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Friday, October 8, 2010, 8:00-8:30Session A10: Bearings and TribologyOxinium*Seyedesmaeil Shafiei - Mazandaran - Sari, IRAN*Email: dr.e.shafiei@gmail.comOXINIUMS.E.ShafieiTotal joint arthroplasty is a safe and effective procedure as an end-stage treatment for arthritis.In the case of hip replacement mean patient age has decreased from sixty-eight to sixty-fiveyears over the past eight years, raising concerns over implant longevity and the complicationsthat occur in association with revision surgery.The dominant mode of failure of total joint replacements is aseptic loosening, which in manycases is caused by the reaction of bone to the presence of implant debris .In an attempt toincrease implant longevity ,bearing surfaces that minimize the volume of debris generated fromthe articular surface are being developed .Ultra- high molecular weight polyethylene , which hasbeen the mainstay of arthroplasty , changing the material with which the polyethylenearticulates has also been addressed in an effort to further improve wear characteristics .Oxinium is the brand family name of a material used for replacement joints manufactured bythe reconstructive orthopedic surgery division of medical devices company Smith& nephew .Itconsists of a Zirconium alley metal substrate that transitions into a ceramic Zirconium oxideouter surface. The ceramic surface is extremely abrasion resistant compared to traditional metalimplants such as cobalt chromium .It also has a lower coefficient of friction against ultra-highmolecular weight polyethylene(UHMWPE) ,The typical counter face material used in total jointreplacements.These two factors likely contribute to the significantly lower UHMWPE wear rates observed insimulator testing.Reducing UHMWPE wear is thought to decrease the risk of implant failure due to osteolysis.All ceramic material can have a similar effect in reducing wear, but are brittle and difficult tomanufacture .The metal substrate of oxinium implants makes component easier to manufactureand gives them greater toughness(a combination of strength and ductility).In essence, thistechnology combines the abrasion resistance and low friction of a ceramic with the workabilityand toughness of a metal.MATERIAL:The oxinium(OxZr) component are produced from a wrought zirconium alley(Zr-2.5%Nb) byprocessing that oxygen naturally diffuses into the Zirconium alley, Oxygen is absorbed into themetal, actually transforming the surface to ceramic that is about um thick while the rest of thematerial remain metal to retain its strength .The result is in a superior bearing surface. Theceramic is an enhanced surface that is part of metal substrate rather than an external coating ,making it very durable with unusual damage tolerance.file:///E|/ISTA2010-Abstracts.htm[12/7/2011 3:15:47 PM]