Histopathologic and morphometric changes in rat nerve and blood vessels associated with femoral lengthening

Obj ectives : We investigated histopathologic and morpho¬metric changes in rat femoral arteries, veins, and nerves associated with femoral lengthening. Methods: The study included 42 male Wistar-albino rats. All the rats underwent left femoral osteotomy which was sta¬bilized with an external fixator device. The rats were divid¬ed into five groups except for seven control rats which were left untreated. Femoral lengthening was performed with a distraction of 0.35 mm four times a day, which was contin¬ued for three days in group 1 (10%), and seven days in the other groups (30%). Before sacrification of each group of rats under general anesthesia after 3, 7, 14, 21, and 31 days of osteotomy, respectively, biopsy samples were obtained from distraction sites involving femoral artery, vein, and nerves for histopathologic and histomorphometric studies. Results : Arterial changes observed in the first four groups were flattening and/or focal absence of the lamina elastica interna and externa, and hydropic degeneration and cytoplas¬mic vacuolization of the smooth muscle cells of the tunica media. Group 5 exhibited a normal arterial appearance except for fibrosis. Femoral vein changes were characterized by smooth muscle cell degeneration and cytoplasmic vacuoliza¬tion in the first three groups, and by irregularities in elastic fibres and fibrosis in the remaining two. In group 5, the diam¬eter of the femoral vein decreased by 27.9%. No histologic changes were noted in nerve morphology. In group 2, per¬ineurium thickness and the diameter of myelinated nerve fibers notably increased by 164.6% and 58.4%, respectively. Conclusion : Our results show that the effect of femoral lengthening is heavily on blood vessels rather than nerves.