patients.
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Affiliation(s)
- Philipp Damm
- Berlin Institute of Health at Charité-Universitätsmedizin Berlin, Julius Wolff Institute, Berlin, Germany.
| | - Alwina Bender
- Berlin Institute of Health at Charité-Universitätsmedizin Berlin, Julius Wolff Institute, Berlin, Germany
| | - Vivian Waldheim
- Berlin Institute of Health at Charité-Universitätsmedizin Berlin, Julius Wolff Institute, Berlin, Germany
| | - Tobias Winkler
- Berlin Institute of Health at Charité-Universitätsmedizin Berlin, Julius Wolff Institute, Berlin, Germany
- Center for Musculoskeletal Surgery, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
- Berlin Institute of Health Center for Regenerative Therapies, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Georg N Duda
- Berlin Institute of Health at Charité-Universitätsmedizin Berlin, Julius Wolff Institute, Berlin, Germany
- Berlin Institute of Health Center for Regenerative Therapies, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
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Yorifuji M, Affatato S, Tateiwa T, Takahashi Y, Shishido T, Marin E, Zanocco M, Zhu W, Pezzotti G, Yamamoto K. Wear Simulation of Ceramic-on-Crosslinked Polyethylene Hip Prostheses: A New Non-Oxide Silicon Nitride versus the Gold Standard Composite Oxide Ceramic Femoral Heads. MATERIALS 2020; 13:ma13132917. [PMID: 32610510 PMCID: PMC7372377 DOI: 10.3390/ma13132917] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 06/24/2020] [Accepted: 06/24/2020] [Indexed: 11/16/2022]
Abstract
The purpose of the present study was to compare the wear behavior of ceramic-on-vitamin-E-diffused crosslinked polyethylene (Vit-E XLPE) hip bearings employing the gold standard oxide ceramic, zirconia (ZrO2)-toughened alumina (Al2O3) (ZTA, BIOLOX®delta) and a new non-oxide ceramic, silicon nitride (Si3N4, MC2®). In vitro wear test was performed using a 12-station hip joint simulator. The test was carried out by applying the kinematic inputs and outputs as recommended by ISO 14242-1:2012. Vitamin-E-diffused crosslinked polyethylene (Vit-E XLPE) acetabular liners (E1®) were coupled with Ø28-mm ZTA and Si3N4 femoral heads. XLPE liner weight loss over 5 million cycles (Mc) of testing was compared between the two different bearing couples. Surface topography, phase contents, and residual stresses were analyzed by contact profilometer and Raman microspectroscopy. Vit-E XLPE liners coupled with Si3N4 heads produced slightly lower wear rates than identical liners with ZTA heads. The mean wear rates (corrected for fluid absorption) of liners coupled with ZTA and Si3N4 heads were 0.53 ± 0.24 and 0.49 ± 0.23 mg/Mc after 5 Mc of simulated gait, respectively. However, after wear testing, the ZTA heads retained a smoother topography and showed fewer surface stresses than the Si3N4 ones. Note that no statistically significant differences were found in the above comparisons. This study suggests that the tribochemically formed soft silica layer on the Si3N4 heads may have reduced friction and slightly lowered the wear of the Vit-E XLPE liners. Considering also that the toughness of Si3N4 is superior to ZTA, the present wear data represent positive news in the future development of long-lasting hip components.
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Affiliation(s)
- Makiko Yorifuji
- Department of Orthopedic Surgery, Tokyo Medical University, 6-7-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo 160-0023, Japan; (M.Y.); (T.T.); (Y.T.); (T.S.); (G.P.)
| | - Saverio Affatato
- Laboratorio di Tecnologia Medica, IRCCS Istituto Ortopedico Rizzoli, Via di Barbiano 1/10, 40136 Bologna, Italy
- Correspondence: (S.A.); (K.Y.)
| | - Toshiyuki Tateiwa
- Department of Orthopedic Surgery, Tokyo Medical University, 6-7-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo 160-0023, Japan; (M.Y.); (T.T.); (Y.T.); (T.S.); (G.P.)
| | - Yasuhito Takahashi
- Department of Orthopedic Surgery, Tokyo Medical University, 6-7-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo 160-0023, Japan; (M.Y.); (T.T.); (Y.T.); (T.S.); (G.P.)
| | - Takaaki Shishido
- Department of Orthopedic Surgery, Tokyo Medical University, 6-7-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo 160-0023, Japan; (M.Y.); (T.T.); (Y.T.); (T.S.); (G.P.)
| | - Elia Marin
- Ceramic Physics Laboratory, Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, Kyoto 606-8585, Japan; (E.M.); (M.Z.); (W.Z.)
| | - Matteo Zanocco
- Ceramic Physics Laboratory, Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, Kyoto 606-8585, Japan; (E.M.); (M.Z.); (W.Z.)
| | - Wenliang Zhu
- Ceramic Physics Laboratory, Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, Kyoto 606-8585, Japan; (E.M.); (M.Z.); (W.Z.)
| | - Giuseppe Pezzotti
- Department of Orthopedic Surgery, Tokyo Medical University, 6-7-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo 160-0023, Japan; (M.Y.); (T.T.); (Y.T.); (T.S.); (G.P.)
- Ceramic Physics Laboratory, Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, Kyoto 606-8585, Japan; (E.M.); (M.Z.); (W.Z.)
| | - Kengo Yamamoto
- Department of Orthopedic Surgery, Tokyo Medical University, 6-7-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo 160-0023, Japan; (M.Y.); (T.T.); (Y.T.); (T.S.); (G.P.)
- Correspondence: (S.A.); (K.Y.)
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Wear and Friction of UHMWPE-on-PEEK OPTIMA™. J Mech Behav Biomed Mater 2018; 89:65-71. [PMID: 30265867 PMCID: PMC6195677 DOI: 10.1016/j.jmbbm.2018.09.021] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 09/11/2018] [Accepted: 09/17/2018] [Indexed: 12/28/2022]
Abstract
PEEK-OPTIMA™ is being considered as an alternative bearing material to cobalt chrome in the femoral component of total knee replacement to provide a metal-free implant. The aim of this study was to investigate the influence of lubricant temperature (standard rig running and elevated temperature (~36 °C)) on the wear of a UHMWPE-on-PEEK OPTIMA™ bearing couple using different lubricant protein concentrations (0%, 2%, 5%, 25% and 90% bovine serum) in a simple geometry pin-on-plate configuration. Friction was also investigated under a single temperature condition for different lubricant protein concentrations. The studies were repeated for UHMWPE-on-cobalt chrome in order to compare relationships with temperature (wear only) and lubricant protein concentration (wear and friction). In low lubricant protein concentrations (≤ 5%) there was no influence of temperature on the wear factors of UHMWPE-on-PEEK. With 25% bovine serum, the wear factor of UHMWPE-on-PEEK reduced by half at elevated temperature. When tested in high protein concentration (90% serum), there was no influence of temperature on the wear factor of UHMWPE-on-PEEK. These temperature dependencies were not the same for UHMWPE-on-cobalt chrome. For both material combinations, there was a trend of decreasing friction with increasing protein concentration once protein was present in the lubricant. This study has shown the importance of the selection of appropriate test conditions when investigating the wear and friction of different materials, in order to minimise test artefacts such as polymer transfer, and protein precipitation and deposition.
