Biologic Responses to Orthopedic Implants: Innate and Adaptive Immune Responses to Implant Debris

Almost 20% of joint replacement implants fail at 15 to 20 years. Reports suggest that systemic effects of metal-on-metal implants and local effects of total joint arthroplasty implants contributing to implant failure are immune system based. Sometimes implant wear debris can cause implant failure resulting from bone fracture, infection, or implant fracture/failure; most often, aseptic osteolysis or loosening leads to wear debris. Debris is produced by wear (primary) or by corrosion. Corrosion-chemical oxidation comprising reduction reactions involving electron transport-produces electrochemical degradation. Metallic implant degradation occurs when electrochemical dissolution and mechanical/physical wear are combined (i.e., tribocorrosion). With metal-on-metal implants, even with relatively low levels of wear and particle release, pathology caused by metal debris such as pseudotumor/fibrous tissue growth can lead to early implant failure.