title: Relation between vertical orientation and stability of acetabular component in the dysplastic hip simulated by nonlinear three-dimensional finite element method.
abstract: In acetabular dysplasia, more vertical orientation of the acetabular component is often used to minimize the superolateral bone grafting. This study was designed to determine the effects of vertical orientation of the cup on the stability and polyethylene wear of the acetabular component in uncemented total hip arthroplasty (THA). Three-dimensional finite element models of the hemipelvis with dysplastic acetabulum were developed. Metal-backed hemispherical cups were placed in the true acetabulum with abduction angles of 35, 45, 55, and 65 degrees. It was found that more vertical orientation of the cup was associated with larger relative motion of the metal shell between the acetabulum and metal shell. Furthermore, tilting and torsional shear stresses in the model of the cup abduction angle of 65 degrees were found to be 1.7 times larger than that in the model with 35 degrees at the bone-metal shell interface. More vertically oriented cups caused larger contact stresses at the articulating surfaces of the polyethylene liners. The results suggest that the abduction angle of the acetabular component significantly influences cup loosening and polyethylene wear in THA.
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Medicine, University of Fukui, Matsuoka, Fukui, Japan. SEIKEI68@fmsrsa.fukui-med.ac.jp
authors.forename: Hisashi
authors.initials: H
authors.lastname: Oki
authors.forename: Masao
authors.initials: M
authors.lastname: Ando
authors.forename: Hironori
authors.initials: H
authors.lastname: Omori
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Okumura
authors.forename: Kohei
authors.initials: K
authors.lastname: Negoro
authors.forename: Kenzo
authors.initials: K
authors.lastname: Uchida
authors.forename: Hisatoshi
authors.initials: H
authors.lastname: Baba
mesh_terms: D000077:Acetabulum / Q000000981:diagnostic imaging / Q000601:surgery*; D019644:Arthroplasty, Replacement, Hip; D020099:Coated Materials, Biocompatible; D005260:Female; D020342:Finite Element Analysis; D006618:Hip Dislocation, Congenital / Q000000981:diagnostic imaging / Q000601:surgery*; D006622:Hip Prosthesis; D006801:Humans; D021621:Imaging, Three-Dimensional; D008954:Models, Biological; D011095:Polyethylenes; D011474:Prosthesis Design; D011859:Radiography; D013314:Stress, Mechanical
chemical_list: D020099:Coated Materials, Biocompatible; D011095:Polyethylenes