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Döring J, Bormann T, Buchholz A, Hembus J, Rothammer B, Uhler M. [Tribology in arthroplasty : Friction and wear, a key to a long lifetime]. ORTHOPADIE (HEIDELBERG, GERMANY) 2024; 53:479-486. [PMID: 38833160 DOI: 10.1007/s00132-024-04520-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 05/02/2024] [Indexed: 06/06/2024]
Abstract
This article is intended to highlight one of the key roles in endoprosthetic treatment with artificial implants and the extension of service life. Like every joint, artificial joints are subject to the physical laws of friction and wear-in short, tribology. Material pairings, surfaces and mechanisms of action in particular play a decisive role here. The special features and current findings relating to the three largest synovial joints (hip, knee and shoulder) will be discussed in detail and suggestions will be made for future developments. Continuous developments in the field of the tribology of artificial joints can massively improve care for patients. The revision figures and reasons already show the success of individual improvements in recent years.
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Affiliation(s)
- Joachim Döring
- Orthopädische Universitätsklinik, Medizinische Fakultät, Otto-von-Guericke-Universität Magdeburg, Leipziger Str. 44, 39120, Magdeburg, Deutschland.
| | - Therese Bormann
- Sektion für Biomechanik und Implantatforschung, Klinik für Orthopädie, Universitätsklinikums Heidelberg, Schlierbacher Landstraße 200a, 69118, Heidelberg, Deutschland
| | - Adrian Buchholz
- Orthopädische Universitätsklinik, Medizinische Fakultät, Otto-von-Guericke-Universität Magdeburg, Leipziger Str. 44, 39120, Magdeburg, Deutschland
| | - Jessica Hembus
- Forschungslabor für Biomechanik und Implantattechnologie, Orthopädische Klinik, Universitätsmedizin Rostock, Doberaner Str. 142, 18057, Rostock, Deutschland
| | - Benedict Rothammer
- Lehrstuhl für Konstruktionstechnik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Deutschland
| | - Maximilian Uhler
- Sektion für Biomechanik und Implantatforschung, Klinik für Orthopädie, Universitätsklinikums Heidelberg, Schlierbacher Landstraße 200a, 69118, Heidelberg, Deutschland
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McCarty CP, Park SH, Ho NC, Sangiorgio SN, Ebramzadeh E. Taper Material Loss in Total Hip Replacements: Is It Affected by Joint Friction? J Bone Joint Surg Am 2022; 104:796-804. [PMID: 35167500 DOI: 10.2106/jbjs.21.00579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
BACKGROUND Metal debris and corrosion products generated from the taper junctions of modular joint replacements have been recognized as contributors to failure. Therefore, understanding the factors associated with increased taper wear and corrosion is fundamental to improving implant performance. METHODS A cohort of 85 large-diameter metal-on-metal heads and cups retrieved at revision surgery, after 10 to 96 months of service, was evaluated. First, metrology was conducted to quantify head taper material loss and implant articular surface wear. Then, joint frictional moments for each retrieved head-and-cup pair were measured during 10 cycles of simulated physiological gait in a biomechanical model. Taper material loss was evaluated for correlations with frictional moments, articular wear, head diameter, head-cup clearance, and time in vivo. RESULTS Peak resultant frictional moments ranged from 9.1 to 26.3 Nm, averaging 17.3 ± 2.7 Nm. Fretting and corrosion damage during in vivo service resulted in material loss from the head tapers ranging between 0.04 and 25.57 mm3, compared with combined head and cup articular wear of 0.80 to 351.75 mm3 in this cohort. Taper material loss was not correlated with higher frictional moments (R = -0.20 to 0.11, p = 0.07 to 0.81). Higher frictional moments from axial rotation were correlated with higher head and cup wear (R = 0.33, p < 0.01). The correlation between taper material loss and head diameter was weak and did not reach statistical significance (R = 0.20, p = 0.07). Taper material loss was not correlated with nominal head-cup clearance (R = 0.06, p = 0.6). Finally, taper material loss increased significantly over time (R = 0.34, p < 0.01). CONCLUSIONS Despite serious concerns regarding trunnionosis, volumes of head taper wear were generally lower than those of articular surface wear. There was no statistical correlation between taper wear and frictional moments. Therefore, the results suggest that high friction in metal-on-metal implants does not contribute to higher material loss at the head taper, despite high bending moments. CLINICAL RELEVANCE The amount of metal debris and corrosion products from taper junctions of the joint arthroplasties, widely recognized as an insidious cause of failure, was not correlated with joint frictional moments. Multiple factors affect taper wear: implant design, material, size, surface finish, and patient weight and activity level. However, in the present cohort, high friction of metal-on-metal total hip replacements likely did not contribute to increased volume of material loss at taper interfaces, despite increased moments at the locations of taper material loss.
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Affiliation(s)
- Colin P McCarty
- The J. Vernon Luck, Sr., M.D. Orthopaedic Research Center, Orthopaedic Institute for Children in Alliance with UCLA, Los Angeles, California
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Wight CM, Schemitsch EH. In vitro testing for hip head-neck taper tribocorrosion: A review of experimental methods. Proc Inst Mech Eng H 2022; 236:9544119221074582. [PMID: 35139678 PMCID: PMC8915230 DOI: 10.1177/09544119221074582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In vitro test methods are challenged by the multi-factorial nature of head-neck taper connection tribocorrosion due to the consequences of simplification. Incorrect study design and misinterpretation of results has led to contradictory findings regarding important factors affecting head-neck taper tribocorrosion. This review seeks to highlight important considerations when developing in vitro test methods, to help researchers strengthen their study design and analyze the implications of others' design decisions. The advantages, disadvantages, limitations and procedural considerations for finite element analyses, electrochemical studies and in vitro simulations related to head-neck taper connection tribocorrosion are discussed. Finite element analysis offers an efficient method for studying large ranges of mechanical parameters. However, they are limited by neglecting electrochemical, biological and fluid flow factors. Electrochemical studies may be preferred if these factors are considered important. Care must be taken in interpreting data from electrochemical studies, particularly when different materials are compared. Differences in material valence and toxicity affect clinical translation of electrochemical studies' results. At their most complex, electrochemical studies attempt to simulate all aspects of headneck taper connection tribocorrosion in a bench top study. Effective execution requires in-depth knowledge of the tribocorrosion phenomenon, the involved mechanisms, and their measures such that each study design decision is fully informed.
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Affiliation(s)
- Christian M Wight
- Institute of Biomaterial and Biomedical Engineering, University of Toronto, Toronto, ON, Canada
| | - Emil H Schemitsch
- Division of Orthopaedic Surgery, Department of Surgery, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, Canada
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Mjöberg B. Hip prosthetic loosening: A very personal review. World J Orthop 2021; 12:629-639. [PMID: 34631447 PMCID: PMC8472441 DOI: 10.5312/wjo.v12.i9.629] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 05/03/2021] [Accepted: 08/03/2021] [Indexed: 02/06/2023] Open
Abstract
Hip prosthetic loosening is often difficult to detect at an early stage, and there has been uncertainty for a long time as to when the loosening occurs and thus to the basic causes. By comparing different diagnostic methods, we found that loosening is best defined as prosthetic migration and measured by radiostereometric analysis. Convincing evidence indicates that poor interlock, poor bone quality, and resorption of a necrotic bone bed may initiate loosening during or shortly after surgery; this forms the basis of the theory of early loosening. Biomechanical factors do affect the subsequent progression of loosening, which may increase subclinically during a long period of time. Eventually, the loosening may be detected on standard radiographs and may be interpreted as late loosening but should to be interpreted as late detection of loosening. The theory of early loosening explains the rapid early migration, the development of periprosthetic osteolysis and granulomas, the causality between wear and loosening, and largely the epidemiology of clinical failure of hip prostheses. Aspects discussed are definition of loosening, the pattern of early migration, the choice of migration threshold, the current understanding of loosening, a less exothermic bone cement, cemented taper-slip stems, a new exciting computed tomography-based technique for simpler implant migration studies, and research suggestions.
