骨牵张术修复犬下颌骨高速投射物伤性骨缺损的实验研究

Experiment study of distraction osteogenesis for rehabilitation of mandible defect injured by high velocity projectile in dogs

目的研究应用双焦点骨牵张术Ⅰ期修复下颌骨高速投射物伤性骨缺损的可行性。方法6只犬以多功能生物撞击机的二级撞击机系统致伤,清创后即刻植入钛质内牵张器,7天后开始骨牵引,速率为1mm/d,0.5mm/次,2次/d,连续10天。在牵张结束后的2、4、10周分别行大体观察、X线片检查、苏木精-伊红染色(HE染色)组织学观察,并测量新生骨区骨密度;在固定期10周后使用三点弯法测量牵引区的抗弯强度并进行骨密度测量,均以未致伤侧下颌骨作为对照。结果所有实验动物都顺利完成下颌骨牵张,伤口愈合良好,平均下颌骨牵张长度为(9.62±0.7)mm。放射线观察显示:固定期10周后,牵引区已无明显的透光区,有皮质骨形成。组织学观察:牵张结束后即可见牵张骨端边缘有少量新生骨形成,牵张区充满胶原纤维组织;固定期10周后,牵引区两端骨小梁呈网状,基本平行于牵引长轴,可见形成的成熟皮质骨。三点弯法测试牵引区抗弯强度结果牵张组的常温抗弯强度和骨密度与对照组抗弯强度均无统计学差异。结论骨牵引术Ⅰ期修复犬下颌骨高速投射物伤骨缺损是可行的,新骨形成依靠膜内成骨和软骨成骨两种方式,新生骨质经放射线、组织学观察与正常骨质类似,抗弯强度好。

Objective To study the feasibility of rehabilitation of mandible defect injured by high velocity projectile by the way of instant bifocal distraction osteogenesis in dogs. Methods Six dogs were injured by secondary impact system of the new multifunctional bio-impact on maxillofacial region. The titanium distractors were implanted into the injured canine mandible after debridement. The distractors were stretched 0.5mm each time and two times each day for 10 days consecutively. New bone formation was examined by X-ray, histological observa- tion,bone densitometry and in the way of gross observation at different time after fixation period. And 3-point bending test was used to assess its mechanical property. Results The mandibles were lengthened 9.62mm on average in experimental group, and new bone formation was obviously without bone nonunion and deformity healing. In X-ray examination,bone defect was connected by new bone and trabecula could be observed after 10-week fixation. In histological section, new bone was obvious and lamellar bone could be seen as well as mature cortex. And there were no statistical differences in bending strength and bone density between the experimental and control groups （ P 〉 0.05）. Conclusion It is feasible to rehabilitate canine mandible defect due to high velocity projectile by distraction osteogenesis instantly. The new bone is formed mainly by the way of intramembranous ossification.