兔骨质疏松模型的快速建立和硫酸钙复合bBMP在椎体强化中的实验研究

发布时间：2018-01-04 02:35

本文关键词：兔骨质疏松模型的快速建立和硫酸钙复合bBMP在椎体强化中的实验研究　出处：《第四军医大学》2009年博士论文　论文类型：学位论文

【摘要】： 一、研究背景骨质疏松症最常见的并发症是椎体压缩骨折,手术治疗包括脊柱内固定和椎体成形术或球囊扩张椎体成形术。椎体成形术是近年来发展起来一种新的脊柱微创手术,该技术已广泛应用于治疗椎体的多种良恶性病变及骨质疏松性骨折,取得了很好的临床疗效,可以快速缓解疼痛,纠正脊柱畸形,由于椎体成形术创伤小、效果好且疗效快,已成为脊柱微创介入治疗的又一重要方法。临床上现在最常用的椎体成形术的材料为聚甲基丙烯酸甲酯(PMMA)。但PMMA充填材料具有许多缺点:病变椎体术后与相邻椎体的力学强度不同,因应力集中易导致相邻椎体的骨折;组织相容性差,无成骨作用,无生物降解性,最终不被自体骨取代;单体有细胞毒性,放热反应,其体外聚合温度达40～122℃,术中可能会引起邻近组织和神经元的热损伤。而且临床越来越要求成形材料能够携带有特殊治疗作用的药物,而PMMA并不能满足这些临床治疗的需要。如何探索一种具有良好生物相容性的成形材料,其在作为固定材料的同时又能成为携带具有特殊治疗作用的药物的载体,是本研究的目的。二、研究目的 1.探索采用去势法+甲强龙诱导法快速建立兔子骨质疏松模型的方法;评估去势+甲强龙诱导后松质骨及皮质骨的微观结构和宏观力学性能的改变;从而建立一种适用于骨科领域研究的兔骨质疏松模型的快速建模方法。 2.在已经建立的骨质疏松模型体内,采用“二维组织形态—三维空间结构—生物力学特性”的综合手段,评估硫酸钙以及硫酸钙复合bBMP对提高骨质疏松椎体骨密度、骨小梁微观结构及力学强度的作用。三研究内容和方法第一部分建立并分析评价兔骨质疏松动物模型采用随机对照研究方案,将20只新西兰大白兔随机分为去势(OVX)A组(n=4)、B组(n=8)和假手术组(Sham,n=8)。A组为单纯OVX组,B组为OVX+甲强龙肌注(4周)组。所有动物术前和术后2月均采用双能X线吸收骨密度仪测定腰椎骨密度。于术后2个月:①采用组织病理学切片方法对骨小梁结构进行组织病理学观察;②采用DEXA测定所有动物股骨髁部及皮质骨的骨密度;③采用显微CT分析松质骨骨小梁三维结构改变;④采用生物力学实验,比较实验组和对照组的松质骨和皮质骨的力学强度。第二部分硫酸钙(calcium sulfate CSC)复合bBMP材料在椎体强化中的实验研究采用随机对照研究方案,将60只新西兰大白兔随机分为C1组、C2组、C3组、C4组(n=12)和假手术组(Sham,n=12)。C组按照实验一方法建立骨质疏松模型,实验分为假手术对照组(Sham),骨质疏松对照组(C1),注射PMMA组(C2),注射CSC组(C3),注射CSC/bBMP组(C4),通过模拟椎体成形术,分别在每只兔子L2、L4、L6椎体注射材料,每组均于术后24小时,6周、12周处死4只。①采用组织病理学对骨小梁结构进行组织病理学观察;②采用MicroCT对骨小梁微观三维结构进行分析;③采用生物力学实验评估椎体骨质的结构力学强度。通过“微观结构-宏观密度-功能强度”的方法,全面衡量硫酸钙和硫酸钙复合bBMP材料对脊柱骨质疏松的治疗作用。四研究结果第一部分:手术前,Sham组、OVX-A组和OVX-B组的腰椎BMD分别为(266.7±38.58)mg/cm2、(270.1±25.38)mg/cm2和(272.8±27.08)mg/cm2手术2个月后,Sham组、OVX-A组和OVX-B组的BMD分别为(281.8±39.22)mg/cm2、(248.9±26.14)mg/cm2和(199.9±30.76)mg/cm2。OVX-B组的BMD较术前平均下降为26.72%。组织学切片观察发现,去势2个月后,OVX-B组椎体及股骨松质骨骨小梁明显稀疏、变细,局部存在骨小梁骨折及骨缺损;而对Sham和OVX-A照组骨小梁结构完整,呈圆形或椭圆形拱形结构。MicroCT分析表明,OVX-B组的骨小梁三维构筑较Sham组及OVX-A组均有显著改变(骨小梁明显变细、连接率明显下降),而OVX-A组骨小梁结构与Sham组无显著性差别。生物力学研究显示,OVX-B组椎体抗压缩强度(6.8±2.02MPa)较Sham组(14.5±3.74MPa)和OVX-A组(12.8±3.12MPa)均有显著性降低,而OVX-A组与Sham组无显著性差异。第二部分:组织形态学观察发现,CSC组和CSC/bBMP组骨小梁连接性在术后6周和12周明显优于C1对照组,形态较为规则,小梁间连接程度优于对照组。骨小梁变粗,骨折、微骨缺损处出现连接和修复;12周时骨小梁结构已经接近Sham对照组。MicroCT三维重建显示,6周时, CSC组和CSC/bBMP组骨小梁组的骨小梁三维结构参数明显优于C1对照组(P0.05),骨密度值也明显优于C1对照组(P0.05);12周时,已与Sham对照组无显著性差别。生物力学实验结果表明,在6周时,CSC组椎体的最大抗压缩强度有增加,但与C1对照组相比无显著性差异,而CSC/bBMP组椎体抗压缩强度在6周时显著高于C1对照组;在12周时,CSC组和CSC/bBMP组椎体最大抗压缩强度均较C1对照组有显著性差异(P0.05),与Sham组及PMMA组相比,未见显著性差异(P0.05)。五结论 1.通过去势+甲强龙肌注的方法,可以在2个月内快速建立兔的骨质疏松模型。 2.兔骨质疏松模型建成后,二维及三维图像显示椎体松质骨内骨小梁稀疏、变细、断裂,微观三维构筑受到破坏,并且局部形成骨小梁微骨折及微骨缺损,最终导致其力学性能下降。是一种理想可用的骨质疏松动物模型。 3.CSC以及CSC为载体复合bBMP的注射型成骨材料具有强大的骨诱导能力,可以迅速有效地改善骨质疏松椎体骨小梁的三维构筑,提高其椎体力学强度,是具有良好应用前景的椎体充填材料。
[Abstract]:First, research background
The most common complication of osteoporosis is vertebral compression fractures, surgical treatment including spinal fixation and vertebroplasty or kyphoplasty, vertebroplasty is developed in recent years a new minimally invasive spine surgery, the technology has been widely used in the treatment of benign and malignant vertebral lesions and osteoporotic fractures. We have got good curative effect, can quickly relieve pain, correct spinal deformity, because vertebroplasty has small trauma, good effect and quick effect, has become an important method of minimally invasive interventional therapy in clinic. Now the most commonly used materials for vertebroplasty polymethyl methacrylate (PMMA). But the PMMA filling material has many disadvantages: the mechanical strength of vertebral lesions and postoperative adjacent vertebral body is different, due to the stress concentration easily lead to adjacent vertebral fractures; bad histocompatibility, no