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Matsuoka T, Takahashi Y, Ishida T, Tateiwa T, Shishido T, Yamamoto K. In vivo creep and wear performance of vitamin-E-diffused highly crosslinked polyethylene in total hip arthroplasty. Arch Orthop Trauma Surg 2023; 143:7195-7203. [PMID: 37438580 DOI: 10.1007/s00402-023-04972-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Accepted: 06/26/2023] [Indexed: 07/14/2023]
Abstract
INTRODUCTION An acetabular liner thickness of around 6 mm remains the "gold standard" in total hip arthroplasty. Some surgeons have been recommending the use of the thickest possible liner because contact stress and strain in articulating surfaces decrease with increasing the wall thickness. The purpose of this study was to determine whether in vivo creep and wear performance could be enhanced using a thicker liner over the standard thickness in vitamin-E-diffused highly crosslinked polyethylene (HXLPE). MATERIALS AND METHODS One hundred and twenty-two hips were allocated to age-matched, sex-matched, and body mass index-matched two subgroups implanted either with a 6.8- or 8.9-mm-thick vitamin-E-diffused HXLPE liner against 28-mm cobalt-chrome femoral head, and followed-up for 7 years. Linear and volumetric penetration of femoral head into the liners attributed to creep and wear were analyzed for each group. RESULTS Compressive creep strain generated at the initial 6 months was significantly larger in the 6.8-mm group (2.6%) than in the 8.9-mm group (2.2%). The linear steady-state wear observed after 2 years was 0.0019 and 0.0015 mm/year, whereas the volumetric steady-state wear was 0.54 and 0.45 mm3/years in the 6.8- and 8.9-mm-thick groups, respectively. Although less strain in the thicker group resulted in a slightly less wear, it did not reach significant differences in the steady-state wear rates between the groups. CONCLUSION No clinical significance for using a thicker liner over the standard thickness (6.8 mm → 8.9 mm) was confirmed in the vitamin-E-diffused HXLPE according to the 7-year follow-up. The wear rates for both thicknesses were very low enough to prevent osteolysis, and no mechanical failure was observed at any follow-up interval. Nevertheless, since the significantly higher strain was seen in the thinner liner, further follow-up is needed to compare the longer term wear and the incidence of osteolysis and component fracture.
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Affiliation(s)
- Tsunehiro Matsuoka
- Department of Orthopedic Surgery, Tokyo Medical University, 6-7-1, Nishishinjuku, Shinjuku-ku, Tokyo, 160-0023, Japan
| | - Yasuhito Takahashi
- Department of Orthopedic Surgery, Tokyo Medical University, 6-7-1, Nishishinjuku, Shinjuku-ku, Tokyo, 160-0023, Japan.
- Department of Bone and Joint Biomaterial Research, Tokyo Medical University, 6-7-1, Nishishinjuku, Shinjuku-ku, Tokyo, 160-0023, Japan.
| | - Tsunehito Ishida
- Department of Orthopedic Surgery, Tokyo Medical University, 6-7-1, Nishishinjuku, Shinjuku-ku, Tokyo, 160-0023, Japan
| | - Toshiyuki Tateiwa
- Department of Orthopedic Surgery, Tokyo Medical University, 6-7-1, Nishishinjuku, Shinjuku-ku, Tokyo, 160-0023, Japan
| | - Takaaki Shishido
- Department of Orthopedic Surgery, Tokyo Medical University, 6-7-1, Nishishinjuku, Shinjuku-ku, Tokyo, 160-0023, Japan
| | - Kengo Yamamoto
- Department of Orthopedic Surgery, Tokyo Medical University, 6-7-1, Nishishinjuku, Shinjuku-ku, Tokyo, 160-0023, Japan
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Ruhr M, Baetz J, Pueschel K, Morlock MM. Influence of acetabular cup thickness on seating and primary stability in total hip arthroplasty. J Orthop Res 2022; 40:2139-2146. [PMID: 34855229 DOI: 10.1002/jor.25232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 11/05/2021] [Accepted: 11/20/2021] [Indexed: 02/04/2023]
Abstract
Insufficient primary stability of acetabular hip cups is a complication resulting in early cup loosening. Available cup designs vary in terms of wall thickness, potentially affecting implant fixation. This study investigated the influence of different wall thicknesses on the implantation process and the resulting primary stability using excised human acetabula. Implantations were performed using a powered impaction device providing consistent energy with each stroke. Two different wall thicknesses were compared in terms of seating progress, polar gap remaining after implantation, bone-to-implant contact area, cup deflection, and lever out moment. Thin-walled cups showed higher lever out resistance (p < 0.001) and smaller polar gaps (p < 0.001) with larger bone contact toward the dome of the cup (p < 0.001) compared to thick-walled cups. Small seating steps at the end of the impaction process were observed if a high number of strokes were needed to seat the cup (p = 0.045). A high number of strokes led to a strain release of the cup during the final strokes (p = 0.003). This strain release is indicative for over-impaction of the cup associated with bone damage and reduced primary stability. Adequate cup seating can be achieved with thin-walled cups with lower energy input in comparison to thicker ones. Thin-walled cups showed improved primary stability and enable implantation with lower energy input, reducing the risk of over-impaction and bone damage. Additional strokes should be avoided as soon as no further seating progress has been observed.
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Affiliation(s)
- Miriam Ruhr
- Institute of Biomechanics, Hamburg University of Technology, Hamburg, Germany
| | - Johanna Baetz
- Institute of Biomechanics, Hamburg University of Technology, Hamburg, Germany
| | - Klaus Pueschel
- Department of Legal Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Michael M Morlock
- Institute of Biomechanics, Hamburg University of Technology, Hamburg, Germany
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Fischman D, Mahatma MM, Slullitel P, Farzi M, Grammatopoulos G, Poitras S, Wilkinson JM, Beaulé PE. Does a Monoblock Acetabular Component With a Ceramic Liner Cause More Pelvic Bone Loss Than a Conventional Modular Cementless Acetabular Component? A 2-Year Randomized Clinical Trial. J Arthroplasty 2022; 37:75-82. [PMID: 34649747 DOI: 10.1016/j.arth.2021.08.033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 08/19/2021] [Accepted: 08/30/2021] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND Ceramic-on-ceramic bearings permit the use of large femoral head size while maintaining a favorable effect on wear rates. However, because of increased device rigidity, periprosthetic bone quality could be negatively affected due to stress shielding. The purpose of this study is to assess pelvic periprosthetic bone remodeling around a monoblock ceramic-on-ceramic acetabular component compared to that around a conventional modular metal-on-polyethylene device. METHODS Participants were randomized to receive hip replacement using either a porous-coated, modular metal-on-polyethylene acetabular component (n = 46) or a hydroxyapatite and titanium-coated monoblock shell with an integrated ceramic-on-ceramic bearing (n = 40). Radiographic assessments were completed preoperatively and postoperatively, and measurements of bone mineral density (BMD) using dual-energy X-ray absorptiometry with region free analysis were performed postoperatively and over 2-years of follow-up. RESULTS There was no significant difference in BMD between the 2 groups at baseline or over the following 2 years. At follow-up, complete shell-to-bone contact without a radiolucent line was observed in 26 (67%) of the modular devices and in 37 (93%) of monoblock (P < .001). The modular device was an independent predictor of radiolucent lines (odds ratio 19.1, P = .007). No cases underwent revision surgery for acetabular loosening. CONCLUSION Both the porous-coated modular and hydroxyapatite-coated monoblock acetabular components showed successful clinical results at short-term follow-up with no difference in pixel-level BMD. Using a large head monoblock device does not appear to be associated with an adverse effect on the local bone environment when compared to a modular device. NCT: NCT01558752.
