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Clarke SG, Phillips ATM, Bull AMJ, Cobb JP. A hierarchy of computationally derived surgical and patient influences on metal on metal press-fit acetabular cup failure. J Biomech 2012; 45:1698-704. [PMID: 22513086 DOI: 10.1016/j.jbiomech.2012.03.026] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Revised: 02/20/2012] [Accepted: 03/14/2012] [Indexed: 10/28/2022]
Abstract
The impact of anatomical variation and surgical error on excessive wear and loosening of the acetabular component of large diameter metal-on-metal hip arthroplasties was measured using a multi-factorial analysis through 112 different simulations. Each surgical scenario was subject to eight different daily loading activities using finite element analysis. Excessive wear appears to be predominantly dependent on cup orientation, with inclination error having a higher influence than version error, according to the study findings. Acetabular cup loosening, as inferred from initial implant stability, appears to depend predominantly on factors concerning the area of cup-bone contact, specifically the level of cup seating achieved and the individual patient's anatomy. The extent of press fit obtained at time of surgery did not appear to influence either mechanism of failure in this study.
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Affiliation(s)
- S G Clarke
- Structural Biomechanics, Department of Civil and Environmental Engineering, Imperial College London, Skempton Building, South Kensington Campus, London SW7 2AZ, UK.
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52
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Daniel J, Holland J, Quigley L, Sprague S, Bhandari M. Pseudotumors associated with total hip arthroplasty. J Bone Joint Surg Am 2012; 94:86-93. [PMID: 22218386 DOI: 10.2106/jbjs.j.01612] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Pseudotumors are a rare but important complication occurring with all types of hip replacements.The true prevalence of pseudotumors is debated.Potential causes of pseudotumors may include foreign-body reaction, hypersensitivity, and wear debris.The conduct of clinical trials on the incidence, causes, and treatments of pseudotumors has been inadequate as few investigators have used a randomized controlled design to compare various implant types.
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Affiliation(s)
- Joseph Daniel
- Hip and Knee Reconstruction, The McMinn Centre, 25 Highfield Road, Edgbaston, Birmingham, B15 3DP, UK
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53
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Meng QE, Liu F, Fisher J, Jin ZM. Transient elastohydrodynamic lubrication analysis of a novel metal-on-metal hip prosthesis with a non-spherical femoral bearing surface. Proc Inst Mech Eng H 2011; 225:25-37. [PMID: 21381485 DOI: 10.1243/09544119jeim795] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Effective lubrication performance of metal-on-metal hip implants only requires optimum conformity within the main loaded area, while it is advantageous to increase the clearance in the equatorial region. Such a varying clearance can be achieved by using non-spherical bearing surfaces for either acetabular or femoral components. An elastohydrodynamic lubrication model of a novel metal-on-metal hip prosthesis using a non-spherical femoral bearing surface against a spherical cup was solved under loading and motion conditions specified by ISO standard. A full numerical methodology of considering the geometric variation in the rotating non-spherical head in elastohydrodynamic lubrication solution was presented, which is applicable to all non-spherical head designs. The lubrication performance of a hip prosthesis using a specific non-spherical femoral head, Alpharabola, was analysed and compared with those of spherical bearing surfaces and a non-spherical Alpharabola cup investigated in previous studies. The sensitivity of the lubrication performance to the anteversion angle of the Alpharabola head was also investigated. Results showed that the non-spherical head introduced a large squeeze-film action and also led to a large variation in clearance within the loaded area. With the same equatorial clearance, the lubrication performance of the metal-on-metal hip prosthesis using an Alpharabola head was better than that of the conventional spherical bearings but worse than that of the metal-on-metal hip prosthesis using an Alpharabola cup. The reduction in the lubrication performance caused by the initial anteversion angle of the non-spherical head was small, compared with the improvement resulted from the non-spherical geometry.
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Affiliation(s)
- Q E Meng
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK.
