FEATURES OF USING ORTHOPEDIC IMPLANTS ON AN EXPERIMENTAL MODEL OF SENSITIZATION TO NICKEL (NI)

Introduction. The theme of metal hypersensitivity (MHS) reactions is among the most controversial and complex issues in orthopedic and trauma practice. MHS diagnoses are diagnostically challenging because they are exclusionary diagnoses. It is currently uncertain which biomarkers can reliably predict a potential pathological response to implants. The aim of this research is to investigate hypersensitivity reactions to orthopedic implants containing nickel (Ni). Materials and methods. This research was conducted on female Wistar rats in accordance with the standards of bioethical principles. To obtain conclusive results, the animals were divided into two experimental groups: with prior sensitization to Freund's adjuvant containing Ni and without it. Nickel plates with a total surface area of 24 mm2 were implanted in the rats under general anesthesia. Five months after the intervention, the animals were removed from the experiment, and histological examination of the obtained samples was conducted. Extracted implants were examined using electron microscopy to assess the implant surface. The local elemental composition of the implants was analyzed using an energy-dispersive spectrometer. Results. Under the experimental conditions, it was demonstrated that after 5 months following the operation, a dense connective tissue capsule with an inflammatory infiltrate in the capsule lumen had formed around the implants in the rats. This suggests a possible manifestation of hypersensitivity reactions to implants containing Ni. Electron microscopy of the surface of the extracted implants revealed corrosion phenomena in all the samples. The degree of corrosion was more pronounced in the group of animals with prior sensitization to Ni, and distant particles of Ni were detected, which can be characterized as the beginning of implant degradation. Conclusions. A connective tissue capsule forms around the implants, and it was found to be 34.8% denser in animals sensitized to Ni prior to implantation, which may indicate tissue reactions with signs of hypersensitivity. Further research will provide a deeper understanding of the fundamental inflammatory and immunological reactions to metals present in implants. This, in turn, will facilitate the identification of clinically useful applications necessary for the development of diagnostic or prognostic tests for patients with metal implants.