An Animal Model Of The Femoral Head Osteonecrosis Induced By Ethanol Injection In Canine

BackgroundOwing to lack of optimal models of big animals, such as dogs or sheep, theresearch and development of new treatment modalities are hampered. There areseveral methods of establishing models of big animals, including cryogenicinsult of liquid nitrogen[1-4]and ethanol injection[5-8], which are most commonlyused. The method of cryogen insult has some disadvantages, for example, thetrapdoor needed contains a large part of the femoral head and the liquid nitrogenis difficult to handle. Researchers are trying their best to improve them. In2002,Manggold et al[5]introduced a new way of establishing animal model ofosteonecrosis of the femoral head (ONFH) induced by ethanol injection inMerino sheep, which has been widely used in the following years. However,there is no report on establishing models in canine by this method.ObjectiveThe aim of this study is to investigate the influence of ethanol injectionon the femoral head osteonecrosis and to establish experimental base for prevention and treatment of ONFH.Methods18adult mongrel dogs were divided into3groups randomly, and eachgroup contained6animals. One femoral head of the animal was administered byethanol injection, and the other was left as control. X-ray, CT and histologicalexamination were performed3,6,9weeks after the operation. The percentage ofempty lacunae was counted and analyzed statistically.Results3,6,9weeks after the operation, there were obvious evidences ofphotographic changes in operated femoral heads. X-ray examination showedthere were belts of low bone mineral density below the articular surface of theoperated femoral heads, paralleled with belts of high bone mineral density. CTscan examination showed several areas of low bone mineral density below thearticular surface, around which was several sclerosis. Radioisotope imagingshowed hyper-metabolism changes of the operated femoral heads and acetabula.3weeks after the operation, histological examination showed dominant changesof necrosis, including decreased hematopoietic cells, destroyed adipocytes andempty lacunae;6weeks after the operation, repairing process began to appear,and there were fibroblast cells in the medullary cavities. Trabeculae becamethinner caused by absorption.9week after the operation, abundant fibroblastcells were fully filled in the medullary cavities, and new vessels were found.LSD-t analysis showed that the percentage of empty lacunae of each operatedgroup was higher than control group (P<0.05). Aside from2animals (one diedfrom anesthesia accident, and the femoral head of the other animal wasdislocated),16animals showed obvious evidence of femoral head osteonecrosis. ConclusionEthanol injection can induce osteonecrosis of the femoral head in caninesuccessfully, and this method can provide a reference for similar researches.