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54
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Langton DJ, Joyce TJ, Jameson SS, Lord J, Van Orsouw M, Holland JP, Nargol AVF, De Smet KA. Adverse reaction to metal debris following hip resurfacing: the influence of component type, orientation and volumetric wear. ACTA ACUST UNITED AC 2011; 93:164-71. [PMID: 21282753 DOI: 10.1302/0301-620x.93b2.25099] [Citation(s) in RCA: 293] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
We sought to establish the incidence of joint failure secondary to adverse reaction to metal debris (ARMD) following metal-on-metal hip resurfacing in a large, three surgeon, multicentre study involving 4226 hips with a follow-up of 10 to 142 months. Three implants were studied: the Articular Surface Replacement; the Birmingham Hip Resurfacing; and the Conserve Plus. Retrieved implants underwent analysis using a co-ordinate measuring machine to determine volumetric wear. There were 58 failures associated with ARMD. The median chromium and cobalt concentrations in the failed group were significantly higher than in the control group (p < 0.001). Survival analysis showed a failure rate in the patients with Articular Surface Replacement of 12.8% [corrected] at five years, compared with < 1% at five years for the Conserve Plus and 1.5% at ten years for the Birmingham Hip Resurfacing. Two ARMD patients had relatively low wear of the retrieved components. Increased wear from the metal-on-metal bearing surface was associated with an increased rate of failure secondary to ARMD. However, the extent of tissue destruction at revision surgery did not appear to be dose-related to the volumetric wear.
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Affiliation(s)
- D J Langton
- Northern Deanery, Goldcrest Way, Newcastle-upon-Tyne, NE15 8NY, UK.
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55
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Deformation characteristics and eigenfrequencies of press-fit acetabular cups. Clin Biomech (Bristol, Avon) 2011; 26:46-51. [PMID: 20888676 DOI: 10.1016/j.clinbiomech.2010.08.015] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2010] [Revised: 08/30/2010] [Accepted: 08/31/2010] [Indexed: 02/07/2023]
Abstract
BACKGROUND elastic deformation of press-fitted acetabular cups during implantation provides primary stability. Excessive deformation can lead to chipping or improper seating of ceramic inlays and is dictated by cup stiffness, which also affects its vibrational characteristics. Purpose was to investigate the influence of cup design on deformation during press-fitting and on vibration properties. METHODS deformation of ten acetabular cups (with and without ceramic inlay) was tested for radial loads clinically occurring during press-fitting (0-2000N). Eigenfrequencies were measured using experimental modal analysis and related to mass and stiffness. FINDINGS the first eigenfrequency of the shells varied greatly (4-9kHz); insertion of inlays caused an increase (16-33 kHz). The range of shell stiffness was high (2.7-48.4kN/mm), increasing due to inlay insertion (124.7-376.2kN/mm). Stiffness and mass were sufficient predictors for eigenfrequencies (p<0.001,R²=0.94). INTERPRETATION the cups investigated represent a large stiffness range. Lower cup stiffness can increase primary stability but jeopardize inlay seating, and a suitable balance must be achieved by the designer. Eigenfrequencies also decrease with decreasing stiffness but were all found to lie considerably above clinically observed squeaking frequencies, indicating that these cup designs play no predominant role in the squeaking phenomenon. The observed relation between eigenfrequencies and the quotient of stiffness and mass might be used in the development of new thin walled cup designs so that their contribution to system vibrations is prevented. Presently, surgeons should be aware of the deformation characteristics of cups in order to select a suitable press-fit magnitude.
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56
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Markel D, Day J, Siskey R, Liepins I, Kurtz S, Ong K. Deformation of metal-backed acetabular components and the impact of liner thickness in a cadaveric model. INTERNATIONAL ORTHOPAEDICS 2010; 35:1131-7. [PMID: 20625898 DOI: 10.1007/s00264-010-1077-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2010] [Revised: 06/02/2010] [Accepted: 06/05/2010] [Indexed: 10/19/2022]
Abstract
Shell deformation of resurfacing and all-metal modular cups following press-fit implantation has been reported, but not for conventional metal-backed cups with polyethylene liners. The deformation of acetabular components with historical and thin polyethylene inserts after press-fit insertion was evaluated using a cadaveric model. All shells and liners deformed upon implantation. Following joint loading, shell pinch decreased from 0.32 to 0.22 mm (p = 0.019) and from 0.29 to 0.13 mm (p = 0.003) for the thin and thick liner groups, respectively. Liner pinch also decreased from 0.17 to 0.04 mm (p = 0.031) and from 0.06 to 0 mm (p = 0.103) for the thin and thick liner groups, respectively. There were no significant differences between the thin and thick liners. Liner deformation was influenced by the initial shell deformation and donor bone quality. Shell and liner pinch decreased following joint loading, suggesting a settling in effect.
