山羊牵张成骨术后下颌骨三维有限元模型建立

牵张成骨是矫治颅颌面先天发育畸形和获得性骨节段缺损的新兴技术.本研究在实施山羊下颌骨牵张成骨术的动物实验基础上,通过CT断层扫描技术结合专业图像处理软件Mimics和自编Matlab程序建立可用于应力分析的山羊下颌骨三维有限元模型.     

生长因子与下颌骨牵张成骨

牵张成骨（distraction osteogenesis，DO）是指在骨缝处或截开骨段处用牵引装置按一定的速度和频率牵开而产生的骨间隙中形成新骨。1973年，Synder等第1次完成狗半侧下颌骨牵张延长的实验研究；1992年，McCarthy等首次将牵张成骨技术用于治疗下颌先天畸形患者。现牵张成骨技术已广泛应用于颌骨及长干骨延长的动物实验和临床应用研究中。研究表明，牵张骨的形成不仅是一种骨愈合过程，还是一个骨再生过程，在这个过程中有多种生长因子的参与。现就下颌骨牵张成骨中一些相关生长因子的研究做一综述。     

单侧下颌骨牵张成骨的数值模拟

目的针对颜面短小患者建立下颌骨及咀嚼肌模型,通过有限元方法研究牵张成骨过程中下颌骨的形变规律,并与患者实际手术效果进行对比,为类似病例的治疗过程提出改进意见。方法依据临床颜面短小患者原始数据,结合MIMICS医学影像控制系统软件,运用三维重建技术构造患者下颌骨及咀嚼肌的实体结构,最后导入ANSYS有限元软件完成单侧下颌骨延长的有限元模型,并模拟手术效果。结果所建立的术前术后有限元分析模型具有数字化、个性化特征。结论数值模拟结果与手术效果进行对比,重合度较好,可以为不同病情的病人术前提供个性化的手术指导。     

骨形态形成蛋白在下颌骨快速牵张成骨中的应用*

背景：牵张成骨已经成为治疗不同类型颅面畸形和骨缺损的有效的方法,但是牵张成骨的主要缺点是牵张期和稳定期比较长,可能导致牵张过程中严重的并发症。 目的：总结骨形态形成蛋白在快速牵张成骨过程中作用的研究现状。 方法：电子检索计算机Pubmed数据库(1989/2011)收录的骨形态形成蛋白和牵张成骨相关综述和论文报告。 结果与结论：共纳入骨形态形成蛋白在快速牵张成骨中的作用相关文献32篇。骨形态形成蛋白具有很强的成骨活性,能促进骨再生和骨改建。目前的研究显示应用骨形态形成蛋白能加快牵张成骨过程中新骨形成和缩短治疗的疗程。但是骨形态形成蛋白应用于临床还需要进一步的研究。     

兔下颌骨牵张成骨中HIF-1α和c-fos的表达及其相关性

目的 探讨兔下颌骨牵张成骨中HIF-1α和c-fos的表达及其相关性.方法 建立25只成年健康家兔下颌骨牵张成骨模型,采用免疫组织化学方法,分别在牵张中期、牵张末期、固定期第1、3、5周,检测牵张区新骨组织中HIF-1α和c-fos的分布及表达变化. 结果 HIF-1α在牵张末期和固定第1周表达为强阳性,c-fos在牵张中、末期和固定第1周表达为强阳性,两者均明显强于固定第3、5周.且均主要表达于成纤维细胞、成骨细胞和新埋入骨基质中的骨细胞中. 结论 在下颌骨缺损牵张成骨中HIF-1α和c-fos在细胞中的分布及在时间点的表达具有显著的相关性,对骨及血管的生成可能起着重要的生物学作用.     