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O'Dwyer Lancaster-Jones O, Williams S, Jennings LM, Thompson J, Isaac GH, Fisher J, Al-Hajjar M. An in vitro simulation model to assess the severity of edge loading and wear, due to variations in component positioning in hip joint replacements. J Biomed Mater Res B Appl Biomater 2017; 106:1897-1906. [PMID: 28941162 PMCID: PMC6088455 DOI: 10.1002/jbm.b.33991] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 06/22/2017] [Accepted: 08/30/2017] [Indexed: 12/03/2022]
Abstract
The aim of this study was to develop a preclinical in vitro method to predict the occurrence and severity of edge loading condition associated with the dynamic separation of the centres of the head and cup (in the absence of impingement) for variations in surgical positioning of the cup. Specifically, this study investigated the effect of both the variations in the medial–lateral translational mismatch between the centres of the femoral head and acetabular cup and the variations in the cup inclination angles on the occurrence and magnitude of the dynamic separation, the severity of edge loading, and the wear rate of ceramic‐on‐ceramic hip replacement bearings in a multi‐station hip joint simulator during a walking gait cycle. An increased mismatch between the centres of rotation of the femoral head and acetabular cup resulted in an increased level of dynamic separation and an increase in the severity of edge loading condition which led to increased wear rate in ceramic‐on‐ceramic bearings. Additionally for a given translational mismatch, an increase in the cup inclination angle gave rise to increased dynamic separation, worst edge loading conditions, and increased wear. To reduce the occurrence and severity of edge loading, the relative positions (the mismatch) of the centres of rotation of the head and the cup should be considered alongside the rotational position of the acetabular cup. This study has considered the combination of mechanical and tribological factors for the first time in the medial–lateral axis only, involving one rotational angle (inclination) and one translational mismatch. © 2017 The Authors Journal of Biomedical Materials Research Part B: Applied Biomaterials Published by Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1897–1906, 2018.
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Affiliation(s)
- O O'Dwyer Lancaster-Jones
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, United Kingdom
| | - S Williams
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, United Kingdom
| | - L M Jennings
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, United Kingdom
| | - J Thompson
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, United Kingdom.,DePuy Synthes Joint Reconstruction, Leeds, United Kingdom
| | - G H Isaac
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, United Kingdom.,DePuy Synthes Joint Reconstruction, Leeds, United Kingdom
| | - J Fisher
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, United Kingdom
| | - M Al-Hajjar
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, United Kingdom
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7
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Sonntag R, Braun S, Al-Salehi L, Reinders J, Mueller U, Kretzer JP. Three-dimensional friction measurement during hip simulation. PLoS One 2017; 12:e0184043. [PMID: 28886102 PMCID: PMC5590873 DOI: 10.1371/journal.pone.0184043] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Accepted: 08/16/2017] [Indexed: 11/19/2022] Open
Abstract
Objectives Wear of total hip replacements has been the focus of many studies. However, frictional effects, such as high loading on intramodular connections or the interface to the bone, as well as friction associated squeaking have recently increased interest about the amount of friction that is generated during daily activities. The aim of this study was thus to establish and validate a three-dimensional friction setup under standardized conditions. Materials and methods A standard hip simulator was modified to allow for high precision measurements of small frictional effects in the hip during three-dimensional hip articulation. The setup was verified by an ideal hydrostatic bearing and validated with a static-load physical pendulum and an extension-flexion rotation with a dynamic load profile. Additionally, a pendulum model was proposed for screening measurement of frictional effects based on the damping behavior of the angular oscillation without the need for any force/moment transducer. Finally, three-dimensional friction measurements have been realized for ceramic-on-polyethylene bearings of three different sizes (28, 36 and 40 mm). Results A precision of less than 0.2 Nm during three-dimensional friction measurements was reported, while increased frictional torque (resultant as well as taper torque) was measured for larger head diameters. These effects have been confirmed by simple pendulum tests and the theoretical model. A comparison with current literature about friction measurements is presented. Conclusions This investigation of friction is able to provide more information about a field that has been dominated by the reduction of wear. It should be considered in future pre-clinical testing protocols given by international organizations of standardization.
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Affiliation(s)
- Robert Sonntag
- Laboratory of Biomechanics and Implant Research, Clinic for Orthopedics and Trauma Surgery, Heidelberg University Hospital, Heidelberg, Germany
- * E-mail:
| | - Steffen Braun
- Laboratory of Biomechanics and Implant Research, Clinic for Orthopedics and Trauma Surgery, Heidelberg University Hospital, Heidelberg, Germany
| | - Loay Al-Salehi
- Laboratory of Biomechanics and Implant Research, Clinic for Orthopedics and Trauma Surgery, Heidelberg University Hospital, Heidelberg, Germany
| | - Joern Reinders
- Laboratory of Biomechanics and Implant Research, Clinic for Orthopedics and Trauma Surgery, Heidelberg University Hospital, Heidelberg, Germany
| | - Ulrike Mueller
- Laboratory of Biomechanics and Implant Research, Clinic for Orthopedics and Trauma Surgery, Heidelberg University Hospital, Heidelberg, Germany
| | - J. Philippe Kretzer
- Laboratory of Biomechanics and Implant Research, Clinic for Orthopedics and Trauma Surgery, Heidelberg University Hospital, Heidelberg, Germany
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8
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Damm P, Bender A, Duda G, Bergmann G. In vivo measured joint friction in hip implants during walking after a short rest. PLoS One 2017; 12:e0174788. [PMID: 28350858 PMCID: PMC5370152 DOI: 10.1371/journal.pone.0174788] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 03/15/2017] [Indexed: 11/18/2022] Open
Abstract
Introduction It has been suspected that friction in hip implants is higher when walking is initiated after a resting period than during continuous movement. It cannot be excluded that such increased initial moments endanger the cup fixation in the acetabulum, overstress the taper connections in the implant or increase wear. To assess these risks, the contact forces, friction moments and friction coefficients in the joint were measured in vivo in ten subjects. Instrumented hip joint implants with telemetric data transmission were used to access the contact loads between the cup and head during the first steps of walking after a short rest. Results The analysis demonstrated that the contact force is not increased during the first step. The friction moment in the joint, however, is much higher during the first step than during continuous walking. The moment increases throughout the gait cycle were 32% to 143% on average and up to 621% individually. The high initial moments will probably not increase wear by much in the joint. However, comparisons with literature data on the fixation resistance of the cup against moments made clear that the stability can be endangered. This risk is highest during the first postoperative months for cementless cups with insufficient under-reaming. The high moments after a break can also put taper connections between the head and neck and neck and shaft at a higher risk. Discussion During continuous walking, the friction moments individually were extremely varied by factors of 4 to 10. Much of this difference is presumably caused by the varying lubrication properties of the synovia. These large moment variations can possibly lead to friction-induced temperature increases during walking, which are higher than the 43.1°C which have previously been observed in a group of only five subjects.
