title: Understanding the differences between the wear of metal-on-metal and ceramic-on-metal total hip replacements.
abstract: Hip simulator studies have been carried out extensively to understand and test artificial hip implants in vitro as an efficient alternative to obtaining long-term results in vivo. Recent studies have shown that a ceramic-on-metal material combination lowers the wear by up to 100 times in comparison with a typical metal-on-metal design. The reason for this reduction remains unclear and for this reason this study has undertaken simple tribometer tests to understand the fundamental material loss mechanisms in two material combinations: metal-on-metal and ceramic-on-ceramic. A simple-configuration reciprocating pin-on-plate wear study was performed under open-circuit potential (OCP) and with applied cathodic protection (CP) in a serum solution using two tribological couples: firstly, cobalt-chromium (Co-Cr) pins against Co-Cr plates; secondly, Co-Cr pins against alumina (Al2O3) plates. The pin and plate surfaces prior to and after testing were examined by profilometry and scanning electron microscopy. The results showed a marked reduction in wear when CP was applied, indicating that total material degradation under the OCP condition was attributed to corrosion processes. The substitution of the Co-Cr pin with an Al2O3 plate also resulted in a dramatic reduction in wear, probably due to the reduction in the corrosion-wear interactions between the tribological pair.
authors.affiliation: Departamento de Engenharia Mecânica, EST Setúbal, Instituto Politecnico de Setúbal, Estefanilha, Setúbal, Portugal.
authors.forename: C G
authors.initials: CG
authors.lastname: Figueiredo-Pina
authors.forename: Y
authors.initials: Y
authors.lastname: Yan
authors.forename: A
authors.initials: A
authors.lastname: Neville
authors.forename: J
authors.initials: J
authors.lastname: Fisher
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry* / Q000627:therapeutic use; D019644:Arthroplasty, Replacement, Hip; D002516:Ceramics / Q000737:chemistry / Q000627:therapeutic use; D002858:Chromium Alloys / Q000737:chemistry* / Q000627:therapeutic use; D020099:Coated Materials, Biocompatible / Q000737:chemistry / Q000627:therapeutic use; D003035:Cobalt / Q000737:chemistry / Q000627:therapeutic use; D003343:Corrosion; D017276:Friction; D006622:Hip Prosthesis / Q000009:adverse effects; D006801:Humans; D008422:Materials Testing / Q000295:instrumentation* / Q000379:methods; D008961:Models, Structural; D010014:Osteolysis / Q000209:etiology / Q000517:prevention & control; D011475:Prosthesis Failure; D013499:Surface Properties
chemical_list: D002858:Chromium Alloys; D020099:Coated Materials, Biocompatible; D003035:Cobalt; D000537:Aluminum Oxide