放疗后兔下颌骨牵张成骨模型的实验研究

Development of an Animal Model of Distraction Osteogenesis in Irradiated Rabbit Mandible

目的建立放疗后兔下颌骨牵张成骨的实验模型。方法选用12只新西兰兔,使用直线加速器照射兔下颌骨,每次5.4Gy,隔日1次,共5次,3月后行牵张成骨。5d间歇期后开始牵引,每日2次,每次0.5mm,连续牵引10d。牵张结束后的0d、4周、8周分别行下颌骨X线片及CT平扫+三维重建检查,并取牵张区组织行组织学检查。结果所有兔均顺利完成放疗后牵张成骨,影像学和组织学检查结果都证实牵张过程中新骨形成,新生骨随着固定时间的延长不断成熟。结论采用该方法建立的兔放疗后下颌骨牵张成骨模型具有很好的可操作性和重复性。

Objective To establish an experimental model of distraction osteogenesis in irradiated rabbit mandible.Methods 12 adult New Zealand rabbits were divided into 3 groups randomly,4 in each group.Rabbits were irradiated by linear accelerator at 5.4 Gy once every other day for five times.Transverse osteotomies were performed on irradiated mandibles 3 months later.After a 5-day latency period,distraction steps were activated at 0.5 mm twice daily for 10 days.Then distractors were remained in the final expended position for 3 consolidation periods,i.e.0,4 and 8 weeks after distraction respectively.X-rays and CT scans combined with 3D image reconstruction were taken and distracted calluses were processed for histopathologic evaluation at the end of each consolidation period.Results All rabbits completed this experiments and healed uneventfully.New-formed bones were observed in radiographic and histologic examinations.All of the examinations showed that new-formed bones were maturing gradually with the time of fixation consuming.Conclusion Rabbit is a proper experimental animal for distraction osteogenesis following irradiation.The methods used in this study were practical and repeatable.