title: In vivo oxidation of retrieved cross-linked ultra-high-molecular-weight polyethylene acetabular components with residual free radicals.
abstract: Wear of ultra-high-molecular-weight polyethylene (UHMWPE) contributes to debris that can lead to periprosthetic osteolysis in total hip arthroplasty. Irradiation not only decreases wear of UHMWPE but also generates residual free radicals that can oxidize the UHMWPE in the long term. Melting or annealing is used to quench the free radicals. Melting is more effective than annealing. We hypothesized that the postirradiation annealed UHMWPE components would oxidize in vivo and that postirradiation melted ones would not. We analyzed surgical explants of UHMWPE acetabular liners. The irradiated and annealed explants showed embrittlement, oxidation, and an increase in crystallinity. The irradiated and melted UHMWPE explants showed no oxidation, no increase in crystallinity, and no embrittlement. To prevent long-term chemical changes in highly cross-linked UHMWPE components, the residual free radicals must be stabilized after irradiation, preferably by melting and not annealing.
authors.affiliation: Orthopaedic Biomechanics and Biomaterials Laboratory, Massachusetts General Hospital, Boston, MA 02114, USA.
authors.forename: Keith K
authors.initials: KK
authors.lastname: Wannomae
authors.forename: Shayan
authors.initials: S
authors.lastname: Bhattacharyya
authors.forename: Andrew
authors.initials: A
authors.lastname: Freiberg
authors.forename: Daniel
authors.initials: D
authors.lastname: Estok
authors.forename: William H
authors.initials: WH
authors.lastname: Harris
authors.forename: Orhun
authors.initials: O
authors.lastname: Muratoglu
mesh_terms: D000077:Acetabulum; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation*; D005609:Free Radicals; D006622:Hip Prosthesis; D006801:Humans; D010014:Osteolysis / Q000209:etiology; D010084:Oxidation-Reduction; D020959:Polyethylene / Q000737:chemistry / Q000528:radiation effects; D011183:Postoperative Complications; D011475:Prosthesis Failure
chemical_list: D005609:Free Radicals; D020959:Polyethylene