Epiphyseal tilt produced by experimental overload

After segmental resection of the diaphysis of the radius in growing dogs, the distal ulna epiphyseal plate is submitted to a mechanical overload which provokes a progressive tilt of the epiphysis. A full exail realignment is developed in two or three months as shown in radiographic follow-up studies. Histologically, the first lesion is a fissure starting and the convex side of the growth line, passing along the epiphyseal plate and located somewhere between the proliferative layer which is seldom affected and the zone of enchondral ossification. The separated segment of the growth cartilage situated between the fissure and metaphysis stops growing and the cartilaginous tissue becomes disorganized and necrotic. It is then reabsorbed, and replaced by vascular-connective tissue coming from the bone marrow. Growth usually goes on form the deep proliferative layer of the epiphyseal plate when its vascular connections are intact. After three months a normal epiphyseal line is rebuilt correcting the defective axis of the bone.