LOSS OF HYDROXYAPATITE COATING ON RETRIEVED, TOTAL HIP COMPONENTS

The goal of this study was to examine the early retrievals of hydroxya patite-(HA) coated hip prostheses to assess evidence of osteoconductiv ity, resorption of HA, and the integrity of the HA/implant bond. Six r etrieved HA-coated hip prostheses (3 femoral hip stems, 3 acetabular c ups) were analyzed for the amount of bone ongrowth or ingrowth of the HA-coated surface and the extent to which the coating was still presen t after in vivo service. The examination of these six HA-coated prosth eses indicates that HA appeared to be osteoconductive. There was evide nce of debonding of HA from the smooth-surfaced femoral prosthesis, al though that may have been a result of the extraction process. The five plasma-spray surfaced, HA-coated prostheses showed evidence of consid erable loss of the HA coating at the time of receipt in the authors' l aboratory, although it is was not possible to determine the cause of t he loss of coating.