LOCAL AND DISTANT PRODUCTS FROM MODULARITY

In this study, the local acid distant distribution of solid and solubl e products of corrosion from the head and neck junction of modular fem oral total hip prosthetic components were characterized. Particulate c orrosion products from retrieved implants and surrounding tissues were analyzed, Serum transport and urinary excretion of metal was measured in correlation with the degree of corrosion at the head and neck junc tion. Particles of metal oxides, metal chlorides, and chromium phospha te corrosion products were identified on implants of 10 designs from 6 manufacturers. The most abundant solid corrosion product on the impla nt and within the periprosthetic tissues (size range, <1-200 micromete rs) was an amorphous chromium orthophosphate hydrate-rich material. Se rum cobalt and urine chromium concentrations were elevated significant ly in patients with implants that had moderate to severe corrosion in comparison with those with no to mild corrosion. Solid corrosion produ cts from modular femoral stems may accelerate articular wear via a 3-b ody mechanism. Phagocytosable particles of these corrosion products ma y stimulate macrophage-mediated periprosthetic bone loss. Systemic dis semination of metallic corrosion products raises the issue of systemic toxicity; however, no overt evidence of metal toxicity was observed i n this study.