[Preliminary study on cryosurgery for osteonecrosis of femoral head in three-foot canine model].

Objective: To establish a animal model of osteonecrosis of femoral head in canine like human.
Methods: The thermal field of canine's femoral head was three-dimensionally analyzed with fluent 6.2 software so that the best cryosurgery patent could be designed to maximize the osteonecrosis and minimize extra surgery trauma with the cryosurgery system invented by Shanghai Jiaotong University. Liquid nitrogen was pressurized to 0.5 MPa, poured into femoral head for 6.5 minutes, rewarming to 2 degrees C for 5 minutes and then repoured into it again for another 6.5 minutes. Ten three-foot canines were conducted as the animal models of osteonecrosis of femoral head according to the method above. At the end of follow-up, the results were reviewed by radiologic and pathologic check. Two dogs were conducted as control group.
Results: In the experimental group, one of the ten canines was testified to occur osteonecrosis of femoral head after one week pathologically, cell death and vessel breakage of cavitas medullaris in the femoral head was obvious under microscope; in other nine canines being still under follow-up, five with three-month follow-up at least progressed to the collapse of femoral head like human (Ficat III). In control group, no osteonecrosis was found.
Conclusion: Cryosurgery for osteonecrosis of the femoral head in three-foot canine model may become a method to establish the animal model of osteonecrosis of femoral head like human.