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Affiliation(s)
- Philipp Damm
- Julius Wolff Institute, Charité–Universitätsmedizin Berlin, Berlin, Germany
- * E-mail:
| | - Alwina Bender
- Julius Wolff Institute, Charité–Universitätsmedizin Berlin, Berlin, Germany
| | - Georg Duda
- Julius Wolff Institute, Charité–Universitätsmedizin Berlin, Berlin, Germany
| | - Georg Bergmann
- Julius Wolff Institute, Charité–Universitätsmedizin Berlin, Berlin, Germany
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A Tribological Assessment of Ultra High Molecular Weight Polyethylene Types GUR 1020 and GUR 1050 for Orthopedic Applications. LUBRICANTS 2016. [DOI: 10.3390/lubricants4030025] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Smith SL, Li L, Joyce TJ. Engineering of a multi-station shoulder simulator. Proc Inst Mech Eng H 2016; 230:470-80. [PMID: 27160564 DOI: 10.1177/0954411915611161] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 09/15/2015] [Indexed: 11/16/2022]
Abstract
This work aimed to engineer a multi-station shoulder simulator in order to wear test shoulder prostheses using recognized shoulder activities of daily living. A bespoke simulator was designed, built and subject to commissioning trials before a first wear test was conducted. Five JRI Orthopaedics Reverse Shoulder VAIOS 42 mm prostheses were tested for 2.0 million cycles and a mean wear rate and standard deviation of 14.2 ± 2.1 mm(3)/10(6) cycles measured for the polymeric glenoid components. This result when adjusted for prostheses diameters and test conditions showed excellent agreement with results from hip simulator studies of similar materials in a lubricant of bovine serum. The Newcastle Shoulder Simulator is the first multi-station shoulder simulator capable of applying physiological motion and loading for typical activities of daily living.
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Affiliation(s)
- Simon L Smith
- School of Mechanical and Systems Engineering, Newcastle University, Newcastle upon Tyne, UK
| | - Lisa Li
- School of Engineering Technology and Maritime Operations, Liverpool John Moores University, Liverpool, UK
| | - Thomas J Joyce
- School of Mechanical and Systems Engineering, Newcastle University, Newcastle upon Tyne, UK
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Saikko V. Friction measurement in a hip wear simulator. Proc Inst Mech Eng H 2016; 230:366-72. [DOI: 10.1177/0954411915610602] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Accepted: 09/14/2015] [Indexed: 11/16/2022]
Abstract
A torque measurement system was added to a widely used hip wear simulator, the biaxial rocking motion device. With the rotary transducer, the frictional torque about the drive axis of the biaxial rocking motion mechanism was measured. The principle of measuring the torque about the vertical axis above the prosthetic joint, used earlier in commercial biaxial rocking motion simulators, was shown to sense only a minor part of the total frictional torque. With the present method, the total frictional torque of the prosthetic hip was measured. This was shown to consist of the torques about the vertical axis above the joint and about the leaning axis. Femoral heads made from different materials were run against conventional and crosslinked polyethylene acetabular cups in serum lubrication. Regarding the femoral head material and the type of polyethylene, there were no categorical differences in frictional torque with the exception of zirconia heads, with which the lowest values were obtained. Diamond-like carbon coating of the CoCr femoral head did not reduce friction. The friction factor was found to always decrease with increasing load. High wear could increase the frictional torque by 75%. With the present system, friction can be continuously recorded during long wear tests, so the effect of wear on friction with different prosthetic hips can be evaluated.
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Affiliation(s)
- Vesa Saikko
- Department of Engineering Design and Production, School of Engineering, Aalto University, Espoo, Finland
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13
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Smith SL, Li BL, Buniya A, Lin SH, Scholes SC, Johnson G, Joyce TJ. In vitro wear testing of a contemporary design of reverse shoulder prosthesis. J Biomech 2015; 48:3072-9. [PMID: 26278181 DOI: 10.1016/j.jbiomech.2015.07.022] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2015] [Revised: 07/18/2015] [Accepted: 07/23/2015] [Indexed: 11/28/2022]
Abstract
Reverse shoulder arthroplasty is an increasingly common surgical intervention. However there are concerns and known limitations in relation to such joint replacement, while novel designs of reverse shoulder prostheses continue to appear on the market. Many claim to offer improvements over older designs but such assertions are difficult to validate when there is no consensus as to how such implants should be tested in vitro or even if such testing is necessary. In order to permit appropriate in vitro testing of reverse shoulder prostheses a unique, multi-station test rig was designed which was capable of applying motion in three axes to test prostheses. The shoulder simulator can apply up to 110° of motion in the flexion-extension and abduction-adduction axes and up to 90° in the internal-external rotation axis. Dynamic loading of up to 1500 N can be provided. The simulator is computer controlled so that the motions and loading associated with particular activities of daily living can be applied. A 4.5 million cycle wear test of commercially available reverse shoulder prostheses was undertaken using a 'mug to mouth' activity of daily living. Gravimetric analysis was used to characterise wear. After 4.5 million cycles of 'mug to mouth', the average wear rate of the test components was 14.3mm(3)/million cycles. Polyethylene test components showed a reduction in roughness and the median wear particle diameter was 167 nm. A three axis shoulder simulator has been designed and used to successfully test multiple samples of a commercially available reverse shoulder prosthesis.
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Affiliation(s)
- S L Smith
- School of Mechanical and Systems Engineering, Newcastle University, Claremont Road, Newcastle upon Tyne, NE1 7RU England, UK
| | - B L Li
- School of Engineering, Technology and Maritime Operations, Liverpool John Moores University, James Parsons Building, Byrom Street, England, UK
| | - A Buniya
- Biomedical Engineering Department, Al-khwarizmi Engineering College, Baghdad University, Iraq
| | - S Ho Lin
- School of Mechanical and Systems Engineering, Newcastle University, Claremont Road, Newcastle upon Tyne, NE1 7RU England, UK
| | - S C Scholes
- School of Mechanical and Systems Engineering, Newcastle University, Claremont Road, Newcastle upon Tyne, NE1 7RU England, UK
| | - G Johnson
- School of Mechanical and Systems Engineering, Newcastle University, Claremont Road, Newcastle upon Tyne, NE1 7RU England, UK
| | - T J Joyce
- School of Mechanical and Systems Engineering, Newcastle University, Claremont Road, Newcastle upon Tyne, NE1 7RU England, UK.
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15
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Damm P, Bender A, Bergmann G. Postoperative changes in in vivo measured friction in total hip joint prosthesis during walking. PLoS One 2015; 10:e0120438. [PMID: 25806805 PMCID: PMC4373913 DOI: 10.1371/journal.pone.0120438] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Accepted: 01/22/2015] [Indexed: 12/02/2022] Open
Abstract
Loosening of the artificial cup and inlay is the most common reasons for total hip replacement failures. Polyethylene wear and aseptic loosening are frequent reasons. Furthermore, over the past few decades, the population of patients receiving total hip replacements has become younger and more active. Hence, a higher level of activity may include an increased risk of implant loosening as a result of friction-induced wear. In this study, an instrumented hip implant was used to measure the contact forces and friction moments in vivo during walking. Subsequently, the three-dimensional coefficient of friction in vivo was calculated over the whole gait cycle. Measurements were collected from ten subjects at several time points between three and twelve months postoperative. No significant change in the average resultant contact force was observed between three and twelve months postoperative. In contrast, a significant decrease of up to 47% was observed in the friction moment. The coefficient of friction also decreased over postoperative time on average. These changes may be caused by ‘running-in’ effects of the gliding components or by the improved lubricating properties of the synovia. Because the walking velocity and contact forces were found to be nearly constant during the observed period, the decrease in friction moment suggests an increase in fluid viscosity. The peak values of the contact force individually varied by 32%-44%. The friction moment individually differed much more, by 110%-129% at three and up to 451% at twelve months postoperative. The maximum coefficient of friction showed the highest individual variability, about 100% at three and up to 914% at twelve months after surgery. These individual variations in the friction parameters were most likely due to different ‘running-in’ effects that were influenced by the individual activity levels and synovia properties.