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Affiliation(s)
- Bengt Mjöberg
- Department of Orthopedics, Lund University, Lund SE-221 00, Sweden
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Polster V, Fischer S, Steffens J, Morlock MM, Kaddick C. Experimental validation of the abrasive wear stage of the gross taper failure mechanism in total hip arthroplasty. Med Eng Phys 2021; 95:25-29. [PMID: 34479689 DOI: 10.1016/j.medengphy.2021.07.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 04/30/2021] [Accepted: 07/05/2021] [Indexed: 10/20/2022]
Abstract
BACKGROUND Gross taper failure (GTF) is a rare but catastrophic failure mode of the head-stem-taper junction of hip prostheses, facilitated by massive material loss. GTF is a two stage process initiated by corrosion leading to head bottoming out, followed by abrasive wear due to the head rotating on the stem. The purpose of this study was to reproduce the clinical failure patterns and to determine the material loss during simulated gait. METHODS Six cobalt-chromium alloy heads (36 mm, 12/14 taper) with three different head lengths (short / medium / extra long) were combined with stem taper replicas made from titanium alloy sized to achieve bottoming out. A hip simulator was used to simulate gait loading after (ISO 14242-1 for 2 million cycles). RESULTS Wear patterns from in-vitro testing match the clinical failure patterns. Stem taper wear increased linearly with time (p< 0.001). After two million cycles the material loss of short / medium / extra long heads was (M+-STD) 1168±242 mg / 400±23 mg / 94±12 mg on the stem side and 46±36 mg / 46±24 mg / 70±8 mg on the head side. Stem taper wear decreased with increasing head length (p=0.01), whereas clinical failures are mostly seen for long and extra long heads.
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Affiliation(s)
- Valerie Polster
- Institute of Biomechanics, Hamburg University of Technology,Denickestraße 15, Hamburg 21073, Germany.
| | - Sarah Fischer
- Institute of Biomechanics, Hamburg University of Technology,Denickestraße 15, Hamburg 21073, Germany
| | | | - Michael M Morlock
- Institute of Biomechanics, Hamburg University of Technology,Denickestraße 15, Hamburg 21073, Germany
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Morlock MM, Hube R, Wassilew G, Prange F, Huber G, Perka C. Taper corrosion: a complication of total hip arthroplasty. EFORT Open Rev 2020; 5:776-784. [PMID: 33312704 PMCID: PMC7722945 DOI: 10.1302/2058-5241.5.200013] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The focus on taper corrosion in modular hip arthroplasty increased around 2007 as a result of clinical problems with large-head metal-on-metal (MoM) bearings on standard stems. Corrosion problems with bi-modular primary hip stems focused attention on this issue even more. Factors increasing the risk of taper corrosion were identified in laboratory and retrieval studies: stiffness of the stem neck, taper diameter and design, head diameter, offset, assembly force, head and stem material and loading. The high variability of the occurrence of corrosion in the clinical application highlights its multi-factorial nature, identifying the implantation procedure and patient-related factors as important additional factors for taper corrosion. Discontinuing the use of MoM has reduced the revisions due to metal-related pathologies dramatically from 49.7% (MoM > 32 mm), over 9.2% (MoM ⩽ 32 mm) to 0.8% (excluding all MoM). Further reduction can be achieved by omitting less stiff Ti-alloys and large metal heads (36 mm and above) against polyethylene (PE). Standardized taper assembly of smaller and ceramic heads will reduce the clinical occurrence of taper corrosion even further. If 36 mm heads are clinically indicated, only ceramic heads should be used. Taper-related problems will not comprise a major clinical problem anymore if the mentioned factors are respected.
Cite this article: EFORT Open Rev 2020;5:776-784. DOI: 10.1302/2058-5241.5.200013
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Affiliation(s)
| | | | - Georgi Wassilew
- Department for Orthopaedics and Orthopaedic Surgery, University of Greifswald, Greifswald, Germany
| | - Felix Prange
- TUHH Hamburg University of Technology, Hamburg, Germany
| | - Gerd Huber
- TUHH Hamburg University of Technology, Hamburg, Germany
| | - Carsten Perka
- Center for Musculoskeletal Surgery, Orthopedic Department, Charité - Universitätsmedizin Berlin, Berlin, Germany
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Influence of Different Damage Patterns of the Stem Taper on Fixation and Fracture Strength of Ceramic Ball Heads for Total Hip Replacement. BIOMED RESEARCH INTERNATIONAL 2020; 2020:7542062. [PMID: 32509869 PMCID: PMC7244970 DOI: 10.1155/2020/7542062] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 04/01/2020] [Accepted: 04/15/2020] [Indexed: 11/17/2022]
Abstract
Background Modularity finds frequent application in total hip replacement, allowing a preferable individual configuration and a simplified revision by retaining the femoral stem and replacing the prosthetic head. However, micromotions within the interface between the head and the stem taper can arise, resulting in the release of wear debris and corrosion products. The aim of our experimental study was to evaluate the influence of different taper damages on the fixation and fracture stability of ceramic femoral heads, after static and dynamic implant loading. Methods Ceramic ball heads (36 mm diameter) and 12/14 stem tapers made of titanium with various mild damage patterns (intact, scratched, and truncated) were tested. The heads were assembled on the taper with a quasistatic load of 2 kN and separated into a static and a dynamic group afterwards. The dynamic group (n = 18) was loaded over 1.5 million gait cycles in a hip wear simulator (ISO 14242-1). In contrast, the static group (n = 18) was not mechanically loaded after assembly. To determine the taper stability, all heads of the dynamic and static groups were either pulled off (ASTM 2009) or turned off (ISO 7206-16). A head fracture test (ISO 7206-10) was also performed. Subsequent to the fixation stability tests, the taper surface was visually evaluated in terms of any signs of wear or corrosion after the dynamic loading. Results In 10 of the 18 cases, discoloration of the taper was determined after the dynamic loading and subsequent cleaning, indicating the first signs of corrosion. Pull-off forces as well as turn-off moments were increased between 23% and 54% after the dynamic loading compared to the unloaded tapers. No significant influence of taper damage was determined in terms of taper fixation strength. However, the taper damage led to a decrease in fracture strength by approximately 20% (scratched) and 40% (truncated), respectively. Conclusion The results suggest that careful handling and accurate manufacturing of the stem taper are crucial for the ceramic head fracture strength, even though a mild damage showed no significant influence on taper stability. Moreover, our data indicate that a further seating of the prosthetic head may occur during daily activities, when the resulting hip force increases the assembly load.
