牵张成骨修复下颌骨缺损组织学研究

目的探讨牵张成骨修复兔下颌骨缺损时骨组织再生的组织学改变。方法选取25只成年健康家兔，并随机分为实验组（20只）和对照组（5只），分别行一侧下颔骨缺损牵张成骨术，实验组在牵张第4、8天及固定期第1、3、5周，分别处死4只兔子，对照组在相应时间分别处死1只兔子，均取骨组织标本并观察其组织学改变。结果牵张第4、8天实验组家兔牵张区均为纤维结缔组织，并存在成纤维细胞，骨基质周缘可见大量活跃增生的成骨细胞；固定期第1、3周牵张区两端可见大量新骨形成，但中间仍为纤维结缔组织，新形成的骨组织表面始终附着大量活跃增生的成骨细胞，成行或以复层排列：固定期5周，成骨细胞明显减少，并逐渐呈现出哈佛系统。在整个观察过程中对照组截骨间隙处的成骨过程与一般的骨折愈合情况类似，以软骨化骨为主。结论牵张成骨修复下颌骨缺损以膜内成骨为主，同时辅以少量的软骨化骨。

A histological study on osteogenesis of rabbit mandibular defect treated by mandibular distraction

Objective To investigate the histological changes in mandibular defect treated by the mandibular distraction in rabbits. Methods Twenty-five adult healthy rabbits were randomly divided into experimental group （n=20） and control group （n=5）. In experimental group unilateral mandibular osteotomy was performed, a self-made distraction device was implanted. Four rabbits in experimental group and 1 in control group were sacrificed at d4 and d8 after distraction, week 1, 3 and 5 of consolidation; histological examinations of mandibular bone were performed. Results Histological examinations showed that the distraction zones were filled with fibril connective tissues at d4 and d8 after distraction; the osteotomized bone edges were surrounded by a small amount of newly formed trabecular bone; adjacent to them were a large number of osteobiasts. In the distraction zone at wl and w3 after consolidation, there were numerous newly formed bones at both sides with fibril connective tissues in the middle; and many fibroblasts, osteoblasts and osteocytes were observed on the surface of newly formed bones. In distraction zone at w5 after consolidation, there were reduced numbers of osteoblasts. For the control group, the ossification process was the same as general union of fracture, which was mainly endochondral ossification. Conclusion The major mode of new bone formation in mandibular distraction osteogenesis is intramembranous ossification rather than endochondral ossification.