title: Factory-assembled polyethylene linings in metal backing show higher wear rates compared to equisized all-polyethylene sockets.
abstract: Two series of cementless total hip arthroplasty with acetabular sockets of a threaded truncated cone design were compared regarding volumetric wear rates. The first series included all-polyethylene acetabular sockets of the type Endler (E-PE); in the second series, a nonmodular titanium metal-backed polyethylene (E-MB) socket with an identical outer shape to E-PE was implanted. Bearings were articulated with alumina 32-mm diameter ball heads. Ninety-five retrieved devices were examined with a modified fluid displacement method using dental self-polymerizing precision casts. The sockets had to be revised mainly because of wear-induced osteolysis: E-PE after 10.6 years on average and E-MB after 7.8 years (P = .002). Comparison with unused sockets showed mean wear rates of 63 mm(3)/y for E-PE and 120 mm(3)/y for E-MB (P = .0008). Increased contact stress and load deformation due to reduction of polyethylene thickness in E-MB compared to E-PE were identified as predominant reasons for higher wear rates.
authors.affiliation: Department of Orthopedic Surgery, University Hospital of Goettingen, Goettingen, Germany.
authors.forename: Matthias W
authors.initials: MW
authors.lastname: Jentschke
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Schultz
authors.forename: Gottfried H
authors.initials: GH
authors.lastname: Buchhorn
mesh_terms: D000077:Acetabulum / Q000000981:diagnostic imaging / Q000601:surgery; D000328:Adult; D000368:Aged; D000537:Aluminum Oxide; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation*; D020878:Device Removal; D005260:Female; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000601:surgery; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008670:Metals; D008875:Middle Aged; D020959:Polyethylene; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011859:Radiography; D012086:Reoperation
chemical_list: D008670:Metals; D020959:Polyethylene; D000537:Aluminum Oxide