Comparative Study Of Ultrasoud And X-ray Examination Used On Monitoring Fracture Healing Process Of Rabbit Mandible Body

Background:Mandible is the biggest part of maxillofacial bone. It is easy to get hurt because of its outstanding position. About 55 to 72 percent of maxillofacial bone fractures happened in mandible. Among these, the mandible body fracture has the highest occurrency.Currently, clinical valuation about fracture healing is mainly relied on monitoring the density and area of the bone callus by X-ray examination. However, X-ray is harmful for human body, so X-ray examination is restricted in the pregnant women and children patients.Ultrasound examination also can be used to monitor the process of fracture healing through detecting the width of fracture, the strength of echo, the formation of bone callus, the appearance of shadow, and the change of blood stream around the fracture end. Compared to X-ray examination, ultrasound examination has its limitation such as vague image, can not penetrate deep-seated bone callus, can not be used in case of skin infection and exposed "wound, etc. However, the ultrasound examination has certain advantage on monitoring fracture compared to X-ray examination, for example, the ultrasound examination is relatively simple and quick, is harmless for human body, can avoid miss-diagnosis by multi-direction scan, can detect very early stage of bone callus formation, etc. Moreover, ultrasound examination has special value on pregnant women and children fracture because of its harmless.Objective:To monitor the fracture healing process of rabbit mandible body through ultrasound examination, and to evaluate the significance of ultrasound examination on monitoringfracture healing process.Material and methods:10 New Zealand white rabbits were divided into operation group (8 rabbits) and normal control group (2 rabbits) randomly. Anterior mandibulectomy was performed on operation group to make mandible fracture model. Briefly, l~2mm mandible body was cut out, and the residual was fixed by the titanium plate to make a l~2mm bone fissure. Clinical examination, as well as ultrasound and X-ray examination was done at day 1, week 1, 2, 4, 6, and 8 of post-operation. The results of the examination was graded by certain standard and analyzed by spearman's correlation coefficients.Results:The X-ray examination showed that fracture fissure became narrow gradually, bone callus appeared and bone fracture line disappeared gradually through out the follow up duration. The ultrasound examination showed that the echo of fracture became stronger gradually and the echo type changed from asymmetrical echo to symmetrical echo. The ultrasound wave across fracture fissure disappeared gradually and turned into ultrasound shadow behind the fracture. The arciform structure of fracture became smooth gradually. Finally, it was difficult to distinguish the echo of fracture from the normal mandible. The results of ultrasound examination were compatible with the X-ray examination through out the follow up duration. The analysis of spearman correlation showed that Spearman correlation coefficient was 0.966, p=0.000(p<0.001), indicating the result of ultrasound examination and X-ray examination was consistent,the ultrasound examination is helpful and useful in making diagnosis and monitoring the healing process.Conclusion:As a substitute of X-ray examination, ultrasound examination can be used to make the diagnosis and to monitor fracture healing process of rabbit mandible body.