摘要
目的 牵引器设计是牵引成骨技术的基础，应用内置式、自动化牵引器进行持续加力牵引成骨，不仅能显著减少患者承受的痛苦，避免手动实施牵引操作的繁琐，而且更有利于骨再生延长，已成为目前发展牵引成骨技术的关键性研究课题之一。本研究工作希望利用医用镍钛合金独特的形状记忆和超弹性，设计制作多用途、完全内置式的下颌骨自动弹力牵引器，并应用于下颌骨节段性缺损重建，探索持续弹力牵引成骨适用的的外科技术。
方法 建立兔下颌支节段性缺损重建动物模型，初步考察弹力牵引成骨可行性：手术截除成年新西兰白兔一侧下颌支及髁状突1．5cm骨段，采用无间歇期骨传送方法，即时安置0.8mm直径镍钛丝制作的“S”形牵引器，缝合伤口，2月后取材观察缺损下颌支重建情况。
建立犬下颌体节段性缺损重建动物模型，进一步探索弹力牵引成骨适用的外科技术：手术截除成年杂种犬一侧下颌体部1-3cm骨段，采用双焦点牵引成骨方式，无间歇期安置1.33mm直径“W”形镍钛丝牵引器，分别根据缺损节段大小、传送盘形成方式(骨切开或皮质骨切开术)、有无克氏针辅助导引传送盘等分组，比较分析适用于弹力牵引成骨的外科操作方式。
利用确立的犬下颌骨弹力牵引成骨方法，观察镍钛牵引器超弹性加载强度和距离对牵引成骨的影响：1mm、1.3mm、1.33mm直径镍钛丝分别制成最大张开距离为4cm和6cm的牵引器，测量其压缩．回复弹力曲线，制作犬下颌体4cm缺损模型，分组安置不同牵引器，术后分别测量传送盘移动速度、最大牵引距离。
复制犬下颌体4cm缺损重建模型，选用1.3mm、1.33mm牵引器，形成长度超过3cm的再生骨段，分期处死取材，测量再生骨密度、强度，初步了解弹力牵引模式下骨再生和改建成熟进程。
基于前述研究，探索引导骨再生技术与弹力牵引成骨技术结合的可能性：常规手术制作犬下颌节段缺损重建模型并安置镍钛牵引器后，于骨缺损和牵引骨缝颊侧缝合固定聚四氟乙烯膜，术后3个月取材与未安置引导膜的动物模型比较缺损重建结果。
改进克氏针辅助导引传送盘设计，采用重建钛板和小型钛板组合构成多用途三维固定导引装置，制作犬下颌颏部缺损模型，试验此装置与镍钛牵引器进行三焦点牵引成骨的可行性。
结果：兔下颌支缺损重建模型初步证实弹力牵引成骨可行性，牵引区形成0.8～1cm完整
岩昌旨尝鉴‘‘硫而声声一~~~~
再生什段并与正常卜领骨形成骨性连接，、一卜领支得以重建，再生‘FJ’‘}李化均匀，到}.织学表现
类似膜内成骨，皮质骨板和骨小梁呈与牵引力一向一致的规则排列。
经犬下领体缺损重建模型的进一步研究，适用于弹力牵引成骨的手术技术为:保护舌
侧及牙槽峭骨膜附着全层切骨形成传送盘，无间歇期即刻安置镍钦牵引器，设置必要的传
送盘导引装置，可以保留传送盘骨段的牙齿。
各镍钦牵引器的压缩一回复弹力曲线证实其超弹性，即可在相当长的复形距离内产生
较稳定弹力。牵引速度与加载弹力强度呈正相关，早期牵引速度最高可达每天3mm，随
牵引器弹力下降牵引速度减缓;最大牵引距离与弹力强度和超弹性加载距离正相关，直径
1.3mm和1.33mm的两种6cm镍钦牵引器均可重建4cm的下领骨缺损。
弹力牵引可稳定获得骨再生结果，但再生骨段总体厚度与高度较正常下领骨薄窄，特
别在较大的再生骨段比较明显，其中未剥离骨膜的牙槽峭和舌侧部分成骨较好，而受重建
钦板等固定导引装置影响，下缘及颊侧部分成骨较差，组织学表现为膜内成骨。
再生骨存在骨化较晚的中央生长区，长度超过3cm的再生骨段，术后4个月时生长区
密度和强度可超过正常下领骨的三分之一，术后5个月时可达正常骨的三分之二。
膜引导技术可促使传送盘与对侧骨断端间的压力区早期形成节段性再生骨接合，避免
了常见的软组织粘连造成的骨不连，并且减小了传送盘移动距离，张力区和压力区再生骨
骨化成熟速度均较快，术后3个月时即可接近正常下领骨密度和强度，再生骨段高度和厚
度也明显优于无膜引导时牵引成骨结果。
改进克氏针导引为重建钦板和小型钦板组合固定导引，避免了克氏针取出时的困难，
以及克氏针占据成骨空间对骨再生的不良影响。由于犬颊部两侧下领骨夹角狭窄，软组织
厚硬，三焦点牵引成骨时两侧延长的下领骨间为粘连组织阻隔，未能形成颁联合。
结论:内置式镍钦牵引器能自动加载弹力完成持续牵引成骨，能实现较大节段骨缺损的再
生重建，可不设置间歇期且牵引速度较快，骨再生结果稳定，牵引固定装置简易且能作个
体化调节，手术操作简单，术后实验动物耐受良好，在辅助膜引导技术后，再生骨质量和
骨化成熟速度还可得到进一步提高。我们认为，镍钦牵引器弹力牵引成骨可望成为一种简
便易行的下领骨重建技术，能提高患者治疗期间的舒适度、缩短临床治疗时间、降低医疗
成本支出。
Objective Rational design of distractor is the foundation of distraction osteogenensis. Continuous distraction, by using internal automatic distractor, can reduce suffering of patients and avoid tiresome procedure of manual distraction. Furthermore, it is more feasible for bone regeneration. Some recent researches have been focused on this thesis and are considered important for further development of distraction osteogenesis. The aims of this study are to develop multi-purpose and self-activated internal distractor, utilizing shape memory and super-elasticity of Nitinol, and to establish practicable surgical technique for segmental mandibular reconstruction via continuous elasticity distraction osteogenesis using Nitinol distractor.
