HISTOLOGIC IDENTIFICATION OF POLYETHYLENE WEAR DEBRIS USING OIL RED-OSTAIN

Ultra high molecular weight polyethylene (UHMWPE) wear particles are f requently implicated in causing failure of total joint arthroplasties by eliciting a foreign body reaction. The majority of these particles are subcellular and many are submicron in size. Identification of thes e small particles of UHMWPE by conventional histologic techniques is d ifficult. We have therefore investigated the utility of Oil Red 0 (ORO ) stain to identify UHMWPE on histologic sections. A wide variety of s pecimens was studied including an experimental rabbit model with subcu taneous implantation of polyethylene particles as well as specimens fr om clinical cases with joint arthroplasties. The sensitivity and speci ficity of ORO stain was compared to conventional polarized light micro scopy for the identification of particulate UHMWPE debris. The ORO sta in was found to be as sensitive in identifying particulate UHMWPE debr is as polarized light microscopy. However, ORO stain was less specific : two specimens that did not contain any UHMWPE also stained with ORO. Careful examination of standard hematoxylin and eosin stained section s with polarized light was therefore more specific for the identificat ion of particulate UHMWPE. As a single test, the ORO stain does not ap pear to offer any clear advantage specifically for the identification of UHMWPE.