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Affiliation(s)
- David Markel
- Department of Orthopaedic Surgery, Providence Hospital, Southfield, MI, USA
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57
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Acetabular Component Deformation under Rim Loading Using Digital Image Correlation and Finite Element Methods. ACTA ACUST UNITED AC 2010. [DOI: 10.4028/www.scientific.net/amm.24-25.275] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Total hip replacement is a highly successful operation; restoring function and reducing pain in arthritis patients. In recent years, thinner resurfacing acetabular cups have been introduced in order to preserve bone stock and reduce the risk of dislocation. However concerns have been raised that deformation of these cups could adversely affect the lubrication regime of the bearing; leading to equatorial and edge contact, possibly causing the implants to jam. This study aims to assess the amount of deformation which occurs due to the tight peripheral fit experienced during press-fit by applying rim loading to three different designs of acetabular cup: a clinically successful cobalt chrome resurfacing cup, a prototype composite resurfacing cup and a clinically successful polyethylene monobloc cup.
Digital Image Correlation (DIC) was used to measure the deformation and to validate Finite Element (FE) models. DIC provided a non-contacting method to measure displacement; meaning the load could be increased continuously rather than in steps as in previous studies.
The physical testing showed that the cobalt chrome cups were significantly stiffer than the composite prototype and polyethylene cups. The FE models were in good agreement with the experimental results for all three cups and were able to predict the deformation to within 10%. FE models were also created to investigate the effect of cup outside diameter and wall thickness on stiffness under rim loading. Increasing outside diameter resulted in a linear reduction in stiffness for all three materials. Increasing the wall thickness resulted in an exponential increase in cup stiffness.
Rim loading an acetabular shell does not accurately simulate the in vivo conditions; however it does provide a simple method for comparing cups made of different materials.
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58
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Schmidig G, Patel A, Liepins I, Thakore M, Markel DC. The effects of acetabular shell deformation and liner thickness on frictional torque in ultrahigh-molecular-weight polyethylene acetabular bearings. J Arthroplasty 2010; 25:644-53. [PMID: 19493649 DOI: 10.1016/j.arth.2009.03.020] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2008] [Accepted: 03/22/2009] [Indexed: 02/01/2023] Open
Abstract
The purposes of this study were to determine if there were differences in the frictional torque generated between spherical acetabular shells and acetabular shells deformed as a result of implantation and to evaluate how changes in polyethylene insert thickness and head diameter affected these frictional torque data. An established bench top model was used for mechanical testing. A total of 70 samples were tested. Acetabular shells were impacted into polyurethane foam that was designed to create spherical or deformed shell models. We found that deformed acetabular shells produced higher frictional torque than spherical shells. Also, larger femoral head sizes produced greater frictional torque than smaller femoral head sizes. For the deformed models, the thicker polyethylene inserts produced greater frictional torque than the thinner polyethylene inserts.
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59
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Shimmin AJ, Walter WL, Esposito C. The influence of the size of the component on the outcome of resurfacing arthroplasty of the hip. ACTA ACUST UNITED AC 2010; 92:469-76. [DOI: 10.1302/0301-620x.92b4.22967] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The survivorship of contemporary resurfacing arthroplasty of the hip using metal-on-metal bearings is better than that of first generation designs, but short-term failures still occur. The most common reasons for failure are fracture of the femoral neck, loosening of the component, osteonecrosis of the femoral head, reaction to metal debris and malpositioning of the component. In 2008 the Australian National Joint Registry reported an inverse relationship between the size of the head component and the risk of revision in resurfacing hip arthroplasty. Hips with a femoral component size of ≤ 44 mm have a fivefold increased risk of revision than those with femoral components of ≥ 55 mm irrespective of gender. We have reviewed the literature to explore this observation and to identify possible reasons including the design of the implant, loading of the femoral neck, the orientation of the component, the production of wear debris and the effects of metal ions, penetration of cement and vascularity of the femoral head. Our conclusion is that although multifactorial, the most important contributors to failure in resurfacing arthroplasty of the hip are likely to be the design and geometry of the component and the orientation of the acetabular component.
