REACTIVE-ADJUSTABLE RESTRUCTURING OF STERNUM IN RATS AFTER MODELING OF MECHANICAL LOADING IN THE BIOMECHANICAL SYSTEM...

Aim of the research - to conduct histological analysis of the sternum immature rats after modeling mechanical loading in the biomechanical system "sternum - ribs - spine". The studies were conducted on 14 rats. In 8 rats a spinal deformity was simulated according to the method of Sarwark JF et al. in our modification. In control 6 animals were used. X-ray studies were performed in the 1, 2 and 3 months after modeling, histological research was carried out in the 1 and 3 months with definition a gradation (in points) of changes in the structural elements of a sternum. Significant abnormalities were observed mainly in the intersegmental synchondrosis, areas of attachment of ribs and growth zones of the sternum segments. The cracks and crevices with adjacent degeneratively altered chondrocytes - with pycnosis or nuclear lysis form in the area of synchondrosis and places of its fusion with ossified costal cartilage. Severe disorders are observed in the growth zones of sternum body segments. The narrowing of a growth plate due to its destruction in some areas was revealed. Violations in the organization a zone of proliferation of chondrocytes, narrowing a zone of hypertrophy lead to the violation a growth process in the sternum. Reparative manifestations are present in these structures after removal of a mechanical loading, but with the partially preserved deformations of a spine, however, destructive disorders are persisting. Creation state of a prolonged mechanical loading in the "sternum - ribs - spine" system is negatively affects on the trophism and leads to degenerative changes in the bone-cartilaginous structures. Over time a tendency to decrease and develop recovery processes is observed in a case of decreasing degree of tension.