脂联素对兔下颌快速牵张成骨的影响☆

背景：脂联素可参与骨代谢及成血管过程,但目前关于脂联素对牵张成骨有无促进作用尚不清楚。 目的：通过建立兔下颌快速牵张动物模型,探讨局部应用脂联素对骨牵张新骨再生的影响。 方法：16只新西兰大白兔随机摸球法均分为对照组及实验组,建立兔下颌单侧快速牵张模型,牵张速率为2 mm/d。在牵张开始的1,3,5 d,对照组及实验组分别于牵张间隙注入200 μL磷酸盐缓冲液或含有2 μg重组人脂联素的磷酸盐缓冲液。 结果与结论：两组动物牵张间隙内均可观察到新骨生成,组织学及显微CT检查显示实验组的新骨生成与钙化明显高于对照组。实验结果显示局部应用脂联素可有效促进兔下颌快速骨牵张的新骨再生。 关键词：脂联素;牵张成骨;动物模型;新骨再生;下颌骨 doi:10.3969/j.issn.1673-8225.2012.11.002      

富血小板血浆在兔下颌骨牵张成骨中的作用

目的探讨富血小板血浆对兔下颌骨牵张成骨的影响。方法将24只成年健康白兔随机分为2组,实验组在牵张期注射自体富血小板血浆于牵张间隙中,对照组不注射富血小板血浆。牵张结束后2、4、8周每组各处死4只动物取材,进行骨密度测量、组织学和扫描电镜观察。结果所有实验动物下颌骨均被成功延长7.0mm,牵张间隙中可见新骨组织生成与改建。同对照组相比,实验组新骨生成与矿化较快,牵张间隙中骨小梁分布密度及成熟度也较高。结论自体富血小板血浆对兔下颌骨牵张成骨可能有明显的促进作用。     

牵张成骨区成骨方式的有限元分析

背景：有研究报道牵张间隙内存在软骨内成骨及膜内成骨两种成骨方式,也有研究认为在只有轴向牵张力作用而无其他方向外力干扰情况下,牵张新骨仅以膜内成骨一种方式成骨。 目的：研究不同咬合状态下牵张区新生组织所处的力学环境,并验证该环境是否具有诱导和促进成软骨的能力,解释成骨方式不一致的矛盾。 方法：建立下颌骨双侧牵张成骨模型,设定牵开距离为1 cm,固定后4周,在骨面咀嚼肌附着部位施加肌肉力来模拟实际咀嚼运动。选择双侧后牙咬合、左侧磨牙咬合及前牙咬合状态进行模拟分析,考察压应力/张应力、剪应力、范式应力变化。 结果与结论：①双侧后牙咬合状态：范式应力及剪应力自舌侧向颊侧力值有所增加。自远中舌侧下缘至远中颊侧上缘,压应力逐渐转为张应力。②前牙咬合状态：范式应力及剪应力自舌侧面逐渐向颊侧减小。压应力/张应力在舌侧面压应力较大,向颊侧逐渐减小,过渡为张应力。③左侧磨牙咬合状态：左侧牵张区各应力和双侧后牙咬合状态下的各应力分布特点很相近,但最大值均要比双侧后牙咬合状态下的相应力值小。右侧牵张区范式应力在远中面的上缘和下缘出现应力最大值,近中颊侧下缘出现应力最小值,之间为过渡区。剪应力与范式应力特点相似。压应力/张应力则主要出现在近中下缘。说明在固定早期若牵张器不够稳定,咀嚼运动可以在新生组织内形成一个促使软骨形成的力学环境,为成骨方式不一致的矛盾指出了明确的答案。     

下颌骨牵引成骨术对下牙槽神经的影响

牵引成骨术[1] 在颌面外科主要用于矫治小下颌畸形、半侧颜面发育不全畸形 ,并在上下颌骨宽度不足、严重上颌后缩畸形、下颌骨或牙槽骨缺损治疗方面显示出独特优势。下牙槽神经 (ｉｎｆｅｒｉｏｒａｌｖｅｏｌａｒｎｅｒｖｅ ,ＩＡＮ)位于骨性下颌管中 ,在下颌骨牵引过程中会同时受到牵拉 ,这是否会损伤ＩＡＮ的形态结构 ,能否完全恢复 ,目前意见不统一。我们通过动物实验研究 ,探讨下颌骨牵引成骨术对ＩＡＮ形态结构的动态影响。一、材料和方法青年恒河猴 16只 ,年龄 3～ 4岁 ,体重 5～ 7ｋｇ。 10只行单侧下颌骨牵引延长 ,6只行双侧下颌骨…     

