应用半环槽外固定器建立山羊胫骨缺损模型

背景:方便成骨及其成骨量的检测、占用空间相对较小,半环槽式外固定器属于骨外固定器,结构相对简单,多平面式固定,作者尚未查到用其建立胫骨缺损大动物模型可信性的较多实验报告.目的:验证半环槽外固定器构建山羊胫骨段缺损模型的可操作性及可重复性.设计、时间、地点:随机对照观察.实验于2005-03/2007-02在第三军医大学动物实验室完成.材料:9只健康成年山羊由第三军医大学动物中心提供;半环槽外固定器为第三军医大学李起鸿教授研制、直径2.5 mm骨元针为上海医疗器械公司产品.方法:动物经麻醉后,在距胫骨上关节面1.5～2.0 cm的松质骨同一平面各穿两针为第1组,两针夹角为40°在第1组下3.0～5.0cm处与第1组任一针平行穿一针为第2组.第4组穿针处距胫骨下端关节面2.0 cm松质骨处.第3组与第4组任一针平行,与第2组交叉成40°角,两组相距3.5～5.0 cm,共6针.上半环槽外固定器,游离胫骨中段,根据X线片得到的胫骨长度,在胫骨中下段中间两穿针处之间用线锯锯断胫骨和骨膜,造成20%骨与骨膜缺损.主要观察指标:①术后动物一般情况及半环槽外固定器应用状况.②采用X线及Lane-Sandhu评分观察骨缺损自行修复成骨情况.结果:纳入实验山羊9只,1只因术后感染死亡,1只出现针道感染,已予补充,其余均存活并进入结果分析.①实验动物术后2～6 h苏醒,并能站立进食.螺母松动后及时旋紧,无外固定松动失败,皮肤无坏死.术后2 d内伤肢能落地,但不能负重,2周后可以部分负重,3周有轻微跛行,4周后能自由活动,无跛行.②术后5周X-侧位片胫骨缺损处可见少许骨膜反应,术后10周断端有硬化,髓腔开始有闭合迹象,术后15周残端髓腔闭合,残端骨膜反应未加重,各时间点Lane-Sandhu X线评分均为0分.术后5,10,15周组织学检查未见骨形成,各时间点Lane-Sandhu组织学评分均为0分.结论:应用半环槽外固定器在造成山羊胫骨20%缺损的条件下构建的骨缺损动物模型,术后15周经检X线及组织学检测未出现骨愈合现象,证明该方法具有可操作性及可重复性,适用于组织工程用大段骨缺损动物模型的建立.

Constructing a goat tibial defect model by half-ring sulcated external fixator

BACKGROUND:Half-ring sulcated external fixator is a bone external fixation device.Its structure is relatively simple,with multi-plane fixed,and small occupying space.So far,there are few experimental reports about construction of tibial defect model by it in large animals.OBJECTIVE:To validate the practicality and repeatability of half-ring sulcated external fixator in establishing tibial defect models in goats.DESIGN,TIME AND SETTING:The randomized controlled observation was performed at the Animal Laboratory of the Third Military Medical University from March 2005 to February 2007.MATERIALS:Nine healthy adult(Animal Center of Third Military Medical University);Half-ring sulcated external fixator,made by Professor Li of the Third Military Medical University;Osseous pin,ψ2.5 mm,Shanghai Medicai Instruments Co.,Ltd.METHODS:After animals were anesthetized,two needles were threaded in the same plane of cancellous bone about 1.5-2.0 cm above the superior articular surface of the tibia,named group 1.The angle between the two needles was 40°.One needle was threaded at the place of 3.0 to 5.0 cm under the group 1 and parallel with optional needle of the group 1,named group 2.Needles of group 4 were threaded at the cancellous bone that was 2.0 cm from the joint surface of inferior extremity of the tibia.One needle was threaded at the place of 3.0 to 5.0 cm from group 4 and parallel with optional needle of the group 4.The included angle between these two needles of group 2 and group 3 was 60°.There were totally 6 needles.Tibia was fixed by half-ring sulcated external fixator.According to the length of the tibia from X-ray,tibia and periosteum were amputated by wire saw between the two needles in the middle and inferior segment of the tibia to make segmental bone and periosteal defects of 20 percent of tibia.MAIN OUTCOME MEASURES:①Postoperative general state of the animals and effect of half-ring sulcated external fixator.②Self-repair of bone defects by X-ray and Lane-Sandhu scoring standards.RESULTS:Of the 9 selected goats,1 died of postoperative infection,and 1 developed pinhole infection and supplemented.All the others survived and were included in final analysis.The goats were awake within 2-6 hours after surgery and able to stand up to eat.The loosening nuts were screwed up.No external fixation failure or loosening was found.No skin was necrotic.Injured limb could touch the ground in 2 days,but could not bear load until 2 weeks.The goats could walk in three weeks with a slight limp,then moved freely without claudication in four weeks after the operation.At the 5th week after operation,the radiographs showed little periosteal reaction.At the 10th week after operation,sclerosis was found in the fracture ends,and medullary cavity started to close.Fifteen weeks after operation,the medullary cavity closed and periosteal reaction did not aggravate.Inaddition.Lane score was 0 at any time point.No bone formation was found in the histological examination at 5,10 and 15 weeks after operation,and Lane score was 0 at any time point.CONCLUSION:The goat model established in goat tibia with 20%defects by the half-ring sulcated external fixator shows no bone healing after 15 weeks by X-ray or histological exanimation,indicating this is a practical and repetitive method to establish animal models of large segmental defect for bone tissue engineering.