[Healing of segmental defects in long bones. Animal experiments. Part II. Histological and micro-angiographical findings (author's transl)].

In part I of this paper the radiological findings in segmental defects of long bones were discussed. The histological regeneration originates from the marrow cavity. An endostal framework of bone is formed; this is more pronounced on the proximal resection place than on the distal one. The new bone formation within the defect depends on the revascularization through medullar blood vessels. The increased osteogenesis on the proximal site of resection is due to the increased formation of vessels in this area. The vascularization and the filling of segmental defects in tubular bone occurs faster, if only one metal plate and on the opposite side an autologous bone graft (cortical bone) is used in order to stabilize the bone. This method is superior to the use of a double-plate osteosynthesis. The graft unites with the underlying bone within twelve weeks by forming a trabecular network of new bone. If the autologous bone graft has become stable, it is vascularized from the bone and from the sorrounding soft tissue. Afterwards an osteolysis and at the same time an osteogenesis take place. The dead bone graft is replaced by newly formed bone within about 40 weeks. The loss of stability which occurs does not endanger the osteosynthesis.