The synovial response to intraarticular cobalt-chrome wear particles

The intraarticular effects of alloy wear particles similar in size to those present in the tissues around loose total joint prostheses were studied in rat knee joints injected with laboratory-prepared particulate cobalt-chrome. The particles induced rapid proliferation of macrophages and focal degeneration of synovial tissues similar to the response seen in the articular tissues around loose total joint prostheses in humans. Bacteriologic tests excluded infection as a factor. Wear particles may contribute to the changes in the tissues around total joint prostheses and may contribute to bone resorption resulting in prosthetic loosening. Experiments on animals provide useful information about the biocompatibility of materials used in the manufacture of total joint prostheses.