EFFECT OF DISTRACTION OSTEOGENESIS ON THE PERIPHERAL-NERVE - EXPERIMENTAL-STUDY IN THE RAT

Distraction osteogenesis is the current method of choice for bone leng thening. Despite the gain in experience, various complications are rep orted, among them, adverse effects on peripheral-nerve function. In or der to thoroughly investigate the effect of distraction on neural tiss ue, a distraction osteogenesis model in the rat was established, using the femur of 30 Sprague-Dawley rats. The animals were randomized in t hree groups, following different rates of distraction (0.5 mm, 1.0 mm, and 1.5 mm/day) for 50, 25, and 16 days, respectively, so that the fi nal length of distraction was the same in all groups. The mean sciatic function index ranged near normal in all groups. All groups demonstra ted decrease of conduction velocity and the area under the curve of th e compound action potential, while morphologic alterations consisted o f decrease in the number of axons and evidence of active degeneration. Animals in Groups 1 (0.5 mm/day) and 2 (1 mm/day) displayed comparabl e changes, while in Group 3 animals (1.5 mm/day), changes were signifi cantly more adversely dramatic. The safest and fastest rate of distrac tion in this rat model was determined to be 1 mm/day.