兔下颌骨放射后牵引成骨术式选择的实验研究

目的探讨兔下颌骨在放射后牵引成骨术的截骨术式。方法取术前1个月已完成一侧下颌骨50Gy放射的雄性成年新西兰兔8只,随机分为2组。实验组4只,双侧下颌骨截断,放射侧牵引,对侧不固定;对照组4只,放射侧下颌骨截骨、牵引,对侧不截断。两组在术后8 d后开始牵引,骨段牵引距离0.4mm/次,2次/d,连续牵引10 d,固定6周。通过临床表现、X线检查和离体标本等评价结果。结果 8只兔均存活。对照组4只兔下颌没有明显的偏斜和伸长;X线检查和离体下颌骨显示下颌骨未能牵开。实验组4只兔下颌明显偏向对侧;X线检查显示牵引侧成功牵开,对侧截骨间隙没有明显变化;离体下颌骨实验侧延长（7.1±1.2）mm,对侧截骨线临床愈合。讨论单侧下颌骨截断不能确保兔下颌骨放射后牵引成骨术的成功,双侧下颌骨截断、单侧牵引的截骨方式可作为兔下颌骨放射后牵引成骨术的截骨模式。

Osteotomy of distraction osteogenesis on previously irradiated rabbit mandible

Objective To investigate the osteotomy mode of distraction osteogenesis on previously irradiated rabbit mandible.Methods Eight male adult New Zealand rabbits were included which were received in the mandible irradiation 50 Gy.Osteotomy was made one month after completion of radiotherapy.Eight rabbits were randomly divided into 2 groups equally.Experimental group： both mandibles of the rabbits were osteomised,and the irradiated side distracted and no fixation was made on the other side.Control group： the irradiated side was osteomised and distracted,and no operation was done on the other side.Eight days later,distraction was activated at a rate of 0.4 mm（twice a day）,continueing for 10 days,and keeping fixed for 6 weeks.The results were evaluated by clinical manifestation,radiography and macrography.Results All the rabbits survived.Among experimental group,there was no obvious mandibular deviation;radiography and macrography showed the mandibles could not depart effectively.In control group,mandibular deviation and elongation were obvious.Radiography showed the bone was elongated successfully and no elongation on the other side.Bone generation was（7.1±1.2） mm.Conclusion Unilateral mandibular osteotomy can not assure successful distraction in previously irradiated rabbit.Bilateral osteotomy plus unilateral osteodistraction could be the mode for the previously irradiated rabbit.