兔下颌骨牵张成骨中HIF-1α和EM>c-fos/EM>的表达及其相关性

目的 探讨兔下颌骨牵张成骨中HIF-1α和c-fos的表达及其相关性。 方法 建立25只成年健康家兔下颌骨牵张成骨模型,采用免疫组织化学方法,分别在牵张中期、牵张末期、固定期第1、3、5周,检测牵张区新骨组织中HIF-1α和c-fos的分布及表达变化。 结果 HIF-1α在牵张末期和固定第1周表达为强阳性,c-fos在牵张中、末期和固定第1周表达为强阳性,两者均明显强于固定第3、5周。且均主要表达于成纤维细胞、成骨细胞和新埋入骨基质中的骨细胞中。 结论 在下颌骨缺损牵张成骨中HIF-1α和c-fos在细胞中的分布及在时间点的表达具有显著的相关性,对骨及血管的生成可能起着重要的生物学作用。     

富血小板纤维蛋白对兔下颌骨牵引成骨区骨形态发生蛋白-4表达的影响

目的:探讨富血小板纤维蛋白(PRF)对牵引成骨区骨形态发生蛋白-4(BMP-4)表达的影响。方法:25只大耳白兔随机分2组,分别行双侧下颌骨皮质骨切开术,一侧下颌骨牵引间隙放置PRF膜作为实验组,对侧作为对照组,分别于稳定期第3、7、14、21、28天处死一组动物,切取牵引间隙处骨痂行H-E染色和BMP-4免疫组织化学显色,细胞图像分析仪测量牵引间隙处骨痂BMP-4表达情况。结果:下颌牵引延长后牵引间隙均有新骨形成,免疫组织化学显色显示BMP-4主要定位于成骨细胞的细胞质中。实验组在稳定期3、7、14、21 d BMP-4表达的阳性细胞率和阳性面积百分比均显著高于对照组,稳定期28 d BMP-4表达的阳性细胞率和阳性面积百分比与对照组比较差异均无统计学意义。结论:PRF能促进兔下颌骨牵引成骨区新骨的生成,BMP-4可能在牵引成骨过程中调控组织细胞应力信号传递,发挥成骨作用。     

Strategies of enhancing bone regenerate formation in distraction osteogenesis

Distraction osteogenesis (DO) is a commonly used technique in multiple orthopedic sub-specialties, including trauma, oncology and pediatrics. This technique aims to produce new bone formation in the distraction gap in a controlled manner. The issue with this technique has been the high risk of complications, one of which is poor regenerate formation during the distraction process. Although several factors (including patient and operative factors) and techniques (including surgical, mechanical and pharmacological) have been described to ensure successful regenerate formation during the process of DO, these factors are sometimes difficult to control clinically. Our aim from this review is to highlight the different factors that affect DO, modalities to assess the regenerate and review treatment options for poor regenerate in the distraction gap. In addition, we propose a management protocol derived from the available literature that can be used to facilitate the management of inadequate regenerate formation.     

犬牙槽骨牵张成骨的生物力学和组织学分析

背景：牙槽骨牵张成骨是解决严重牙槽骨萎缩的重要方法,其成骨过程和生物力学对于以后的种植和修复极为重要,目前一直缺少相关的实验研究。 目的：分析犬牙槽骨牵张成骨的生物力学和组织学特点。 方法：先拔除12只杂种犬双侧下颌前磨牙,牙槽骨修整后,制作萎缩牙槽骨模型。3个月后,植入骨内型牙槽骨牵张器。经过7 d的间歇期,以1 mm/d,1次/d的频率进行牙槽骨垂直向增高。在固定期的1,2和3个月,对牵张后的牙槽骨进行临床、生物力学、放射学和组织学检测。 结果与结论：所有牵张器与周围组织愈合良好。牵张结束时,临床和放射学检查显示：萎缩牙槽骨分别增高 (4.80±0.50) mm和(5.12±0.67) mm。组织学检测发现牵张区骨小梁在固定期的1-3个月成熟,其剪切力逐步提高,固定期3个月时和自体骨的剪切力相当。结果显示牙槽骨牵张成骨的组织学和生物力学性能在固定期3个月时与自体骨相当。 中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程全文链接：     

