Comparative analysis of the change of bone tissue metabolism condition and cytokine profiles in patients with endoprosthesis instability after primary knee arthroplasty

Aim. To define relations between serum concentrations of sRANKL and BMP-2, IL-1β, TNFα, IL-4 as well as their role in endoprosthesis instability pathogenesis in patients following primary knee arthroplasties. Materials and Methods. 80 patients were retrospectively divided into 2 groups: there were 40 patients with osteolysis and aseptic instabilities of knee endoprosthesises that had developed before 12 months after the surgery in the 1st group; the 2nd group was made up of 40 patients with implantat-associated inflammations that had developed in 4 weeks to 12 months after primary knee arthroplasties. 20 volunteer donors made up the control group. The enzyme-linked assay was used to define serum content of sRANKL (pg/ml, Biomedica, Austria), BMP-2 (pg/ml, Ray Bio, USA), cytokines TNFα (pg/ml), IL-1β (pg/ml) and IL-4 (pg/ml) (Vector-Best, CJSC, Novosibirsk, Russian Federation). The comparative analysis of statistically significant indicants was performed defining Spearman rank correlation coefficient. Results. Positive statistically valid relations of average force between concentrations of sRANKL and BMP-2, TNFα, IL-4 were found in patients of the first group in 1 month after surgeries. In 12 months positive relations of the parameters under study subsisted although the relation with IL-4 absented. The emerging of moderate negative statistically significant relations of sRANKL with BMP-2 and TNFα was observed in patients of the 2nd group in 1 month after surgeries. In 12 months negative relations of average force between sRANKL and BMP-2 subsisted, also new moderate relations emerged: negative relation of BMP-2 with IL-1β as well as positive of sRANKL with IL-1β and TNFα, IL-1β with IL-4. Conclusion. We found that the disorder of metabolic processes in bone tissue surrounding the implantat with the predominance of osteoclastogenesis activating pro-inflammatory cytokines might be the pathogenic factors of endoprosthesis instability development in patients following primary knee arthroplasty.