title: Comparison of surface characteristics of retrieved cobalt-chromium femoral heads with and without ion implantation.
abstract: Nitrogen ion implantation of CoCr is reported to produce increased surface hardness and a lower friction surface. Femoral heads with and without ion implantation retrieved from 1997 to 2003 were evaluated for surface roughness (average surface roughness [Ra], mean peak height [Rpm], and maximum distance from peak to valley [Rmax]), nanohardness, and the ion-treated layer thickness. The difference in average Rmax (P = .033) and average Rpm (P = .008) was statistically significant, but there was no correlation between the average or maximum roughness parameters (average surface roughness, Rmax, and Rpm) and time in vivo (P > .05). Overall, nanohardness was greater for the low-friction ion-treated heads (P < .001); and it decreased with increasing time in vivo (P = .01). Ion treatment produces an increased surface hardness, but the advantage of this increased hardness appears to dissipate over time in vivo.
authors.affiliation: Maine Joint Replacement Institute, Portland, Maine, USA.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: McGrory
authors.forename: James M
authors.initials: JM
authors.lastname: Ruterbories
authors.forename: Vivek D
authors.initials: VD
authors.lastname: Pawar
authors.forename: Reginald K
authors.initials: RK
authors.lastname: Thomas
authors.forename: Abraham B
authors.initials: AB
authors.lastname: Salehi
mesh_terms: D002857:Chromium; D003035:Cobalt; D005260:Female; D005270:Femur Head; D006245:Hardness Tests; D006622:Hip Prosthesis; D006801:Humans; D007477:Ions; D008297:Male; D008422:Materials Testing; D009584:Nitrogen; D011474:Prosthesis Design; D013499:Surface Properties
chemical_list: D007477:Ions; D002857:Chromium; D003035:Cobalt; D009584:Nitrogen