Effect of ligating dogs’ arteries and veins on femoral heads

BACKGROUND: We separately ligated the arteries and veins of dogs to establish a canine femoral head necrosis model, then compared the differences between the outcomes of the two ligation methods on canine femoral heads. METHODS: Twenty-four dogs in this experiment were randomly and evenly sorted into two groups (Group A, the arterial group; and Group B, the venous group). In dogs in Group A, the unilateral deep femoral arteries of the hips were ligated. In dogs in Group B, the unilateral deep femoral veins of the hips were ligated. Two dogs from each group were randomly selected at the 2nd, 4th, 6th, 8th, 10th, and 12th weeks postoperatively and were marked as Groups A(1)–A(6) and B(1)–B(6) according to the selection times. The dogs underwent X-ray (DR) and a magnetic resonance imaging (MRI) plain scan (1.5 T) on both hip joints and were then sacrificed. Bilateral femoral head specimens were soaked in formalin and then decalcified. Hematoxylin–eosin (HE) staining and histopathologic evaluation were performed on the tissue sections. RESULTS: In dogs in Group B, abnormal pathologic changes, such as adipocytes fusing into cysts, were observed at the 4th week after establishing the model. MRI scans showed abnormal signal intensity at the 6th week, and fibrocyte regrowth was demonstrated in the necrotic area of the femoral heads at the 10th week. At the same time, indicators of tissue repair and fresh granulation tissue emerged. Changes in dogs in Group A, such as interstitial haemorrhage and oedema, were not noted in pathologic sections until 6 weeks after the model was established. MRI showed abnormal signals, such as a linear low signal intensity in the weight-bearing area of the femoral heads at the 8th week. New blood vessels emerged in the necrotic area at the 12th week, while there was no proliferation of fibrocytes and tissues. CONCLUSIONS: The development and evolution of femoral head necrosis caused by ligation of the main veins of the femoral head in dogs appeared earlier than in dogs with arterial ligation, and pathologic changes, such as necrosis and repair, were more significant in dogs in the venous group than in dogs in the other group.