Intracellular measurement of polyethylene particles - A histomorphometric study

A histological and histomorphometric study was carried out on pseudo-capsul es retrieved from patients during revision surgery of cementless total hip replacement. Polyethylene loading and areal polyethylene particle size in d ifferent cells of the reticuloendothelial cell line were determined within the tissue by histomorphometry. In the reticuloendothelial cell line, forei gn-body giant cells are considered to be the result of confluence of mononu clear macrophages caused by large particles or other unknown stimuli. The a im of this study was to investigate whether polyethylene particle size and polyethylene loading are different in mononuclear macrophages and foreign-b ody giant cells. The specimens were examined under the light-optical micros cope with plain and polarized light. The polyethylene loading of 329 macrop hages (mononuclear), 81 small foreign-body giant cells (2-5 visible nuclei) , and 103 large foreign-body giant cells (6 or more visible nuclei) was det er-mined and the intracellular polyethylene particle size analyzed by histo morphometry. The mean polyethylene loading was 13 8 mum(2), 25 +/- 16 mum(2 ), and 49 +/- 42 mum(2), respectively. This difference was statistically si gnificant (Student's t-test, P < 0.05). The mean polyethylene particle size was 2.34 +/- 3.2 mum(2), 3.02 +/- 3.46 mum(2), and 4.70 +/- 11.25 mum(2), respectively. This difference was statistically significant between macroph ages and large foreign-body giant cells (t-test, P < 0.05). The findings of this light-optical study show that the mean intracellular polyethylene par ticle size is greater in foreign-body giant cells. In addition, absolute po lyethylene loading tends to be higher in foreign-body giant cells than in m ononuclear macrophages.