(iv) Enhancing the safety and reliability of joint replacement implants

Jennings, Louise; Al-Hajjar, Mazen; Brockett, Claire; Williams, Sophie; Tipper, Joanne L.; Ingham, Eileen; Fisher, John

doi:10.1016/j.mporth.2012.05.006

Cited by 22 publications

(29 citation statements)

References 43 publications

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“…The test conditions used in this study are expected to represent conforming hip bearing contact leading to idealised two body wear. 6 The wide envelope of conditions in vivo including the variations in surgical positioning of the hip joint implant, prosthetic design, patient activities and conditions 62 – 64 may lead to a wider variation in wear scars to those produced by the standard conditions used in the simulators in this study.…”

Section: Discussionmentioning

confidence: 99%

Influence of hip joint simulator design and mechanics on the wear and creep of metal-on-polyethylene bearings

Ali

Al-Hajjar

Partridge

et al. 2016

Proc Inst Mech Eng H

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Hip joint simulators are used extensively for preclinical testing of hip replacements. The variation in simulator design and test conditions used worldwide can affect the tribological performance of polyethylene. The aim of this study was to assess the effects of simulator mechanics and design on the wear and creep of ultra-high-molecular-weight polyethylene. In the first part of this study, an electromechanical simulator and pneumatic simulator were used to compare the wear and creep of metal-on-polyethylene components under the same standard gait conditions. In the second part of the study, the same electromechanical hip joint simulator was used to investigate the influence of kinematics on wear. Higher wear rates and penetration depths were observed from the electromechanical simulator compared with the pneumatic simulator. When adduction/abduction was introduced to the gait cycle, there was no significant difference in wear with that obtained under the gait cycle condition without adduction/abduction. This study confirmed the influence of hip simulator design and loading conditions on the wear of polyethylene, and therefore direct comparisons of absolute wear rates between different hip joint simulators should be avoided. This study also confirmed that the resulting wear path was the governing factor in obtaining clinically relevant wear rates, and this can be achieved with either two axes or three axes of rotations. However, three axes of rotation (with the inclusion of adduction/abduction) more closely replicate clinical conditions and should therefore be the design approach for newly developed hip joint simulators used for preclinical testing.

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Section: Discussionmentioning

confidence: 99%

Influence of hip joint simulator design and mechanics on the wear and creep of metal-on-polyethylene bearings

Ali

Al-Hajjar

Partridge

et al. 2016

Proc Inst Mech Eng H

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“…The volumetric wear of MoM bearings has been documented as ranging between 0.2 mm 3 /million cycles to 2.5 mm 3 /million cycles [35] . This is notably less than wear rates for metal-on-ultra high molecular weight polyethylene or cross linked polyethylene, documented at 32.8 mm 3 /million cycles and 9 mm 3 /million cycles respectively [36,37] , albeit greater than that of ceramic-on-ceramic (CoC), which ranges between 0.02 and 0.1 mm 3 /million cycles [38] . However, it is not only the volume of wear that is important but also the number, size and shape (aspect ratio) of the wear particles [39] .…”