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Affiliation(s)
- Philipp Damm
- Julius Wolff Institute, Charité—Universitaetsmedizin Berlin, Berlin, Germany
- * E-mail:
| | - Alwina Bender
- Julius Wolff Institute, Charité—Universitaetsmedizin Berlin, Berlin, Germany
| | - Georg Bergmann
- Julius Wolff Institute, Charité—Universitaetsmedizin Berlin, Berlin, Germany
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Reinders J, Sonntag R, Kretzer JP. Synovial fluid replication in knee wear testing: an investigation of the fluid volume. J Orthop Res 2015; 33:92-7. [PMID: 25244424 DOI: 10.1002/jor.22736] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 08/22/2014] [Indexed: 02/04/2023]
Abstract
Wear testing cannot replicate the variations in wear rates and wear mechanisms seen in vivo, which may be related to differences between in vivo and in vitro conditions. A considerable difference exists between the in vivo synovial fluid volume (few milliliter) and the in vitro substituted bovine serum volume (several hundred milliliter). The aim of this study was to analyze the effects of a reduced fluid volume on the wear behavior in a knee wear simulator study. Four wear tests with decreasing fluid volumes (250, 150, 75, and 45 ml) were carried out. Using a large fluid volume of 250 ml for wear testing resulted in a wear rate of 9.7±1.2 mm3/10(6) cycles. Decreasing the fluid volume consecutively reduced the wear rate to down to 8.8±1.4 mm3/10(6) for 150 ml (p=1.00), 5.6±1.2 mm3/10(6) for 75 ml (p=0.01), and 1.0±0.2 mm3/10(6) cycles for 45 ml fluid volume (p≤0.01). Additionally, higher serum degradation and larger wear particles were observed with smaller fluid volumes used for testing. This study demonstrates the high relevance of the protein-based lubricant on the wear behavior and the technical limitation to replicate the synovial fluid in simulator tests. Wear testing should be carried out using larger fluid volumes (e.g., 250 ml) to generate physiological relevant wear masses.
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Affiliation(s)
- Jörn Reinders
- Laboratory of Biomechanics and Implant Research, Clinic for Orthopedics and Trauma Surgery, Center for Orthopedics, Trauma Surgery and Spinal Cord Injury, Heidelberg University Hospital, Schlierbacher Landstrasse 200a, 69118, Heidelberg, Germany
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17
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Reinders J, Sonntag R, Kretzer JP. How do gait frequency and serum-replacement interval affect polyethylene wear in knee-wear simulator tests? JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2014; 25:2463-2469. [PMID: 25015325 DOI: 10.1007/s10856-014-5271-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Accepted: 07/01/2014] [Indexed: 06/03/2023]
Abstract
Polyethylene wear (PE) is known to be a limiting factor in total joint replacements. However, a standardized wear test (e.g. ISO standard) can only replicate the complex in vivo loading condition in a simplified form. In this study, two different parameters were analyzed: (a) Bovine serum, as a substitute for synovial fluid, is typically replaced every 500,000 cycles. However, a continuous regeneration takes place in vivo. How does serum-replacement interval affect the wear rate of total knee replacements? (b) Patients with an artificial joint show reduced gait frequencies compared to standardized testing. What is the influence of a reduced frequency? Three knee wear tests were run: (a) reference test (ISO), (b) testing with a shortened lubricant replacement interval, (c) testing with reduced frequency. The wear behavior was determined based on gravimetric measurements and wear particle analysis. The results showed that the reduced test frequency only had a small effect on wear behavior. Testing with 1 Hz frequency is therefore a valid method for wear testing. However, testing with a shortened replacement interval nearly doubled the wear rate. Wear particle analysis revealed only small differences in wear particle size between the different tests. Wear particles were not linearly released within one replacement interval. The ISO standard should be revised to address the marked effects of lubricant replacement interval on wear rate.
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Affiliation(s)
- Jörn Reinders
- Laboratory of Biomechanics and Implant Research, Department of Orthopedics and Traumatology, Heidelberg University Hospital, Schlierbacher Landstrasse 200a, 69118, Heidelberg, Germany,
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18
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Choudhury D, Ay Ching H, Mamat AB, Cizek J, Abu Osman NA, Vrbka M, Hartl M, Krupka I. Fabrication and characterization of DLC coated microdimples on hip prosthesis heads. J Biomed Mater Res B Appl Biomater 2014; 103:1002-12. [DOI: 10.1002/jbm.b.33274] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Revised: 07/26/2014] [Accepted: 08/08/2014] [Indexed: 12/27/2022]
Affiliation(s)
- Dipankar Choudhury
- Faculty of Mechanical Engineering, Brno University of Technology; Technicka 2896/2 616 69 Brno Czech Republic
- Central European Institute of Technology, Brno University of Technology; Technicka 3058/10 616 00 Brno Czech Republic
- Institute of Machine and Industrial Design, NETME Centre, Brno University of Technology; Technicka 2896/2 616 69 Brno Czech Republic
| | - Hee Ay Ching
- Department of Biomedical Engineering; Faculty of Engineering, University of Malaya; 50603 Kuala Lumpur Malaysia
| | - Azuddin Bin Mamat
- Department of Mechanical Engineering; Faculty of Engineering, University of Malaya; 50603 Kuala Lumpur Malaysia
| | - Jan Cizek
- Institute of Materials Science and Engineering, NETME Centre, Brno University of Technology; Technicka 2896/2 616 69 Brno Czech Republic
| | - Noor Azuan Abu Osman
- Department of Biomedical Engineering; Faculty of Engineering, University of Malaya; 50603 Kuala Lumpur Malaysia
| | - Martin Vrbka
- Faculty of Mechanical Engineering, Brno University of Technology; Technicka 2896/2 616 69 Brno Czech Republic
- Central European Institute of Technology, Brno University of Technology; Technicka 3058/10 616 00 Brno Czech Republic
- Institute of Machine and Industrial Design, NETME Centre, Brno University of Technology; Technicka 2896/2 616 69 Brno Czech Republic
| | - Martin Hartl
- Faculty of Mechanical Engineering, Brno University of Technology; Technicka 2896/2 616 69 Brno Czech Republic
- Institute of Machine and Industrial Design, NETME Centre, Brno University of Technology; Technicka 2896/2 616 69 Brno Czech Republic
| | - Ivan Krupka
- Faculty of Mechanical Engineering, Brno University of Technology; Technicka 2896/2 616 69 Brno Czech Republic
- Central European Institute of Technology, Brno University of Technology; Technicka 3058/10 616 00 Brno Czech Republic
- Institute of Machine and Industrial Design, NETME Centre, Brno University of Technology; Technicka 2896/2 616 69 Brno Czech Republic
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19
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Guenther LE, Pyle BW, Turgeon TR, Bohm ER, Wyss UP, Schmidt TA, Brandt JM. Biochemical analyses of human osteoarthritic and periprosthetic synovial fluid. Proc Inst Mech Eng H 2014; 228:127-39. [DOI: 10.1177/0954411913517880] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Biochemical analyses were performed on osteoarthritic and periprosthetic synovial fluid in order to propose changes to lubricant specifications currently outlined in orthopaedic wear testing standards. Osteoarthritic and periprosthetic synovial fluid samples were obtained from the hip and knee joints of 40 patients. The samples in each group were analysed and compared in order to identify differences between the protein concentration, constituent fractions, osmolality, thermal stability and the hyaluronic acid concentration and molecular weight distribution of osteoarthritic and periprosthetic synovial fluid. The average total protein concentration was approximately 30 g/L, which was much higher than the 20 g/L currently specified in the knee wear testing standard; however, the 30 g/L protein concentration matched the recently revised standard for hip simulator wear testing. No significant difference was found between the protein concentration, osmolality, thermal stability, and hyaluronic acid concentration of osteoarthritic and periprosthetic synovial fluid. The clinical data provided should be used to better define the composition of a more clinically relevant lubricant for orthopaedic wear testing.
