Polyethylene loading of foreign-body giant cells in aseptic loosening of hip arthroplasty.

Introduction: In aseptic loosening of cementless hip arthroplasty polyethyl ene particles are phagocytized by macrophages and foreign-body giant cells. This initiates an osteolytic cascade. In this study, the authors investiga ted if there are correlations between the size of foreign-body giant cells and the polyethylene loading and number of intracellular particles as deter mined by light microscopy. Material and Method: Histological specimens were processed from tissues retrieved during revision surgery of 7 cases of cem entless hip arthroplasty which had become aseptically loose. The specimens were analyzed by histolomorphology and histomorphometry. The cell size, pol yethylene loading and intracellular particle number of 111 foreign-body gia nt cells were determined. A regression analysis was performed to investigat e if there was a correlation between these variables. Results: The mean cel l size was 1417+/-487 mum(2), the mean polyethylene loading was 49+/-42 mum (2) and the mean intracellular particle number was 10.4+/-5.4. The cell siz e correlated with both the intracellular particle number (r = 0.25) and the polyethylene loading (r = 0.39). Conclusions: In the cellular reaction to polyethylene particles in aseptic loosening of cementless total hip arthrop lasty, the size of foreign-body giant cells correlates with intracellular p olyethylene loading and intracellular polyethylene particle number as deter mined by light microseopy. The presence of large foreign body giant cells m ight be associated with a high particle load of the tissue and a high osteo lytic activity.