We compared wear particles from two different designs of total hip arthroplasty with polycrystalline alumina-ceramic bearings of different production periods (group 1, before ISO 6474: group 2, according to ISO 6474). The neocapsules and interfacial connective tissue membranes were retrieved after mean implantation times of 131 months and 38 months, respectively. Specimen blocks were freed from embedding media, either methylmethacrylate or paraffin and digested in concentrated nitric acid. Particles were then counted and their sizes and composition determined by SEM and energy-dispersive x-ray analysis (EDXA). The mean numbers and sizes of most alumina wear particles did not differ for both production periods, but the larger sizes of particle in group 1 point to more severe surface destruction. The increased metal wear in group 2 was apparently due to alumina-induced abrasion of the stems. In this study the concentrations of particles in the periprosthetic tissues were 2 to 22 times lower than those observed previously with polyethylene and alumina/polyethylene wear couples.

W e compared wear particles from two different designs of total hip arthroplasty with polycrystalline alumina-ceramic bearings of different production periods (group 1, before ISO 6474: group 2, according to ISO 6474). The neocapsules and interfacial connective tissue membranes were retrieved after mean implantation times of 131 months and 38 months, respectively. Specimen blocks were freed from embedding media, either methylmethacrylate or paraffin and digested in concentrated nitric acid. Particles were then counted and their sizes and composition determined by SEM and energy-dispersive x-ray analysis (EDXA).The mean numbers and sizes of most alumina wear particles did not differ for both production periods, but the larger sizes of particle in group 1 point to more severe surface destruction. The increased metal wear in group 2 was apparently due to alumina-induced abrasion of the stems. In this study the concentrations of particles in the periprosthetic tissues were 2 to 22 times lower than those observed previously with polyethylene and alumina/polyethylene wear couples. [Br] 2000;82-B:901-9. J Bone Joint Surg Received 11 December 1998; Accepted after revision 20 September 1999The size, shape and composition of wear particles play a central role in the development of aseptic loosening and osteolysis in total hip replacement (THR). [1][2][3][4][5][6][7][8][9][10][11][12][13][14] Various studies have shown the good performance of the alumina ceramic-on-ceramic articular surfaces in terms of frictional behaviour, low annual rates of wear and relatively low reactivity of debris in the periprosthetic tissues, compared with polyethylene wear from metal-polyethylene couples. [15][16][17][18][19][20][21][22][23] Light-microscope studies of membranes around revised ceramic THRs reported sizes of alumina particle of between 1 and 3 m which is similar to the grain size of alumina used for production. 15,24,25 Since a size of 1 m is at the lower limit for light microscopy, more sensitive methods have been developed to evaluate submicron debris in tissue membranes. 26-28The purpose of the present study was to describe the histology of periarticular tissues around failed alumina ceramic-on-ceramic total hip prostheses and to compare the tissue concentration and physical characteristics of isolated wear particles originating from two types of Al 2 O 3 ceramic used for these THRs: 1) a series of cementless, monolithic ceramic cups with ceramic heads, produced after 1975 but before the ISO 6474; and 2) more recently manufactured ceramic inserts for a commercially pure (cp) Ti-backed acetabular cup and ceramic ball head (BIOLOX, according to ISO 6474; Ceramtec, Plochingen, Germany) with a Tialloy stem. We have compared our findings with the results from previously published studies which used identical techniques of isolation and characterisation of wear particles to analyse tissues adjacent to failed cemented and uncemented metal-polyethylene total hip prostheses. [26][27][28] Materials and Methods (Table I) Group 1. Betwee...