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Affiliation(s)
- Daniel Fischman
- Division of Orthopaedic Surgery, The Ottawa Hospital, Ottawa, Canada
| | - Mohit M Mahatma
- Department of Oncology and Metabolism, University of Sheffield, Sheffield, UK
| | - Pablo Slullitel
- Division of Orthopaedic Surgery, The Ottawa Hospital, Ottawa, Canada; Institute of Orthopaedics 'Carlos E. Ottolenghi', Italian Hospital of Buenos Aires, Buenos Aires, Argentina
| | - Mohsen Farzi
- Centre for Computational Imaging and Simulation Technologies in Bioscience, University of Leeds, Leeds, UK
| | | | - Stéphane Poitras
- School of Rehabilitation, Faculty of Health Sciences, University of Ottawa, Ottawa, Ontario, Canada
| | - J Mark Wilkinson
- Department of Oncology and Metabolism, University of Sheffield, Sheffield, UK
| | - Paul E Beaulé
- Division of Orthopaedic Surgery, The Ottawa Hospital, Ottawa, Canada
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4
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Doyle R, van Arkel RJ, Muirhead-Allwood S, Jeffers JRT. Impaction technique influences implant stability in low-density bone model. Bone Joint Res 2020; 9:386-393. [PMID: 32793333 PMCID: PMC7393184 DOI: 10.1302/2046-3758.97.bjr-2019-0303.r1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Aims Cementless acetabular components rely on press-fit fixation for initial stability. In certain cases, initial stability is more difficult to obtain (such as during revision). No current study evaluates how a surgeon’s impaction technique (mallet mass, mallet velocity, and number of strikes) may affect component fixation. This study seeks to answer the following research questions: 1) how does impaction technique affect a) bone strain generation and deterioration (and hence implant stability) and b) seating in different density bones?; and 2) can an impaction technique be recommended to minimize risk of implant loosening while ensuring seating of the acetabular component? Methods A custom drop tower was used to simulate surgical strikes seating acetabular components into synthetic bone. Strike velocity and drop mass were varied. Synthetic bone strain was measured using strain gauges and stability was assessed via push-out tests. Polar gap was measured using optical trackers. Results A phenomenon of strain deterioration was identified if an excessive number of strikes was used to seat a component. This effect was most pronounced in low-density bone at high strike velocities. Polar gap was reduced with increasing strike mass and velocity. Conclusion A high mallet mass with low strike velocity resulted in satisfactory implant stability and polar gap, while minimizing the risk of losing stability due to over-striking. Extreme caution not to over-strike must be exercised when using high velocity strikes in low-density bone for any mallet mass. Cite this article: Bone Joint Res 2020;9(7):386–393.
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Affiliation(s)
- Ruben Doyle
- Department of Mechanical Engineering, Imperial College London, London, UK
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5
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Li G, Peng Y, Zhou C, Jin Z, Bedair H. The effect of structural parameters of total hip arthroplasty on polyethylene liner wear behavior: A theoretical model analysis. J Orthop Res 2020; 38:1587-1595. [PMID: 31876311 DOI: 10.1002/jor.24577] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 12/21/2019] [Indexed: 02/04/2023]
Abstract
Using large femoral heads in total hip arthroplasty (THA) has been widely advocated to improve the function and longevity of the components. However, increasing the head size has been shown to accelerate polyethylene liner wear. Few studies have investigated the effect of other important structural parameters (such as polyethylene liner thickness, metal cup size, head-liner conformity, loading conditions, etc.) on the biomechanical functions of the THAs. In this study, an analytical model was used to evaluate the polyethylene liner wear characteristics of the THAs (defined using a biomechanical wear factor) with various structural parameters of the THAs and loading conditions. For all the THA systems examined in this study, under the same loading conditions, a larger head leads to increasing contact areas, lower contact stresses, and higher biomechanical wear factors. When the head size is fixed, a decrease in the polyethylene liner thickness or a decrease in the head-liner conformity leads to higher peak contact stresses and smaller contact areas and consequently, lower biomechanical wear factors. This study provides a parametric analysis tool for the optimal design/selection of the THA systems and for prediction of early effects of various structural parameters on the biomechanical function (such as contact stresses) and longevity (such as polyethylene liner wear) of the THA systems.
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Affiliation(s)
- Guoan Li
- Department of Orthopaedic Surgery, Orthopaedic Bioengineering Research Center, Newton-Wellesley Hospital, Harvard Medical School, Newton, Massachusetts
| | - Yun Peng
- Department of Orthopaedic Surgery, Orthopaedic Bioengineering Research Center, Newton-Wellesley Hospital, Harvard Medical School, Newton, Massachusetts
| | - Chaochao Zhou
- Department of Orthopaedic Surgery, Orthopaedic Bioengineering Research Center, Newton-Wellesley Hospital, Harvard Medical School, Newton, Massachusetts.,Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
| | - Zhongmin Jin
- Tribology Research Institute, School of Mechanical Engineering, Southwest Jiaotong University, Chengdu, Sichuan, China.,Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK
| | - Hany Bedair
- Department of Orthopaedic Surgery, Orthopaedic Bioengineering Research Center, Newton-Wellesley Hospital, Harvard Medical School, Newton, Massachusetts.,Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
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6
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Al-Saffar AA, Evans SL. Effect of gap outside contact area on lubrication of metal-on-Metal total hip replacement. Comput Methods Biomech Biomed Engin 2020; 23:675-689. [PMID: 32396392 DOI: 10.1080/10255842.2020.1758679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Ball-in-socket metal on metal (MOM) contacts were analysed using the Abaqus Finite Element package to simulate dry contact between the acetabular cup and the femoral head. Different cup thicknesses of 4, 6, 8, and 10 mm were considered using a polyurethane foam block support system. Elastohydrodynamic lubrication (EHL) analyses were developed for the contacts using three different approaches to specify the contact. These were (i) A simple model based on the radii of relative curvature, (ii) An equivalent contact model developed so that its dry contact area and maximum pressure replicated the values obtained from the FE analysis, and (iii) A modified version of (ii) that also ensured equivalence of the gap shape outside the contact area. Published in vivo information for the hip joint contact forces over the walking cycle was used to specify the operating conditions for the EHL analysis. The analysis method was found to be effective for all points of the walking cycle for cases where the cup thickness exceeded 5 mm and modelling approach (ii) was identified as satisfactory. For a cup thickness of 4 mm, membrane action began to emerge in the FE analyses so that such contacts behaved in a different way.
