May 28, 2015 11:26 Material for Total Joint Arthroplasty 9in x 6in 1st Reading b2135-ch11 page 341 Chapter 11 1 Surface-Oxidized Zirconium Shantanu Patil and Darryl D. D’Lima 2 Shiley Center for Orthopaedic Research & Education, 3 Scripps Health, La Jolla, USA 4 Abstract: Cobalt chrome alloys articulating against ultra-high molecu- 5 lar weight polyethylene are currently the most popular bearing surfaces 6 for total joint arthroplasty. Ceramic materials wear less due to their 7 greater hardness but carry a risk of implant fracture. Zirconium with 8 an oxidized surface layer has the dual advantage of toughness compa- 9 rable to metal components and surface hardness comparable to ceramic 10 components. This chapter reviews the performance of oxidized zirconium 11 as an alternative bearing surface for hip and knee arthroplasty. Results 12 integrating in vitro and clinical studies as well as retrievals are pre- 13 sented. In vitro studies have reported increased surface hardness, reduced 14 polyethylene wear, and low cytotoxicity of particles generated from oxi- 15 dized zirconium. Oxidized zirconium has not been associated with signif- 16 icant material-related adverse events supporting the high safety of this 17 bearing material. However, clinical studies have not yet supported the 18 promise of better clinical performance or longer survival, in part because 19 of the lack of long-term follow-up investigations and in part because of 20 the high survival rates of current-generation cobalt chrome alloy femoral 21 head designs. 22 1. Background 23 Ceramic oxides such as alumina and zirconia have greater wear 24 performance compared to metals and have attributed to higher 25 hardness and enhanced wettability. Niobium (2.5%) when alloyed 26 with zirconium generates a two-phase microstructure that provides 27 the mechanical strength necessary for joint replacement implants. 28 Zirconium and niobium have excellent biocompatibility, which is 29 341