Can ultrastructural particle location predict aseptic loosening? A biopsy study of nonloose hip implants one year...

To find predisposing parameters for aseptic loosening the present study determined the ultrastructural morphology in the pseudosynovial membrane from non-loose hip arthroplasties to compare the intra- and extracellular distribution of wear particles one year after total hip replacement using three different bearing material combinations.A total of 37 patients from a larger prospective randomised trial of 225 patients had biopsies taken arthroscopically from the pseudosynovial membrane one year after insertion of identical endoprostheses except for the bearing materials, polyethylene-on-zirconia (n=15), alumina-on-alumina (n=13), and CoCr-CoCr (n=9), respectively. The granulomatous inflammation seen in biopsies from these well-fixated implants was qualitatively comparable to the pattern seen in aseptic loose implants. Wear particles were seen in the extracellular matrix and intracellularily in macrophages, fibroblasts, and in endothelial cells. It was not possible systematically to distinguish the morphology between the three groups, though in one patient with CoCr-CoCr bearing material necrotic tissue was seen and exclusively extracellular location was not found in this group. The transport mechanism may vary with these materials and particle number. At this initial stage after hip surgery, the present study did not provide evidence for different types of bearing materials having significant impact on ultrastructural morphology adjacent to hip arthroplasties within the first year after surgery.