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Affiliation(s)
- Ali A Al-Saffar
- Department of Mechanical Engineering, Faculty of Engineering, University of Kufa, Kufa, Iraq
| | - Sam L Evans
- School of Engineering, University of Cardiff, Cardiff, UK
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Influence of the Acetabular Cup Material on the Shell Deformation and Strain Distribution in the Adjacent Bone-A Finite Element Analysis. MATERIALS 2020; 13:ma13061372. [PMID: 32197478 PMCID: PMC7142599 DOI: 10.3390/ma13061372] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 03/06/2020] [Accepted: 03/13/2020] [Indexed: 12/22/2022]
Abstract
In total hip arthroplasty, excessive acetabular cup deformations and altered strain distribution in the adjacent bone are potential risk factors for implant loosening. Materials with reduced stiffness might alter the strain distribution less, whereas shell and liner deformations might increase. The purpose of our current computational study was to evaluate whether carbon fiber-reinforced poly-ether-ether-ketones with a Young´s modulus of 15 GPa (CFR-PEEK-15) and 23 GPa (CFR-PEEK-23) might be an alternative shell material compared to titanium in terms of shell and liner deformation, as well as strain distribution in the adjacent bone. Using a finite element analysis, the press-fit implantation of modular acetabular cups with shells made of titanium, CFR-PEEK-15 and CFR-PEEK-23 in a human hemi-pelvis model was simulated. Liners made of ceramic and polyethylene were simulated. Radial shell and liner deformations as well as strain distributions were analyzed. The shells made of CFR-PEEK-15 were deformed most (266.7 µm), followed by CFR-PEEK-23 (136.5 µm) and titanium (54.0 µm). Subsequently, the ceramic liners were radially deformed by up to 4.4 µm and the polyethylene liners up to 184.7 µm. The shell materials slightly influenced the strain distribution in the adjacent bone with CFR-PEEK, resulting in less strain in critical regions (<400 µm/m or >3000 µm/m) and more strain in bone building or sustaining regions (400 to 3000 µm/m), while the liner material only had a minor impact. The superior biomechanical properties of the acetabular shells made of CFR-PEEK could not be determined in our present study.
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Beckmann NA, Bitsch RG, Bormann T, Braun S, Jaeger S. Titanium Acetabular Component Deformation under Cyclic Loading. MATERIALS 2019; 13:ma13010052. [PMID: 31861893 PMCID: PMC6981461 DOI: 10.3390/ma13010052] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 12/15/2019] [Accepted: 12/17/2019] [Indexed: 12/30/2022]
Abstract
Acetabular cup deformation may affect liner/cup congruency, clearance and/or osseointegration. It is unclear, whether deformation of the acetabular components occurs during load and to what extent. To evaluate this, revision multi-hole cups were implanted into six cadaver hemipelvises in two scenarios: without acetabular defect (ND); with a large acetabular defect (LD) that was treated with an augment. In the LD scenario, the cup and augment were attached to the bone and each other with screws. Subsequently, the implanted hemipelvises were loaded under a physiologic partial-weight-bearing modality. The deformation of the acetabular components was determined using a best-fit algorithm. The statistical evaluation involved repeated-measures ANOVA. The mean elastic distension of the ND cup was 292.9 µm (SD 12.2 µm); in the LD scenario, 43.7 µm (SD 11.2 µm); the mean maximal augment distension was 79.6 µm (SD 21.6 µm). A significant difference between the maximal distension of the cups in both scenarios was noted (F(1, 10) = 11.404; p = 0.007). No significant difference was noted between the compression of the ND and LD cups, nor between LD cups and LD augments. The LD cup displayed significantly lower elastic distension than the ND cup, most likely due to increased stiffness from the affixed augment and screw fixation.
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Affiliation(s)
- Nicholas A. Beckmann
- Clinic for Orthopedics and Trauma Surgery, Heidelberg University Hospital, Heidelberg University, 69118 Heidelberg, Germany
- Department of Orthopaedic Surgery and Traumatology, Inselspital, Bern University Hospital, 3010 Bern, Switzerland
- Correspondence: or
| | - Rudi G. Bitsch
- National Joint Center, ATOS Clinics, 69115 Heidelberg, Germany;
| | - Theresa Bormann
- Laboratory of Biomechanics and Implant Research, Clinic for Orthopedics and Trauma Surgery, Heidelberg University Hospital, Heidelberg University, 69118 Heidelberg, Germany; (T.B.); (S.B.); (S.J.)
| | - Steffen Braun
- Laboratory of Biomechanics and Implant Research, Clinic for Orthopedics and Trauma Surgery, Heidelberg University Hospital, Heidelberg University, 69118 Heidelberg, Germany; (T.B.); (S.B.); (S.J.)
| | - Sebastian Jaeger
- Laboratory of Biomechanics and Implant Research, Clinic for Orthopedics and Trauma Surgery, Heidelberg University Hospital, Heidelberg University, 69118 Heidelberg, Germany; (T.B.); (S.B.); (S.J.)
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9
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Doyle R, van Arkel RJ, Jeffers JRT. Effect of impaction energy on dynamic bone strains, fixation strength, and seating of cementless acetabular cups. J Orthop Res 2019; 37:2367-2375. [PMID: 31317554 PMCID: PMC6851739 DOI: 10.1002/jor.24418] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 07/02/2019] [Indexed: 02/04/2023]
Abstract
Seating a cementless acetabular cup via impaction is a balancing act; good cup fixation must be obtained to ensure adequate bone in-growth and cup apposition, while acetabular fracture must be avoided. Good impaction technique is essential to the success of hip arthroplasty. Yet little guidance exists in the literature to inform surgeons on "how hard" to hit. A drop rig and synthetic bone model were used to vary the energy of impaction strikes in low and high-density synthetic bone, while key parameters such as dynamic strain (quantifying fracture risk), implant fixation, and polar gap were measured. For high energy impaction (15 J) in low-density synthetic bone, a peak tensile strain was observed during impaction that was up to 3.4× as large as post-strike strain, indicating a high fracture risk. Diminishing returns were observed for pushout fixation with increasing energy. Eighty-five percent of the pushout fixation achieved using a 15 J impaction strike was attained by using a 7.5 J strike energy. Similarly, polar gap was only minimally reduced at high impaction energies. Therefore it is suggested that higher energy strikes increase fracture risk, but do not offer large improvements to fixation or implant-bone apposition. It may difficult be for surgeons to accurately deliver specific impaction energies, suggesting there is scope for operative tools to manage implant seating. © 2019 The Authors. Journal of Orthopaedic Research® published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 37:2367-2375, 2019.
