Biocompatibility and Osseointegration of Calcium Phosphate-Coated and Non-Coated Titanium Implants with Various Porosities.

The aim of the investigation was to study the influence of pore size and the presence of a biologically active calcium phosphate coating in porous 3D printed titanium implants on the process of integration with the bone tissue. Materials and Methods: Samples of cylindrical implants with three different pore diameters (100, 200, and 400 µm) were fabricated from titanium powder on the Arcam 3D printer (Sweden) using electron beam melting technology. A calcium phosphate coating with a thickness of 20±4 µm was applied to some of the products by microarc oxidation. Cytotoxicity of the implants was determined in vitro on human dermal fibroblast cultures. The samples were implanted in the femoral bones of 36 rabbits in vivo. The animals were divided into 6 groups according to the bone implant samples. The prepared samples and peri-implant tissues were studied on days 90 and 180 after implantation using scanning electron microscopy and histological methods. Results: All samples under study were found to be non-toxic and well biocompatible with the bone tissue. There were revealed no differences between coated and non-coated implants of 100 and 200 µm pore diameters in terms of their histological structure, intensity of vascularization in the early stages, and bone formation in the later stages. Samples with pore diameters of 100 and 200 µm were easily removed from the bone tissue, the depth of bone growth into the pores of the implant was lower than in the samples with pore diameter of 400 µm (p<0.001). There were differences between coated and non-coated samples of 400 µm pore diameter, which was expressed in a more intensive osseointegration of samples with calcium phosphate coating (p<0.05). Conclusion: The optimal surface characteristics of the material for repairing bone defects are a pore diameter of 400 µm and the presence of a calcium phosphate coating.

[Characteristics of periprosthetic femoral fractures after total hip replacement in elderly patients.]

In our study we analyzed 76 patients (78 hip joints) with periprosthetic femoral fractures after total hip replacement treated at Privolzhsky Federal Research Medical Centre in 2006-2016 period. We outlined specific features of periprosthetic fractures in elderly patients such as women having it more often, arise due to traumatic causes. Also elderly patients require more elaborate hardware such as cerclage wires, periprosthetic plates and additional surgical techniques such as extended trochanteric osteotomy to successfully treat periprosthetic fractures. Thorough preoperative diagnostics and planning, special educational courses which consider age-related factors could help decrease periprosthetic fractures incidence in elderly patients undergoing total hip replacement.