title: Migration stability of alpha-tocopherol in irradiated UHMWPE.
abstract: The oxidation resistance of irradiated ultra-high molecular weight polyethylene (UHMWPE) components used in total joint arthroplasty can be improved by adding alpha-tocopherol (vitamin E) through diffusion. To ensure long-term oxidative stability, a minimum alpha-tocopherol concentration needs to be maintained throughout these components. Migration of alpha-tocopherol out of the components is one mechanism that could compromise long-term oxidative stability. We hypothesized that alpha-tocopherol could elute out during standard implant fabrication steps such as cleaning as well as during in vivo use. We doped 85 kGy irradiated UHMWPE with alpha-tocopherol at 120 degrees C and homogenized at 120 degrees C. We determined the extent of elution of alpha-tocopherol or its effect on oxidative stability following cleaning in isopropyl alcohol (IPA) and following 5 million cycles (MC) of simulated normal gait in bovine serum. There was no significant elution of alpha-tocopherol in repeated and prolonged cleaning in IPA as measured by average surface and bulk alpha-tocopherol concentrations. There was no change in the oxidative stability following 5 MC of hip simulator testing, indicating minimal elution during simulated normal gait.
authors.affiliation: Orthopaedic Biomechanics and Biomaterials Laboratory, Department of Orthopaedic Surgery, Massachusetts General Hospital, 55 Fruit Street, GRJ 1206, Boston, MA 02114, USA.
authors.forename: Ebru
authors.initials: E
authors.lastname: Oral
authors.forename: Keith K
authors.initials: KK
authors.lastname: Wannomae
authors.forename: Shannon L
authors.initials: SL
authors.lastname: Rowell
authors.forename: Orhun Kamil
authors.initials: OK
authors.lastname: Muratoglu
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D002417:Cattle; D004355:Drug Stability; D006801:Humans; D066298:In Vitro Techniques; D007595:Joint Prosthesis; D008422:Materials Testing; D010084:Oxidation-Reduction; D011095:Polyethylenes / Q000528:radiation effects*; D017550:Spectroscopy, Fourier Transform Infrared; D024502:alpha-Tocopherol / Q000008:administration & dosage* / Q000493:pharmacokinetics
chemical_list: D001672:Biocompatible Materials; D011095:Polyethylenes; C111601:ultra-high molecular weight polyethylene; D024502:alpha-Tocopherol