title: Comparison of 10-year clinical wear of annealed and remelted highly cross-linked polyethylene: A propensity-matched cohort study.
abstract: No previous studies comparing the clinical wear rates of the two different kinds of cross-linked ultra-high-molecular-weight polyethylene (XLPE), annealed and remelted, are available. We compared the creep and steady wear rates of 36 matched pairs (72 hips in total) adjusting for baseline characteristics with propensity score matching techniques. Zirconia femoral heads with 26-mm diameter were used in all cases. The femoral-head cup penetration was measured digitally on radiographs. Significantly greater creep (p=0.006) was detected in the remelted (0.234mm) than annealed (0.159mm) XLPE. However, no significant difference (p=0.19) was found between the steady wear rates (0.003 and 0.008mm/year, respectively) of the annealed and remelted XLPE. Multiple regression analyses showed that remelted XLPE is significant independent variable (p<0.001) that is positively associated with creep. However, the patient age and body weight, cup size, the liner thickness, cup inclination, follow-up periods, and postoperative Merle d'Aubigné hip score had no significant effects (p>0.05) on the steady wear rates. No patients exhibited above the osteolysis threshold of 0.1mm/year, progressive radiolucencies, osteolysis, or polyethylene fracture. This　propensity-matched cohort study document no significant difference in wear resistant performances of annealed and remelted XLPE over an average period of 10 years.
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan; Department of Artificial Joints and Biomaterials, Faculty of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Hamai
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan. Electronic address: yasunaka@ortho.med.kyushu-u.ac.jp.
authors.forename: Yasuharu
authors.initials: Y
authors.lastname: Nakashima
authors.affiliation: Department of Bone and Joint Surgery, Graduate School of Medicine, Ehime University, Shitsukawa, Toon, Ehime 791-0295, Japan.
authors.forename: Naohiko
authors.initials: N
authors.lastname: Mashima
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
authors.forename: Takuaki
authors.initials: T
authors.lastname: Yamamoto
authors.affiliation: Department of Bone and Joint Surgery, Graduate School of Medicine, Ehime University, Shitsukawa, Toon, Ehime 791-0295, Japan.
authors.forename: Tomomi
authors.initials: T
authors.lastname: Kamada
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
authors.forename: Goro
authors.initials: G
authors.lastname: Motomura
authors.affiliation: Department of Bone and Joint Surgery, Graduate School of Medicine, Ehime University, Shitsukawa, Toon, Ehime 791-0295, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Imai
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
authors.forename: Jun-Ichi
authors.initials: JI
authors.lastname: Fukushi
authors.affiliation: Department of Bone and Joint Surgery, Graduate School of Medicine, Ehime University, Shitsukawa, Toon, Ehime 791-0295, Japan.
authors.forename: Hiromasa
authors.initials: H
authors.lastname: Miura
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
authors.forename: Yukihide
authors.initials: Y
authors.lastname: Iwamoto
mesh_terms: D019644:Arthroplasty, Replacement, Hip; D015331:Cohort Studies; D006622:Hip Prosthesis; D006801:Humans; D010014:Osteolysis; D020959:Polyethylene / Q000032:analysis*; D011474:Prosthesis Design; D011475:Prosthesis Failure
chemical_list: D020959:Polyethylene
keywords: Anneal; Cross-linked; Polyethylene; Remelt; Total hip arthroplasty; Wear