Comparison of tissues adjacent to different mechanical stress areas from patients with clinically failed implants

Implants consisting of metallic and polymeric components are used to treat musculoskeletal diseases. At revision surgery, significant wear products maybe recovered from tissues adjacent to failed implants. The failing implant is clinically associated with pain, and radiographic analysis demonstrates deterioration of the bone surrounding the implant. There is concern that areas of high contact stresses and articulating surfaces lead to the generation of wear particles that trigger a biological response that mediates the lysis of bone. This study compares the tissues retrieved from various areas exposed to different mechanical stresses. Tissues were processed for biochemical and immunohistochemical factors (cytokines) responsible for bone resorption. The results from this study showed by both quantitative enzyme linked immunoassay and qualitatively by immunohistology a marked increase in cytokines, interleukin-1 and tumor necrosis factor, in areas of articulation compared to other areas. Evaluation of tissues histochemically demonstrated the presence of fibroblast, macrophages, and multinucleated giant cells. Overall, the results indicate that the generation of wear particles lead to the production of biological mediators responsible for the failure of the implants.