osteogenesis, no biological Degradation, eventually not be replaced with autogenous bone; single cell toxicity, exothermic reaction, the in vitro polymerization temperature reaches 40 to 122 DEG C, may cause thermal damage to adjacent tissues and neurons in operation. The clinical and more and more requirements of forming materials can carry drugs special treatment function, but PMMA does not meet the the need of clinical treatment. To explore a biological forming material, it becomes the carrier of carrying drugs with special therapeutic effect in materials at the same time as fixed, is the purpose of this study.
Two, the purpose of the study
1. the ovariectomy + method of methylprednisolone induced by the rapid establishment of rabbit model of osteoporosis; microstructure and mechanical properties evaluation of OVX + methylprednisolone induced cancellous and cortical bone after the change; rapid modeling method to establish a suitable field of Department of orthopedics rabbit model of osteoporosis.
2. in vivo model of osteoporosis has been established, the organizational form of two-dimensional three-dimensional space structure and biomechanical properties of the comprehensive evaluation method, calcium sulfate and calcium sulfate combined with bBMP to improve the osteoporosis vertebral bone mineral density, trabecular bone microstructure and mechanical strength.
Three research content and method
The first part is to establish and analyze the animal model of rabbit osteoporosis
A randomized study, 20 New Zealand white rabbits were randomly divided into ovariectomized (OVX) group A (n=4), B group (n=8) and sham operation group (Sham, n=8).A group, pure OVX group, B group for OVX+ intramuscular injection of methylprednisolone (4 weeks) group. All the animal before operation and after February were measured by dual energy X-ray absorptiometry bone mineral density of lumbar spine bone density instrument. In 2 months after operation: using histopathological methods for histopathological observation of bone trabecular structure; bone density of femoral condyle were measured in all animal and cortical bone by DEXA; the changes of bone little Liang Sanwei bone structure loose by micro CT; the biomechanical experiment, comparing the experimental group and control group of cancellous bone and cortical bone strength.
Experimental study of second parts of calcium sulfate (calcium sulfate CSC) composite bBMP in vertebral enhancement
A randomized controlled study, 60 New Zealand white rabbits were randomly divided into C1 group, C2 group, C3 group, C4 group (n=12) and sham operation group (Sham, n=12).C group to establish the model of osteoporosis according to a method of experiment, the experiment was divided into sham operation group (Sham), according to osteoporosis group (C1), PMMA (C2) injection group, CSC injection group (C3), CSC/bBMP injection group (C4), through the simulation of vertebroplasty, respectively in each rabbit L2, L4, L6 body injection materials, each group in 24 hours after surgery, 6 weeks, 12 weeks and 4 Dead only. The trabecular structure for histopathological observation using histopathology; using MicroCT to analyze trabecular micro 3D structure; evaluation of structural mechanics of the vertebral bone strength by biomechanical experiment. Through the method of "micro - macro - structure density functional strength", a comprehensive measure of calcium sulfate and calcium sulfate composite material bBMP of spinal osteoporosis Therapeutic effect.
