An antioxidant stabilized, chemically cross‐linked UHMWPE with superior toughness. Issue 6 (26th December 2018)

• Record Type: Journal Article
• Authors: Oral, Ebru; Wannomae, Keith K.; Bichara, David A.; Micheli, Brad; Doshi, Brinda N.; O'Brien, Caitlin; Nielsen, G. Petur; Muratoglu, Orhun K.
• Is Part Of: Journal of biomedical materials research. Volume 107:Issue 6(2019)
• Page Start: 1945
• Page End: 1952
• Publication Date: 2018-12-26
• Subjects: biocompatibility -- high temperature melting -- large scale peroxide crosslinking; Biomedical materials -- Periodicals; 610.28
• DOI: 10.1002/jbm.b.34287
• Languages: English
• ISSNs: 1552-4973

Abstract

Abstract: Chemical cross‐linking of ultrahigh molecular weight polyethylene (UHMWPE) using an organic peroxide followed by high temperature melting results in a large increase in toughness accompanied by a decrease in cross‐link density, which, surprisingly does not compromise the wear resistance. We compared the mechanical properties and wear behavior of a vitamin E blended, chemically cross‐linked and high temperature melted UHMWPE produced by ram extrusion (PRX HTM) to those measured with the clinically available 100‐kGy irradiated and melted UHMWPE (CISM 100). We also assessed the local biocompatibility of PRX‐HTM in rabbit subcutaneous pouch and osteochondral defect models. The ultimate tensile strength and pin‐on‐disc wear rate were similar to CISM 100; whereas the elongation‐at‐break and impact toughness were much higher with PRX‐HTM. The stress intensity factor range at crack inception was also higher with PRX‐HTM. Accelerated aging did not result in any measurable oxidation or changes in mechanical properties. Hip simulator wear rate of acetabular liners made with PRX‐HTM was 0.3 ± 0.4 mg/million‐cycle, similar to that reported for CISM 100 liners. The wear particles were largely spherical with a number‐averaged particle size of 0.95 μm with ~75% of particles below 1 μm. The subcutaneous and osteochondral rabbit implantations showed no histological differences between PRX‐HTM and the control CISM 100. Pre‐clinical wear, mechanical, and biocompatibility testing of PRX HTM showed feasibility for the use of this material as a total joint arthroplasty implant bearing surface. This process has the potential of eliminating the additional step of radiation cross‐linking by combining consolidation and cross‐linking while improving toughness. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1945–1952, 2019.