Review of the local tissue reaction to metallic spinal implant debris: Ions and nanoparticles

Biologic reactivity to implant debris is the primary determinant of long-term clinical performance. The metallic implants placed in human bodies can exhibit electrochemical or mechanical corrosion that yields in the liberation of metallic products. Such implants-derived metal wear products can be present in the form of metal ions and particulate metal debris with still unknown effects on human health. In situ generation of metallic wear particles, corrosion products and in vivo trace metal ions release from metal and metallic alloys implanted into the body in spine surgery is becoming a major cause for concern regarding the health and safety of patients. In vivo clinical studies addressing the adverse local tissue reaction effects of metallic wear products on surrounding soft tissues and bodily fluids are less numerous. Although numerous studies have focused on the clinical significance of corrosion and wear of hip and knee replacements, research involving spine instrumentation is not well documented. This review explores how migration of metallic wear nanoparticles and trace metal ions in the area of metallic spinal implants influences the surrounding tissues and bodily fluids, and what the clinical consequences of this process may be.