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Abstract
Total Joint Replacement (TJR) devices undergo standardized wear testing in mechanical simulators while submerged in a proteinaceous testing solution to mimic the environmental conditions of artificial joints in the human body. Typically, bovine calf serum is used to provide the required protein content. However, due to lot-to-lot variability, an undesirable variance in testing outcome is observed. Based on an earlier finding that yellowish-orange serum color saturation is associated with wear rate, we examined potential sources of this variability, by running a comparative wear test with bilirubin; hemin; and a fatty acid, oleic acid, in the lubricant. All these compounds readily bind to albumin, the most abundant protein in bovine serum. Ultrahigh molecular weight polyethylene (UHMWPE) pins were articulated against CoCrMo discs in a pin-on-disc tribometer, and the UHMWPE wear rates were compared between lubricants. We found that the addition of bilirubin increased wear by 121%, while hemin had a much weaker, insignificant effect. When added at the same molar ratio as bilirubin, the fatty acid tended to reduce wear. Additionally, there was a significant interaction with respect to bilirubin and hemin in that UHMWPE wear rate decreased with increasing fatty acid concentration. We believe the conformational change in albumin by binding bilirubin makes it more likely to form molecular bridges between UHMWPE and the metal counterface, thus increasing adhesive wear. However, fatty acids compete for binding sites on albumin, and can prevent this conformational change. Hence, the protein is stabilized, and the chance for albumin to form bridges is lowered. Ultimately, UHMWPE wear rate is driven by the competitive binding of bilirubin and fatty acid to albumin.
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Duan Y, Liu Y, Zhang C, Chen Z, Wen S. Insight into the Tribological Behavior of Liposomes in Artificial Joints. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:10957-10966. [PMID: 27687876 DOI: 10.1021/acs.langmuir.6b02822] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Liposomes are widely used in drug delivery and gene therapy, and their new role as boundary lubricant in natural/artificial joints has been found in recent years. In this study, the tribological properties of liposomes on titanium alloy (Ti6Al4 V)/UHMWPE interface were studied by a ball-on-disc tribometer. The efficient reduction of friction coefficient and wear on both surfaces under various velocities and loads is found. A multilayer structure of physically adsorbed liposomes on Ti6Al4 V surface was also observed by atomic force microscope (AFM). Except for the hydration mechanism by phosphatidylcholine (PC) groups, the well-performed tribological properties by liposomes is also attributed to the existence of adsorbed liposome layers on both surfaces, which could reduce asperities contact and show great bearing capacity. This work enriches the research on liposomes for lubrication improvement on artificial surface and shows their value in clinical application.
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Affiliation(s)
- Yiqin Duan
- State Key Laboratory of Tribology, Tsinghua University , Beijing 100084, China
| | - Yuhong Liu
- State Key Laboratory of Tribology, Tsinghua University , Beijing 100084, China
| | - Caixia Zhang
- Beijing Key Laboratory of Advanced Manufacturing Technology, Beijing University of Technology , Beijing 100124, China
| | - Zhe Chen
- State Key Laboratory of Tribology, Tsinghua University , Beijing 100084, China
| | - Shizhu Wen
- State Key Laboratory of Tribology, Tsinghua University , Beijing 100084, China
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Role of hyaluronic acid and phospholipid in the lubrication of a cobalt-chromium head for total hip arthroplasty. Biointerphases 2015; 9:031007. [PMID: 25280848 DOI: 10.1116/1.4886255] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The tribological performance of total hip arthroplasty has an important influence on its success rate. This study examined the concentration-dependent role of hyaluronic acid (HA) and phospholipid (dipalmitoylphosphatidylcholine, DPPC) in the boundary lubricating ability of retrieved cobalt-chromium femoral heads. The microscale frictional coefficients (μ) were measured by atomic force microscopy using a rectangular silicon cantilever integrated with sharp silicon tips. In the case of HA lubricant, the frictional coefficients decreased significantly at concentrations of 2.0 (0.16 ± 0.03) and 3.5 mg/ml (0.11 ± 0.01) while increased at 5.0 mg/ml (0.15 ± 0.01), compared to that with phosphate buffer saline (0.25 ± 0.03). The concentration-dependent lubrication behavior of DPPC was most effective when DPPC was in the physiological concentration range, showing μ = 0.16 ± 0.01 in polypropylene glycol, and 0.05 ± 0.01, 0.02 ± 0.01, and 0.03 ± 0.01 at a DPPC concentration of 0.05, 0.2, and 3.0 mg/ml, respectively. Results obtained show significant differences between the DPPC concentration groups. Conclusively, the microscale frictional response of the retrieved CoCr femoral head has a significant dependence on the concentrations of HA and DPPC. Moreover, observed optimal concentration of HA and DPPC for effective lubrication is similar to that observed in normal human synovial fluid. Therefore, a retrieval of the synovia may be considered during total hip replacement surgeries in an effort for reduction of friction between head and liner of total hip replacement implants.