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Affiliation(s)
- Leah E Guenther
- Department of Mechanical and Manufacturing Engineering, University of Manitoba, Winnipeg, MB, Canada
- Concordia Joint Replacement Group, Winnipeg, MB, Canada
| | - Bryan W Pyle
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
| | | | - Eric R Bohm
- Concordia Joint Replacement Group, Winnipeg, MB, Canada
| | - Urs P Wyss
- Department of Mechanical and Manufacturing Engineering, University of Manitoba, Winnipeg, MB, Canada
| | - Tannin A Schmidt
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
| | - Jan-M Brandt
- Department of Mechanical and Manufacturing Engineering, University of Manitoba, Winnipeg, MB, Canada
- Concordia Joint Replacement Group, Winnipeg, MB, Canada
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20
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Chamani A, Mehta HP, McDermott MK, Djeffal M, Nayyar G, Patwardhan DV, Attaluri A, Timmie Topoleski LD, Zhu L. Theoretical simulation of temperature elevations in a joint wear simulator during rotations. J Biomech Eng 2013; 136:021027. [PMID: 24317017 DOI: 10.1115/1.4026158] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Accepted: 12/05/2013] [Indexed: 11/08/2022]
Abstract
The objective of this study is to develop a theoretical model to simulate temperature fields in a joint simulator for various bearing conditions using finite element analyses. The frictional heat generation rate at the interface between a moving pin and a stationary base is modeled as a boundary heat source. Both the heat source and the pin are rotating on the base. We are able to conduct a theoretical study to show the feasibility of using the COMSOL software package to simulate heat transfer in a domain with moving components and a moving boundary source term. The finite element model for temperature changes agrees in general trends with experimental data. Heat conduction occurs primarily in the highly conductive base component, and high temperature elevation is confined to the vicinity of the interface in the pin. Thirty rotations of a polyethylene pin on a cobalt-chrome base for 60 s generate more than 2.26 °C in the temperature elevation from its initial temperature of 25 °C at the interface in a baseline model with a rotation frequency of 0.5 Hz. A higher heat generation rate is the direct result of a faster rotation frequency associated with intensity of exercise, and it results in doubling the temperature elevations when the frequency is increased by100%. Temperature elevations of more than 7.5 °C occur at the interface when the friction force is tripled from that in the baseline model. The theoretical modeling approach developed in this study can be used in the future to test different materials, different material compositions, and different heat generation rates at the interface under various body and environmental conditions.
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21
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22
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O'Brien S, Luo Y, Wu C, Petrak M, Bohm E, Brandt JM. Prediction of backside micromotion in total knee replacements by finite element simulation. Proc Inst Mech Eng H 2012; 226:235-45. [PMID: 22558838 DOI: 10.1177/0954411911435593] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The micromotion at the interface between the polyethylene tibial insert and metal tibial tray [corrected] in modular total knee replacements [corrected] has been shown to contribute to wear particle-induced osteolysis and may [corrected] cause implant failure. Therefore, studying the design parameters that are involved in the backside wear process is an important task that may lead to improvement in new total knee replacements. In the present study, a finite element model was developed to predict the backside micromotion along the entire modular interface. Both the linear elastic constitutive model and non-linear J2-plasticity constitutive model were considered in the finite element model for polyethylene and were corroborated against published results obtained from displacement controlled knee simulator wear tests. The finite element simulation with the non-linear J2-plasticity constitutive model was able to predict backside micromotion [corrected] more accurately than the simulation with the linear elastic constitutive model. [corrected] The developed finite element model (including the non-linear J2-plasticity constitutive model) was then applied to assess the effects of the tibial tray locking mechanism design (dovetails versus fullperipheral [corrected] design) and different levels of interference fit on insert micromotion. The developed finite element model, implementing the non-linear J2-plasticity constitutive model, was shown to successfully predict clinical amounts of backside micromotion and could be used for the design and development of total knee replacements for the reduction of backside micromotion and polyethylene [corrected] wear.
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Affiliation(s)
- Sean O'Brien
- Department of Mechanical and Manufacturing Engineering, Faculty of Engineering University of Manitoba, Canada
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23
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Brandt JM, Charron K, Zhao L, MacDonald SJ, Medley JB. Calf serum constituent fractions influence polyethylene wear and microbial growth in knee simulator testing. Proc Inst Mech Eng H 2012; 226:427-40. [DOI: 10.1177/0954411912444248] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Calf serum lubricants consisting of various polypeptide constituent fractions are routinely used in knee wear simulators as part of the standardized test protocol. Three calf sera (bovine, new-born and alpha) were diluted as per the recommendation of ISO 14243-3 and used in displacement-controlled knee wear simulators to investigate their effects on polyethylene wear. Biochemical analyses included measuring total polypeptide degradation, electrophoretic profiles and low-molecular weight polypeptide concentrations to elucidate their involvement in the wear process. The effects of the various calf sera constituent fractions on microbial growth were also explored. The polyethylene wear rates and the results from the biochemical analyses for the three calf serum lubricants were all found to be statistically significantly different from each other. The lubricant derived from the alpha-calf serum was closest in constituent fractions to human synovial fluid. It also showed the lowest polyethylene wear rate (14.38 ± 0.85 mm3/million cycles) and the lowest amount of polypeptide degradation (7.77 ± 3.87%). Furthermore, the alpha-calf serum lubricant was associated with the least amount of change in the electrophoretic profile, the least change in low-molecular weight polypeptide concentration, and the lowest microbial growth in the presence of sodium azide (a microbial inhibitor conventionally used in implant wear testing). Replacing sodium azide with a broad spectrum antibiotic-antimycotic eradicated the microbial growth. Some speculation was entertained regarding the effect of alpha-calf serum on colloid-mediated boundary lubrication. Based on the results, it was recommended that ISO 14243-3 be modified to include guidelines on calf serum constituent fractions that would favour using alpha-calf serum in order to improve the fidelity of the simulation in knee implant wear testing.
