Features of regeneration of bone and cartilage tissue after traumatic intraarticular damage (experimental study)
Background. Today, the technology of open reposition and external osteosynthesis (AO) is leading one in the treatment of intraarticular fractures. In the presence of many positive characteristic of these technologies, their high invasiveness, causing a significant amount of early infection necrotic complications and late regeneration disorders, is an objective factor. These circumstances are forcing again to focus on the objectification of indications for open surgical interventions in severe intraarticular traumatic injuries. Extrafocal technologies for the treatment of intraarticular fractures do not raise questions regarding the morbidity and the risk of infection necrotic complications, but the reposition possibilities of the extrafocal osteosynthesis and fixation method are considered limited. One of the ways to improve the functional results of closed technologies is to use the effect of functional remodeling. This phenomenon was observed in clinical practice, when the primary controversial results of closed fragment reposition improved significantly during functional treatment, and the subsequent functional results of treatment were quite acceptable. Such positive perspectives required an in-depth study and determination of the conditions necessary for the implementation of the effect of functional remodeling and, first of all, the optimal time for the start of functional treatment. The issue of timing did not arise by chance, since the existing thesis “the sooner the better” looks doubtful in practice, and, moreover, it has no evidence base. The purpose was to establish the optimal time parameters for the rehabilitation treatment in order to realize the effect of functional remodeling of traumatic injuries of the articular surfaces. Materials and methods. An experimental study was performed on 28 adult rats that, after arthrotomy of the knee joint, were subjected to standard traumatic injuries of the lateral condyle of the femur. To standardize the mechanism of injury, a special device was developed. Experimental animals were combined into 4 groups of 7 individuals. On days 3, 7, 14, 28, they were sacrificed, and histomorphological study of preparations from the damage zone was performed. Results. It was found that during the first two weeks after injury, regenerative processes in the damage zone occur, with the formation of organ-specific structures, however, the mechanical properties of the regenerate are not yet sufficient for the primary immobilization of the margins of the cartilage defect, which, as proved, is the main condition for the formation of cartilage. For this reason, functional treatment during this period can only slow down the regeneration process. On day 14, an intensive formation of bone tissue of the subchondral zones was established that is a positive prognostic sign, on which (as also proven) the regeneration of cartilage directly depends. This indicates the signs of regenerate readiness for remodeling cartilage defects. Over the past two weeks, modeling of the articular surfaces has been observed by defect replacing of a bone lamellar structure and forming fibrous cartilage; hyaline cartilage recovery did not occur. Conclusions. The reasonable time to start functional treatment is the period from the beginning of the third and no later than the end of the fourth week after the injury, which is optimal for realizing the effect of functional remodeling of damaged articular surfaces.