Study of the biocompatibility of porous 3D-TiNi implants in vivo

Introduction. Porous TiNi alloys are widely used in medicine as osteoreplacement implants due to their unique properties of superelasticity and biocompatibility, but their clinical use is severely limited by time-consuming manual fabrication and the inability to create precise geometries. Reconstructive surgery for the replacement of bone defects requires biocompatible endoprostheses of individual shape and complex geometry. The use of porous 3D-TiNi implants can be a solution to many problems in traumatology and bone oncology. Aim: To evaluate the possibility of using porous 3D-TiNi implants in osteoplastic surgery based on a study of the structure and biocompatibility of the material under in vivo conditions. Material and Methods. Porous samples in the form of cones and a single implant for maxillofacial surgery were prepared from TiNi powder by selective laser melting. To print an individual implant for maxillofacial surgery, the personal data of the patient at the Oncology Research Institute were used. The macrostructure, elemental and phase composition of porous titanium nickelide samples were investigated using scanning microscopy and X-ray diffraction analysis. The biocompatibility of porous cone-shaped samples was evaluated in vivo using guinea pigs whose condition was analysed by CT scanning. Results. Structural studies of porous titanium nickelide samples showed that selective laser melting can be used to obtain a continuous porous structure with strong contact bridges between particles of a three-phase powder. In vivo testing of the cone-shaped implants showed no local inflammatory changes, rejection or deformation of the hind limb axes of the experimental animals. The basic feasibility of fabricating a custom implant of complex geometry from TiNi powder using selective laser melting according to a patient’s MSCT data was demonstrated. Conclusions. Porous 3D-TiNi implants obtained by selective laser melting showed high biocompatibility under in vivo conditions. An experimental study confirmed the efficacy and ease of use of 3D TiNi implants, their excellent self-fixation in bone tissue, and bone tissue augmentation at the interface with the implant. The macrostructure, chemical and phase composition of the implant material was found to be close to traditional porous TiNi alloys. It was shown that the method of selective laser melting makes it possible to create complex geometric defects in bone tissue from TiNi.