THE MORPHOLOGICAL CHARACTERIZATION OF THE STRUCTURAL COMPONENTS OF THE ARTICULAR CARTILAGE OF THE KNEE JOINT UNDER CONDITIONS OF THE MULTIPLE SKELETAL INJURY

• Main Author: Tkachenko А. S.
• Format: Article
• Language: English
• Published: Ukrainian Medical Stomatological Academy 2020-09-01
• Series: Вісник проблем біології і медицини
• Subjects: knee joint; articular cartilage; injury; femur and tibia; rats; microstructure; ultrastructure; morphometry
• Online Access: https://vpbm.com.ua/upload/2020-3(157)/61-min.pdf

It is well known that the trophic disorders and damaging the surrounding tissue in the area of limb damage are the one of the main reasons for increasing the time of fractures healing. This fact occupies a special place in preserving the functionality of the joints. In addition, the hypokinesia associated with the partial exclusion of limb function in the treatment of bone fractures plays a key role in the mechanism of changes in the structure of articular cartilage. It is impossible to have a clear picture of the nature of changes in articular cartilage under trauma of the bones that form the joint based on the analysis of clinical material. In order to develop an adequate pathogenetically and morphologically justified rehabilitation program aimed to improve the quality of life of the affected individuals and to prevent the negative impact of bone trauma on joint structure, it is necessary to have the knowledge about the structure of articular cartilage against the background of the trauma of the bones forming the articular cartilage. Thus, the aim of this study was to examine the micro-, ultramicroscopic and histomorphometric features of the articular cartilage of the knee joint in the rats under conditions of the multiple skeletal injury of femoral and tibial diaphysis. Object and methods. The studies were performed on 40 white laboratory mature males rats which were divided into the following groups: І – a control group (20 rats), ІІ – a group of animals with multiple trauma of the femoral and tibial diaphysis (20 rats). The holey defect was modulated in the in the proximal tibial diaphysis of the animals from II group using a portable dental drill with the sterile burs (d 1.6 mm) at low speeds with cooling and the holes were formed in the distal diaphysis of the femur for the bone marrow canal. The animals were removed from the experiment by the overdose of thiopental anesthesia (4 mg/100 g body weight) on the 60th day after trauma. The samples examination was performed using the electron transmission microscopy (JEM-1230, JEOL, Japan) and the light microscopy (Olympus BH-2, Japan). The morphometric analysis was performed using a microgrid, microwave line, and Digimizer computing software (Version 5.3.5). Statistical processing of all obtained numerical data was performed using SPSS (version 17.0, Chicago, IL, USA). Validation for normality of distribution was implemented using the Kolmogorov-Smirnov criterion. The data are presented as mean (M) and standard deviation (SD). The significance of differences between two groups was determined using Student’s criterion (t). The difference was considered significant if the probability of chance (P) did not exceed 0.05 (P < 0.05). Results. It has been found that the greatest changes in micro- and ultrastructure have been occured in the articular surface of the proximal tibia epiphysis on the 60th day after the multiple injury of femoral and tibial diaphysis. Also, the articular surface of the proximal epiphysis of the tibia was the most vulnerable. The cytoarchitectonics and positional organization of cell layers were changed. However, the distinct changes in the organization of cell layers were observed in the cartilage of the distal epiphysis of the femur but these changes were more local in nature. The surface layer of the articular cartilage of the tibia did not contain cells. It was loosened and of an uneven color. The relief of the surface layer of the femur was deformed but contained cells. The intermediate layer of the articular surface of the tibia had a lower density of chondrocytes compared to the femur. In addition, the chondrocytes were in different functional states. The chondrocytes had the main morphological characteristics in the intermediate layer of articular cartilage of the femur. The morphometric analysis has been revealed the largest deviations in the articular surface of the proximal epiphysis of the tibia. The thickness of the articular surface of the tibia decreased by 29.05% (p = 0.0001) according to the control, whereas the thickness of the articular surface of the distal epiphysis of the femur decreased by 20.49% (p = 0.0001). The thickness of the superficial, intermediate and deep layers of articular cartilage of the proximal epiphysis of the tibia decreased by 31.51% (p = 0.0001), 27.53% (p = 0.022) and 30.11% (p = 0.0001). At the same time, the thickness of the superficial, intermediate and deep layers of the articular cartilage of the femur decreased by 25.61% (p = 0.002), 19.45% (p = 0.007) and 21.37% (p = 0.014), respectively. Conclusion. Thus, it has been found that the greatest changes in micro- and ultrastructure have been occured in the articular surface of the proximal tibia epiphysis on the 60th day after the multiple injury of femoral and tibial diaphysis. Furthermore, the significant changes were observed in the thickness of the articular surface of the proximal epiphysis of the tibia.