The histomorphometric characteristics of articular cartilage changes for leg experimental «fan-like» lengthening

The articular cartilage of femoral lateral condyles has been studied in 11 dogs - 8 experimental and 3 intact (control) using the methods of light microscopy, computer morpho- and stereometry. Lengthening of the right leg in the experimental group after closed flexion osteoclasia of leg bones was performed with the Hizarov fixator by 2,0 mm for 4 times. In the first week distraction was applied to the back pair of hinge unit half-pins, the next week - to the front pair, and with similar alternation subsequently. The results of the study made have demonstrated the presence of superficial damages, manifested themselves in the destruction of a part of cells and superficial zone matrix, in the articular cartilage of the joints, adjacent to the segment being lengthened in the period of distraction. In parallel, the regenerative changes in cartilage tissue, which are the most marked in the intermediate zone and basal one, appear at the stages of fixation and after the fixator removal. The activation of proliferative and biosynthetic processes is the main factor giving the possibility of reversibility of the changes. By the end of the experiment the reparative process in the articular cartilage is of non-completed character. The data obtained show the necessity to take into consideration the condition of the articular cartilage and to prevent the development of pathologic processes in it.