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Affiliation(s)
- Ruben Doyle
- Department of Mechanical EngineeringImperial College LondonLondonSW7 2AZUnited Kingdom
| | - Richard J. van Arkel
- Department of Mechanical EngineeringImperial College LondonLondonSW7 2AZUnited Kingdom
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10
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Messer-Hannemann P, Campbell GM, Morlock MM. Deformation of acetabular press-fit cups: Influence of design and surgical factors. Clin Biomech (Bristol, Avon) 2019; 69:96-103. [PMID: 31325804 DOI: 10.1016/j.clinbiomech.2019.07.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 07/11/2019] [Accepted: 07/11/2019] [Indexed: 02/07/2023]
Abstract
BACKGROUND Deformation of acetabular cups when press-fitted into an undersized cavity is inevitable due to the inhomogeneous stiffness of acetabular bone. Thinner cups or screw holes might increase the risk of high cup deformation. The aim of this study was to examine the influence of cup design and liner assembly on the deformation response during cup implantation. METHODS Acetabular cups with different designs were implanted into polyurethane foam models simulating the anatomical situation with nominal press-fits of 1mm and without nominal press-fits (line-to-line). Deformations were determined using a tactile coordinate measuring machine. A 3D laser scanner was used to determine the contact conditions at the cup-cavity interface. Polyethylene and ceramic liners were assembled to the implanted cups and the influence of the insertion on the deformation response evaluated. Fixation strength of the cups was determined by push-out testing. FINDINGS Cup deformation increased with smaller wall thickness (P < 0.037) and screw holes (P < 0.001). Insertion of ceramic liners reduced the deformation (P < 0.001), whereas polyethylene liners adapted to the deformation of the implanted cups (P > 0.999). Thin-walled cups exhibited a higher fixation strength for similar implantation forces (P = 0.011). INTERPRETATION Thin-walled cups achieved higher fixation strengths and might be more bone-preserving. However, in combination with screw holes and high press-fit levels, wall thickness should be considered carefully to avoid excessive cup deformations leading to potential complications during liner assembly. Line-to-line insertion of thin-walled cups should be accompanied with a rough surface coating to minimize the loss of fixation strength due to the low press-fit fixation.
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Affiliation(s)
| | - Graeme M Campbell
- Institute of Biomechanics, Hamburg University of Technology, Hamburg, Germany
| | - Michael M Morlock
- Institute of Biomechanics, Hamburg University of Technology, Hamburg, Germany
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11
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Jahnke A, Bott CC, Fonseca Ulloa CA, Jahnke GW, Rickert M, Ishaque BA, Ahmed GA. In vitro examination of the primary stability of three press-fit acetabular cups under consideration of two different bearing couples. Med Eng Phys 2019; 67:49-54. [PMID: 30902521 DOI: 10.1016/j.medengphy.2019.03.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 01/09/2019] [Accepted: 03/10/2019] [Indexed: 12/21/2022]
Abstract
BACKROUND For preclinical statements about the anchoring behavior of prostheses, the primary stability of the prosthesis is of special importance. It was the aim of this study to examine and compare the relevant relative micromotions of three different acetabulum prostheses by introducing three-dimensional torques. METHODS The cups were implanted under standard conditions into an anatomical artificial bone model. Three-dimensional torques were applied to the acetabular cups. Taking into account the resulting frictional moments of two different bearing couples, ceramic-on-ceramic and ceramic-on-polyethylene, the relative micromotions of the cups were recorded as maximum total micromotion, translational and rotational micromotion, and the primary stability values of the three cups were compared. RESULTS Relative micromotion of all cup models was always significantly smaller with the CoC bearing couples than with the CoP bearing couples (p < 0.001). The rotational micromotion was always lower (p < 0.001) than the translational micromotion, and the rotational as well as the translational micromotions were each always lower than the maximum total micromotion (p < 0.001, p < 0.010). The thinnest-walled cup system always showed the largest relative micromotions. CONCLUSION The results of our study can be interpreted as indicating that the low relative micromotions of all cups - irrespective of the use of CoC or CoP bearing couples - are within an acceptable range favoring secondary osseointegration of the implants. Furthermore, we were able to show that the cup wall thickness and the surface quality of the cup systems have an influence on the primary stability and the elastic deformability of the examined cup systems.
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Affiliation(s)
- Alexander Jahnke
- Laboratory of Biomechanics, Justus-Liebig-University Giessen, Klinikstrasse 29, 35392 Giessen, Germany.