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Saikko V. Effect of wear, acetabular cup inclination angle, load and serum degradation on the friction of a large diameter metal-on-metal hip prosthesis. Clin Biomech (Bristol, Avon) 2019; 63:1-9. [PMID: 30784784 DOI: 10.1016/j.clinbiomech.2019.02.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 02/06/2019] [Accepted: 02/12/2019] [Indexed: 02/07/2023]
Abstract
BACKGROUND The large-scale clinical problem caused by unacceptable tribological behaviour of certain large diameter metal-on-metal prosthetic hips has directed attention to adverse condition testing. High metal-on-metal wear is connected with adverse reaction to metal debris. Friction is important because high friction may be associated with high wear, risk the fixation of the cup, and cause detrimental heating of periprosthetic tissues. METHODS A friction measurement system was added to a multidirectional, established hip joint wear simulator, and its functionality was evaluated. In preliminary tests, a 50 mm diameter metal-on-metal prosthesis was tested in an optimal acetabular cup inclination angle (48°) and in a steep angle (70°) using a normal peak load (2 kN) and an increased peak load (3 kN). The test length was 100 h. Long-term adverse condition tests of 3 million cycles were run for three 52 mm metal-on-metal prostheses. The lubricant was diluted calf serum at 37 °C. FINDINGS In the 100 h tests, metal-on-metal frictional torque was not highly sensitive to the angle, load and serum degradation, and it was close to that of a conventional 28 mm prosthesis with a polyethylene cup, mostly below 5 Nm. However, a manyfold higher frictional torque (10 to 20 Nm) was observed in long-term metal-on-metal tests with substantial wear. INTERPRETATION To obtain a realistic prediction of the frictional behaviour of a hip design, long-term, multidirectional wear tests are necessary. The friction should preferably be measured during the wear test. In addition to normal conditions, adverse condition testing is strongly recommended.
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Affiliation(s)
- Vesa Saikko
- Aalto University School of Engineering, Department of Mechanical Engineering, PO Box 14300, FI-00076 Aalto, Finland.
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Ramos A, Soares dos Santos MP, Mesnard M. Predictions of Birmingham hip resurfacing implant offset - In vitro and numerical models. Comput Methods Biomech Biomed Engin 2019; 22:352-363. [DOI: 10.1080/10255842.2018.1556973] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- A. Ramos
- Biomechanics Research Group, TEMA, University of Aveiro, Aveiro, Portugal
| | | | - M. Mesnard
- Institut de Mécanique et d'Ingénierie, Université de Bordeaux, Talence, France
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O'Rourke D, Al-Dirini RM, Taylor M. Primary stability of a cementless acetabular cup in a cohort of patient-specific finite element models. J Orthop Res 2018; 36:1012-1023. [PMID: 28833500 DOI: 10.1002/jor.23709] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2017] [Accepted: 08/01/2017] [Indexed: 02/04/2023]
Abstract
The primary stability achieved during total hip arthroplasty determines the long-term success of cementless acetabular cups. Pre-clinical finite element testing of cups typically use a model of a single patient and assume the results can be extrapolated to the general population. This study explored the variability in predicted primary stability of a Pinnacle® cementless acetabular cup in 103 patient-specific finite element models of the hemipelvis and examined the association between patient-related factors and the observed variability. Cups were inserted by displacement-control into the FE models and then a loading configuration simulating a complete level gait cycle was applied. The cohort showed a range of polar gap of 284-1112 μm and 95th percentile composite peak micromotion (CPM) of 18-624 μm. Regression analysis was not conclusive on the relationship between patient-related factors and primary stability. No relationship was found between polar gap and micromotion. However, when the patient-related factors were categorised into quartile groups, trends suggested higher polar gaps occurred in subjects with small and shallow acetabular geometries and cup motion during gait was affected most by low elastic modulus and high bodyweight. The variation in primary stability in the cohort for an acetabular cup with a proven clinical track record may provide benchmark data when evaluating new cup designs. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1012-1023, 2018.
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Affiliation(s)
- Dermot O'Rourke
- Medical Device Research Institute, Flinders University, Adelaide, Australia
| | - Rami Ma Al-Dirini
- Medical Device Research Institute, Flinders University, Adelaide, Australia
| | - Mark Taylor
- Medical Device Research Institute, Flinders University, Adelaide, Australia
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Mueller U, Panzram B, Braun S, Sonntag R, Kretzer JP. Mixing of Head-Stem Components in Total Hip Arthroplasty. J Arthroplasty 2018; 33:945-951. [PMID: 29174405 DOI: 10.1016/j.arth.2017.10.047] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 10/17/2017] [Accepted: 10/21/2017] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND Implant manufacturers proclaim that the tapers of modular total hip arthroplasty are not standardized and can vary from manufacturer to manufacturer. That is why the combination of various components from different manufacturers ("Mix and Match") is not permitted. In this study, different taper combinations were investigated experimentally to assess the effect of "Mix and Match" regarding the taper connection strength. METHODS Torque-off tests using hip stems and metal femoral heads from 6 different implant manufacturers were performed. First the components were tested as intended and afterwards the stems were combined with metal heads from other manufacturers. RESULTS There was no significant difference in taper connection strength when stems from the manufacturers Link, Smith & Nephew, and Zimmer were combined with heads from other manufacturers. The Biomet stems showed a significantly reduced taper connection strength if femoral heads of Aesculap, DePuy, or Smith & Nephew were used. On the contrary, the DePuy stems in combination with the originally intended femoral heads showed a significantly lower taper connection strength compared to the use of heads from Link, Biomet, and Zimmer. The same was observed for the Aesculap stems in combination with Zimmer heads. CONCLUSION The results of this study suggest that mixing components from different manufacturers may affect the taper connection strength and could reduce the stability. As safety should be a high priority in patient treatment, any potential risks should be avoided. Therefore, mixing and matching of heads and femoral stems from different manufacturers cannot be recommended.
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Affiliation(s)
- Ulrike Mueller
- Laboratory of Biomechanics and Implant Research, Clinic for Orthopedics and Trauma Surgery, Heidelberg University Hospital, Heidelberg, Germany
| | - Benjamin Panzram
- Laboratory of Biomechanics and Implant Research, Clinic for Orthopedics and Trauma Surgery, Heidelberg University Hospital, Heidelberg, Germany
| | - Steffen Braun
- Laboratory of Biomechanics and Implant Research, Clinic for Orthopedics and Trauma Surgery, Heidelberg University Hospital, Heidelberg, Germany
| | - Robert Sonntag
- 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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Panagiotidou A, Cobb T, Meswania J, Skinner J, Hart A, Haddad F, Blunn G. Effect of impact assembly on the interface deformation and fretting corrosion of modular hip tapers: An in vitro study. J Orthop Res 2018; 36:405-416. [PMID: 28485507 DOI: 10.1002/jor.23601] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Accepted: 05/03/2017] [Indexed: 02/04/2023]
Abstract
Wear and corrosion at the modular head-neck junction has been recognised to be a potential clinical concern, with multiple reports on adverse local tissue reactions and subsequent early failure of metal-on-metal hip replacements. Furthermore, reports on head-neck taper corrosion are also being described with conventional metal-on-polyethylene bearings. Manufacturing tolerances, surgical technique, non-axial alignment, material combination, high frictional torque and high bending moment have all been implicated in the failure process. There is limited guidance on the force of impaction with which surgeons should assemble modular hip prostheses. This study aims to investigate the effect of impaction force on the deformation and corrosion of modular tapers. Short neck tapers with high surface roughness (average Rz = 16.58 μm, Ra = 4.14μm) and long neck tapers with low surface roughness (average Rz = 3.82 μm, Ra = 0.81μm), were assembled with CoCrMo alloy heads (smooth finish) under controlled conditions with 2, 4 or 8 kN of impaction force. Material combinations tested included CoCrMo-head/CoCrMo-neck and CoCrMo-head/Ti-6Al-4V-neck. Assessment of surface deformation before and after impaction was made using surface profilometry. Measurement of fretting current during sinusoidal cyclic loading evaluated mechanically assisted corrosion for each assembly load during short-term cyclic loading (1000-cycles) and long-term cyclic loading (5 million-cycles). Deformation on head and neck tapers increased with assembly load. Fretting currents during short term simulation testing showed significantly lower currents (p < 0.05), in 8 kN assemblies when compared to 2 and 4 kN, especially for the short-rough tapers. Long-term simulator testing demonstrated a progressive reduction in fretting corrosion for samples impacted with 4 and 8 kN; however, this reduction was greater for samples impacted at 8 kN even at the start of testing. Based on our results, surgeons could minimise mechanically assisted crevice corrosion by using higher impact loads when assembling the head to the stem in total hip arthroplasty. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:405-416, 2018.