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Affiliation(s)
- Jan-M Brandt
- Concordia Joint Replacement Group, Concordia Hip and Knee Institute, Canada
| | - Kory Charron
- Division of Orthopaedic Surgery, University of Western Ontario, Canada
| | - Lin Zhao
- Department of Biochemistry, University of Western Ontario, Canada
| | | | - John B Medley
- Department of Mechanical and Mechatronics Engineering, University of Waterloo, Canada
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The use of self-mating PEEK as an alternative bearing material for cervical disc arthroplasty: a comparison of different simulator inputs and tribological environments. EUROPEAN SPINE JOURNAL : OFFICIAL PUBLICATION OF THE EUROPEAN SPINE SOCIETY, THE EUROPEAN SPINAL DEFORMITY SOCIETY, AND THE EUROPEAN SECTION OF THE CERVICAL SPINE RESEARCH SOCIETY 2012; 21 Suppl 5:S717-26. [PMID: 22415761 DOI: 10.1007/s00586-012-2252-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Revised: 01/17/2012] [Accepted: 02/26/2012] [Indexed: 10/28/2022]
Abstract
PURPOSE The hypothesis for this study was that the simulated wear behavior of a hydroxyapatite coated, self-mating PEEK cervical disc arthroplasty device would be dependent on the simulated testing environment. METHODS Five groups of devices were evaluated under suggested ASTM and ISO load and motion profiles. The groups utilized different testing frequencies and protein content of simulator fluid, in addition to assessing the potential for third body wear. The average wear rates were determined using linear regression analysis with a generalized estimating equation. Significant differences between groups were determined using the Wald's test. RESULTS The simulated wear behavior was shown to be highly dependent on the testing environment, where protein content more than decreasing the cyclic loading frequency resulted in increased wear, but was not dependent on the suggested load and motion profiles. It was demonstrated that a self-mating PEEK cervical disc arthroplasty device has wear rates that are similar to existing material combinations for cervical disc arthroplasty. CONCLUSIONS This study showed that at a time when data from retrieval analyses is deficient, it is important to test the wear resistance of cervical disc arthroplasty devices under various conditions. Long-term clinical results and ongoing implant retrievals are required for validation between clinical performance and simulator inputs.
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Brandt JM, Brière LK, Marr J, MacDonald SJ, Bourne RB, Medley JB. Biochemical comparisons of osteoarthritic human synovial fluid with calf sera used in knee simulator wear testing. J Biomed Mater Res A 2010; 94:961-71. [PMID: 20730933 DOI: 10.1002/jbm.a.32728] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Osteoarthritic human synovial fluid was obtained from the knees of 20 patients and was compared with four different calf sera solutions frequently used as lubricants in knee simulator wear testing. Assuming that the fluid after arthroplasty was the same as the fluid in patients with osteoarthritis, the total protein concentration, protein constituent fractions, osmolality, trace element concentrations, and the thermal stability obtained via differential scanning calorimetry were determined. Human synovial fluid, with an average total protein concentration of 34 g/L, was significantly different from all undiluted calf sera. However, alpha-calf serum and iron-supplemented alpha-calf serum were closest in protein constituent fractions (albumin, alpha-1-globulin, alpha-2-globulin, ss-globulin, and gamma-globulin) to human synovial fluid. Diluting calf sera with low-ion distilled water to a total protein concentration of 17 g/L (as recommended by ISO 14243) produced non-clinically relevant total protein concentration and osmolality levels. Performing the same dilution of iron-supplemented alpha-calf serum with phosphate-buffered saline solution and 1.5 g/L hyaluronic acid produced an artificial lubricant with both a clinically relevant level of osmolality and clinically relevant thermal stability as seen in human synovial fluid from patients with osteoarthritis. The present study suggested that alpha-calf serum, phosphate-buffered saline solution and hyaluronic acid were essential constituents of an artificial lubricant to mimic the major biochemical properties of human synovial fluid for simulator wear testing of total knee replacements.
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Affiliation(s)
- J-M Brandt
- Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, Ontario, Canada.
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26
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Kettler A, Bushelow M, Wilke HJ. Influence of the loading frequency on the wear rate of a polyethylene-on-metal lumbar intervertebral disc replacement. EUROPEAN SPINE JOURNAL : OFFICIAL PUBLICATION OF THE EUROPEAN SPINE SOCIETY, THE EUROPEAN SPINAL DEFORMITY SOCIETY, AND THE EUROPEAN SECTION OF THE CERVICAL SPINE RESEARCH SOCIETY 2010; 21 Suppl 5:S709-16. [PMID: 20936310 DOI: 10.1007/s00586-010-1582-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2010] [Revised: 09/09/2010] [Accepted: 09/24/2010] [Indexed: 11/29/2022]
Abstract
Pre-clinical wear testing of intervertebral disc prostheses is commonly carried out according to ISO 18192-1. Ten million multiaxial loading cycles are applied at a frequency of 1 Hz. At this frequency, testing takes about 4 months. Testing at higher frequencies would therefore be desirable. ISO 18192-1 also offers testing at 2 Hz; however, it says the impact on the implant material behaviour as well as on the accuracy of the test machine shall be investigated by the user. Since such data are not available so far, the aim of this study was to carry out comparative wear tests at 1 and 2 Hz. Seven Prodisc-L lumbar disc prostheses were tested. After a pre-soak period, the implants were placed in specimen cups filled with calf serum, mounted to a Spine Wear Simulator and loaded according to ISO 18192-1. Testing was carried out at a temperature of 37 ± 2 °C. Four million loading cycles were applied at 1 Hz and eight million at 2 Hz in an alternating sequence. Each time after 12 days of testing the implants were removed to measure the weight and the height of the polyethylene cores. Then, the test serum was exchanged and the implants were remounted to the testing machine. The mean wear rate was 5.6 ± 2.3 mg per million cycles at 1 Hz and 7.7 ± 1.6 mg per million cycles at 2 Hz during the first six million loading cycles (p < 0.05) and 2.0 ± 0.6 and 4.1 ± 0.7 mg per million cycles during the second six million cycles (p < 0.05). Similarly, the mean heightloss was also smaller at 1 Hz than at 2 Hz (p < 0.05) with -0.02 ± 0.02 mm versus -0.04 ± 0.02 mm per million cycles during the first half of testing and -0.01 ± 0.01 versus -0.02 ± 0.01 mm per million cycles during the second half. The accuracy of the test machine was within the limits described by ISO 18192-1 at both frequencies. The results showed that the wear rate was higher at the beginning than at the end of testing. Also, the results indicated that testing at 2 Hz increases the wear rate compared with 1 Hz in case of a polyethylene-on-metal implant design. In the absence of retrieval studies it is difficult to decide which rate results in a more physiological wear pattern. However, a loading frequency of 1 Hz is probably closer to physiology than 2 Hz since the loading amplitudes prescribed by ISO 18192-1 are high. They rather represent movements like tying shoes or standing up from a chair than walking or sitting. The authors therefore suggest testing at 1 Hz.
