title: Testing of silicon nitride ceramic bearings for total hip arthroplasty.
abstract: Modern ceramic bearings used in total hip arthroplasty (THA) consist of a femoral head (ball) articulating inside a hemispherical acetabular cup (socket); the ball and socket are made of alumina (Al(2)O(3)) and Al(2)O(3)-based composite materials. In the present study, total hip bearings were made from a different ceramic material, silicon nitride (Si(3)N(4)), by sintering and hot isostatic pressing of powders. The resulting material had improved mechanical properties over modern Al(2)O(3) THA bearings, with a flexural strength of 920 +/- 70 MPa, a Weibull modulus of 19, and a fracture toughness of 10 +/- 1 MPa m(1/2). Unlike zirconia-based ceramics that have also been used in THA, accelerated aging of Si(3)N(4) did not adversely affect the flexural strength. In simulated wear tests, Si(3)N(4) acetabular cups produced low-volumetric wear whether articulating against Si(3)N(4) or cobalt-chromium (CoCr) femoral heads. The results of this investigation suggest that Si(3)N(4) may allow improved THA bearings that combine the reliability of metal femoral heads with the low wear advantages of ceramic materials.
authors.affiliation: Department of Orthopaedic Surgery, University of Missouri-Columbia, Columbia, Missouri 65211, USA. balb@health.missouri.edu
authors.forename: B Sonny
authors.initials: BS
authors.lastname: Bal
authors.forename: Ashok
authors.initials: A
authors.lastname: Khandkar
authors.forename: R
authors.initials: R
authors.lastname: Lakshminarayanan
authors.forename: Ian
authors.initials: I
authors.lastname: Clarke
authors.forename: Aaron A
authors.initials: AA
authors.lastname: Hoffman
authors.forename: Mohamed N
authors.initials: MN
authors.lastname: Rahaman
mesh_terms: D019643:Arthroplasty, Replacement / Q000295:instrumentation*; D002516:Ceramics; D006622:Hip Prosthesis; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D017655:Silicon Compounds; D013314:Stress, Mechanical; D014961:X-Ray Diffraction
chemical_list: D017655:Silicon Compounds; C032734:silicon nitride