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Affiliation(s)
- A. J. Shimmin
- Melbourne Orthopaedic Group Research Foundation, 33 The Avenue, Windsor, 3181 Victoria, Australia
| | - W. L. Walter
- Specialist Orthopaedic Group Mater Clinic, Suite 1.08, 3-9 Gillies Street, North Sydney, New South Wales 2060, Australia
| | - C. Esposito
- Specialist Orthopaedic Group Mater Clinic, Suite 1.08, 3-9 Gillies Street, North Sydney, New South Wales 2060, Australia
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60
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Amanatullah DF, Cheung Y, Di Cesare PE. Hip resurfacing arthroplasty: a review of the evidence for surgical technique, outcome, and complications. Orthop Clin North Am 2010; 41:263-72. [PMID: 20399365 DOI: 10.1016/j.ocl.2010.01.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Hip resurfacing arthroplasty has reemerged as a valid reconstruction option for the osteoarthritic hip. Patient selection is critical for excellent surgical outcomes, especially when compared with total hip arthroplasty. However, concerns regarding surgical technique and postsurgical complications persist. The authors review the evidence for surgical technique, outcomes, and complications related to modern metal-on-metal hip resurfacing arthroplasty.
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Affiliation(s)
- Derek F Amanatullah
- Department of Orthopaedic Surgery, University of California Davis Medical Center, 4860 Y Street, Suite 3800, Sacramento, CA 95817, USA
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61
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Meng Q, Gao L, Liu F, Yang P, Fisher J, Jin Z. Contact mechanics and elastohydrodynamic lubrication in a novel metal-on-metal hip implant with an aspherical bearing surface. J Biomech 2009; 43:849-57. [PMID: 20003978 DOI: 10.1016/j.jbiomech.2009.11.018] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2009] [Revised: 11/15/2009] [Accepted: 11/16/2009] [Indexed: 12/16/2022]
Abstract
Diameter and diametral clearance of the bearing surfaces of metal-on-metal hip implants and structural supports have been recognised as key factors to reduce the dry contact and hydrodynamic pressures and improve lubrication performance. On the other hand, application of aspherical bearing surfaces can also significantly affect the contact mechanics and lubrication performance by changing the radius of the curvature of a bearing surface and consequently improving the conformity between the head and the cup. In this study, a novel metal-on-metal hip implant employing a specific aspherical bearing surface, Alpharabola, as the acetabular surface was investigated for both contact mechanics and elastohydrodynamic lubrication under steady-state conditions. When compared with conventional spherical bearing surfaces, a more uniform pressure distribution and a thicker lubricant film thickness within the loaded conjunction were predicted for this novel Alpharabola hip implant. The effects of the geometric parameters of this novel acetabular surface on the pressure distribution and lubricant thickness were investigated. A significant increase in the predicted lubricant film thickness and a significant decrease in the dry contact and hydrodynamic pressures were found with appropriate combinations of these geometric parameters, compared with the spherical bearing surface.
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Affiliation(s)
- Qingen Meng
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, UK.
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62
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Langton DJ, Sprowson AP, Joyce TJ, Reed M, Carluke I, Partington P, Nargol AVF. Blood metal ion concentrations after hip resurfacing arthroplasty: a comparative study of articular surface replacement and Birmingham Hip Resurfacing arthroplasties. ACTA ACUST UNITED AC 2009; 91:1287-95. [PMID: 19794161 DOI: 10.1302/0301-620x.91b10.22308] [Citation(s) in RCA: 169] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
There have been no large comparative studies of the blood levels of metal ions after implantation of commercially available hip resurfacing devices which have taken into account the effects of femoral size and inclination and anteversion of the acetabular component. We present the results in 90 patients with unilateral articular surface replacement (ASR) hip resurfacings (mean time to blood sampling 26 months) and 70 patients with unilateral Birmingham Hip Resurfacing (BHR) implants (mean time 47 months). The whole blood and serum chromium (Cr) and cobalt (Co) concentrations were inversely related to the size of the femoral component in both groups (p < 0.05). Cr and Co were more strongly influenced by the position of the acetabular component in the case of the ASR, with an increase in metal ions observed at inclinations > 45 degrees and anteversion angles of < 10 degrees and > 20 degrees. These levels were only increased in the BHR group when the acetabular component was implanted with an inclination > 55 degrees. A significant relationship was identified between the anteversion of the BHR acetabular component and the levels of Cr and Co (p < 0.05 for Co), with an increase observed at anteversion angles < 10 degrees and > 20 degrees. The median whole blood and serum Cr concentrations of the male ASR patients were significantly lower than those of the BHR men (p < 0.001). This indicates that reduced diametral clearance may equate to a reduction in metal ion concentrations in larger joints with satisfactory orientation of the acetabular component.
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Affiliation(s)
- D J Langton
- Joint Replacement Unit, University Hospital of North Tees, Hardwick, Stockton-on-Tees, UK.
