Influence of simulator kinematics on the wear of metal-on-metal hip prostheses

Firkins, P; Tipper, Joanne L.; Ingham, Eileen; Stone, Martin; Farrar, R.; Fisher, John

doi:10.1243/0954411011533481

Cited by 57 publications

(29 citation statements)

References 5 publications

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“…15,21 Analysis of the wear paths produced by different simulators has shown a wide variation, ranging from simple linear paths with infinite aspect ratios to open circular paths with low aspect ratios. 22 The potential importance of variations in individual THA patient's wear paths on wear rates has recently been recognized, with altered gait cycle inputs used to predict wear rate in a finite element model.…”

Section: Discussionmentioning

confidence: 99%

The influence of wear paths produced by hip replacement patients during normal walking on wear rates

Bennett¹,

Humphreys²,

O’Brien³

et al. 2008

Journal Orthopaedic Research

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Variation in wear paths is known to greatly affect wear rates in vitro, with multidirectional paths producing much greater wear than unidirectional paths. This study investigated the relationship between multidirectional motion at the hip joint, as measured by aspect ratio, sliding distance, and wear rate for 164 hip replacements. Kinematic input from three-dimensional gait analysis was used to determine the wear paths. Activity cycles were determined for a subgroup of 100 patients using a pedometer study, and the relationship between annual sliding distance and wear rate was analyzed. Poor correlations were found between both aspect ratio and sliding distance and wear rate for the larger group and between annual sliding distance and wear rate for the subgroup. However, patients who experienced a wear rate <0.08 mm/year showed a strong positive correlation between the combination of sliding distance, activity levels, and aspect ratio and wear rate (adjusted r 2 ¼ 55.4%). This group may represent those patients who experience conditions that most closely match those that prevail in simulator and laboratory tests. Although the shape of wear paths, their sliding distance, and the number of articulation cycles at the hip joint affect wear rates in simulator studies, this relationship was not seen in this clinical study. Other factors such as lubrication, loading conditions and roughness of the femoral head may influence the wear rate. ß

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Section: Discussionmentioning

confidence: 99%

The influence of wear paths produced by hip replacement patients during normal walking on wear rates

Bennett¹,

Humphreys²,

O’Brien³

et al. 2008

Journal Orthopaedic Research

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show abstract

“…The weight-loss curve for the GUR 1020 polyethylene is nearly identical to that published by McKellop in 1997 for the same material, 27 confirming that the data being generated is consistent with that being produced in other laboratories. Other published studies of hipsimulator wear of metal-on-metal bearings have reported wear rates two times, 28 four times, 29 and up to nine or ten times 30,31 with the use of metal-on-metal bearing combinations with similar radial clearances but using serum that had been diluted to 25% as a lubricant. One of these studies 30 also involved the use of nearly undiluted (90%) serum with wear rates similar to those of the current research.…”

Section: Discussionmentioning

confidence: 99%

Wear evaluation of cobalt–chromium alloy for use in a metal‐on‐metal hip prosthesis

John

Zardiackas

Poggie³

2003

J Biomed Mater Res

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Wear of the polyethylene in total joint prostheses has been a source of morbidity and early device failure, which has been extensively reported in the last 20 years. Although research continues to attempt to reduce the wear of polyethylene joint-bearing surfaces by modifications in polymer processing, there is a renewed interest in the use of metal-on-metal bearing couples for hip prostheses. Wear testing of total hip replacement systems involving the couple of metal or ceramic heads on polymeric acetabular components has been performed and reported, but, until recently, there has been little data published for pin-on-disk or hip-simulator wear studies involving the combination of a metallic femoral head component with an acetabular cup composed of the same or a dissimilar metal. This study investigated the in vitro wear resistance of two cobalt/chromium/molybdenum alloys, which differed primarily in the carbon content, as potential alloys for use in a metal-on-metal hip-bearing couple. The results of pin-on-disk testing showed that the alloy with the higher (0.25%) carbon content was more wear resistant, and this alloy was therefore chosen for testing in a hip-simulator system, which modeled the loads and motions that might be exerted clinically. Comparison of the results of metal-on-polyethylene samples to metal-on-metal samples showed that the volumetric wear of the metal-on-polyethylene bearing couple after 5,000,000 cycles was 110 -180 times that for the metal-bearing couple. Polyethylene and metal particles retrieved from either the lubricant for pin-on-disk testing or hip simulator testing were characterized and compared with particles retrieved from periprosthetic tissues by other researchers, and found to be similar. Based upon the results of this study, metal-on-metal hip prostheses manufactured from the high carbon cobalt/chromium alloy that was investigated hold sufficient promise to justify human clinical trials.

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“…13,20,21 The particle sizes were typically Ͻ100 nm. Such a wear debris fraction has been generated using the disc-on-pin apparatus.…”

Section: Particlesmentioning

confidence: 99%

Subsurface microstructure of metal‐on‐metal hip joints and its relationship to wear particle generation

et al. 2004

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To control and minimize wear of metal-on-metal hip joints it is essential to understand the mechanisms of debris generation. In vivo, mainly nanosize globular and needle-shaped particles are found. These can neither stem from the action of abrasion nor from tribochemical reactions. In this study the acting wear mechanisms have been first identified on the surface by means of scanning electron microscopy (SEM). Afterwards, the microstructures of the subsurface regions of explants have been investigated using a transmission electron microscope (TEM). Observation of the subsurface gave additional insight about the microstructural changes of cobalt-base alloys subjected to wear. At some distance from the surface, a network of stacking faults and hexagonal ⑀-martensite was found strengthening the bulk material. This microstructure changed into a nanocrystalline type moving closer towards the surface. A comparison of in vivo debris size and grain size of the surface suggests that the globular wear particles result from torn off nanocrystals, while the needle shaped particles are generated by fractured ⑀-martensite. Identified cracks, propagating through the nanocrystalline layer, further support these findings. Thus, it is suggested that the dominating mechanism of particle generation for metal-on-metal joints is surface fatigue within a nanocrystalline surface layer.

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Influence of simulator kinematics on the wear of metal-on-metal hip prostheses

Cited by 57 publications

References 5 publications

The influence of wear paths produced by hip replacement patients during normal walking on wear rates

The influence of wear paths produced by hip replacement patients during normal walking on wear rates

Wear evaluation of cobalt–chromium alloy for use in a metal‐on‐metal hip prosthesis

Subsurface microstructure of metal‐on‐metal hip joints and its relationship to wear particle generation

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