Six (6) mongrel dogs at the age of six (6) months underwent transphyseal elastic intramedullary osteosynthesis for tibial shaft fracture. Clinical, X-ray, and physiological methods were used. As determined, the transphyseal reinforcement of the injured bone doesn't influence the lib function, but it retards the segment longitudinal growth. The eccentric arrangement of rods leads to forming angular deformity of the articular surface. Changes occur in the temperature of the covering tissues of the lateral tibial condyle. Consolidation period of the bone fragments is not increased. The union is formed through the blood flow of hypokinetic type in soft tissues. When intramedullary elastic rods being inserted the endosteal and periosteal response contributes to increasing the thickness of bone cortical plates and diameter.