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Fröhlich SM, Archodoulaki VM, Allmaier G, Marchetti-Deschmann M. MALDI-TOF Mass Spectrometry Imaging Reveals Molecular Level Changes in Ultrahigh Molecular Weight Polyethylene Joint Implants in Correlation with Lipid Adsorption. Anal Chem 2014; 86:9723-32. [DOI: 10.1021/ac5025232] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Sophie M. Fröhlich
- Institute of Chemical
Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9, 1090 Vienna, Austria
| | - Vasiliki-Maria Archodoulaki
- Institute
of Materials
Science and Technology, Vienna University of Technology, Favoritenstrasse 9-11, 1040 Vienna, Austria
| | - Günter Allmaier
- Institute of Chemical
Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9, 1090 Vienna, Austria
| | - Martina Marchetti-Deschmann
- Institute of Chemical
Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9, 1090 Vienna, Austria
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Jennings LM, Al-Hajjar M, Brockett CL, Williams S, Tipper JL, Ingham E, Fisher J. (iv) Enhancing the safety and reliability of joint replacement implants. ACTA ACUST UNITED AC 2012; 26:246-252. [PMID: 23335949 PMCID: PMC3546063 DOI: 10.1016/j.mporth.2012.05.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
A new Stratified Approach For Enhanced Reliability (SAFER) pre-clinical simulation testing of joint prostheses is presented in this article. The aim of this approach is preclinical systematic testing of wear performance in the much wider envelope of conditions found clinically rather than relying only on the standard testing conditions that are currently used. The approach includes variations in surgical delivery, variations in kinematics, variations in the patient population and degradation of the biomaterial properties. Clinical experience of existing prostheses has been used to validate the new in vitro methods.
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Affiliation(s)
- Louise M Jennings
- Principal Research and Innovation Fellow, Institute of Medical and Biological Engineering iMBE, University of Leeds, Leeds, UK and Leeds Musculoskeletal Biomedical Research Unit, Leeds Teaching Hospital Trust, Leeds, UK. Conflict of interest: none
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Lubrication of metal-on-metal hip joints: The effect of protein content and load on film formation and wear. J Mech Behav Biomed Mater 2012; 6:30-40. [DOI: 10.1016/j.jmbbm.2011.09.008] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Revised: 09/12/2011] [Accepted: 09/14/2011] [Indexed: 11/20/2022]
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Fisher J. A stratified approach to pre-clinical tribological evaluation of joint replacements representing a wider range of clinical conditions advancing beyond the current standard. Faraday Discuss 2012; 156:59-68; discussion 87-103. [DOI: 10.1039/c2fd00001f] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Harsha AP, Joyce TJ. Challenges associated with using bovine serum in wear testing orthopaedic biopolymers. Proc Inst Mech Eng H 2011; 225:948-58. [DOI: 10.1177/0954411911416047] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
For appropriate in vitro wear testing of prostheses and their biomaterials, the choice of lubricant is critical. Bovine serum is the lubricant recommended by several international standards for wear testing artificial joints and their biomaterials because the wear rate and wear mechanisms closely match clinical results of polyethylene bearings. The main problem with the use of bovine serum as a lubricant is protein degradation and precipitation formation, effects that are recognized as having a direct impact on wear processes. Hence, some researchers have questioned the validity of using bovine serum in simulator testing. This paper reviews the various lubricants used in laboratory wear studies and also the properties of the synovial fluid that the lubricant is trying to replicate. It is clear from the literature survey that the composition of bovine-serum-based lubricants does not match that of synovial fluid. In view of this conclusion, it is suggested that there is a need to develop an alternative lubricant that can replace bovine serum.