| | - Catharina Chiara Bott
- Laboratory of Biomechanics, Justus-Liebig-University Giessen, Klinikstrasse 29, 35392 Giessen, Germany
| | | | - Gerhard Walter Jahnke
- Laboratory of Biomechanics, Justus-Liebig-University Giessen, Klinikstrasse 29, 35392 Giessen, Germany
| | - Markus Rickert
- Laboratory of Biomechanics, Justus-Liebig-University Giessen, Klinikstrasse 29, 35392 Giessen, Germany; Department of Orthopaedics and Orthopaedic Surgery, University Hospital Giessen and Marburg (UKGM), Klinikstrasse 33, 35392 Giessen, Germany
| | - Bernd Alexander Ishaque
- Laboratory of Biomechanics, Justus-Liebig-University Giessen, Klinikstrasse 29, 35392 Giessen, Germany; Department of Orthopaedics and Orthopaedic Surgery, University Hospital Giessen and Marburg (UKGM), Klinikstrasse 33, 35392 Giessen, Germany
| | - Gafar Adam Ahmed
- Laboratory of Biomechanics, Justus-Liebig-University Giessen, Klinikstrasse 29, 35392 Giessen, Germany; Department of Orthopaedics and Orthopaedic Surgery, University Hospital Giessen and Marburg (UKGM), Klinikstrasse 33, 35392 Giessen, Germany
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Jahnke A, Schroeder S, Fonseca Ulloa CA, Ahmed GA, Ishaque BA, Rickert M. Effect of bearing friction torques on the primary stability of press-fit acetabular cups: A novel in vitro method. J Orthop Res 2018; 36:2745-2753. [PMID: 29744927 DOI: 10.1002/jor.24041] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 04/27/2018] [Indexed: 02/04/2023]
Abstract
Aseptic loosening is the main reason for revision of total hip arthroplasty, and relative micromotions between cementless acetabular cups and bone play an important role regarding their comparatively high loosening rate. Therefore, the aim of the present study was to analyze the influence of resulting frictional torques on the primary stability of press-fit acetabular cups subjected to two different bearing partners. A cementless press-fit cup was implanted in bone-like foam. Primary stability of the cup was analyzed by determining spatial total, translational, and rotational interface micromotions by means of an eddy current sensor measuring system. Torque transmission into the cup was realized by three synchronous servomotors considering resultant friction torques based on constant friction for ceramic-on-ceramic (CoC: μ = 0.044; max. resultant torque: 1.5 Nm) and for ceramic-on-polyethylene (CoP: μ = 0.063; max. resultant torque: 1.9 Nm) bearing partners. Rotational micromotion of CoC was 8.99 ± 0.85 µm and of CoP 13.39 ± 1.43 µm. Translational micromotion of CoC was 29.93 ± 1.44 μm and of CoP 39.91 ± 2.25 μm. Maximum total relative micromotions were 37.10 ± 1.07 μm for CoC and 51.64 ± 2.18 μm for CoP. Micromotions resulting from CoC were statistically lower than those resulting from CoP (p < 0.05). The described 3D-measuring set-up offers a novel in vitro method of measuring primary stability of acetabular cups. We can therefore conclude, that primary stability of acetabular cup systems can be observed using either the lower friction curve (CoC) or the higher friction curve (CoP). In future studies different cup designs or cup fixation mechanisms may be tested and compared in vitro and assessed prior to implantation. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2745-2753, 2018.
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Affiliation(s)
- Alexander Jahnke
- Laboratory of Biomechanics, Justus-Liebig-University Giessen, Klinikstrasse 29, 35392, Giessen, Germany
| | - Stefan Schroeder
- Laboratory of Biomechanics, Justus-Liebig-University Giessen, Klinikstrasse 29, 35392, Giessen, Germany
| | - Carlos A Fonseca Ulloa
- Laboratory of Biomechanics, Justus-Liebig-University Giessen, Klinikstrasse 29, 35392, Giessen, Germany
| | - Gafar A Ahmed
- Laboratory of Biomechanics, Justus-Liebig-University Giessen, Klinikstrasse 29, 35392, Giessen, Germany.,Department of Orthopaedics and Orthopaedic Surgery, University Hospital Giessen and Marburg (UKGM), Klinikstrasse 33, 35392, Giessen, Germany
| | - Bernd A Ishaque
- Laboratory of Biomechanics, Justus-Liebig-University Giessen, Klinikstrasse 29, 35392, Giessen, Germany.,Department of Orthopaedics and Orthopaedic Surgery, University Hospital Giessen and Marburg (UKGM), Klinikstrasse 33, 35392, Giessen, Germany
| | - Markus Rickert
- Laboratory of Biomechanics, Justus-Liebig-University Giessen, Klinikstrasse 29, 35392, Giessen, Germany.,Department of Orthopaedics and Orthopaedic Surgery, University Hospital Giessen and Marburg (UKGM), Klinikstrasse 33, 35392, Giessen, Germany
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Vogel D, Schulze C, Dempwolf H, Kluess D, Bader R. Biomechanical behavior of modular acetabular cups made of poly-ether-ether-ketone: A finite element study. Proc Inst Mech Eng H 2018; 232:1030-1038. [DOI: 10.1177/0954411918797600] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
After total hip arthroplasty, stress-shielding is a potential risk factor for aseptic loosening of acetabular cups made of metals. This might be avoided by the use of acetabular cups made of implant materials with lower stiffness. The purpose of this numerical study was to determine whether a modular acetabular cup with a shell made of poly-ether-ether-ketone or poly-ether-ether-ketone reinforced with carbon fibers might be an alternative to conventional metallic shells. Therefore, the press-fit implantation of modular cups with shells made of different materials (Ti6Al4V, poly-ether-ether-ketone, and poly-ether-ether-ketone reinforced with carbon fibers) and varying liner materials (ceramics and ultra-high-molecular-weight polyethylene) into an artificial bone cavity was simulated using finite element analysis. The shell material had a major impact on the radial shell deformation determined at the rim of the shell, ranging from 17.9 µm for titanium over 92.2 µm for poly-ether-ether-ketone reinforced with carbon fibers up to 475.9 µm for poly-ether-ether-ketone. Larger radial liner deformations (up to 618.4 µm) occurred in combination with the shells made of poly-ether-ether-ketone compared to titanium and poly-ether-ether-ketone reinforced with carbon fibers. Hence, it can be stated that conventional poly-ether-ether-ketone is not a suitable shell material for modular acetabular cups. However, the radial shell deformation can be reduced if the poly-ether-ether-ketone reinforced with carbon fiber material is used, while deformation of ceramic liners is similar to the deformation in combination with titanium shells.
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Affiliation(s)
- Danny Vogel
- Department of Orthopaedics, Biomechanics and Implant Technology Research Laboratory, University of Rostock, Rostock, Germany
| | - Christian Schulze
- Department of Orthopaedics, Biomechanics and Implant Technology Research Laboratory, University of Rostock, Rostock, Germany
| | - Henry Dempwolf
- Department of Orthopaedics, Biomechanics and Implant Technology Research Laboratory, University of Rostock, Rostock, Germany
| | - Daniel Kluess
- Department of Orthopaedics, Biomechanics and Implant Technology Research Laboratory, University of Rostock, Rostock, Germany
| | - Rainer Bader
- Department of Orthopaedics, Biomechanics and Implant Technology Research Laboratory, University of Rostock, Rostock, Germany
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Small SR, Meding JB, Oja JW, Lakstins KS, Gehron DJ, Rogge RD, Buckley CA. Shell design and reaming technique affect deformation in mobile-bearing total hip arthroplasty acetabular components. Proc Inst Mech Eng H 2017; 231:691-698. [DOI: 10.1177/0954411917701952] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Press-fit acetabular components are susceptible to rim deformation. The inherent variability within acetabular reaming techniques may generate increased press-fit and, subsequently, additional component deformation. The purpose of this study was to analyze the insertion and deformation characteristics of acetabular components designed for dual-mobility systems based on component design, size, and reaming technique. Shell deformation was quantified in a validated worst-case scenario foam pinch model. Thin-walled, one-piece, and modular dual-mobility shells of varying size were implanted in under- and over-reamed cavities with insertion force measured and shell deformation assessed using digital image correlation. Increased shell size resulted in larger rim deformation in one-piece components, with a reduction in press-fit by 1 mm resulting in up to 48% reduction in insertion forces and between 23% and 51% reduction in shell deformation. Lower insertion forces and deformations were observed in modular components. Variability in acetabular reaming plays a significant role in the ease of implantation and component deformation in total hip arthroplasty. Modular components are less susceptible to deformation than thin-walled monoblock shells. Care should be taken to avoid excessive under-reaming, particularly in the scenario of large shell size and high-density patient bone stock.