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Affiliation(s)
- Anna Panagiotidou
- John Scales Centre for Biomedical Engineering, Institute of Orthopaedics and Musculo-Skeletal Science, Division of Surgery & Interventional Science, University College London, Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, Middlesex, HA7 4LP, United Kingdom.,London Implant Retrieval Centre, Institute of Orthopaedics and Musculo-Skeletal Science, Division of Surgery & Interventional Science, University College London, Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, Middlesex, HA7 4LP, United Kingdom
| | - Timothy Cobb
- John Scales Centre for Biomedical Engineering, Institute of Orthopaedics and Musculo-Skeletal Science, Division of Surgery & Interventional Science, University College London, Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, Middlesex, HA7 4LP, United Kingdom
| | - Jay Meswania
- John Scales Centre for Biomedical Engineering, Institute of Orthopaedics and Musculo-Skeletal Science, Division of Surgery & Interventional Science, University College London, Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, Middlesex, HA7 4LP, United Kingdom.,London Implant Retrieval Centre, Institute of Orthopaedics and Musculo-Skeletal Science, Division of Surgery & Interventional Science, University College London, Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, Middlesex, HA7 4LP, United Kingdom
| | - John Skinner
- London Implant Retrieval Centre, Institute of Orthopaedics and Musculo-Skeletal Science, Division of Surgery & Interventional Science, University College London, Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, Middlesex, HA7 4LP, United Kingdom.,Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, Middlesex, HA7 4LP, United Kingdom
| | - Alister Hart
- John Scales Centre for Biomedical Engineering, Institute of Orthopaedics and Musculo-Skeletal Science, Division of Surgery & Interventional Science, University College London, Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, Middlesex, HA7 4LP, United Kingdom.,London Implant Retrieval Centre, Institute of Orthopaedics and Musculo-Skeletal Science, Division of Surgery & Interventional Science, University College London, Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, Middlesex, HA7 4LP, United Kingdom
| | - Fares Haddad
- Department of Orthopaedics, University College Hospital, 235 Euston Rd, London, NW1 2BU, United Kingdom
| | - Gordon Blunn
- John Scales Centre for Biomedical Engineering, Institute of Orthopaedics and Musculo-Skeletal Science, Division of Surgery & Interventional Science, University College London, Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, Middlesex, HA7 4LP, United Kingdom.,London Implant Retrieval Centre, Institute of Orthopaedics and Musculo-Skeletal Science, Division of Surgery & Interventional Science, University College London, Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, Middlesex, HA7 4LP, United Kingdom
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Farhoudi H, Fallahnezhad K, Oskouei RH, Taylor M. A finite element study on the mechanical response of the head-neck interface of hip implants under realistic forces and moments of daily activities: Part 1, level walking. J Mech Behav Biomed Mater 2017; 75:470-476. [DOI: 10.1016/j.jmbbm.2017.08.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 08/04/2017] [Accepted: 08/08/2017] [Indexed: 10/19/2022]
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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: 6] [Impact Index Per Article: 0.9] [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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15
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Vogel D, Falkenberg A, Bierbaum S, Schulze C, Bader R, Kluess D. Mechanical Stability of the Taper Connection of Large Metal Femoral Heads With Adapter Sleeves in Total Hip Arthroplasty Analyzed Using Explicit Finite Element Simulations. J Arthroplasty 2017; 32:2580-2586. [PMID: 28416253 DOI: 10.1016/j.arth.2017.03.033] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 02/28/2017] [Accepted: 03/13/2017] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND Large diameter heads (LDHs) of metal-on-metal bearings in total hip arthroplasty provide increased range of motion and reduced dislocation rates. However, major concerns grew over high wear rates from the modular connection between femoral stem and head, especially in combination with adapter sleeves. METHODS A computational study on the taper connection stability of LDH (50 mm) with adapter sleeves of different lengths (S, M, L, and XL) compared with a standard femoral head (32 mm) without adapter sleeves was conducted using explicit finite element analyses. Four different impact configurations were considered resulting from varied mallet mass (0.5 vs 1.0 kg) and velocity (1.0 vs 2.0 m/s). The taper stability was evaluated by determination of the pull-off forces and micromotions due to simulated joint loads during walking (2 kN and 7.9 Nm, respectively). Moreover, the deformations of the adapter sleeves and the contact area in the taper connections were evaluated. RESULTS Although the pull-off forces of the LDH with different-sized adapter sleeves were comparable, contact area decreased and adapter sleeve deformations increased (up to 283%) with an increasing adapter sleeve length. Moreover, the micromotions of LDH with adapter sleeves were up to 7-times higher, as compared with the standard femoral head without an adapter sleeve. CONCLUSION The present numerical study confirms that the assembly technique of LDH with adapter sleeves reveals increased micromotions compared with standard femoral head sizes. We could demonstrate that deviations of the stem trunnion geometry and improper surgical instructions led to worse mechanical stability of the taper connection.
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Affiliation(s)
- Danny Vogel
- Department of Orthopaedics, Biomechanics and Implant Technology Research Laboratory, University Medicine Rostock, Rostock, Germany
| | - Adrian Falkenberg
- Department of Orthopaedics, Biomechanics and Implant Technology Research Laboratory, University Medicine Rostock, Rostock, Germany; Institute of Biomechanics, School of Mechanical Engineering, Hamburg University of Technology, Hamburg, Germany
| | - Sarah Bierbaum
- Department of Orthopaedics, Biomechanics and Implant Technology Research Laboratory, University Medicine Rostock, Rostock, Germany
| | - Christian Schulze
- Department of Orthopaedics, Biomechanics and Implant Technology Research Laboratory, University Medicine Rostock, Rostock, Germany
| | - Rainer Bader
- Department of Orthopaedics, Biomechanics and Implant Technology Research Laboratory, University Medicine Rostock, Rostock, Germany
| | - Daniel Kluess
- Department of Orthopaedics, Biomechanics and Implant Technology Research Laboratory, University Medicine Rostock, Rostock, Germany
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16
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Cementing a polyethylene cup into a well fixed acetabular metal-on-metal resurfacing component? An experimental investigation. Hip Int 2017; 27:373-377. [PMID: 28165599 DOI: 10.5301/hipint.5000474] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/20/2016] [Indexed: 02/04/2023]
Abstract
INTRODUCTION Adverse reactions to metal debris often indicate revision surgery in metal-on-metal (MoM) hip arthroplasty and an exchange of the MoM bearing into either a metal on polyethylene or a ceramic-on-polyethylene articulation. At the moment the removal of the entire implant system is the most reasonable method. In order to avoid bone loss caused by the removal of a well-fixed acetabular component, the purpose of this study was to measure the stability of a cemented polyethylene (PE) cup in an acetabular hip resurfacing component and to examine if such a method could be suitable for clinical use. METHODS PE cups were cemented into 2 different hip resurfacing components and biomechanical tests were applied to measure failure torques under lever out and rotational load. RESULTS In all cases failure of the interface between the resurfacing components and the cement layer occurred at a very low load (0.14 Nm-61.50 Nm). DISCUSSION The early failure occurred due to lacking interdigitation of cement and the polished metal surface. Thus we warn against cementing a PE cup into acetabular hip resurfacing components for clinical use.