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Affiliation(s)
- A P Harsha
- Department of Mechanical Engineering, Institute of Technology, Banaras Hindu University, Varanasi, India
| | - T J Joyce
- School of Mechanical and Systems Engineering, Newcastle University, Newcastle upon Tyne, UK
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Bruck AL, Kanaga Karuppiah KS, Sundararajan S, Wang J, Lin Z. Friction and wear behavior of ultrahigh molecular weight polyethylene as a function of crystallinity in the presence of the phospholipid dipalmitoyl phosphatidylcholine. J Biomed Mater Res B Appl Biomater 2010; 93:351-8. [DOI: 10.1002/jbm.b.31587] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Oral E, Muratoglu OK. Radiation cross-linking in ultra-high molecular weight polyethylene for orthopaedic applications. NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH. SECTION B, BEAM INTERACTIONS WITH MATERIALS AND ATOMS 2007; 265:18-22. [PMID: 19050735 PMCID: PMC2151736 DOI: 10.1016/j.nimb.2007.08.022] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The motivation for radiation cross-linking of ultra-high molecular weight polyethylene (UHMWPE) is to increase its wear resistance to be used as bearing surfaces for total joint arthroplasty. However, radiation also leaves behind long-lived residual free radicals in this polymer, the reactions of which can detrimentally affect mechanical properties. In this review, we focus on the radiation cross-linking and oxidative stability of first and second generation highly cross-linked UHMWPEs developed in our laboratory.
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Affiliation(s)
- Ebru Oral
- Massachusetts General Hospital, Department of Orthopaedic Surgery
- Harvard Medical School
| | - Orhun K. Muratoglu
- Massachusetts General Hospital, Department of Orthopaedic Surgery
- Harvard Medical School
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12
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The 2007 Otto Aufranc Award. Ceramic-on-metal hip arthroplasties: a comparative in vitro and in vivo study. Clin Orthop Relat Res 2007; 465:23-32. [PMID: 18090468 DOI: 10.1097/blo.0b013e31814da946] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The performance of novel ceramic-on-metal bearing couples has been compared with metal-on-metal and ceramic-on-ceramic bearing couples in laboratory and short-term clinical studies. Laboratory studies compared ceramic-on-metal with metal-on-metal and ceramic-on-ceramic bearings with diameters of 28 and 36 mm under standard conditions and under adverse conditions with head loading on the rim of the cup. Clinical studies compared metal ion levels in ceramic-on-metal with metal-on-metal, ceramic-on-ceramic, and ceramic-on-polyethylene bearings in a randomized prospective study. In the laboratory studies, friction, wear, and ion levels were lower in ceramic-on-metal bearings compared with metal-on-metal, with results similar to ceramic-on-ceramic couples. Under adverse conditions and rim loading, all bearings showed increased wear with lower wear and absence of stripe wear in ceramic-on-metal compared with metal-on-metal bearings. Short-term studies in 31 patients at 6 months revealed lower metal ion levels (cobalt and chromium) in those with ceramic-on-metal compared with metal-on-metal bearings.
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Taddei P, Affatato S, Fagnano C, Toni A. Oxidation in ultrahigh molecular weight polyethylene and cross-linked polyethylene acetabular cups tested against roughened femoral heads in a hip joint simulator. Biomacromolecules 2006; 7:1912-20. [PMID: 16768414 DOI: 10.1021/bm060007u] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This study was aimed at comparing the oxidative degradation of commercial acetabular cups made of cross-linked polyethylene (XLPE) and conventional ultrahigh molecular weight polyethylene (UHMWPE). After testing against deliberately scratched CoCrMo femoral heads in a hip joint simulator, the cups, microtomed parallel to the articulating surface, were analyzed by IR spectroscopy. Due to the potential for artifacts caused by absorbed contaminants, the IR spectra were compared only after hexane extraction; actually, XLPE was found to absorb more serum than UHMWPE. The two sets of unworn acetabular cups showed different oxidation patterns with consequently different distributions of carbonyl species; unworn XLPE was characterized by lower contents of carbonyl species and hydrogen-bonded alcohols and higher contents of trans-vinylene species than unworn UHMWPE. Upon simulator testing, UHMWPE showed more significant changes in oxidation indexes and distribution of carbonyl compounds than XLPE, confirming a better wear behavior for XLPE under the adopted testing conditions.