OP-1 injection increases VEGF expression but not angiogenesis in a rabbit model of distraction osteogenesis

We have previously shown that a single injection of rhBMP-7 (OP-1) applied to the regenerate early during distraction accelerates bone consolidation in a rabbit model of distraction osteogenesis. In the present study, we hypothesised that the injection of OP-1 improves bone consolidation by increasing blood flow to the distracted site. Blood flow into the regenerate of a rabbit model was measured and vascular endothelial growth factor (VEGF) expression was tested using semi-quantitative PCR. Immunohistochemistry was used for assessing the temporal and spatial expression of platelet endothelial cell adhesion molecule (PECAM), VEGF and its receptors following OP-1 injection. We observed a higher expression of VEGF and its receptors in the regenerate with OP-1 treatment. However, there was no difference in the increase in bone blood flow nor PECAM expression between the treated and control groups of animals. Interestingly, the increased expression of VEGF and its receptors was associated with chondrocyte and fibroblast-like cells, but not with endothelial cells. These results suggest that accelerated ossification by OP-1 may depend on a non-vascular mechanism, possibly involving a non-angiogenic function of VEGF signalling.     

The role of masticatory muscles in the continuous loading of the mandible

Muscles are considered to play an important role in the ongoing daily loading of bone, especially in the masticatory apparatus. Currently, there are no measurements describing this role over longer periods of time. We made simultaneous and wireless in vivo recordings of habitual strains of the rabbit mandible and masseter muscle and digastric muscle activity up to ～25 h. The extent to which habitually occurring bone strains were related to muscle-activity bursts in time and in amplitude is described. The data reveal the masseter muscle to load the mandible almost continuously throughout the day, either within cyclic activity bouts or with thousands of isolated muscle bursts. Mandibular strain events rarely took place without simultaneous masseter activity, whereas the digastric muscle only played a small role in loading the mandible. The average intensity of masseter-muscle activity bouts was strongly linked to the average amplitude of the concomitant bone-strain events. However, individual pairs of muscle bursts and strain events showed no relation in amplitude within cyclic loading bouts. Larger bone-strain events, presumably related to larger muscle-activity levels, had more constant principal-strain directions. Finally, muscle-to-bone force transmissions were detected to take place at frequencies up to 15 Hz. We conclude that in the ongoing habitual loading of the rabbit mandible, the masseter muscle plays an almost non-stop role. In addition, our results support the possibility that muscle activity is a source of low-amplitude, high-frequency bone loading.     

Stimulation of reparative osteogenesis by millimeter band electromagnetic radiation in experimental traumatic defects of the mandible

I. M. Sechenov First Moscow Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR D. S. Sarkisov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 111, No. 4, pp. 436–439, April, 1991.     

Biomechanical response of a mandible in a patient affected with hemifacial microsomia before and after distraction osteogenesis

Distraction osteogenesis (DO) has gained wide acceptance in the craneofacial surgery due to the huge possibilities it offers. However this orthopaedic field is under continuous development as it still presents uncertainties. In this context, numerical modelling/analysis may help us to design patient specific treatments once they have been experimentally verified. This paper presents a finite element analysis of the biomechanical behavior of a patient's mandible with hemifacial microsomia (HFM) before and after distraction. In order to check the effectiveness of the clinical protocol, the predicted biomechanical response will also be compared with that of a symmetrical healthy mandible. Strain and displacement fields, masticatory forces as well as reaction forces at the condyles are evaluated in each mandible analyzed. The results show that the present model is a useful tool to understand the normal function of the mandible and to predict changes due to alterations in the mandible geometry, such as those occurring in hemifacial microsomia.