Four research results
The first part: before the operation, Sham group, OVX-A group and OVX-B group respectively for lumbar BMD (266.7 + 38.58) mg/cm2, (270.1 + 25.38) mg/cm2 and (272.8 + 27.08) mg/cm2 2 months after surgery, Sham group, OVX-A group and OVX-B group BMD respectively (281.8 + 39.22) mg/cm2. (248.9 + 26.14) mg/cm2 and (199.9 + 30.76) mg/cm2.OVX-B group BMD compared with the preoperative average decline of 26.72%. histological observation found that 2 months after ovariectomy group OVX-B vertebral and femoral cancellous bone Liang Mingxian sparse, thin, the local existence of trabecular bone fracture and bone defects of Sham; OVX-A and control group trabecular bone structure, a round or oval arch structure.MicroCT analysis showed that OVX-B group of trabecular structures compared with Sham group and OVX-A group were significantly changed (trabecular bone was significantly thinner, the connection rate decreased significantly, while OVX-A group) of trabecular bone structure and Sham was not significant difference. Biomechanical study showed that OV The compressive strength of vertebral body in group X-B (6.8 + 2.02MPa) was significantly lower than that in group Sham (14.5 + 3.74MPa) and OVX-A group (12.8 + 3.12MPa), but there was no significant difference between OVX-A group and Sham group.
The second part: the morphological observation, CSC group and CSC/bBMP group trabecular connectivity after 6 weeks and 12 weeks were significantly better than the control group C1, form a more rules, small beam connection degree than the control group. Bone fracture, micro Liang Biancu, bone defects and repair connection; at 12 weeks, bone the beam structure is close to the Sham control group.MicroCT three-dimensional reconstruction showed that at 6 weeks, CSC group and CSC/bBMP group of trabecular bone group trabecular structure parameters was significantly better than the control group (C1 P0.05), the bone density was significantly better than the control group (C1 P0.05); at 12 weeks, and control group without Sham significant differences in biomechanical. Experimental results show that, at 6 weeks, the maximum compressive strength of CSC vertebral body increased, but with the C1 control group had no significant difference compared with CSC/bBMP group, vertebral compressive strength at 6 weeks was significantly higher than that of C1 control group; after 12 weeks, CSC group and CSC/bBMP group of vertebral body The maximum compressive strength was significantly different from that of the C1 control group (P0.05), and there was no significant difference compared with that of the Sham group and the PMMA group (P0.05).
Five conclusion
1. the osteoporotic model of rabbit can be quickly established within 2 months by the method of castration + methylprednisolone intramuscular injection.
Built in 2. rabbit osteoporosis model, 2D and 3D images show vertebral cancellous bone trabecular sparse, thin, micro fracture, three-dimensional damage and local formation of trabecular bone micro fractures and micro bone defect, result in the decrease of mechanical properties. It is an ideal animal model of osteoporosis can be used.
3.CSC and CSC as carrier compound bBMP have strong osteoinductive ability, which can rapidly and effectively improve the three-dimensional structure of vertebral trabecular bone and improve their vertebral mechanical strength. It is a promising filling material for vertebral body.

【学位授予单位】：第四军医大学
【学位级别】：博士
【学位授予年份】：2009
【分类号】：R580;R-332;R687

【引证文献】