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Affiliation(s)
- Paola Taddei
- Centro di Studio sulla Spettroscopia Raman, Dipartimento di Biochimica G. Moruzzi, Sezione di Chimica e Propedeutica Biochimica, Via Belmeloro 8/2, Università di Bologna, Bologna, Italy.
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Bell CJ, Ingham E, Fisher J. Influence of hyaluronic acid on the time-dependent friction response of articular cartilage under different conditions. Proc Inst Mech Eng H 2006; 220:23-31. [PMID: 16459443 DOI: 10.1243/095441105x69060] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Therapeutic lubricant injections of hyaluronic acid are a relatively recent treatment for osteoarthritis. Their efficacy, however, in vivo has been subject to much debate. Frictional properties of cartilage-cartilage contacts under both static and dynamic loading conditions have been investigated, using healthy cartilage and cartilage with a physically disrupted surface, with and without the addition of a therapeutic lubricant, hyaluronic acid. Most of the cartilage friction models produced typical time-dependent loading curves, with a rise in static friction with loading time. For the dynamic loading conditions the rise in friction with loading time was dependent on the spatial (and time) variation in the load on the cartilage plate. For sliding distances of 4 mm or greater, when the cartilage plate was unloaded during sliding, the dynamic friction remained low whereas, with shorter sliding distances, the dynamic friction increased with increasing loading time. Static friction was higher than dynamic friction (under the same tribological conditions). The 'damaged' cartilage models produced higher friction than healthy cartilage under equivalent tribological conditions. It was shown that hyaluronic acid was an effective boundary lubricant for articular cartilage under static conditions with both healthy and damaged cartilage surfaces. Hyaluronic acid was less effective under dynamic conditions. However, these dynamic conditions had low friction values with the control lubricant because of the effectiveness of the intrinsic biphasic lubrication of the cartilage. It was only under the tribological conditions in which the cartilage friction was higher and rising with increasing loading time because of depletion of the intrinsic biphasic lubrication, that the role of hyaluronic acid as an effective therapeutic lubricant was demonstrated.
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Affiliation(s)
- C J Bell
- School of Mechanical Engineering, Institute of Medical and Biological Engineering, University of Leeds, Leeds LS2 9JT, UK
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Williams S, Jalali-Vahid D, Brockett C, Jin Z, Stone MH, Ingham E, Fisher J. Effect of swing phase load on metal-on-metal hip lubrication, friction and wear. J Biomech 2006; 39:2274-81. [PMID: 16143337 DOI: 10.1016/j.jbiomech.2005.07.011] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2004] [Accepted: 07/17/2005] [Indexed: 12/28/2022]
Abstract
There is renewed interest in metal-on-metal (MOM) total hip replacements (THRs), however, variable wear rates have been observed clinically. It is hypothesised that changes in soft tissue tensioning during surgery may alter loading of THRs during the swing phase of gait leading to changes in fluid film lubrication, friction and wear. This study aimed to assess the effect of swing phase load on the lubrication, friction and wear of MOM hip replacements. Theoretical lubrication modelling was carried out using elastohydrodynamic theory. All the governing equations were solved numerically for the lubricant film thickness between the articulating surfaces under the transient dynamic conditions with low and high swing phase loads. Friction testing was completed using a single axis pendulum simulator, simplified loading cycles were applied with low and high swing phase loads. MOM hip replacements were tested in a hip simulator, modified to provide different swing phase loading regimes; a low (100 N) and a high load (as per ISO 14242-1; 280 N). Results demonstrated that the performance of MOM bearings is highly dependent on swing phase load. Hence, changes in the tension of the tissues at surgery and variations in muscle forces may increase swing phase load, reduce lubrication, increase friction and accelerate wear. This may explain some of the variations that have been observed with clinical wear rates.
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Affiliation(s)
- Sophie Williams
- School of Mechanical Engineering, Institute of Medical and Biological Engineering, University of Leeds, Leeds, LS2 9JT, UK.
