Investigation of wear of knee prostheses in a new displacement/force-controlled simulator

Barnett, P.I.; McEwen, H.M.J.; Auger, D D; Stone, Martin; Ingham, Eileen; Fisher, John

doi:10.1243/0954411021536289

Cited by 55 publications

(56 citation statements)

References 13 publications

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“…The central axis of the two implant 'total knees' was offset from the aligned axes of applied load and tibial rotation from the centre of the joint by 7 per cent of its width, in accordance with ISO 14243-1, to replicate a right knee. In order to eliminate station specific differences the UKRs were moved around the stations every million cycles [33].…”

Section: Methodsmentioning

confidence: 99%

The wear of fixed and mobile bearing unicompartmental knee replacements

Brockett

Jennings

Fisher

2011

Proc Inst Mech Eng H

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Unicompartmental knee replacements (UKR) are an option for surgical intervention for the treatment of single-compartment osteoarthritis. The aim of this study was to compare the wear of a low-conformity fixed-bearing UKR with a conforming mobile bearing UKR under two kinematic conditions, to investigate the effect of implant design and kinematics on wear performance in a physiological knee wear simulator. Under both sets of kinematic conditions, the relatively low-conforming fixed UKR showed lower wear, compared with the more conforming anterior-posterior sliding mobile bearing. However, it should be noted that differences in materials between the two designs also contribute to the relative wear performance of the bearings. The combined wear of the medial and lateral bearings of the fixed-bearing UKR as a 'total knee' were significantly reduced compared with a fixed-bearing total knee replacement studied under the same kinematic conditions.

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Section: Methodsmentioning

confidence: 99%

The wear of fixed and mobile bearing unicompartmental knee replacements

Brockett

Jennings

Fisher

2011

Proc Inst Mech Eng H

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“…Simple geometry multidirectional pin-on-plate studies [13] were used to investigate the fundamental material wear properties as a function of cross shear and contact area/ pressure. Knee simulator studies [4] were used to investigate the effect of the two different design configurations, rotating platform mobile-bearing knees with small amplitude tangential curvilinear (rotation) motion on the lower tibial surface with zero cross shear and reduced cross shear on the upper femoral surface, and low conformity fixed-bearing knees with reduced surface area, on surface wear.…”

Section: Methodsmentioning

confidence: 99%

“…Over 1 billion cycles of testing have been completed and published in the last decade in both pin-on-plate and knee simulator studies, providing a robust platform for standardized comparison of both materials and designs. Knee simulator studies were undertaken on the Prosim knee simulator (Simulation Solutions, Manchester, UK) [4,11,12,22]. Two sets of tests were carried out: (1) comparison of fixed-bearing PFC sigma knee to the PFC sigma rotating platform knee (DePuy International) and (2) comparison of sigma fixed-bearing knee with low conforming fixed-bearing knee, where the curved tibial insert was replaced by a flat polymer insert.…”

Section: Methodsmentioning

confidence: 99%

“…It is important to differentiate the delamination wear mechanisms, which produce fatigue failure [6,19], from the surface wear mechanisms, which produce submicron-and nanometer-sized wear particles and result in long-term osteolysis [16,17,24]. Surface wear leading to the potential of osteolysis is considered the longer-term risk factor, particularly since increased kinematics with more active patients substantially increases wear rates and the total wear volume in fixed-bearing knees [4,22].…”

Section: Introductionmentioning

confidence: 99%

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2009 Knee Society Presidential Guest Lecture: Polyethylene Wear in Total Knees

Fisher

Jennings

Galvin

et al. 2010

Clinical Orthopaedics &Amp; Related Research

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Knee arthroplasties in young and active patients place a substantial increase in the lifetime tribological demand and potential for wear-induced osteolysis. Polyethylene materials have advanced in recent years, reducing the potential for oxidative degradation and delamination failure. It is timely to consider tribological design variables and their potential to reduce surface wear and the long-term risk of osteolysis. The influence of reduced cross shear in rotating platform mobile-bearing knee designs and reduced surface wear area in low conforming fixed-bearing knees has been investigated. A reduction in cross shear substantially reduced wear in both multidirectional pin-on-plate studies and in rotating platform mobile-bearing designs in knee simulator studies. A reduction in bearing surface contact area substantially reduced surface wear in multidirectional pin-on-plate simulations and in low conforming fixed-bearing knee designs in knee simulator studies. This offers potential for a paradigm shift in knee design predicated by enhanced mechanical properties of new polymer materials. We describe two distinct low-wearing tribological design solutions: (1) a rotating platform design solution with reduced cross shear provides reduced wear with conformity and intrinsic stability; and (2) a low conformity fixed bearing with reduced surface area, provides reduced wear, but has less intrinsic stability and requires good soft tissue function.

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“…Ultrahigh molecular weight polyethylene (UHMWPE) wear can result in osteolysis [1], so considerable effort is invested in wear testing (e.g. material tests [2,3] and implant tests [4,5]). The tribology of UHMWPE is not fully understood, so a purely theoretical approach is not possible.…”

Section: Introductionmentioning

confidence: 99%

Targeted computational probabilistic corroboration of experimental knee wear simulator: The importance of accounting for variability

Strickland

Dressler

Render

et al. 2011

Medical Engineering & Physics

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Experimental testing is widely used to predict wear of total knee replacement (TKR) devices.Computational models cannot replace this essential in-vitro testing, but they do have complementary strengths and capabilities, which make in-silico models a valuable support tool for experimental wear investigations. For effective exploitation, these two separate domains should be closely corroborated together; this requires extensive data-sharing and cross-checking at every stage of simulation and testing.However, isolated deterministic corroborations provide only a partial perspective; in-vitro testing is inherently variable, and relatively small changes in the environmental and kinematic conditions at the articulating interface can account for considerable variation in the reported wear rates. Understanding these variations will be key to managing uncertainty in the tests, resulting in a 'cleaner' investigation environment for further refining current theories of wear.This study demonstrates the value of probabilistic in-silico methods by describing a specific, targeted corroboration of the AMTI knee wear simulator, using rigid body dynamics software models. A deterministic model of the simulator under displacement-control was created for investigation. Firstly, a large sample of experimental data (N>100) was collated, and a probabilistic computational study (N>1000 trials) was used to compare the kinematic performance envelopes for in-vitro and in-silico models, to more fully corroborate the mechanical model. Secondly, corresponding theoretical wear-rate predictions were compared to the experimentally reported wear data, to assess the robustness of current wear theories to uncertainty (as distinct from the mechanical variability).The results reveal a good corroboration for the physical mechanics of the wear test rig; however they demonstrate that the distributions for wear are not currently well-predicted. The probabilistic domain is found to be far more sensitive at distinguishing between different wear theories. As such we recommend that in future, researchers move towards probabilistic studies as a preferred framework for investigations into implant wear.

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Investigation of wear of knee prostheses in a new displacement/force-controlled simulator

Cited by 55 publications

References 13 publications

The wear of fixed and mobile bearing unicompartmental knee replacements

The wear of fixed and mobile bearing unicompartmental knee replacements

2009 Knee Society Presidential Guest Lecture: Polyethylene Wear in Total Knees

Targeted computational probabilistic corroboration of experimental knee wear simulator: The importance of accounting for variability

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