Radiation and chemical crosslinking promote strain hardening behavior and molecular alignment in ultra high molecular weight polyethylene during multi-axial loading conditions

Kurtz, Steven M.; Pruitt, Lisa A.; Jewett, Charles W.; Foulds, J.R.; Edidin, Avram A.

doi:10.1016/s0142-9612(99)00038-1

Cited by 96 publications

(55 citation statements)

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“…Cross-linking is known to reduce the large-strain deformation ability of UHMWPE limiting the ultimate chain stretch [21]. Likely ultimate chain stretch reached a saturation level with increasing cross-link density.…”

Section: Discussionmentioning

confidence: 99%

Mechanisms of decrease in fatigue crack propagation resistance in irradiated and melted UHMWPE

2006

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Adhesive/abrasive wear in ultra-high molecular weight polyethylene (UHMWPE) has been minimized by radiation cross-linking. Irradiation is typically followed by melting to eliminate residual free radicals that cause oxidative embrittlement. Irradiation and subsequent melting reduce the strength and fatigue resistance of the polymer. We determined the radiation dose dependence and decoupled the effects of post-irradiation melting on the crystallinity, mechanical properties and fatigue crack propagation resistance of room temperature irradiated UHMWPE from those of irradiation alone. Stiffness and yield strength, were largely not affected by increasing radiation dose but were affected by changes in crystallinity, whereas plastic properties, ultimate tensile strength and elongation at break, were dominated at different radiation dose ranges by changes in radiation dose or crystallinity. Fatigue crack propagation resistance was shown to decrease with increase in radiation dose and with decrease in crystalline content. Morphology of fracture surfaces revealed loss of ductility with increase in radiation dose and more detrimental effects on ductility at lower radiation doses after post-irradiation melting.

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Section: Discussionmentioning

confidence: 99%

Mechanisms of decrease in fatigue crack propagation resistance in irradiated and melted UHMWPE

2006

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“…Research in other laboratories [43][44][45][46][47] has documented the improvements in wear properties and the changes in physical properties of polymers that have been cross linked as a part of the material processing or sterilization process. In addition, research on the same equipment used for the current study with the same protocols 48 -50 has shown that the cross-linked polyethylenes may exhibit wear properties that yield gravimetric weight losses very similar to those for the metal-on-metal samples.…”

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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“…More work is currently being performed to assess surface structure and local material properties. Most notable is the work by Pruitt, Kurtz, and Edidin [22][23][24][25][26] which has focused on surface morphological changes (orientation of surface crystals during wear), and on local material property changes in UHMWPE and on nanoindentation behavior. 27 The molecular alignment and increased strain hardening observed in these studies is supported by the present study.…”

Section: Discussionmentioning

confidence: 99%

Surface micromechanics of ultrahigh molecular weight polyethylene: Microindentation testing, crosslinking, and material behavior

Gilbert

Cumber

Butterfield

2002

J. Biomed. Mater. Res.

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The wear behavior of ultrahigh molecular weight polyethylene (UHMWPE) is critical to the success of total joint replacements. Recent attempts to modify the wear behavior of UHMWPE by processing, in particular, crosslinking UHMWPE have shown promise to increase wear resistance, but concerns persist regarding other mechanical properties. It is also unclear what specific surface mechanical properties govern the wear resistance seen in these materials. The goal of this study was to demonstrate a custom-built surface mechanical test system and method that measures the micromechanical response of microtomed UHMWPE surfaces to depth-sensing microindentation tests. The surface structure of these UHMWPE materials was also examined using scanning electron microscopy and atomic force microscopy. A custom designed microindentation test system assessed the microindentation behavior of three UHMWPE resins: 1. Hylamertrade mark, 2. GUR-1020 CMS, and 3. Marathontrade mark-a lightly crosslinked material. The effects of material and indentation depth were studied. Microindentation tests were performed with indentation depths ranging from 2 to 45 microm. Four different measurements of surface micromechanical behavior were obtained including the surface modulus, microhardness, hysteresis energy (irreversible work done to the sample per unit cycle) and its associated energy dissipation factor, and loading slope. Statistically significant differences in each of these parameters were found for each material. Generally, Hylamer had the largest values for these parameters, followed by the GUR resin and then the Marathon. Surface modulus was independent of depth of testing and found to be 651 MPa for Marathon, 738 MPa for GUR, and 1015 MPa for Hylamer (Modulus for bulk UHMWPE is 540 MPa for Hylamer, 620 for GUR, and 1380 for Hylamer). The microhardness varied between 67 and 162 MPa depending on material and depth of testing. Surface structural characterization shows that the microtoming process for surface preparation generated distinct surface features that varied between materials. Intermittent drawn ribbons of polymer with oriented crystals were observed in both scanning electron microscopy and atomic force microscopy. The surface density and size of these features were characteristic of the materials with the Hylamer having the fewest, but largest ribbons, followed by GUR and then Marathon.

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Radiation and chemical crosslinking promote strain hardening behavior and molecular alignment in ultra high molecular weight polyethylene during multi-axial loading conditions

Cited by 96 publications

References 0 publications

Mechanisms of decrease in fatigue crack propagation resistance in irradiated and melted UHMWPE

Mechanisms of decrease in fatigue crack propagation resistance in irradiated and melted UHMWPE

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

Surface micromechanics of ultrahigh molecular weight polyethylene: Microindentation testing, crosslinking, and material behavior

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