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Affiliation(s)
| | | | - Jordan W Oja
- Department of Biology & Biomedical Engineering, Rose-Hulman Institute of Technology, Terre Haute, IN, USA
| | - Katherine S Lakstins
- Department of Biology & Biomedical Engineering, Rose-Hulman Institute of Technology, Terre Haute, IN, USA
| | - Danielle J Gehron
- Department of Biology & Biomedical Engineering, Rose-Hulman Institute of Technology, Terre Haute, IN, USA
| | - Renee D Rogge
- Department of Biology & Biomedical Engineering, Rose-Hulman Institute of Technology, Terre Haute, IN, USA
| | - Christine A Buckley
- Department of Biology & Biomedical Engineering, Rose-Hulman Institute of Technology, Terre Haute, IN, USA
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Panjeton GD, Kim SE, Chang K, Palm LS, Ifju PG. Deformation of the Zurich cementless acetabular cup caused by implantation in a canine cadaver model. Vet Surg 2017; 46:441-447. [PMID: 28198543 DOI: 10.1111/vsu.12629] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 11/16/2016] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To evaluate the change in geometry of the Zurich total hip arthroplasty (THA) acetabular component after implantation. ANIMALS Hemipelves from adult mix-breed dogs weighing between 20 and 25 kg. METHODS Digital image correlation imaging was performed prior to, immediately after, and 24 hours after impaction of Zurich THA acetabular component, and after removal of the cup from the specimen. Patterns of deformation were qualitatively described, and maximal deformations were compared between time points. RESULTS All cups deformed after implantation into the hemipelves by "pinching" in a cranial-caudal direction and dorsoventral expansion, resulting in an ellipsoid configuration to the peripheral rim. The mean ± SD maximum deformation at the rim immediately post-impaction was 0.202 ± 0.052 mm, or approximately 0.4 mm of diametrical deformation. Deformation did not change after the 24-hour saline bath. Impaction and subsequent extraction had a marginal effect on the original cup geometry, as maximum deformation at the rim after cup extraction was 0.074 ± 0.032 mm, relative to prior to impaction. CONCLUSIONS The original Zurich cup geometry is distorted as a consequence of the press-fit mechanism. Further studies are required to determine whether deformation induced by impaction has any association with polyethylene wear rates or other prosthesis-related complications.
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Affiliation(s)
- Geoffrey D Panjeton
- Comparative Orthopedics Biomechanics Laboratory, University of Florida, Gainesville, Florida
| | - Stanley E Kim
- Comparative Orthopedics Biomechanics Laboratory, University of Florida, Gainesville, Florida
| | - Kelvin Chang
- Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, Florida
| | - Lindsey S Palm
- Comparative Orthopedics Biomechanics Laboratory, University of Florida, Gainesville, Florida
| | - Peter G Ifju
- Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, Florida
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Tensor-resolved Raman spectroscopic analysis of wear-induced residual stress fields in long-term alumina hip-joint retrievals. J Mech Behav Biomed Mater 2017; 66:201-210. [DOI: 10.1016/j.jmbbm.2016.11.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 11/14/2016] [Accepted: 11/16/2016] [Indexed: 12/28/2022]
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Highly cross-linked polyethylene in hip resurfacing arthroplasty: long-term follow-up. Hip Int 2015; 25:39-43. [PMID: 25362872 DOI: 10.5301/hipint.5000190] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/01/2014] [Indexed: 02/04/2023]
Abstract
Highly cross-linked polyethylene (XLPE) has improved wear properties. This study reports the results of a small series of patients treated over 10 years ago with a metal-on-XLPE hip resurfacing.A total of 21 hips in 20 patients received a hip resurfacing with a cobalt-chromium metal femoral head and metal-backed acetabular cup lined with a XLPE insert and were retrospectively studied. Kaplan-Meier Survivorship was calculated.Five patients who had initial extreme cystic disease in the femoral head failed due to femoral loosening. Survivorship was 95.2% at 5 years and 81.0% at 10 years.We found that XLPE wear was not implicated in these failures, which were primarily attributed to poor bone quality of the femoral head, early bone preparation, cementing technique and excessive head reaming to near the neck diameter, necessitated for the implantation of a thick two-part socket.
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Qiu C, Wang L, Li D, Jin Z. The influence of metallic shell deformation on the contact mechanics of a ceramic-on-ceramic total hip arthroplasty. Proc Inst Mech Eng H 2015; 230:4-12. [PMID: 26511269 DOI: 10.1177/0954411915614514] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2015] [Accepted: 09/14/2015] [Indexed: 11/17/2022]
Abstract
Total hip arthroplasty of ceramic-on-ceramic bearing combinations is increasingly used clinically. The majority of these implants are used with cementless fixation that a metal-backing shell is press-fitted into the pelvic bone. This usually results in the deformation of the metallic shell, which may also influence the ceramic liner deformation and consequently the contact mechanics between the liner and the femoral head under loading. The explicit dynamic finite element method was applied to model the implantation of a cementless ceramic-on-ceramic with a titanium shell and subsequently to investigate the effect of the metallic shell deformation on the contact mechanics. A total of three impacts were found to be necessary to seat the titanium alloy shell into the pelvic bone cavity with a 1 mm diameter interference and a 1.3 kg impactor at 4500 mm s(-1) velocity. The maximum deformation of the metallic shell was found to be 160 µm in the antero-superior and postero-inferior direction and 97 µm in the antero-inferior and postero-superior direction after the press-fit. The corresponding values were slightly reduced to 67 and 45 µm after the ceramic liner was inserted and then modified to 74 and 43 µm under loading, respectively. The maximum deformation and the maximum principal stress of the ceramic liner were 31 µm and 144 MPa (tensile stress), respectively, after it was inserted into the shell and further increased to 52 µm and 245 MPa under loading. This research highlights the importance of the press-fit of the metallic shell on the contact mechanics of the ceramic liner for ceramic-on-ceramic total hip arthroplasties and potential clinical performances.