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17
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Morlock M, Bünte D, Gührs J, Bishop N. Corrosion of the Head-Stem Taper Junction-Are We on the Verge of an Epidemic?: Review Article. HSS J 2017; 13:42-49. [PMID: 28167873 PMCID: PMC5264576 DOI: 10.1007/s11420-016-9526-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Accepted: 08/29/2016] [Indexed: 02/07/2023]
Abstract
BACKGROUND The modular head taper junction has contributed to the success of total hip arthroplasty (THA) greatly. Taper corrosion and wear problems reported for large and extra-large metal-on-metal bearings as well as for bi-modular THA stems have cast doubt on the benefit of the taper interface. Presently, corrosion problems are being reported for nearly all kinds of artificial hip joints incorporating metal heads, questioning taper connections in general. QUESTIONS/PURPOSES This study aimed to review the mechanical and electrochemical relationships that may lead to taper corrosion, which have been reported more commonly in recent literature, and to also review the contribution of patient characteristics and surgical techniques involved in taper assembly that may contribute to the problem. METHODS The search criteria "(corrosion) AND (hip arthroplasty) AND (taper OR trunnion)" and "(hip arthroplasty) AND ((pseudotumor) OR (pseudo-tumor))" in PubMed and the JAAOS were used for the literature search. In addition, the arthroplasty registers were considered. RESULTS Most studies acknowledge the multifactorial nature of the problem but concentrate their analysis on taper and implant design aspects, since this is the only factor that can be easily quantified. The sometimes conflicting results in the literature could be due to the fact that the other two decisive factors are not sufficiently considered: the loading situation in the patient and the assembly situation by the surgeon. All three factors together determine the fate of a taper junction in THA. There is no single reason as a main cause for taper corrosion. The combined "outcome" of these three factors has to be in a "safe range" to achieve a successful long-term taper fixation. CONCLUSION No, this is not the beginning of an epidemic. It is rather the consequence of disregarding known mechanical and electrochemical relationships, which in combination have recently caused a more frequent occurrence-and mainly reporting-of corrosion issues.
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Affiliation(s)
- Michael Morlock
- Institute of Biomechanics, TUHH Hamburg University of Technology, Denickestrasse 15, 21073 Hamburg, Germany
| | - Dennis Bünte
- Institute of Biomechanics, TUHH Hamburg University of Technology, Denickestrasse 15, 21073 Hamburg, Germany
| | - Julian Gührs
- Institute of Biomechanics, TUHH Hamburg University of Technology, Denickestrasse 15, 21073 Hamburg, Germany
| | - Nicholas Bishop
- Institute of Biomechanics, TUHH Hamburg University of Technology, Denickestrasse 15, 21073 Hamburg, Germany
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18
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An Analytical Calculation of Frictional and Bending Moments at the Head-Neck Interface of Hip Joint Implants during Different Physiological Activities. MATERIALS 2016; 9:ma9120982. [PMID: 28774104 PMCID: PMC5456991 DOI: 10.3390/ma9120982] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Revised: 11/30/2016] [Accepted: 12/01/2016] [Indexed: 01/20/2023]
Abstract
This study predicts the frictional moments at the head-cup interface and frictional torques and bending moments acting on the head-neck interface of a modular total hip replacement across a range of activities of daily living. The predicted moment and torque profiles are based on the kinematics of four patients and the implant characteristics of a metal-on-metal implant. Depending on the body weight and type of activity, the moments and torques had significant variations in both magnitude and direction over the activity cycles. For the nine investigated activities, the maximum magnitude of the frictional moment ranged from 2.6 to 7.1 Nm. The maximum magnitude of the torque acting on the head-neck interface ranged from 2.3 to 5.7 Nm. The bending moment acting on the head-neck interface varied from 7 to 21.6 Nm. One-leg-standing had the widest range of frictional torque on the head-neck interface (11 Nm) while normal walking had the smallest range (6.1 Nm). The widest range, together with the maximum magnitude of torque, bending moment, and frictional moment, occurred during one-leg-standing of the lightest patient. Most of the simulated activities resulted in frictional torques that were near the previously reported oxide layer depassivation threshold torque. The predicted bending moments were also found at a level believed to contribute to the oxide layer depassivation. The calculated magnitudes and directions of the moments, applied directly to the head-neck taper junction, provide realistic mechanical loading data for in vitro and computational studies on the mechanical behaviour and multi-axial fretting at the head-neck interface.
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19
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Kaddick C, Kretzer JP. Letter to the Editor on "Large Metal Heads and Vitamin E Polyethylene Increase Frictional Torque in Total Hip Arthroplasty". J Arthroplasty 2016; 31:2375-6. [PMID: 27491448 DOI: 10.1016/j.arth.2016.05.072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 05/31/2016] [Indexed: 02/01/2023] Open
Affiliation(s)
| | - J Philippe Kretzer
- Laboratory of Biomechanics and Implant Research, University Hospital of Heidelberg, Heidelberg, Germany
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20
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Scholl L, Longaray J, Raja L, Lee R, Faizan A, Herrera L, Thakore M, Nevelos J. Friction in modern total hip arthroplasty bearings: Effect of material, design, and test methodology. Proc Inst Mech Eng H 2016; 230:50-7. [PMID: 26721426 DOI: 10.1177/0954411915619452] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The purpose of this study was to characterize the effect of a group of variables on frictional torque generated by acetabular components as well as to understand the influence of test model. Three separate test models, which had been previously used in the literature, were used to understand the effect of polyethylene material, bearing design, head size, and material combinations. Each test model differed by the way it simulated rotation of the head, the type of frictional torque value it reported (static vs. dynamic), and the type of motion simulated (oscillating motion vs. continuous motion). It was determined that not only test model may impact product ranking of fictional torque generated but also static frictional torque may be significantly larger than a dynamic frictional torque. In addition to test model differences, it was discovered that the frictional torque values for conventional and highly cross-linked polyethylenes were not statistically significantly different in the more physiologically relevant test models. With respect to bearing design, the frictional torque values for mobile bearing designs were similar to the 28-mm diameter inner bearing rather than the large diameter outer liner. Testing with a more physiologically relevant rotation showed that frictional torque increased with bearing diameter for the metal on polyethylene and ceramic on polyethylene bearings but remained constant for ceramic on ceramic bearings. Finally, ceramic on ceramic bearings produced smaller frictional torque values when compared to metal on polyethylene and ceramic on polyethylene groups.
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21
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Abstract
Corrosion of metallic implants in contact with body fluids is unavoidable, especially at interfaces where movement occurs or in gaps. Corrosion became clinically relevant with the introduction of large modular metal-on-metal total hip joint articulations (MoM THA) early in the 21st century. This review attempts to summarise the scientific knowledge about taper problems available at the time of introduction of these bearings, why this "disaster" could happen. It is speculated that changes to the taper connection made in the 1990s to increase the range of motion with small heads (28 and 32 mm) reduced the mechanical strength of this connection, which did not matter for small heads. With the use of large and very large metal heads in MoM articulations, which have a larger lever arm and can generate high friction in unfavourable situations, suddenly the taper interface exhibited corrosion problems on a previously unknown scale. It is speculated that due to the higher mechanical loading with larger heads, the taper connection became less forgiving with respect to assembly conditions, contamination, manufacturing tolerances and other factors, which are yet not known. Since no major clinical problems had been reported before the introduction of these bearings and the pre-clinical testing was very successful, the disaster took its course. The patient-implant-surgeon system is a very complex intrinsically hazardous system. Pre-clinical testing addresses few and defined factors and such, good results cannot be directly transferred to the clinical reality. A controlled stepwise introduction of innovations is required.
