PARTICULATE METALLIC DEBRIS IN CEMENTED TOTAL HIP-ARTHROPLASTY

Several studies conducted by the authors in the last six years demonst rate that the generation of metallic debris is more severe with titani um alloy than with cobalt-chrome alloy femoral components in cemented total hip arthroplasty (THA). The debris is generated from the articul ating surface, particularly if entrapped acrylic debris produces three -body wear, and from the stem surface when the component loosens and a brades against fragmented cement. In selected cases in which the titan ium metallic debris is copious, premature failure and severe progressi ve bone loss occurs. Electron microscopy demonstrates that the particl es of metallic debris can be extremely small (a few hundredths of 1 mu m). They are phagocytized by the macrophages and transported to the ph agolysosomes. In this highly corrosive environment, the very high surf ace area of the particles may release toxic concentrations of the cons tituents of the alloy intracellularly, probably leading to progressive cell degeneration and death, with subsequent release of intracellular enzymes and ingested metallic debris. This cycle most likely repeats itself, leading to tissue necrosis. The results presented do not suppo rt the use of titanium alloy femoral components for cemented THA, part icularly for the articulating surface.