[Ferrographic analysis of synovial fluid in total hip replacement]

A synovial fluid analysis was carried out on 84 patients with total hip replacements, 53 of which were revision cases. The analysis was done using ferrography. An animal study was carried out whereby alumina ceramic, polyethylene and polymethyl methacrylate particles were inserted into the knees of rabbits, the synovial fluid of which was analysed. In addition, the synovium and surrounding tissues were histologically analysed. One week after insertion of the particulate debris only a few particles were noted in the synovial fluid and none at two weeks post insertion. However, these particles were noted in the synovium and surrounding tissues. Therefore, it was concluded that wear particles, following total hip replacement, may be encapsulated in the early period by the capsule and synovium, and have no adverse affect on the lubricating kinetics of the joint. It is postulated that the difference in tissue reaction to each of these particles may be responsible for the subsequent loosening.