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63
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Kretzer JP, Kleinhans JA, Jakubowitz E, Thomsen M, Heisel C. A meta-analysis of design- and manufacturing-related parameters influencing the wear behavior of metal-on-metal hip joint replacements. J Orthop Res 2009; 27:1473-80. [PMID: 19472378 DOI: 10.1002/jor.20921] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
This article aims to clarify the influence of design- and manufacturing-related parameters on wear of metal-on-metal (MoM) joint bearings. A database search for publications on wear simulator studies of MoM bearings was performed. The results of published studies were normalized; groups with individual parameters were defined and analyzed statistically. Fifty-six investigations studying a total of 200 implants were included in the analysis. Clearance, head size, carbon content, and manufacturing method were analyzed as parameters influencing MoM wear. This meta-analysis revealed a strong influence of clearance on running-in wear for implants of 36-mm diameter and an increase in steady-state wear of heat treated components.
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Affiliation(s)
- Jan Philippe Kretzer
- Laboratory of Biomechanics, Department of Orthopaedics, University of Heidelberg, Heidelberg, Germany
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64
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Ong KL, Rundell S, Liepins I, Laurent R, Markel D, Kurtz SM. Biomechanical modeling of acetabular component polyethylene stresses, fracture risk, and wear rate following press-fit implantation. J Orthop Res 2009; 27:1467-72. [PMID: 19489047 DOI: 10.1002/jor.20918] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Press-fit implantation may result in acetabular component deformation between the ischial-ilial columns ("pinching"). The biomechanical and clinical consequences of liner pinching due to press-fit implantation have not been well studied. We compared the effects of pinching on the polyethylene fracture risk, potential wear rate, and stresses for two different thickness liners using computational methods. Line-to-line ("no pinch") reaming and 2 mm underreaming press fit ("pinch") conditions were examined for Trident cups with X3 polyethylene liner wall thicknesses of 5.9 mm (36E) and 3.8 mm (40E). Press-fit cup deformations were measured from a foam block configuration. A hybrid material model, calibrated to experimentally determined stress-strain behavior of sequentially annealed polyethylene, was applied to the computational model. Molecular chain stretch did not exceed the fracture threshold in any cases. Nominal shell pinch of 0.28 mm was estimated to increase the volumetric wear rate by 70% for both cups and peak contact stresses by 140 and 170% for the 5.9 and 3.8 mm-thick liners, respectively. Although pinching increases liner stresses, polyethylene fracture is highly unlikely, and the volumetric wear rates are likely to be low compared to conventional polyethylene.
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Affiliation(s)
- Kevin L Ong
- Exponent Inc., 3401 Market St., Suite 300, Philadelphia, Pennsylvania 19104, USA.
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65
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Bowsher JG, Clarke IC, Williams PA, Donaldson TK. What is a “Normal” wear pattern for metal-on-metal hip bearings? J Biomed Mater Res B Appl Biomater 2009; 91:297-308. [DOI: 10.1002/jbm.b.31403] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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66
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Heisel C, Kleinhans JA, Menge M, Kretzer JP. Ten different hip resurfacing systems: biomechanical analysis of design and material properties. INTERNATIONAL ORTHOPAEDICS 2009; 33:939-43. [PMID: 18600323 PMCID: PMC2898991 DOI: 10.1007/s00264-008-0607-y] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2008] [Revised: 05/23/2008] [Accepted: 05/23/2008] [Indexed: 10/21/2022]
Abstract
This study gives an overview of the main macro- and microstructural differences of ten commercially available total hip resurfacing implants. The heads and cups of resurfacing hip implants from ten different manufacturers were analysed. The components were measured in a coordinate measuring machine. The microstructure of the heads and cups was inspected by scanning electron microscopy. The mean radial clearance was 84.86 microm (range: 49.47-120.93 microm). The implants were classified into three groups (low, medium and high clearance). All implants showed a deviation of roundness of less than 10 microm. It was shown that all implants differ from each other and a final conclusion about the ideal design and material combination cannot be given based on biomechanical data. Widespread use of specific designs can only be recommended if clinical long-term follow-up studies are performed and analysed for each design.
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Affiliation(s)
- Christian Heisel
- Laboratory of Biomechanics and Implant Research, Department of Orthopaedics, University of Heidelberg, Heidelberg, Germany.
