牵张成骨修复犬腭裂愈合过程的观察

目的:探索截骨牵张联合缝牵张修复犬腭裂中两侧骨岛在中线区愈合的机理。方法: 健康杂种幼犬6只,建立人工Ⅱ°腭裂模型3～4周后沿腭外侧缝内侧1mm纵行切开腭骨水平板,腭横缝区不截骨,立即以250～280g力持续向内侧和后方牵张至硬腭裂隙关闭,裂隙关闭1周后进入保持期。分别于牵张结束即刻、1、2、4、8、12周处死,采用直接观察、X线片和组织学方法评价中线区愈合情况。结果: 牵张5～7d后人工裂隙逐渐关闭,两侧骨岛后移,硬腭平均延长4.78mm。两侧骨岛后份在5～8mm长腭中线上呈叠瓦状重叠,表面粘膜受压凹陷,逐渐融合,4周时出现新生骨桥连结;其前方15～18mm的裂缘粘膜变薄,于正中相互接触,但并未发生组织融合。结论:截骨牵张联合缝牵张可使两侧腭裂裂缘在中线区后分发生骨性融合。

Distraction Osteogenesis Close the Cleft Palate and Lengthen the Hard Palate: the Process of Middle Line Union

Objective: To investigate the process of middle line union during distraction osteogenesis closing palatal cleft. Methods: 6 mongrel dogs in weanling were used in this study. A 6mm-width midline portion of the hard palate was surgically resected in all dogs, which included mucoperiosteal and underlying palatal bone and nasal septum from the transverse palatal suture to the distal bone margin. The soft palate was also halved in the middle line to establish an artificial palatal cleft model, just like a Ⅱ°-cleft-palate patient. 3-4w later, bilateral osteotomy were performed running about 1mm medial to the lateral palatal suture, from the transverse palatal suture to the great palatine foramen, and then extended obliquely to the posterior border of the hard palate. An individually fabricated, ring-shaped distractor made of nickel-titanium shape memory alloy, which produced a continuous traction force of 250-280G medially and distally, was inserted. The continuous distraction began without any latency after the installation and kept retention for a week after the gap had been closed. Dogs were killed immediately,1,2,4,8,12 weeks after distraction, and the middle line union of the palate was assessed by direct examination,histological and radiological methods. Results: The cleft in all dogs decreased gradually at a rate of about 1mm per day after installation of the distractor and were closed completely over a period of 5 to 7 days. Bony healing at the midline was occurred in the distal part for about 5-8mm long. The forehead of the bony cleft remained separation although the bilateral soft tissue contacted very well. The X-ray films revealed that the bone islands in the experimental dogs moved medially and distally and overlapped in the distal part of the middle line.The histological study viewed that the middle line healing was firstly occured through epithelial union,and then new bone formation ,bony bridge eventually connected bilateral bone islands. Conclusion: Bone healing can occur in distal part of middle line during distraction osteogenesis closing the hard palate cleft in dogs.