Abstract
BackgroundThis study aimed to develop a simple method of creating an animal model of non-trauma femoral head osteonecrosis and collapse using African ostriches with weights similar to those of humans.MethodsEighteen African ostriches were subjected to liquid nitrogen cryo-insult in the unilateral femoral head through surgical procedures using homemade cryogenic equipment combined with tract drilling inside the femoral head. Three animals were sacrificed at postoperative weeks 6 and 12, respectively, and the remaining animals were sacrificed at postoperative week 24. Bilateral femoral heads were harvested and subjected to gross observation, histological examination using hematoxylin and eosin staining, and radiographic examination. Micro-computed tomography was performed on a portion of the specimens at postoperative week 24, and angiographic examination of the femoral head was performed before sacrificing the animals.ResultsEight ostriches developed a limp at postoperative week 8, with a mean duration of 16.5 weeks. The postoperative femoral head specimens showed changes in contour and articular cartilage degeneration. Sagittal sectioning of the collapsed femoral head specimens revealed distinct boundaries among the osteonecrotic areas, osteosclerotic areas, and normal trabeculae. Histological examinations revealed active bone resorption in the osteonecrotic area of the subchondral bone, an increased number of fat cells, and active trabecular bone regeneration in the osteosclerotic areas. The postoperative radiographic examinations revealed that the height of the femoral head gradually decreased and progressed to collapse. Micro-computed tomography scans showed the interrupted trabecular bone with an irregular shape in the collapsed femoral head. Compared with the normal samples, angiographic findings revealed interrupted blood supply of the cryo-injured samples in some areas of the femoral heads, blood vessel narrowing, and decreased number of blood vessels in the cryo-injured areas.ConclusionThis study indicates that an animal model of osteonecrotic femoral head progressing to collapse can be established via a simplified method of cryosurgery. This model possesses histological features that are similar to those of humans; thus, it can be used as an ideal animal model for the study of femoral head necrosis.
Highlights
The confirmed causes of osteonecrosis of the femoral head (ONFH) included corticosteroid using, excessive alcohol abuse, trauma, hemoglobinopathies, autoimmune diseases, and other relevant factors, the causes and mechanism of ONFH remained unknown [1, 2]
Among the ostriches that were sacrificed at postoperative week 24, seven were lame
Femoral head collapse is a characteristic change during the mid-late stage of ONFH and is used as a standard feature to evaluate the successful establishment of an ONFH animal model
Summary
The confirmed causes of osteonecrosis of the femoral head (ONFH) included corticosteroid using, excessive alcohol abuse, trauma, hemoglobinopathies, autoimmune diseases, and other relevant factors (smoking, hyperlipidemia), the causes and mechanism of ONFH remained unknown [1, 2]. These factors induced the local ischemic within the femoral head by oneself or multi-factors combined and resulted in the bone cell apoptosis, caused the osteonecrosis and collapse. This study aimed to develop a simple method of creating an animal model of non-trauma femoral head osteonecrosis and collapse using African ostriches with weights similar to those of humans
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