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67
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Langton DJ, Jameson SS, Joyce TJ, Webb J, Nargol AVF. The effect of component size and orientation on the concentrations of metal ions after resurfacing arthroplasty of the hip. ACTA ACUST UNITED AC 2008; 90:1143-51. [PMID: 18757952 DOI: 10.1302/0301-620x.90b9.20785] [Citation(s) in RCA: 270] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Increased concentrations of metal ions after metal-on-metal resurfacing arthroplasty of the hip remain a concern. Although there has been no proven link to long-term health problems or early prosthetic failure, variables associated with high metal ion concentrations should be identified and, if possible, corrected. Our study provides data on metal ion levels from a series of 76 consecutive patients (76 hips) after resurfacing arthroplasty with the Articular Surface Replacement. Chromium and cobalt ion concentrations in the whole blood of patients with smaller (<or= 51 mm) femoral components were significantly higher than in those with the larger (>or= 53 mm) components (p < 0.01). Ion concentrations in the former group were significantly related to the inclination (p = 0.01) and anteversion (p = 0.01) of the acetabular component. The same relationships were not significant in the patients with larger femoral components (p = 0.61 and p = 0.49, respectively). Accurate positioning of the acetabular component intra-operatively is essential in order to reduce the concentration of metal ions in the blood after hip resurfacing arthroplasty with the Articular Surface Replacement implant.
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Affiliation(s)
- D J Langton
- Joint Replacement Unit, University Hospital of North Tees, Hardwick, Stockton-on-Tees TS19 8PE, UK.
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68
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Experimental investigations of the insertion and deformation behavior of press-fit and threaded acetabular cups for total hip replacement. J Orthop Sci 2008; 13:240-7. [PMID: 18528658 DOI: 10.1007/s00776-008-1212-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2007] [Accepted: 01/30/2008] [Indexed: 02/09/2023]
Abstract
BACKGROUND The deformation behavior of threaded and press-fit acetabular cups in correlation with the applied torques and forces to insert the cups has not been widely investigated. The aim of this experimental study was to analyze the deformation behavior of threaded (BICON-PLUS) and press-fit (EP FIT PLUS and Metal shell) acetabular cup designs during insertion and extraction with regard to the possibility of cup failure. METHODS The experiments were carried out using artificial bone and human acetabular bone. The torque needed to insert the threaded cups and the force applied to the press-fit cups was measured. The force and torque were applied manually by a surgeon using common surgical instruments. The strain of the cups was assessed by tangentially and radially applied strain gauges during the insertion process, the implanted state, and extraction. These measurements were used to calculate the change in diameter of the acetabular cups and the strains at the notches of the threaded acetabular cup. RESULTS The results showed that maximum strains and applied torques and force occurred during cup insertion. In the case of the threaded cup, an average maximum insertion torque of 114 Nm was measured using bone substitute, whereas only 47 Nm was assessed using human acetabulum. A maximum change in diameter of 8 microm was calculated during the implanted state for the threaded cup. The impact forces for both press-fit cups ranged from approximately 1.0 to 8.9 kN. The change in diameter was 8 microm for the Metal shell and 4 microm for the EP FIT PLUS. In all cases, no permanent cup deformation was detected. CONCLUSIONS The observed deformations suggest that implant failure of the analyzed acetabular cups is unlikely during insertion, the implanted state, or extraction under normal conditions.
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69
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Udofia I, Liu F, Jin Z, Roberts P, Grigoris P. The initial stability and contact mechanics of a press-fit resurfacing arthroplasty of the hip. ACTA ACUST UNITED AC 2007; 89:549-56. [PMID: 17463130 DOI: 10.1302/0301-620x.89b4.18055] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Finite element analysis was used to examine the initial stability after hip resurfacing and the effect of the procedure on the contact mechanics at the articulating surfaces. Models were created with the components positioned anatomically and loaded physiologically through major muscle forces. Total micromovement of less than 10 μm was predicted for the press-fit acetabular components models, much below the 50 μm limit required to encourage osseointegration. Relatively high compressive acetabular and contact stresses were observed in these models. The press-fit procedure showed a moderate influence on the contact mechanics at the bearing surfaces, but produced marked deformation of the acetabular components. No edge contact was predicted for the acetabular components studied. It is concluded that the frictional compressive stresses generated by the 1 mm to 2 mm interference-fit acetabular components, together with the minimal micromovement, would provide adequate stability for the implant, at least in the immediate post-operative situation.