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Affiliation(s)
- Changdong Qiu
- State Key Laboratory for Manufacturing Systems Engineering, School of Mechanical Engineering, Xi'an Jiaotong University, Xi'an, China
| | - Ling Wang
- State Key Laboratory for Manufacturing Systems Engineering, School of Mechanical Engineering, Xi'an Jiaotong University, Xi'an, China
| | - Dichen Li
- State Key Laboratory for Manufacturing Systems Engineering, School of Mechanical Engineering, Xi'an Jiaotong University, Xi'an, China
| | - Zhongmin Jin
- State Key Laboratory for Manufacturing Systems Engineering, School of Mechanical Engineering, Xi'an Jiaotong University, Xi'an, China Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK
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In-vivo degradation of middle-term highly cross-linked and remelted polyethylene cups: Modification induced by creep, wear and oxidation. J Mech Behav Biomed Mater 2015. [PMID: 26202469 DOI: 10.1016/j.jmbbm.2015.06.028] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In this study Raman (RS) and Fourier Transform Infrared (FT-IR) spectroscopic techniques were exploited to study 11 retrieved liners made of remelted highly cross-linked polyethylene (HXLPE), with the intent to elucidate their in-vivo mechanical and chemical degradation. The retrievals had different follow-ups, ranging from a few months to 7 years of implantation time and belong to the first generation of highly cross-linked and remelted polyethylene clinically introduced in 1999, but still currently implanted. Raman assessments enabled to discriminate contributes of wear and creep on the total reduction of thickness in different locations of the cup. According to our results, although the most of the viscoelastic deformation occurred during the first year (bedding-in period), it progressed during the steady wear state up to 7 years with much lower but not negligible rate. Overall, the wear rate of this remelted HXLPE liner was low. Preliminary analysis on microtomed sections of the liners after in-vivo and in-vitro accelerated aging (ASTM F2003-02) enabled to obtain a phenomenological correlation between the oxidation index (OI) and the amount of orthorhombic phase fraction (αc), which can be easily non-destructively measured by RS. Profiles of αc obtained from different locations of the cups were used to judge the oxidative degradation of the 11 retrievals, considering also the ex-vivo time elapsed from the revision surgery to the spectroscopic experiments. Low but measurable level of oxidation was detected in all the short-term retrievals, while in the middle-term samples peaks of OI were observed in the subsurface (up to OI=4.5), presumably induced by the combined effect of mechanical stress, lipid absorption and prolonged ex-vivo shelf-aging in air.
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20
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Liu F, Fisher J, Jin Z. Effect of motion inputs on the wear prediction of artificial hip joints. TRIBOLOGY INTERNATIONAL 2013; 63:105-114. [PMID: 25540472 PMCID: PMC4270454 DOI: 10.1016/j.triboint.2012.05.029] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Revised: 05/04/2012] [Accepted: 05/30/2012] [Indexed: 06/04/2023]
Abstract
Hip joint simulators have been largely used to assess the wear performance of joint implants. Due to the complexity of joint movement, the motion mechanism adopted in simulators varies. The motion condition is particularly important for ultra-high molecular weight polyethylene (UHMWPE) since polyethylene wear can be substantially increased by the bearing cross-shear motion. Computational wear modelling has been improved recently for the conventional UHMWPE used in total hip joint replacements. A new polyethylene wear law is an explicit function of the contact area of the bearing and the sliding distance, and the effect of multidirectional motion on wear has been quantified by a factor, cross-shear ratio. In this study, the full simulated walking cycle condition based on a walking measurement and two simplified motions, including the ISO standard motion and a simplified ProSim hip simulator motion, were considered as the inputs for wear modelling based on the improved wear model. Both the full simulation and simplified motions generated the comparable multidirectional motion required to reproduce the physiological wear of the bearing in vivo. The predicted volumetric wear of the ProSim simulator motion and the ISO motion conditions for the walking cycle were 13% and 4% lower, respectively, than that of the measured walking condition. The maximum linear wear depths were almost the same, and the areas of the wear depth distribution were 13% and 7% lower for the ProSim simulator and the ISO condition, respectively, compared with that of the measured walking cycle motion condition.
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Affiliation(s)
- Feng Liu
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds LS2 9JT, UK
| | - John Fisher
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds LS2 9JT, UK
| | - Zhongmin Jin
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds LS2 9JT, UK
- School of Mechanical Engineering, Xi'an Jiaotong University, PR China
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21
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The influence of head diameter and wall thickness on deformations of metallic acetabular press-fit cups and UHMWPE liners: a finite element analysis. J Orthop Sci 2013; 18:264-70. [PMID: 23377753 DOI: 10.1007/s00776-012-0340-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Accepted: 11/14/2012] [Indexed: 02/09/2023]
Abstract
BACKGROUND To increase the range of motion of total hip endoprostheses, prosthetic heads need to be enlarged, which implies that the cup and/or liner thickness must decrease. This may have negative effects on the wear rate, because the acetabular cups and liners could deform during press-fit implantation and hip joint loading. We compared the metal cup and polyethylene liner deformations that occurred when different wall thicknesses were used in order to evaluate the resulting changes in the clearance of the articulating region. METHODS A parametric finite element model utilized three cup and liner wall thicknesses to analyze cup and liner deformations after press-fit implantation into the pelvic bone. The resultant hip joint force during heel strike was applied while the femur was fixed, accounting for physiological muscle forces. The deformation behavior of the liner under joint loading was therefore assessed as a function of the head diameter and the resulting clearance. RESULTS Press-fit implantation showed diametral cup deformations of 0.096, 0.034, and 0.014 mm for cup wall thicknesses of 3, 5, and 7 mm, respectively. The largest deformations (average 0.084 ± 0.003 mm) of liners with thicknesses of 4, 6, and 8 mm occurred with the smallest cup wall thickness (3 mm). The smallest liner deformation (0.011 mm) was obtained with largest cup and liner wall thicknesses. Under joint loading, liner deformations in thin-walled acetabular cups (3 mm) reduced the initial clearance by about 50 %. CONCLUSION Acetabular press-fit cups with wall thicknesses of ≤5 mm should only be used in combination with polyethylene liners >6 mm thick in order to minimize the reduction in clearance.
