The pathomorphological and morphometric characteristic of articular cartilage during leg lengthening in different periods of the day

Two experimental series were made: in the 1-st series leg lengthening was performed during 28 days by the day rate of 1 mm for 60 times (autodistraction) in the day-time (8 - 20), in the 2-nd series - in the night-time (20 - 8). Articular cartilage was studied morphologically and morphometrically. It was revealed that similar changes occurred in the articular cartilage of the dogs in both series: cartilage height decrease at the end of distraction and after 30 days of fixation, increase of cellular proliferative activity. At the end of distraction in 1-st series and after 30 days of fixation in 1-st and 2-nd series fibrillation of the superficial cartilage matrix was observed. It should be noted that the fibrillation incidence and zone area were less in 2-nd series in comparison with 1-st one. Restoration of the cartilage structure was observed in the both experimental series 1 month after the fixator removal. The cartilage height approximated to the control. Thus, the pathomorphological studies made and the analysis of morphometric data performed allowed to reveal general regularities of the articular cartilage functional status during leg lengthening in different periods of the day and showed that autodistraction used in the night-time was found to be more sparing for the articular cartilage.