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22
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Morlock MM, Bünte D, Ettema H, Verheyen CC, Hamberg Å, Gilbert J. Primary hip replacement stem taper fracture due to corrosion in 3 patients. Acta Orthop 2016; 87:189-92. [PMID: 26751766 PMCID: PMC4812083 DOI: 10.3109/17453674.2015.1128780] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Affiliation(s)
- Michael M Morlock
- Institute of Biomechanics, TUHH Hamburg University of Technology, Hamburg, Germany,Correspondence:
| | - Dennis Bünte
- Institute of Biomechanics, TUHH Hamburg University of Technology, Hamburg, Germany
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23
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Meneghini RM, Lovro LR, Wallace JM, Ziemba-Davis M. Large Metal Heads and Vitamin E Polyethylene Increase Frictional Torque in Total Hip Arthroplasty. J Arthroplasty 2016; 31:710-4. [PMID: 26482682 DOI: 10.1016/j.arth.2015.09.020] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 09/01/2015] [Accepted: 09/22/2015] [Indexed: 02/01/2023] Open
Abstract
PURPOSE Trunnionosis has reemerged in modern total hip arthroplasty for reasons that remain unclear. Bearing frictional torque transmits forces to the modular head-neck interface, which may contribute to taper corrosion. The purpose of this study is to compare frictional torque of modern bearing couples in total hip arthroplasty. METHODS Mechanical testing based on in vivo loading conditions was used to measure frictional torque. All bearing couples were lubricated and tested at 1 Hz for more than 2000 cycles. The bearing couples tested included conventional, highly crosslinked (XLPE) and vitamin E polyethylene, CoCr, and ceramic femoral heads and dual-mobility bearings. Statistical analysis was performed using Student t test for single-variable and analysis of variance for multivariant analysis. P ≤ .05 was considered statistically significant. RESULTS Large CoCr metal heads (≥36 mm) substantially increased frictional torque against XLPE liners (P = .01), a finding not observed in ceramic heads. Vitamin E polyethylene substantially increased frictional torque compared with XLPE in CoCr and ceramic heads (P = .001), whereas a difference between conventional and XLPE was not observed (P = .69) with the numbers available. Dual-mobility bearing with ceramic inner head demonstrated the lowest mean frictional torque of all bearing couples. CONCLUSION In this simulated in vivo model, large-diameter CoCr femoral heads and vitamin E polyethylene liners are associated with increased frictional torque compared with smaller metal heads and XLPE, respectively. The increased frictional torque of vitamin E polyethylene and larger-diameter femoral heads should be considered and further studied, along with reported benefits of these modern bearing couples.
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Affiliation(s)
- R Michael Meneghini
- Department of Orthopaedic Surgery, Indiana University School of Medicine, Fishers, Indiana; Orthopedics and Sports Medicine, Indiana University Health Physicians, Fishers, Indiana
| | - Luke R Lovro
- Orthopedics and Sports Medicine, Indiana University Health Physicians, Fishers, Indiana
| | - Joseph M Wallace
- Department of Biomedical Engineering, Purdue School of Engineering and Technology at Indiana University-Purdue University, Indianapolis, Indiana
| | - Mary Ziemba-Davis
- Orthopedics and Sports Medicine, Indiana University Health Physicians, Fishers, Indiana
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24
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Farhoudi H, Oskouei RH, Jones CF, Taylor M. A novel analytical approach for determining the frictional moments and torques acting on modular femoral components in total hip replacements. J Biomech 2015; 48:976-83. [PMID: 25721768 DOI: 10.1016/j.jbiomech.2015.02.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2014] [Revised: 01/31/2015] [Accepted: 02/04/2015] [Indexed: 10/24/2022]
Abstract
A three dimensional analytical approach was developed to determine the frictional moment vector generated by the relative sliding of the head-cup bearing couple of a total hip replacement. The frictional moment projection onto the femoral neck was also determined over the loading cycle. Predicted frictional moments for nine combinations of bearing materials and diameters were in close agreement with existing in vitro data. The analytical method was then applied to simplified gait (lubrication conditions of dry and serum), ISO standard gait and physiological level gait loading cycles. ISO standard gait had a total contact force of about two fold of physiological level gait and there was a corresponding increase in the maximum frictional torque on neck from 0.66×BW%m to 0.88×BW%m. For the ISO standard gait, the maximum frictional torque occurred at the same instance of maximum frictional moment and the maximum contact force. In contrast, for the physiological level gait, the frictional torque did not occur at the same instance as the peak load. This suggests that the neck frictional torque is a function of other parameters, such as angle between neck axis and frictional moment vector, as well as the magnitude of the contact force and frictional moment. The developed methodology was able to predict the maximum magnitude and change of directions of moments and the variation of torque at the head neck interface. The data will be useful for experimental studies assessing the fretting behaviour of the head neck junction, by providing appropriate loading data.
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Affiliation(s)
- H Farhoudi
- Discipline of Mechanical Engineering, School of Computer Science, Engineering and Mathematics, Flinders University, Adelaide, Australia
| | - R H Oskouei
- Discipline of Mechanical Engineering, School of Computer Science, Engineering and Mathematics, Flinders University, Adelaide, Australia.
| | - C F Jones
- Adelaide Centre for Spinal Research, SA Pathology, Adelaide, Australia; School of Mechanical Engineering, University of Adelaide, Adelaide, Australia; Centre for Orthopaedic and Trauma Research, School of Medicine, University of Adelaide, Adelaide, Australia
| | - M Taylor
- Medical Device Research Institute, School of Computer Science, Engineering and Mathematics, Flinders University, Adelaide, Australia
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25
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Abstract
We reviewed the literature on the currently available choices of bearing surface in total hip replacement (THR). We present a detailed description of the properties of articulating surfaces review the understanding of the advantages and disadvantages of existing bearing couples. Recent technological developments in the field of polyethylene and ceramics have altered the risk of fracture and the rate of wear, although the use of metal-on-metal bearings has largely fallen out of favour, owing to concerns about reactions to metal debris. As expected, all bearing surface combinations have advantages and disadvantages. A patient-based approach is recommended, balancing the risks of different options against an individual’s functional demands. Cite this article: Bone Joint J 2014;96-B:147–56.