Methods First we created a rabbit model for preliminary feasibility research of elasticity distraction in segmental mandibular ramus reconstruction. Ramus segment of 1.5cm, including the condyle, was removed from one side of rabbit mandible. The S shape distractor, made from 0.8mm Nitinol wire, was settled without .latency to perform bone transport. The incision was closed. Final results of mandibular reconstruction were observed 2 months later. Then a canine model of segmental mandibular reconstruction was created for further investigation of surgical technique suitable for elasticity distraction. Segmental defect of l~3mm was created in canine mandibular body and bifocal distraction was performed without latency using W shape Nitinol distractor made from 1.33mm wire. Several experimental groups were divided according to the size of defect, methods of transport disc formation (osteotomy or corticotomy), methods of transport disc guidance (with or without Kirschner pins). The osteogenesis results were c
ompared to search for feasible surgical operation. Based on the established canine model of elasticity distraction, we observed the effect of strength and stretch distance of Nitinol distractor on distraction osteogenesis. Several kinds of distractor, which stretch distance was 4cm or 6cm, were made from 1mm and 1.3mm and 1.33mm Nitinol wire. Their constriction-recovery elasticity curves were measured beforehand. Canine models of 4cm segmental mandibular defect were created and divided into groups to fix
different distractors. The rate and distance of distraction osteogenesis were measured after
operation.
The canine models of 4cm segmental defect were duplicated, and 1.3mm and 1.33mm
distractors were used to create regenerate bone segment longer than 3cm. Then the animals were
sacrificed at different time after operation for examination of bone density and intensity, so as to
get primary knowledge of bone regeneration and rebuilding process in elasticity distraction
mode.
We further investigated the possibility of combination of guided bone regeneration with
distraction osteogenesis. After the canine segmental mandibular defect was created and Nitinol
distractor was settled routinely, a piece of ePTFE membrane was sutured and covered the buccal
side of the bone defect and distraction gap. The osteogenesis results were observed and
compared with that of none membrane guided distraction 3 months later.
To improve the design of transport disc guidance by Kirschner pins, we used reconstructive plate
and micro-plate to form new device for fixation and guidance. To testify its feasibility, we
applied it with Nitinol distractor in trifocal bone transport reconstruction of canine mandibular
mentis
Results The rabbit model proved feasibility of elasticity distraction in principle. Regenerate
bone segment of 0.8-1cm was formed in distraction zone with bony connection to normal
mandible. The ramus was reconstructed. Radiograph of the regenerate bone showed well
ossification and micrograph show histological appearance similar to intramembranous
ossification with regular arrangement of cortical bone lamella and bone trabecula according with
distraction direction.
Further researches in canine model revealed that, when performing elasticity distraction, tr
引文
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