Experimental study on avascular necrosis of the femoral head
Ohta, K.
Nihon Seikeigeka Gakkai Zasshi 54(12): 1693-1705
1980
ISSN/ISBN: 0021-5325 PMID: 7288226 Document Number: 156418
The pathology of idiopathic avascular necrosis of the femoral head was studied experimentally in adult rabbits. Preliminary experiments ascertained the anatomical detail of the blood vessels around the hip joint of adult rabbit using techniques such as dissection, ordinary angiography, molding of the arteries and microradiography. Experimental interference with the nutrition canals to the femoral head was performed without direct surgical damage to the hip joint itself. Animals were divided into 3 groups, according to the varieties of surgical procedure, to investigate the role of each vessel on the nutrition of the femoral head: Group I ligation of the medial circumflex femoral artery and so-called profunda femoris artery (including the lateral circumflex femoral and the perforating arteries); Group II, filling with the bone cement into the medullary cavity of the femoral metaphysis; Group III, experimental procedures of Group I + Group II. Avascular lesions in the femoral head were observed only in the animals of Group III; they were used as the experimental models of avascular femoral head necrosis. Blood flow in the medullary cavity has an important role to nourish the femoral head, and the medial and lateral circumflex femoral arteries. The nutrition of the femoral head appears mainly supplied by the anastomosis with the intramedullary arteries from the lateral circumflex femoral and the perforating arteries. Arteries in the femoral capital ligament take little part in the nutrition of the femoral head. The nutritional role of individual artery around the femoral head of adult rabbit was clarified anatomically. Using the specimens from the animals of Group III, the pathological changes of the femoral head induced by interference with the blood flow were observed radiologically and histologically. As the histological approaches, ordinary H-E [hematoxylin-eosin] and Azan-Mallory staining, fluoroscopy with tetracycline labeling of the bone and microradiographical methods were appropriately employed to the decalcified or undecalcified specimens. Revascularization of the dead femoral head arises simultaneously from the metaphyseal side and from the epiphyseal side neighboring the margin of the articular cartilage along with the proliferating young connective tissues into the bone marrows. This progresses gradually towards the center of the femoral epiphysis. Even 12 wk after surgery, the regenerative changes have scarcely been detected in the subchondral region, that so-called weight-bearing area. The new bone deposits stratify on the surface of the dead trabeculae in the revascularized area where the young connective tissues occupy the intratrabecular spaces. A little bone absorption is found at the thickened trabeculae with the deposited new bone. Consequently, the space of the bone marrow is diminished by the mature new bone with lamellar structure. The wedge shaped necrotic bone tissues in the subchondral region appears revascularized so hard that they remain avascular for a long period. In accordance with the increase of bone volume due to new bone deposition, radiographic density of the affected femoral head is increased, indicating that revascularization has advanced considerably.