In a time of the technical progress, the rate of high-energy traumatic injuries of the knee joint is increased which is 10-24% of the total number of lower limb injuries, reaching 80% in the young population. There is a plenty of evidence about the changes in the articular cartilage and the development of osteoarthritis as a result of direct trauma of the knee joint. However, the existing data reflecting the influence of limb injuries on the possible changes in the articular cartilage that can be a kind of trigger for the development of osteoarthritis are insufficient. Thus, the purpose of this study was to examine the histological, ultramicroscopic and histomorphometric features of the articular cartilage of the knee joint of rats under conditions of trauma of the diaphysis of the femur and tibia. Material and methods. The experiment was performed on 60 white laboratory male rats of mature age which were divided into the following groups: І – a control group (20 rats), ІІ – a group of animals with trauma of the femoral diaphysis (20 rats), ІІІ – a group of animals with trauma of the tibial diaphysis (20 rats). The holey defect was modulated in the distal diaphysis of the femur 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 of the animals from III group the holes were formed defect in proximal tibial diaphysis 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 examination of the samples was performed by the electron transmission microscopy (JEM-1230, JEOL, Japan) and by the light microscopy (Olympus BH-2, Japan). The morphometric analysis was performed using a microgrid, microwave line, and Digimizer computing software. 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. Results and discussion. The data are presented as mean and standard deviation. The significance of differences between two groups was determined using Student’s criterion. The difference was considered significant if the probability of chance did not exceed 0.05 (P < 0.05). It has been found that under the conditions of injury of the diaphyses of the femur and tibia after 60 days the greatest changes were occurred in the articular surface of the proximal epiphysis of the tibia under the conditions of injury of the tibia. The articular surface of the femur was the most stable. The changes occurred in the cells and cartilage matrix of the articular surface of the proximal epiphysis of the tibia were degenerative-dystrophic in nature. The thickness of the articular surface decreased by 16.31% (p = 0.024) according to the reference value. At the same time, the more significant compensatory processes have occurred in the chondrocytes of the cartilage of the articular surface of the distal epiphysis of the femur under conditions of femur trauma which consisted in the hypertrophy of their organelles. The thickness of the joint surface decreased by 9.19% (p = 0.274) compared to the reference value. Conclusion. Thus, in the conditions of trauma to the diaphyses of the femur and tibia after 60 days, the greatest changes occurred in the articular surface of the proximal epiphysis of the tibia. The articular surface of the femur was the most stable. The changes that occurred in the cells and cartilage matrix of the articular surface of the proximal epiphysis of the tibia were degenerative-dystrophic in nature. At the same time, in chondrocytes of cartilage of the articular surface of the distal epiphysis of the femur revealed more pronounced compensatory processes, which consisted in the hypertrophy of their organelles.
Keywords: knee joint, articular cartilage, injury, rats, morphometry
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