title: Differences in the fretting corrosion of metal-metal and ceramic-metal modular junctions of total hip replacements.
abstract: The use of modular interlocking components is a central design feature of total joint replacements. In this investigation we hypothesized that clinically available ceramic-metal modular connections used in total hip arthroplasty release more metal through fretting corrosion than traditional metal-metal modular connections. This was investigated using an in vitro comparison of ceramic (zirconia, ZrO2) and metal (Co-alloy) femoral-head fretting upon Co-alloy stem components. In vitro fretting corrosion testing consisted of potentiodynamic monitoring and analysis of metal release from zirconia and Co-alloy 28 mm femoral heads with similar surface roughnesses (Ra=0.46 microm) on identical Co-alloy stems at 2.2 kN for 1x10(6) cycles at 2 Hz. In contrast to our original hypothesis, we found greater metal release (approximately 11-fold increase in Co and 3-fold increase in Cr) and potentiodynamic fretting of metal-metal modular junctions when compared to ceramic-metal. Potentiodynamic testing demonstrated that lower initial voltages (-266<153 mV), greater maximum voltage changes (116>56 mV, p<0.05, t-test) and voltage variability (3>0.5 mV, p<0.05, t-test) were associated with the open circuit potentials of Co-alloy on Co-alloy junctions when compared to zirconia on Co-alloy junctions. In this study of a single total hip replacement stem and head design, zirconia heads mated with Co-alloy stems produced less fretting than Co-alloy heads mated with Co-alloy stems. Although further studies are necessary with a variety of implant designs and under different experimental conditions, the evidence presented here should, in part, alleviate concerns of increases in fretting corrosion at modular junctions of ceramic-metal coupled components.
authors.affiliation: Department of Orthopedic Surgery, Rush Presbyterian St. Lukes Medical Center, 1653 W Congress Parkway, Chicago, IL 60612, USA. nhallab@rush.edu
authors.forename: Nadim James
authors.initials: NJ
authors.lastname: Hallab
authors.forename: Carlo
authors.initials: C
authors.lastname: Messina
authors.forename: Anastasia
authors.initials: A
authors.lastname: Skipor
authors.forename: Joshua J
authors.initials: JJ
authors.lastname: Jacobs
mesh_terms: D000328:Adult; D002858:Chromium Alloys / Q000032:analysis*; D003343:Corrosion; D004563:Electrochemistry; D005260:Female; D006622:Hip Prosthesis; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008422:Materials Testing; D016876:Metal Ceramic Alloys / Q000032:analysis*; D011474:Prosthesis Design; D013499:Surface Properties
chemical_list: D002858:Chromium Alloys; D016876:Metal Ceramic Alloys