? The longevity of total hip and knee arthroplasty has been compromised primarily by wear and fatigue failure (delamination) of the polyethylene load-bearing components. In clinical use in total hip arthroplasty since 1998, crosslinking and melting markedly reduces polyethylene wear, but it also reduces its fatigue strength, potentially limiting its use in high stress applications, such as total knee replacements and certain total hip replacements. ? ? We hypothesize that the fatigue-strength loss that occurs with crosslinking and melting is due to reduced plasticity of polyethylene through reduced chain mobility and reduced crystallinity. Crosslinking also lowers the efficiency of energy absorbing mechanisms in the process zone that precedes fatigue cracks. We further hypothesize that the fatigue strength of highly crosslinked polyethylene can be increased by incorporating a plasticizing agent, such as a-tocopherol or very low molecular weight polyethylene, and/ or using methods (other than melting) that do not affect the crystallinity of polyethylene to improve postirradiation oxidative stability. ? ? Our general aim is to improve the fatigue strength of highly crosslinked polyethylene.
Our specific aims are to: 1) Identification of mechanisms that resist fatigue crack propagation and how such mechanisms change with crosslinking and melting; 2) Increasing the fatigue strength of highly crosslinked polyethylene; and 3) Simulated gait and adverse testing of the optimum low-wear, high-fatigue polyethylene formulation. ? ?
|Oral, Ebru; Ghali, Bassem W; Muratoglu, Orhun K (2011) The elimination of free radicals in irradiated UHMWPEs with and without vitamin E stabilization by annealing under pressure. J Biomed Mater Res B Appl Biomater 97:167-74|
|Oral, Ebru; Muratoglu, Orhun K (2011) Vitamin E diffused, highly crosslinked UHMWPE: a review. Int Orthop 35:215-23|
|Bracco, Pierangiola; Oral, Ebru (2011) Vitamin E-stabilized UHMWPE for total joint implants: a review. Clin Orthop Relat Res 469:2286-93|
|Rowell, Shannon L; Oral, Ebru; Muratoglu, Orhun K (2011) Comparative oxidative stability of ?-tocopherol blended and diffused UHMWPEs at 3 years of real-time aging. J Orthop Res 29:773-80|
|Oral, Ebru; Godleski-Beckos, Christine; Ghali, Bassem W et al. (2009) Effect of cross-link density on the high pressure crystallization of UHMWPE. J Biomed Mater Res B Appl Biomater 90:720-9|
|Oral, Ebru; Godleski Beckos, Christine A; Lozynsky, Andrew J et al. (2009) Improved resistance to wear and fatigue fracture in high pressure crystallized vitamin E-containing ultra-high molecular weight polyethylene. Biomaterials 30:1870-80|
|Oral, Ebru; Malhi, Arnaz S; Wannomae, Keith K et al. (2008) Highly cross-linked ultrahigh molecular weight polyethylene with improved fatigue resistance for total joint arthroplasty: recipient of the 2006 Hap Paul Award. J Arthroplasty 23:1037-44|
|Oral, Ebru; Godleski Beckos, Christine; Malhi, Arnaz S et al. (2008) The effects of high dose irradiation on the cross-linking of vitamin E-blended ultrahigh molecular weight polyethylene. Biomaterials 29:3557-60|
|Oral, Ebru; Beckos, Christine Godleski; Muratoglu, Orhun K (2008) FREE RADICAL ELIMINATION IN IRRADIATED UHMWPE THROUGH CRYSTAL MOBILITY IN PHASE TRANSITION TO THE HEXAGONAL PHASE. Polymer (Guildf) 49:4733-4739|
|Oral, Ebru; Wannomae, Keith K; Rowell, Shannon L et al. (2007) Diffusion of vitamin E in ultra-high molecular weight polyethylene. Biomaterials 28:5225-37|
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