The report is of an anatomico-pathological and electron probe microanalyzer study of a patella with osteoarthritic remodelling, that had been in contact with a cast cobalt-chromium-molybdenum prosthesis for two years and seven months. Abrasion of the metal resulted in preferential phagocytosis of chromium, principally in the wall of an osteoarthritis cyst. This observation indicates that a substance administered by intra-articular pathway for the treatment of osteoarthritis can become phagocytosed, and quite deeply, in the remodelled bone.