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The influences of lipid and protein concentration on wear of ultra-high molecular weight polyethylene. ACTA ACUST UNITED AC 2005. [DOI: 10.1016/s0167-8922(05)80019-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Mazzucco D, Spector M. The John Charnley Award Paper. The role of joint fluid in the tribology of total joint arthroplasty. Clin Orthop Relat Res 2004:17-32. [PMID: 15577461 DOI: 10.1097/01.blo.0000150315.47697.b9] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The effect of joint fluid on the tribology (ie, lubrication, friction, and wear) of total hip arthroplasty has not yet been investigated adequately. In the current study, a friction assay was used to assess four hypotheses relating to the effect of human joint fluid and its principal components on the articulation of metal-on-polyethylene. First, joint fluid was found to produce a widely varying amount of friction between cobalt-chromium and polyethylene; this range exceeded the range produced when the articulation was lubricated by water or bovine serum. Second, it was shown that hyaluronic acid, phospholipid, albumin, and gamma-globulin were not acting as boundary lubricants, but that one or more other proteins (as yet unidentified) were responsible for reducing friction in this couple. Third, lower friction was found when oxidized zirconium alloy replaced cobalt-chromium as a bearing surface on polyethylene. Finally, a pilot study suggested that lubricin, which contributes to cartilage-on-cartilage lubrication, is not a protein responsible for the tribological variabiation found among joint fluid samples. The current study showed that joint fluid is a patient factor that influences the tribology of metal-on-polyethylene arthroplasty.
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Affiliation(s)
- Daniel Mazzucco
- Department of Orthopaedic Surgery, Brigham and Women's Hospital, Harvard Medical School, 75 Francis Street, Boston, MA 02115, USA
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Williams S, Stewart TD, Ingham E, Stone MH, Fisher J. Metal-on-metal bearing wear with different swing phase loads. ACTA ACUST UNITED AC 2004; 70:233-9. [PMID: 15264305 DOI: 10.1002/jbm.b.30052] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
There is currently much discussion about the most clinically relevant testing methods for evaluating total hip replacements. This study examined the effect of different swing phase loads, including microseparation, on the wear, friction, and wear particles of metal-on-metal (MOM) hip replacements. MOM hip replacements were tested for 5 million cycles with the use of a hip simulator; prostheses were tested with a low (100-N) and ISO (280-N) swing phase load, and under microseparation conditions. Increasing the swing phase load from 100 to 280 N in the same hip simulator increased the wear of the MOM hip replacements by over tenfold. Introducing microseparation into the gait cycle increased wear further, and stripe wear was observed on the femoral heads, accompanied by corresponding rim damage on the acetabular cups. No significant difference in wear particle size was observed between wear particles produced by low load and microseparation hip simulator conditions. Introducing microseparation into the hip simulator gait cycle increased the wear of MOM prostheses. Joint laxity and separation may lead to increased wear rates of MOM prostheses in vivo. Additionally elevated positive swing phase loads may also increase wear. Variable swing phase load conditions in vivo may contribute to variations in clinical wear rates.
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Affiliation(s)
- Sophie Williams
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, LS2 9JT, United Kingdom.
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Hills BA, Crawford RW. Normal and prosthetic synovial joints are lubricated by surface-active phospholipid: a hypothesis. J Arthroplasty 2003; 18:499-505. [PMID: 12820095 DOI: 10.1016/s0883-5403(03)00072-x] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Much evidence supports the hypothesis that surface-active phospholipid (SAPL), which imparts the thin hydrophobic outermost lining to the normal articular surface, is the boundary lubricant reducing friction to remarkably low levels. We review this evidence and further hypothesize that SAPL produced in type B synoviocytes will also lubricate prostheses after implantation. This could explain why implanted hips display far less wear than hips in simulated wear trials do, even using protein as the lubricant whereas rougher surfaces can be tolerated in vivo. We introduce the concept that a deficiency of SAPL might explain the selective failure of prostheses just as osteoarthritic articular surfaces are deficient. This, in turn, leads to the replenishment of SAPL, as tested in OA, and the concept of prelubricating prostheses before implantation.
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Affiliation(s)
- B A Hills
- Mater Children's Hospital and Department of Medicine university of Queensland, Queensland University ot Technology, Brisbane, Australia
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Fluid film lubrication in artificial hip joints. ACTA ACUST UNITED AC 2003. [DOI: 10.1016/s0167-8922(03)80136-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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