The peroneal nerve for canine leg lengthening using an autodistractor in the mode by 1 mm for 60 times

Purpose. The authors performed the experiments performed in 12 dogs in order to determine the morphological and histomorphometrical changes in the superficial peroneal nerve in the process of leg lengthening using an autodistractor in the mode of 1 mm for 60 times during 12 hours daily. Methods. The sites of the superficial peroneal nerve studied 28 days after distraction of the leg, 30 days after its fixation with device, as well as one month after the device dismounting by means of transverse araldite semi-thin sections stained with Methylene blue and basic fuchsin. Results. Fibrosis and epineurium cellularity increase were marked at the end of distraction and fixation. The marked histologically documented neuropathy of the peroneal nerve (one experiment out of 12 - 8.3%) revealed in the experiment with obliterating the lumens the largest epineural arteries and the most endoneural capillaries, as well as with the necrobiotic changes in the part of them. In the remaining animals the endoneurium hypervascularization marked, along with the increase in the number of vascular bundles in the epineurium, the percentage proportion of destructively changed myelin fibers (MF) in the studied periods amounted to 4.0±0.84 %, 3.3±0.08 %, and 2.40±0.55 %, respectively (for intact control - 1.92±0.31 %). The changes in MF size characteristics were the most marked at the stage of distraction, those in MF distribution by the diameters - at the stage of fixation. 30 days after the device removal the qualitative and quantitative structural parameters of the peroneal nerve in 11 animals of 12 did not differ from those of the intact nerve. Conclusion. The risk of developing the peroneal nerve neuropathy for the studied procedure of canine leg lengthening is caused by the failure of the compensatory-and-adaptive potentials of the epineural vascular bed. The nerve fiber structural characteristics important for conductivity function in most animals change slightly and restored by the end of the experiment.