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Affiliation(s)
- Annette Kettler
- SpineServ GmbH & Co KG, Soeflinger Strasse 100, 89077 Ulm, Germany.
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27
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Maskiewicz VK, Williams PA, Prates SJ, Bowsher JG, Clarke IC. Characterization of protein degradation in serum-based lubricants during simulation wear testing of metal-on-metal hip prostheses. J Biomed Mater Res B Appl Biomater 2010; 94:429-440. [PMID: 20583304 DOI: 10.1002/jbm.b.31671] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
A size exclusion high performance liquid chromatography (SEC-HPLC) method has been developed which is capable of separation and quantitation of bovine serum albumin (BSA) and bovine serum globulin (BSG) components of serum-based lubricant (SBL) solutions. This allowed characterization of the stability profiles of these proteins when acting as lubricants during hip wear simulation, and identification of wear-specific mechanisms of degradation. Using cobalt-chromium metal-on-metal (MOM) hip joints, it was observed that BSA remained stable for up to 3 days (215K cycles) of wear testing after which the protein degraded in a fairly linear fashion. BSG on the other hand, began to degrade immediately and in a linear fashion with a rate constant of 5% per day. Loss of both proteins occurred via the formation of high molecular weight aggregates which precipitated out of solution. No fragmentation of the polypeptide backbone of either protein was observed. Data obtained suggest that protein degradation was not due to microbial contamination, denaturation at the air-water interface, or frictional heating of articulating joint surfaces in these studies. We conclude that the primary source of protein degradation during MOM simulation testing occurs via high shear rates experienced by SBL solutions at articulating surfaces, possibly coupled with metal-protein interactions occurring as new and reactive metal surfaces are generated during wear testing. The development of this analytical methodology will allow new studies to clarify the role of SBL solutions in wear simulation studies and the interactions and lubricating properties of serum proteins with prosthetic surfaces other than MOM.
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Affiliation(s)
- Victoria K Maskiewicz
- Department of Pharmaceutical Sciences, Loma Linda University School of Pharmacy, Loma Linda, California 92354, USA.
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28
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Galetz MC, Glatzel U. An activated energy approach for accelerated testing of the deformation of UHMWPE in artificial joints. J Mech Behav Biomed Mater 2010; 3:331-8. [DOI: 10.1016/j.jmbbm.2010.01.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2009] [Revised: 01/14/2010] [Accepted: 01/17/2010] [Indexed: 10/19/2022]
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Spinelli M, Affatato S, Tiberi L, Carmignato S, Viceconti M. Integrated friction measurements in hip wear simulations: Short-term results. Proc Inst Mech Eng H 2009; 224:865-76. [DOI: 10.1243/09544119jeim683] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Hip joint wear simulators are used extensively to simulate the dynamic behaviour of the human hip joint and, through the wear rate, gain a concrete indicator about the overall wear performance of different coupled bearings. Present knowledge of the dynamic behaviour of important concurrent indicators, such as the coefficient of friction, could prove helpful for the continuing improvement in applied biomaterials. A limited number of commercial or custom-made simulators have been designed specifically for friction studies but always separately from wear tests; thus, analysis of these two important parameters has remained unconnected. As a result, a new friction sensor has been designed, built, and integrated in a commercial biaxial rocking motion hip simulator. The aim of this study is to verify the feasibility of an experimental set-up in which the dynamic measurement of the friction factor could effectively be implemented in a standard wear test without compromising its general accuracy and repeatability. A short wear test was run with the new set-up for 1×106 cycles. In particular, three soft-bearings (metal-on-polyethylene, Φ = 28 mm) were tested; during the whole test, axial load and frictional torque about the vertical loading axis were synchronously recorded in order to calculate the friction factor. Additional analyses were performed on the specimens, before and after the test, in order to verify the accuracy of the wear test. The average friction factor was 0.110 ± 0.025. The friction sensors showed good accuracy and repeatability throughout. This innovative set-up was able to reproduce stable and reliable measurements. The results obtained encourage further investigations of this set-up for long-term assessment and using different combinations of materials.
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Affiliation(s)
- M Spinelli
- Laboratorio di Tecnologia Medica, Istituto Ortopedico Rizzoli, Bologna, Italy
| | - S Affatato
- Laboratorio di Tecnologia Medica, Istituto Ortopedico Rizzoli, Bologna, Italy
| | - L Tiberi
- Laboratorio di Tecnologia Medica, Istituto Ortopedico Rizzoli, Bologna, Italy
| | - S Carmignato
- Laboratorio di Metrologia Geometrica e Industriale, Padova University, Padova, Italy
| | - M Viceconti
- Laboratorio di Tecnologia Medica, Istituto Ortopedico Rizzoli, Bologna, Italy
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Jedenmalm A, Affatato S, Taddei P, Leardini W, Gedde UW, Fagnano C, Viceconti M. Effect of head surface roughness and sterilization on wear of UHMWPE acetabular cups. J Biomed Mater Res A 2009; 90:1032-42. [PMID: 18671264 DOI: 10.1002/jbm.a.32161] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The impact of femoral head surface roughness on wear of gamma-irradiation sterilized (3 MRad in nitrogen, crosslinked) and nonsterilized (not crosslinked) UHMWPE acetabular cups has been evaluated. Gravimetric wear testing was performed in a hip joint simulator for 2 x 10(6) cycles. CoCrMo heads were used with different surface roughness (R(a) = 15 nm and R(a) = 400 nm). The surface roughness after wear test was unchanged for the roughened heads, whereas the initially smooth heads showed a few scratches. The roughened heads increased the wear of the acetabular cups 2-fold. The gamma-irradiated cups tested against rough heads underwent the highest wear. The absorption of water was highest for the gamma-irradiated cups (0.0204% compared to 0.0031% after 85 days). Raman spectroscopy showed small but significant crystallinity changes in the wear zone, where the gamma-irradiated cups with the most extensive abrasion increased in crystallinity, whereas the nonsterilized cups underwent a crystallinity decrease.
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Affiliation(s)
- A Jedenmalm
- Royal Institute of Technology (KTH), School of Chemical Science and Engineering, Fiber and Polymer Technology, SE-100 44 Stockholm, Sweden
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31
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Abstract
STUDY DESIGN In vitro wear simulation. OBJECTIVE To determine the type and amount of wear produced by experimental metal-on-metal artificial discs for the lumbar spine. To minimize the amount of wear by changing the carbon content, clearance, and presence of a keel and notch. SUMMARY OF BACKGROUND DATA In contrast to the extensive number of hip joint replacement simulator studies examining the effects of individual design variables on wear, existing artificial lumbar disc wear publications have measured wear using only the final version of each product. That is, the effects of individual variables such as material, diameter, or clearance on wear of artificial discs are not known, even though the importance of such variables has been established in artificial hip wear studies. METHODS Experimental metal-on-metal artificial discs for the lumbar spine were tested in a 3-station, biaxial spine wear simulator designed and constructed by the investigators. Two versions of the implants were manufactured with differences in carbon content, clearance, and the presence of a keel. Additionally, implants were tested with or without a surgical notch. RESULTS The wear rates of the experimental metal-on-metal lumbar discs in the current study ranged from 6.2 to 15.8 mm3/million cycles. However, changing the carbon content of the ball from low to high, decreasing the initial clearance, and eliminating the anteroposterior keel reduced the wear rate from 12.4 to 7.6 mm3/million cycles. Furthermore, removing the surgical notch reduced the wear rate from 7.6 to 6.2 mm3/million cycles. The surface damage was generally consistent with low lubrication and varying degrees of abrasive and fatigue wear, with impingement of nonbearing surfaces observed at 1.5 million cycles for the longer-term test. CONCLUSION Although the implants tested in the current study were experimental, the results suggest that metal-on-metal lumbar discs have the potential to produce wear of this magnitude and mechanism in vivo. Therefore, careful consideration of individual design variables, including those considered in the current study, is necessary to avoid production of excessive wear in artificial lumbar discs.