Section: Problems With Current Metal-on-metal Designsmentioning

confidence: 78%

Metal-On-Metal Hip Arthroplasty – Development and Demise

Hughes

Orthopaedics²,

Chamberlain

et al. 2018

International Journal of Orthopaedics

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Total hip replacement (THR) has been classed as the Orthopedic operation of the century; improving a patient's quality of life by drastically reducing the pain and mobility issues associated with arthritis. As of 2017 890,681 primary hip replacements were recorded in the National Joint Registry [1]. Of these, < 1% were comprised of metal-on-metal (MoM) bearings, a sharp decline from the peak of MoM implants reaching 20 % in 2005 [1]. The first metal total hip replacement was both designed and conducted by Philip Wiles in 1938 using matched femoral heads and acetabular cups of stainless steel bolted to bone. McKee advanced the prototype designs of MoM bearings. Throughout the 1940's and 1950's he introduced the idea of resecting the femoral head, and using dental acrylic cement to fix the stem into the femur [2]. In 1953 Haboush proposed the idea of using polymethylmethacrylate (PMMA) as bone cement. Professor Sir John Charnley, determined to find a self-lubricating bearing, conducted his first hip replacement in the 1950's using polytetrafluorethylene (PTFE), however, failure was observed after two years, due to the accelerated wear of the polymer and adverse tissue reactions. Charnely tried again with High Density Polyethylene however, this too was unsuccessful. In 1961, on his third attempt, Charnley invented what is known today as the low friction arthroplasty, using Ultra High Molecular Weight Polyethylene, one of the most successful techniques in the world [3]. During this time Mc Kee continued to develop and modify the acetabular cup in his cemented MoM THA, and Watson-Farrar designed a stem with smaller neck geometry. The size of the femoral head was also revised, to incorporate a polar bearing, allowing a slight clearance between the two articulating surfaces. These alterations significantly reduced the wear and with only minor alterations, led to the conclusive McKee-Farrar implant as is known today [4]. Peter Ring, in collaboration with the Russians, pioneered cementless MoM bearings. The final Mark III Ring design consisted of a polar bearing and modified, thicker screw threads. It showed unexpectedly good success rates, but was phased out in the early 1970's, due to the effects of the metal particles released [5]. As early as the 1970's literature investigating the tissue from retrieved MoM hip replacements documented necrosis resulting from the CoCr particles found in the acetabular collagen and phagocytic

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“…24 Such variables will include, for example, the surgical positioning of the components and range and type of activities. The improved capability and performance of the second-generation electromechanically driven knee simulators make them ideal to accurately simulate such variations, which may be responsible for the higher failure rate of TKR in younger and more active patients.…”

Section: Discussionmentioning

confidence: 99%

A comparison between electromechanical and pneumatic-controlled knee simulators for the investigation of wear of total knee replacements

Abdelgaied

Fisher

Jennings

2017

Proc Inst Mech Eng H

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More robust preclinical experimental wear simulation methods are required in order to simulate a wider range of activities, observed in different patient populations such as younger more active patients, as well as to fully meet and be capable of going well beyond the existing requirements of the relevant international standards. A new six-station electromechanically driven simulator (Simulation Solutions, UK) with five fully independently controlled axes of articulation for each station, capable of replicating deep knee bending as well as other adverse conditions, which can be operated in either force or displacement control with improved input kinematic following, has been developed to meet these requirements. This study investigated the wear of a fixed-bearing total knee replacement using this electromechanically driven fully independent knee simulator and compared it to previous data from a predominantly pneumatically controlled simulator in which each station was not fully independently controlled. In addition, the kinematic performance and the repeatability of the simulators have been investigated and compared to the international standard requirements. The wear rates from the electromechanical and pneumatic knee simulators were not significantly different, with wear rates of 2.6 ± 0.9 and 2.7 ± 0.9 mm3/million cycles (MC; mean ± 95% confidence interval, p = 0.99) and 5.4 ± 1.4 and 6.7 ± 1.5 mm3/MC (mean ± 95 confidence interval, p = 0.54) from the electromechanical and pneumatic simulators under intermediate levels (maximum 5 mm) and high levels (maximum 10 mm) of anterior–posterior displacements, respectively. However, the output kinematic profiles of the control system, which drive the motion of the simulator, followed the input kinematic profiles more closely on the electromechanical simulator than the pneumatic simulator. In addition, the electromechanical simulator was capable of following kinematic and loading input cycles within the tolerances of the international standard requirements (ISO 14243-3). The new-generation electromechanical knee simulator with fully independent control has the potential to be used for a much wider range of kinematic conditions, including high-flexion and other severe conditions, due to its improved capability and performance in comparison to the previously used pneumatic-controlled simulators.

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(iv) Enhancing the safety and reliability of joint replacement implants

Cited by 22 publications

References 43 publications

Influence of hip joint simulator design and mechanics on the wear and creep of metal-on-polyethylene bearings

Influence of hip joint simulator design and mechanics on the wear and creep of metal-on-polyethylene bearings

Metal-On-Metal Hip Arthroplasty – Development and Demise

A comparison between electromechanical and pneumatic-controlled knee simulators for the investigation of wear of total knee replacements

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