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Affiliation(s)
- A. Rajpura
- Wrightington Hospital, The Centre
for Hip Surgery, Appley Bridge, Wigan
WN6 9EP, UK
| | - D. Kendoff
- Helios ENDO Klinik, Holstenstr. 2, 22767
Hamburg, Germany
| | - T. N. Board
- Wrightington Hospital, The Centre
for Hip Surgery, Appley Bridge, Wigan
WN6 9EP, UK
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26
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Fan N, Morlock MM, Bishop NE, Huber G, Hoffmann N, Ciavarella M, Chen GX, Hothan A, Witt F. The influence of stem design on critical squeaking friction with ceramic bearings. J Orthop Res 2013; 31:1627-32. [PMID: 23813771 DOI: 10.1002/jor.22413] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Accepted: 05/28/2013] [Indexed: 02/04/2023]
Abstract
Ceramic-on-ceramic hip joints have been reported to squeak, a phenomenon that may occur in compromised lubrication conditions. One factor related to the incidence of in vivo squeaking is the stem design. However, it has not yet been possible to relate stem design to squeaking in deteriorating lubrication conditions. The purpose of this study was to determine critical friction factors for different stem designs. A hip simulator was used to measure the friction factor of a ceramic bearing with different stem designs and gradually deteriorating lubrication represented by evaporation of a volatile fluid lubricant. The critical squeaking friction factor was measured at the onset of squeaking for each stem. Critical friction was higher for the long cobalt chrome (0.32 ± 0.02) and short titanium stems (0.39 ± 0.02) in comparison with a long titanium stem (0.29 ± 0.02). The onset of squeaking occurred at a friction factor lower than that measured for dry conditions, in which squeaking is usually investigated experimentally. The results suggest that shorter or heavier stems might limit the possibility of squeaking as lubrication deteriorates. The method developed can be used to investigate the influence of design parameters on squeaking probability.
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Affiliation(s)
- Na Fan
- Tribology Research Institute, Southwest Jiaotong University, Chengdu, 610031, China
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27
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Sonntag R, Reinders J, Rieger JS, Heitzmann DWW, Kretzer JP. Hard-on-hard lubrication in the artificial hip under dynamic loading conditions. PLoS One 2013; 8:e71622. [PMID: 23940772 PMCID: PMC3737097 DOI: 10.1371/journal.pone.0071622] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Accepted: 07/01/2013] [Indexed: 11/18/2022] Open
Abstract
The tribological performance of an artificial hip joint has a particularly strong influence on its success. The principle causes for failure are adverse short- and long-term reactions to wear debris and high frictional torque in the case of poor lubrication that may cause loosening of the implant. Therefore, using experimental and theoretical approaches models have been developed to evaluate lubrication under standardized conditions. A steady-state numerical model has been extended with dynamic experimental data for hard-on-hard bearings used in total hip replacements to verify the tribological relevance of the ISO 14242-1 gait cycle in comparison to experimental data from the Orthoload database and instrumented gait analysis for three additional loading conditions: normal walking, climbing stairs and descending stairs. Ceramic-on-ceramic bearing partners show superior lubrication potential compared to hard-on-hard bearings that work with at least one articulating metal component. Lubrication regimes during the investigated activities are shown to strongly depend on the kinematics and loading conditions. The outcome from the ISO gait is not fully confirmed by the normal walking data and more challenging conditions show evidence of inferior lubrication. These findings may help to explain the differences between the in vitro predictions using the ISO gait cycle and the clinical outcome of some hard-on-hard bearings, e.g., using metal-on-metal.
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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.
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28
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Bishop N, Witt F, Pourzal R, Fischer A, Rütschi M, Michel M, Morlock M. Wear patterns of taper connections in retrieved large diameter metal-on-metal bearings. J Orthop Res 2013; 31:1116-22. [PMID: 23440943 DOI: 10.1002/jor.22326] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Accepted: 01/24/2013] [Indexed: 02/04/2023]
Abstract
Wear of the modular taper between head and shaft has been related to clinical failure resulting from adverse reactions to metallic debris. The problem has become pronounced in large metal-on-metal bearings, but the mechanism has not yet been fully understood. We analyzed retrieved components from five patients revised with various diagnoses. Two distinct wear patterns were observed for the head tapers. Three samples demonstrated "asymmetric" wear towards the inner end of the head taper. The other two showed "axisymmetric" radial wear (up to 65 µm) presenting the largest wear volumes (up to 20 mm(3)). Stem tapers demonstrated relatively little wear, and the fine thread on the stem taper surface was observed to be imprinted on the taper inside of the head. Our findings demonstrate that the cobalt-chrome head wears preferentially to the titanium stem taper. "asymmetric" wear suggests toggling due to the offset of the joint force vector from the taper. In contrast, samples with "axisymmetric" radial wear and a threaded imprint suggested that corrosion led to head subsidence onto the stem taper with gradual rotation.
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Affiliation(s)
- Nicholas Bishop
- Instistute of Biomechanics, TUHH Hamburg University of Technology, Denickestrasse 15, 21073, Hamburg, Germany.
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Curran S, Hoskin T, Williams S, Scholes SC, Kinbrum A, Unsworth A. Does surface wettability influence the friction and wear of large-diameter CoCrMo alloy hip resurfacings? Proc Inst Mech Eng H 2013; 227:847-58. [PMID: 23852389 DOI: 10.1177/0954411913488508] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The role of surface tension in the lubrication of metal-on-metal (CoCrMo alloy) hip resurfacings has been investigated to try to explain why all metal joints fail to be lubricated with simple water-based lubricants (sodium carboxymethyl cellulose), which have similar rheology to synovial fluid, but are lubricated with the same fluid with the addition of a proportion of bovine serum. As part of this study, surfactants, in the form of detergents, when added to carboxymethyl cellulose, have been shown to produce a predominantly fluid-film lubrication mechanism with friction even lower than the biological lubricant containing serum. Friction factors were reduced by 80% when a detergent was added to the lubricant. It is considered that the failure of the water-based fluids to generate fluid-film lubrication is due to the fact that ‘boundary slip’ takes place where the fluid does not fully attach to the bounding solid surfaces as assumed in Reynolds’ equation, thereby drawing in less lubricant than predicted from hydrodynamic theory. The addition of surfactants either in the form of natural materials such as serum or in the form of detergent reduces surface tension and helps the water-based lubricant to attach more fully to the bounding surfaces resulting in more fluid entrainment and thicker fluid-film formation. This was confirmed by up to 70% lower wear being found when these joints were lubricated in a detergent solution rather than 25% bovine serum.
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Affiliation(s)
- Sarah Curran
- School of Engineering and Computing Sciences, Durham University, Durham, UK
- TATA Steel Projects, UK
| | - Tom Hoskin
- School of Engineering and Computing Sciences, Durham University, Durham, UK
- PricewaterhouseCoopers, UK
| | - Sarah Williams
- School of Engineering and Computing Sciences, Durham University, Durham, UK
- AkzoNobel, UK
| | - Susan C Scholes
- School of Engineering and Computing Sciences, Durham University, Durham, UK
- School of Mechanical and Systems Engineering, Newcastle University, Newcastle upon Tyne, UK
| | - Amy Kinbrum
- School of Engineering and Computing Sciences, Durham University, Durham, UK
- Corin Ltd, Cirencester, UK
| | - Anthony Unsworth
- School of Engineering and Computing Sciences, Durham University, Durham, UK
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30
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Bishop NE, Hothan A, Morlock MM. High friction moments in large hard-on-hard hip replacement bearings in conditions of poor lubrication. J Orthop Res 2013; 31:807-13. [PMID: 23239536 DOI: 10.1002/jor.22255] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Accepted: 10/05/2012] [Indexed: 02/06/2023]
Abstract
Disappointing clinical results for large diameter metal replacement bearings for the hip are related to compromised lubrication due to poor cup placement, which increases wear as well as friction moments. The latter can cause overload of the implant-bone interfaces and the taper junction between head and stem. We investigated the influence of lubrication conditions on friction moments in modern hip bearings. Friction moments for large diameter metal and ceramic bearings were measured in a hip simulator with cup angles varying from 0° to 60°. Two diameters were tested for each bearing material, and measurements were made in serum and in dry conditions, representing severely compromised lubrication. Moments were lower for the ceramic bearings than for the metal bearings in lubricated conditions, but approached those for metal bearings at high cup inclination. In dry conditions, friction moments increased twofold to 12 Nm for metal bearings. For ceramic bearings, the increase was more than fivefold to over 25 Nm. Although large diameter ceramic bearings demonstrate an improvement in friction characteristics in the lubricated condition, they could potentially replicate problems currently experienced due to high friction moments in metal bearings once lubrication is compromised.