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Affiliation(s)
- I Udofia
- Computational Bioengineering Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, UK.
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70
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Squire M, Griffin WL, Mason JB, Peindl RD, Odum S. Acetabular component deformation with press-fit fixation. J Arthroplasty 2006; 21:72-7. [PMID: 16950065 DOI: 10.1016/j.arth.2006.04.016] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2006] [Accepted: 04/13/2006] [Indexed: 02/01/2023] Open
Abstract
Acetabular component deformation secondary to forces encountered during insertion is a potential consequence of the press-fit technique. This study characterized the stiffness of Pinnacle 100 cups (DePuy, Warsaw, Ind) via mechanical testing and used this information with intraoperative measurements of cup deformation to calculate the in vivo forces acting on cups inserted during hip arthroplasty in 21 patients. We found that 90.5% of cups had measurable compression deformity, averaging 0.16 +/- 0.16 mm. The corresponding forces acting on these cups averaged 414 +/- 421 N. For hard-on-hard bearing surfaces, such in vivo deformation of acetabular shells may result in negative clinical consequences such as equatorial loading with increased wear and potential seizing of components, chipping of ceramic inserts, or locking mechanism damage.
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Affiliation(s)
- Matthew Squire
- Department of Orthopedics and Rehabilitation, University of Wisconsin Hospitals and Clinics, Madison, Wisconsin, USA
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71
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Isaac GH, Siebel T, Schmalzried TP, Cobb AG, O'Sullivan T, Oakeshott RD, Flett M, Vail TP. Development rationale for an articular surface replacement: a science-based evolution. Proc Inst Mech Eng H 2006; 220:253-68. [PMID: 16669392 DOI: 10.1243/095441105x69132] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Hip resurfacing has an enduring appeal because of the advantages of bone conservation and maximal joint stability. However, a far from satisfactory experience with earlier resurfacing designs led to its virtual disappearance in the 1980s. The concept was reintroduced in the late 1990s. The current generation of resurfacing devices generally consisted of a large-diameter metal-on-metal articulation, the femoral components being cemented and the acetabular components utilizing various forms of cementless fixation. The encouraging medium-term results, with a follow-up of up to 8 years using the current generation of surface replacement joints, combined with favourable reports related to long-term performance of some metal bearings have led to a rapid increase in the use of such components with these devices. This trend is most marked in younger, more active patients who have expectations of restoration of lifestyle in addition to improved mobility and pain relief and in whom failure with conventional total hip replacement is much higher than previously reported with more sedentary patients. The aim of this paper is, firstly, to highlight a number of areas of improvement and, secondly, to explain how these may be addressed by making modifications to the design of both implants and instrumentation and to the surgical technique. The areas identified for improvement were tissue preservation (thinner components, and reduced steps between sizes), acetabular cup issues (fixation, insertion, and positioning), femoral component issues (design, loading, and cementation), improved bearing surface characteristics, and simplified precise instrumentation with a low-trauma surgical technique.
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Affiliation(s)
- G H Isaac
- DePuy International Limited, Leeds, UK.
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72
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Yew A, Jin ZM, Donn A, Morlock MM, Isaac G. Deformation of press-fitted metallic resurfacing cups. Part 2: Finite element simulation. Proc Inst Mech Eng H 2006; 220:311-9. [PMID: 16669397 DOI: 10.1243/095441105x69105] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The deformation of metallic acetabular cups employed for metal-on-metal hip resurfacing procedures was considered theoretically using the finite element method in the present study, following on the experimental investigation reported in Part 1. Three representative cups, characterized by the cup wall thickness as thin, intermediate, and thick, were considered. For the intermediate cup, the effects of both the size and the diametral interference on the cup deformation were investigated. Both two-dimensional axisymmetric and three-dimensional finite element models were developed to examine the important parameters during and after the press-fit procedure, and in particular the deformation of the metallic cup. The theoretical prediction of the cup deformation was in reasonable agreement with the corresponding experimental measurement reported in Part 1. The most significant factor influencing the cup deformation was the cup wall thickness. Both the size and the diametral interference were also shown to influence the cup deformation. It is important to ensure that the cup deformation does not significantly affect the clearance designed and optimized for tribological performances of metal-on-metal hip resurfacing prostheses. Furthermore the contact parameters at the cup and bone interface associated with the press fit were also discussed.
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Affiliation(s)
- A Yew
- Division of Bioengineering, National University of Singapore, Singapore
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