Light and scanning electron microscopy of articular cartilage in automatic leg lengthening

The articular cartilage of femoral lateral condyles in 12 dogs (9 experimental and 3 intact - control) was studied using the methods of light microscopy of half-thin sections, scanning electron microscopy, computer morpho- and stereometry. In the experimental series graduated lengthening of right leg using autodistraction by 1 mm per day (from 8 a.m. to 20 p.m.) for 60 times was performed during 4 weeks after closed flexion osteoclasia of leg bones. The study was made after 28 days of distraction, 30 days of fixation, in a month after fixator removal. It was established that the changes of articular cartilage structure in graduated leg lengthening consisted in destruction of the cartilage superficial zone. The degree of change manifestation is directly connected with the duration of experimental fixator-on stage. The results obtained are consistent with the data of literature about trophic influence of functional load on articular cartilage, and they confirm the fact that dynamical loads are necessary for maintenance of articular cartilage structural organization.