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Affiliation(s)
- Nicholas E Bishop
- Biomechanics Section, TUHH Hamburg University of Technology, Denickestrasse 15, D-21073 Hamburg, Germany.
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31
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Kretzer JP, Zietz C, Schröder C, Reinders J, Middelborg L, Paulus A, Sonntag R, Bader R, Utzschneider S. [Principles of tribological analysis of endoprostheses]. DER ORTHOPADE 2013; 41:844-52. [PMID: 23052851 DOI: 10.1007/s00132-012-1948-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
For the tribological characterization of artificial joints, various experimental methods are currently available. However, the in vitro test conditions applied are only comparable in a limited way and transferability to the in vivo situation is also restricted. This is due to the different wear simulation concepts used and partly insufficient simulation of clinical worst case situations. In the present paper current scientific methods and procedures for tribological testing of artificial joints are presented. In addition, the biological effects of wear products are described enabling clinicians to challenge tribological studies and to facilitate specific interpretation of scientific results taking the clinical situation into account.
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Affiliation(s)
- J P Kretzer
- Labor für Biomechanik und Implantatforschung, Klinik für Orthopädie und Unfallchirurgie, Universitätsklinikum Heidelberg, 69120, Heidelberg, Deutschland.
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32
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Preuss R, Lars Haeussler K, Flohr M, Streicher RM. Fretting Corrosion and Trunnion Wear—Is it Also a Problem for Sleeved Ceramic Heads? ACTA ACUST UNITED AC 2012. [DOI: 10.1053/j.sart.2013.01.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Hu XQ, Wood RJK, Taylor A, Tuke MA. The tribological behaviour of different clearance MOM hip joints with lubricants of physiological viscosities. Proc Inst Mech Eng H 2012; 225:1061-9. [PMID: 22292204 DOI: 10.1177/0954411911419061] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Clearance is one of the most influential parameters on the tribological performance of metal-on-metal (MOM) hip joints and its selection is a subject of considerable debate. The objective of this paper is to study the lubrication behaviour of different clearances for MOM hip joints within the range of human physiological and pathological fluid viscosities. The frictional torques developed by MOM hip joints with a 50 mm diameter were measured for both virgin surfaces and during a wear simulator test. Joints were manufactured with three different diametral clearances: 20, 100, and 200 microm. The fluid used for the friction measurements which contained different ratios of 25 percent newborn calf serum and carboxymethyl cellulose (CMC) with the obtained viscosities values ranging from 0.001 to 0.71 Pa s. The obtained results indicate that the frictional torque for the 20 microm clearance joint remains high over the whole range of the viscosity values. The frictional torque of the 100 microm clearance joint was low for the very low viscosity (0.001 Pa s) lubricant, but increased with increasing viscosity value. The frictional torque of the 200 microm clearance joint was high at very low viscosity levels, however, it reduced with increasing viscosity. It is concluded that a smaller clearance level can enhance the formation of an elastohydrodynamic lubrication (EHL) film, but this is at the cost of preventing fluid recovery between the bearing surfaces during the unloaded phase of walking. Larger clearance bearings allow a better recovery of lubricant during the unloaded phase, which is necessary for higher viscosity lubricants. The selection of the clearance value should therefore consider both the formation of the EHL film and the fluid recovery as a function of the physiological viscosity in order to get an optimal tribological performance for MOM hip joints. The application of either 25 per cent bovine serum or water in existing in vitro tribological study should also be revised to consider the relevance of clinic synovial fluid viscosities and to avoid possible misleading results.
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Affiliation(s)
- X Q Hu
- National Centre for Advanced Tribology at Southampton (nCATS), School of Engineering Sciences, University of Southampton, UK.
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Moghadas P, Mahomed A, Hukins DW, Shepherd DE. Friction in metal-on-metal total disc arthroplasty: Effect of ball radius. J Biomech 2012; 45:504-9. [DOI: 10.1016/j.jbiomech.2011.11.045] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Revised: 11/21/2011] [Accepted: 11/22/2011] [Indexed: 11/26/2022]
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Rehmer A, Bishop NE, Morlock MM. Influence of assembly procedure and material combination on the strength of the taper connection at the head-neck junction of modular hip endoprostheses. Clin Biomech (Bristol, Avon) 2012; 27:77-83. [PMID: 21903309 DOI: 10.1016/j.clinbiomech.2011.08.002] [Citation(s) in RCA: 114] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Revised: 07/01/2011] [Accepted: 08/01/2011] [Indexed: 02/07/2023]
Abstract
BACKGROUND A stable fixation between femoral head and endoprosthesis taper is necessary to prevent relative motions and corrosion at the taper junction. Although the importance of the component assembly has been recognised, no definitive instructions are available. The purpose of this study was to assess the influence of assembly force, assembly tool and number of hammer strokes on the taper junction strength of various material combinations. METHODS Co-Cr29-Mo (n=10) and Ti-6Al-4V (n=10) neck tapers were assembled with Co-Cr and Al(2)O(3) ceramic heads either by push-on or by impaction with single or multiple hammer blows. The strength of the taper-head connection was evaluated by measuring the head pull-off forces according to ISO 7206-10 and the turn-off moment capacity. FINDINGS The taper strength linearly increased with assembly forces (P<0.001). Co-Cr heads combined with Co-Cr tapers showed significantly lower pull-off forces and turn-off moments than the combination with Ti tapers (0.001<P<0.025). Multiple impaction did not increase taper strength (0.063 <P<0.995). Ceramic and Co-Cr heads showed similar fixation patterns on Ti tapers. Turn-off moments varied between 6 Nm and 19 Nm, dependent on material combination and assembly force. INTERPRETATION It is suggested that sufficient head-taper junction strength in all bearing conditions is achieved by impaction forces of at least 4 kN. A single impact is sufficient to achieve fixation. Special attention should be paid to the assembly of Co-Cr heads on Co-Cr tapers.
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Affiliation(s)
- Annelie Rehmer
- TUHH, Hamburg University of Technology, Biomechanics Section, Hamburg, Germany.
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37
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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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38
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Kaddick C, Catelas I, Pennekamp PH, Wimmer MA. [Implant wear and aseptic loosening. An overview]. DER ORTHOPADE 2009; 38:690-7. [PMID: 19657620 DOI: 10.1007/s00132-009-1431-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Wear of total joint implants is multifactorial in nature. Even for identical materials and geometries, the interaction of those parameters can generate different numbers of particles as well as different particle sizes and shapes. These different wear-particle characteristics will directly influence the biological response to an implant and thereby its clinical success. The long-term success of a total joint replacement requires an optimized compromise among implant material, design, surgical procedure, and biological performance.
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Affiliation(s)
- C Kaddick
- EndoLab GmbH, Seb.-Tiefenthaler Strasse 13, 83101 Thansau/Rosenheim, Deutschland.
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39
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Gebert A, Peters J, Bishop N, Westphal F, Morlock M. Influence of press-fit parameters on the primary stability of uncemented femoral resurfacing implants. Med Eng Phys 2009; 31:160-4. [DOI: 10.1016/j.medengphy.2008.04.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2007] [Revised: 04/15/2008] [Accepted: 04/16/2008] [Indexed: 10/22/2022]
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