Histological features of the interface membrane of failed isoelastic cementless prostheses.

The interface membranes of both components from two isoelastic cementless hip arthroplasties, which were revised for aseptic loosening, were examined histologically. The membranes consisted of densely structured fibrous tissue interspersed with giant cell granulomas, sheets of histiocytes and chronic inflammatory infiltrates. The granulomas and the histiocytes contained polymeric and metallic wear products, respectively. The morphological features of these membranes were compared with those of cemented joint replacements. Apart from the deposits of acrylic cement bordered by macrophages, there were no distinctive differences between the membranes of failed cementless and cemented arthroplasties. The release and deposition of wear products, of whatever nature, are apparently responsible for the formation of exuberant interface membranes.