Bone Implants: Processing, Embedding, Cutting, and Histopathology

The purpose of this review is to discuss the processing, embedding and cutting/sectioning techniques used for bone implants and their associated histopathology. It is well known that all specimen-handling procedures, such as fixation, infiltration, embedding, and cutting/sectioning, impact the quality of the histological, histochemical, and immunohistochemical analysis of specimens. Bone specimens containing implants are particularly difficult specimens to handle for several reasons. First, specimens and their associated embedding material must be of equivalent hardness for quality sections to be obtained. For bone this means either decalcification and subsequent embedding in paraffin or embedding bone specimens in plastic. Second, the hardness of the implant material must be taken into consideration. In addition to influencing the type of embedding material used, the type of implant and whether the bone is decalcified also dictates which types of equipment must be used for cutting/sectioning specimens. For example, as described in more detail below, metal, ceramic, and glass implants must be cut and ground. This requires specialized equipment such as saw microtomes, diamond saws, and grinders/polishers. Third, implants themselves may be altered by the chemicals used in standard histological processing of tissue specimens. Finally, the overall processing of the specimen and implant can impact the interpretation of the results. These bone implant issues are the focus of this review.