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Rocchi M, Affatato S, Falasca G, Viceconti M. Thermomechanical analysis of ultra-high molecular weight polyethylene-metal hip prostheses. Proc Inst Mech Eng H 2007; 221:561-8. [PMID: 17937196 DOI: 10.1243/09544119jeim137] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In order to predict the frictional heating and the contact stresses between the polyethylene cup and the metallic ball-head forming the articulation of a hip prosthesis a three-dimensional finite element model was developed and calculated. The non-linear model includes a fully coupled thermomechanical formulation of the mechanical properties of the ultra-high-molecular-weight polyethylene, and a large-sliding Coulomb frictional contact between the two components. The model predicts the temperature of the polyethylene with an accuracy that was tested by comparing the model predictions with the temperature measurements. The temperature measurements were taken by thermocouples placed on the cup surface, the head surface and the inside of the thermostatic bath, during a complete test within a hip joint wear simulator. The model was found to be very accurate, predicting the measured temperatures with an accuracy better than 2 per cent. The temperature peak (51 degrees C) was predicted at the contact surface. The model results indicate that frictional heat is mostly dissipated through the metallic ball-head. The full coupling between the thermal and the mechanical conditions used in this study appears to be necessary if accurate predictions of the polyethylene deformation are required.
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Affiliation(s)
- M Rocchi
- Laboratorio di Tecnologia Medica, Istituti Ortopedici Rizzoli, Bologna, Italy
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Affatato S, Leardini A, Leardini W, Giannini S, Viceconti M. Meniscal wear at a three-component total ankle prosthesis by a knee joint simulator. J Biomech 2006; 40:1871-6. [PMID: 17014854 DOI: 10.1016/j.jbiomech.2006.08.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2006] [Accepted: 08/08/2006] [Indexed: 10/24/2022]
Abstract
Despite the fundamental value of wear simulation studies to assess wear resistance of total joint replacements, neither specialised simulators nor established external conditions are available for the human ankle joint. The aim of the present study was to verify the suitability of a knee wear simulator to assess wear rates in ankle prostheses, and to report preliminary this rate for a novel three-component total ankle replacement design. Four intact 'small' size specimens of the Box ankle were analysed in a four-station knee wear simulator. Special component-to-actuator holders were manufactured and starting spatial alignment of the three-components was sought. Consistent load and motion cycles representing conditions at the ankle joint replaced exactly with the prosthesis design under analysis were taken from a corresponding mechanical model of the stance phase of walking. The weight loss for the three specimens, after two million cycles, was 32.68, 14.78, and 62.28mg which correspond to a linear penetration of 0.018, 0.008, and 0.034mm per million-cycle, respectively for the specimens #1, #2, and #3. The knee wear simulator was able to reproduce load-motion patterns typical of a replaced ankle. Motion of the meniscal bearing in between the tibial and talar components was smooth, this component remaining in place and in complete congruence with the metal components throughout the test.
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Affiliation(s)
- S Affatato
- Istituti Ortopedici Rizzoli, Laboratorio di Tecnologia Medica, Via di Barbiano 1/10, 40136 Bologna, Italy.
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Abstract
A novel 12-station hip joint simulator with an anatomic position of the prosthesis was designed and built. The motion of the simulator consists of flexion-extension and abduction-adduction. The load is of the double-peak type. The validation test was done with three similar 28 mm CoCr-polyethylene joints in diluted calf serum lubricant for 3.3 × 106 cycles. The bearing surfaces of the polyethylene cups were burnished, the CoCr heads were undamaged, the wear particles were in the 0.1-1 μm size range, and the mean wear factor of the polyethylene cups was 5.7 × 10−7 mm3/N m. These essential observations were in good agreement with clinical findings. In addition, three similar 50 mm CoCR/CoCr joints, representing the contemporary large-diameter metal-on-metal articulation were tested. The wear of the CoCr/CoCr joints was calculated from the Co and Cr concentrations of the used lubricant quantified with atomic absorption spectroscopy. The bearing surfaces of the CoCr/CoCr jonits showed mild criss-cross scratching only. The average wear factor of polyethylene cups was 275 times that of the CoCr/CoCr joints. The tribological behaviour of the large-dia. CoCr/CoCr appeared to be dominated by fluid film lubrication, as indicated by very low frictional heating and wear, making it tribologically superior to the conventional CoCr/polyethylene, and therefore very interesting clinically. In conclusion, the simulator proved to be a valid, reliable, practical, economical, and easy-to-operate tool for wear studies of various hip replacement designs.
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Affiliation(s)
- V Saikko
- Department of Mechanical Engineering, Laboratory of Machine Design, Helsinki University of Technology, Finland.
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Abstract
A novel high-capacity hip wear simulator of the pin-on-disc type was designed, built, and validated. This so-called Super-CTPOD (circularly translating pin-on-disc) device has as many as 100 separate test stations, being an advanced version of the previously validated 12-station CTPOD. A validity test was done so that in all stations the specimens and the test conditions were as similar as possible. Hence, for the first time in this field, an adequate number of similar tests was done for a proper statistical analysis of wear data. The pins were conventional, gamma-sterilized ultra-high molecular weight polyethylene, and the discs were polished CoCr. The lubricant was diluted calf serum and the test length 3 million cycles. In the course of the test, the pins became highly polished, whereas the discs remained practically unchanged. The majority of the polyethylene wear particles were rounded, with a mean diameter of 0.25 μm. The 100 wear factor values computed from the 100 steady state wear rate values of the pins were normally distributed, the mean ±95 per cent confidence interval being 1.63 ± 0.017 × 10−6 mm3/Nm. The standard deviation was 5.4 per cent of the mean. There were no outliers. The wear mechanisms and the wear factor agreed well with clinical findings. Altogether, the Super-CTPOD test system was shown to be a unique combination of validity, low variation, capacity, efficiency, reliability, productivity, economy, ease of operation, and compact size.
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Affiliation(s)
- V Saikko
- Department of Mechanical Engineering, Helsinki University of Technology, Laboratory of Machine Design, PO Box 4300, Helsinki, Fin-02015 HUT, Finland.
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Gómez-Barrena E, Puértolas J. Métodos de análisis del polietileno en la investigación del material y su aplicación en artroplastias. Rev Esp Cir Ortop Traumatol (Engl Ed) 2005. [DOI: 10.1016/s1888-4415(05)76273-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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