Affiliations: Department of Orthopaedics, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, USA | Department of Bioengineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, USA | The Whitaker Institute of Biomedical Engineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, USA
Note: [] Address for correspondence: Dr. K.‐L. Paul Sung, Department of Orthopaedics and Bioengineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093‐0412, USA. Tel.: +1 858 534 5252; Fax: +1 858 534 6896; E‐mail: klsung@ucsd.edu.
Abstract: Total joint replacement prostheses are required to withstand corrosive environments and sustain millions of loading and articulation cycles during their term of implantation. Wear debris generation has been implicated as one of the primary causes of periprosthetic osteolysis and subsequent implant loosening in total joint replacements. Particulate debris consisting of metals, polyethylene, ceramics, and bone cement have each been shown to provoke a biological response in joint tissues. The major cell types within the interfacial granulomatous fibrous tissues consist of fibroblasts, macrophages, lymphocytes, and foreign‐body giant cells. Osteoblasts are one of the principal cell types in the bone tissue adjacent to prostheses, maintaining physiologic bone remodeling through the balanced coordination of bone formation and resorption in concert with osteoclasts. To date the phenomenon of osteoblast phagocytosis of titanium particles has been suggested, but has not been sufficiently studied or confirmed. This study seeks to clarify the influence of titanium particles on osteoblast adhesion, deformability, proliferation, and gene expression profile. These studies were accomplished by performing biorheological testing, Northern blot analysis and RNase protection assay. The uptake of metallic particles by the osteoblast resulted in a particle–filament complex formation, which induced a series of variations in cell function. Understanding these variations is critical to expanding our knowledge of implant loosening and elucidating the nature of prosthetic joint failure. This study suggests that the impact of titanium particles on osteoblast function and subsequent implant loosening may have been previously underestimated.
