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J Orthop Res. 2017 Jun;35(6):1343-1347. doi: 10.1002/jor.23380. Epub 2016 Aug 19.

High temperature homogenization improves impact toughness of vitamin E-diffused, irradiated UHMWPE.

Author information

1
Harris Orthopaedic Laboratory, Massachusetts General Hospital, 55 Fruit Street, GRJ 1260, Boston, Massachusetts 02114.
2
Department of Orthopaedic Surgery, Harvard Medical School, Boston, Massachusetts.

Abstract

Diffusion of vitamin E into radiation cross-linked ultrahigh molecular weight polyethylene (UHMWPE) is used to increase stability against oxidation of total joint implant components. The dispersion of vitamin E throughout implant preforms has been optimized by a two-step process of doping and homogenization. Both of these steps are performed below the peak melting point of the cross-linked polymer (<140°C) to avoid loss of crystallinity and strength. Recently, it was discovered that the exposure of UHMWPE to elevated temperatures, around 300°C, for a limited amount of time in nitrogen, could improve the toughness without sacrificing wear resistance. We hypothesized that high temperature homogenization of antioxidant-doped, radiation cross-linked UHMWPE could improve its toughness. We found that homogenization at 300°C for 8 h resulted in an increase in the impact toughness (74 kJ/m2 compared to 67 kJ/m2 ), the ultimate tensile strength (50 MPa compared to 43 MPa) and elongation at break (271% compared to 236%). The high temperature treatment did not compromise the wear resistance or the oxidative stability as measured by oxidation induction time. In addition, the desired homogeneity was achieved at a much shorter duration (8 h compared to >240 h) by using high temperature homogenization. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1343-1347, 2017.

KEYWORDS:

antioxidant stabilization; arthroplasty; crosslinking; homogenization; total joint implants

PMID:
27487014
DOI:
10.1002/jor.23380
[Indexed for MEDLINE]
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