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Meding JB, Small SR, Jones ME, Berend ME, Ritter MA. Acetabular cup design influences deformational response in total hip arthroplasty. Clin Orthop Relat Res 2013; 471:403-9. [PMID: 22948528 PMCID: PMC3549190 DOI: 10.1007/s11999-012-2553-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND Press-fit acetabular components are susceptible to deformation in an underreamed socket, with excessive deformation of metal-on-metal (MOM) components potentially leading to increased torsional friction and micromotion. Specifically, however, it remains unclear how cup diameter, design, and time from implantation affect shell deformation. QUESTIONS/PURPOSES We asked whether (1) changes in component geometry and material altered maximum shell deformation and (2) time-dependent deformational relaxation processes occurred. METHODS Diametral deformation was quantified after press-fit implantation of metal shells into a previously validated polyurethane model. Experimental groups (n = 6-8) consisted of 48-, 54-, 60-, and 66-mm MOM cups of 6-mm wall thickness, 58-mm cups of 10-mm wall thickness, and CoCrMo and Ti6Al4V 58-mm modular cups. RESULTS Greater cup diameter, thinner wall construction, and Ti6Al4V modular designs generated conditions for maximum shell deformation ranging from 0.047 to 0.267 mm. Relaxation (18%-32%) was observed 120 hours postimplantation in thin-walled and modular designs. CONCLUSIONS Our findings demonstrate a reduction of shell deformation over time and suggest, under physiologic loading, early component deformation varies with design. CLINICAL RELEVANCE Component deformation should be a design consideration regardless of bearing surface. Designs neglecting to adequately address deformational changes in vivo could be susceptible to diminished cup survival, increased wear, and premature revision.
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Affiliation(s)
- John B. Meding
- Joint Replacement Surgeons of Indiana Foundation, Inc, 1199 Hadley Road, Mooresville, IN 46158 USA
| | - Scott R. Small
- Joint Replacement Surgeons of Indiana Foundation, Inc, 1199 Hadley Road, Mooresville, IN 46158 USA
| | - Mary E. Jones
- Department of Applied Biology and Biomedical Engineering, Rose-Hulman Institute of Technology, Terre Haute, IN USA
| | - Michael E. Berend
- Joint Replacement Surgeons of Indiana Foundation, Inc, 1199 Hadley Road, Mooresville, IN 46158 USA
| | - Merrill A. Ritter
- Joint Replacement Surgeons of Indiana Foundation, Inc, 1199 Hadley Road, Mooresville, IN 46158 USA
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Hothi HS, Busfield JJ, Shelton JC. Deformation of uncemented metal acetabular cups following impaction: experimental and finite element study. Comput Methods Biomech Biomed Engin 2012; 17:1261-74. [DOI: 10.1080/10255842.2012.744397] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Musib M, Jones J, Chakote K, Hayes W, Saha S. Microhardness of bi-antibiotic-eluting bone cement scaffolds. Prog Biomater 2012; 1:3. [PMID: 29470667 PMCID: PMC5120661 DOI: 10.1186/2194-0517-1-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Accepted: 09/20/2012] [Indexed: 01/11/2023] Open
Abstract
Bi-antibiotic-impregnated bone cements (BIBCs) are widely used in orthopaedics as a prophylactic agent (depot) to address post-surgical infections. Although hardness is widely considered a viable index to measure the integrity of the cement structure, there are few specific studies involving changes in hardness characteristics of BIBCs post elution of high doses of two widely used antibiotics: tobramycin and gentamicin. Increased doses of antibiotics and increased duration of elution may also decrease the hardness of polymethyl methacrylate (PMMA) bone cement, thus increasing the chances of shattering, scratching, and deformation. In this project, we have investigated the changes in surface hardness of five different antibiotic-loaded specimens: 0.5 g tobramycin and 0.5 g gentamicin together, 1 g tobramycin, 1 g gentamicin, 5 g tobramycin and 5 g gentamicin together, and 10 g tobramycin (each added to 40 g of PMMA), post elution for various time periods (1, 3, and 21 days). The effect of hydration on the hardness of bone cement was studied to replicate in vivo conditions. The micro-indentation tester (Buehler m5103) was utilized to determine if the increased antibiotic loads would compromise the integrity of the bone cement matrix. The results demonstrated that the amount of drug initially incorporated determined the hardness of the cement post elution. As compared to the control (no antibiotic), specimens containing 1 and 10 g of antibiotic exhibited over 50% and 73% decrease in hardness, respectively. The different treatment durations (post 1 day) as well as the hydration conditions had insignificant effect on the hardness of the cement.
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Affiliation(s)
- Mrinal Musib
- Department of Orthopaedic Surgery and Rehabilitation Medicine, SUNY Downstate Medical Center, Brooklyn, NY, 11203, USA
| | - Jeremy Jones
- Department of Orthopaedic Surgery and Rehabilitation Medicine, SUNY Downstate Medical Center, Brooklyn, NY, 11203, USA
| | - Karunesh Chakote
- Department of Orthopaedic Surgery and Rehabilitation Medicine, SUNY Downstate Medical Center, Brooklyn, NY, 11203, USA
| | - Westley Hayes
- Department of Orthopaedic Surgery and Rehabilitation Medicine, SUNY Downstate Medical Center, Brooklyn, NY, 11203, USA
| | - Subrata Saha
- Department of Orthopaedic Surgery and Rehabilitation Medicine, SUNY Downstate Medical Center, Brooklyn, NY, 11203, USA.
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Derivation of Clinically Relevant Boundary Conditions Suitable for Evaluation of Chronic Impingement of Lumbar Total Disk Replacement: Application to Standard Development. ACTA ACUST UNITED AC 2011. [DOI: 10.1520/jai103556] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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26
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Liu F, Galvin A, Jin Z, Fisher J. A New Formulation for the Prediction of Polyethylene Wear in Artificial Hip Joints. Proc Inst Mech Eng H 2010; 225:16-24. [DOI: 10.1243/09544119jeim819] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Artificial joints employing ultra-high molecular weight polyethylene (UHMWPE) are widely used to treat joint diseases and trauma. Wear of the polymer bearing surface largely limits the use of these joints in younger and more active patients. Previous studies have shown the wear factor used in Archard's law for the conventional polyethylene to be highly dependent on contact pressure and this has produced variability in experimental data and has constrained the reliability and applicability of previous computational predictions. A new wear law is proposed, based on wear volume being dependent on, and proportional to, the product of the sliding distance and contact area. The dimensionless proportional constant, wear coefficient, which was independent of contact pressure, was determined from a multi-directional pin on plate study. This was used in computational predictions of the wear of the conventional UHMWPE hip joints. The wear of the polyethylene cup was independently experimentally determined in physiological full hip joint simulator studies. The predicted wear rate from the new computational model was generally increased, with an improved agreement with the experimental measurement compared with the previous computational model. It was shown that wear in the UHMWPE hip joints increased as head size and contact area increased. This resulted in a much larger increase in the wear rate as the head size increased, compared with the previous computational model, and is consistent with clinical observations. This new understanding of the wear mechanism in artificial joints using the UHMWPE bearing surfaces, and the improved ability to predict wear independently and to address previously described discrepancies offer new opportunities to optimize design parameters.
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Affiliation(s)
- F Liu
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK
| | - A Galvin
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK
| | - Z Jin
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK
| | - J Fisher
- Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, UK
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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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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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