title: Late failure of annealed highly cross-linked polyethylene acetabular liner.
abstract: Highly cross-linked polyethylene (HXPE) in total hip arthroplasty (THA) has been shown to significantly decrease wear rates compared with conventional polyethylene (CPE). However, crosslinking, thermal treatment and oxidation can decrease the mechanical properties of PE, and several cases of fracture of remelted HXPE liners were reported. We present, for the first time, unexpected failures of THA with the use of annealed HXPE liners in two patients occurring at 7 and 8 years after operation. Operative findings revealed dislocated liners from the metal shell and a fracture of the superior rim at the rim-dome junction in both liners. Scanning electron microscopy showed that the cracks initiated at the rim and propagated toward the articular surface. Both liners showed generally a low amount of oxidation (less than 1.00) at the articular surface and low wear rates; however, oxidation at the rim was relatively higher (mean 1.55). These findings suggested that decreased mechanical properties at the rim-dome junction due to cross-linking, annealing and oxidation might have been caused breakage of the HXPE liners after a long implantation time, although the annealed HXPE achieved low degree of wear.
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Hara
authors.forename: Yasuharu
authors.initials: Y
authors.lastname: Nakashima
authors.forename: Takuaki
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Shinshichiro
authors.initials: S
authors.lastname: Higashihara
authors.forename: Mitsugu
authors.initials: M
authors.lastname: Todo
authors.forename: Masanobu
authors.initials: M
authors.lastname: Hirata
authors.forename: Mio
authors.initials: M
authors.lastname: Akiyama
authors.forename: Yukihide
authors.initials: Y
authors.lastname: Iwamoto
mesh_terms: D000077:Acetabulum / Q000000981:diagnostic imaging; D019644:Arthroplasty, Replacement, Hip; D005260:Female; D006801:Humans; D008297:Male; D008422:Materials Testing; D055595:Mechanical Phenomena; D008875:Middle Aged; D010084:Oxidation-Reduction; D020959:Polyethylene / Q000737:chemistry*; D011475:Prosthesis Failure; D011859:Radiography
chemical_list: D020959:Polyethylene
keywords: Annealing; Cross-linked polyethylene; Fracture; Mechanical property; Total hip arthroplasty