Type I – Periprosthetic membrane of the wear particle induced type
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Infiltration of predominantly macrophages and multinuclear giant cells containing PE particles
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Type II – Periprosthetic membrane of the infectious type
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Activated fibroblasts, proliferation of small blood vessels, oedema, and inflammatory infiltrate of neutrophilic granulocytes
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Type III – Periprosthetic membrane of the combined type
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Combination of the histomorphological changes described for types I and II
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Type IV – Periprosthetic membrane of the indeterminate type (non infected, non wear particle induced)
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Connective tissue low in cells and rich in collagen fibres
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