纤维蛋白胶复合自体骨髓与人工骨促进脊柱融合的现状与展望

背景：如何利用纤维蛋白胶的黏合性在术中复合自体骨髓与人工骨来提高脊柱融合的成功率,值得进一步研究。 目的：综述纤维蛋白胶的研究背景、成分、作用原理及理化特性,纤维蛋白胶及自体骨髓复合人工骨在脊柱融合中应用的现状。 方法：由第一作者检索1994/2010 CNKI系列数据库及PubMed数据库有关纤维蛋白胶的研究背景、成分、作用原理及理化特性,纤维蛋白胶在构建组织工程骨及修复骨缺损中的应用,自体骨髓复合人工骨移植在修复骨缺损中的应用,脊柱融合中植骨方法应用等方面的文献。 结果与结论：自体骨髓复合人工骨移植修复骨缺损在临床取得了较好的疗效,因此在脊柱融合中利用自体骨髓复合人工骨来提高脊柱融合率应该是可行的方案,但以往自体骨髓混合人工骨的过程相对简单,又由于自体骨髓流动性大,注射后容易流失,明显降低了自体骨髓的成骨作用。因此设想在临床手术中,利用纤维蛋白胶的黏合特性将自体骨髓与人工骨黏合在一起,植入脊柱关节突、横突部位,充分发挥骨髓的最大成骨作用,这将是临床一个提高脊柱融合率的简易、快速、有效的方法,有待进一步的深入研究。     

Micro-architecture of calcium phosphate granules and fibrin glue composites for bone tissue engineering

Calcium phosphate ceramics are currently used as bone graft substitutes in various types of clinical applications. Fibrin glue is also used in surgery due to its haemostatic, chemotactic and mitogenic properties. By combining these two biomaterials, new composite scaffolds were prepared. In this study, we attempt to analyse whether thrombin concentration in the fibrin glue could influence the properties of the composite. The association between fibrin glue and calcium phosphate ceramic granules was characterized at the ultra structural level. Micro and macroporous biphasic calcium phosphate ceramic granules with a diameter of 1-2mm composed of hydroxyapatite and beta-tricalcium phosphate (60/40) were associated to fibrin glue. The composites were observed by scanning and transmission electron microscopy and microcomputed tomography. Fibre thickness, porosity and homogeneity of the fibrin clot were modified by increased the thrombin concentration. Mixing fibrin glue with calcium phosphate granules (1:2) did not modify the microstructure of the fibrin clot in the composite. Nevertheless, thrombin interacted with the bioceramic by inducing the nucleation of crystalline precipitate at the ceramic/fibrin glue interface. Combining fibrin sealant and calcium phosphate ceramics could lead to new scaffolds for bone tissue engineering with the synergy of the properties of the two biomaterials.     

Enhanced bioactivity of a poly(propylene fumarate) bone graft substitute by augmentation with nano-hydroxyapatite

The bioactivity of a nano-hydroxyapatite-augmented, bioresorbable bone graft substitute made from the unsaturated polyester, poly(propylene fumarate), was analyzed by evaluating biocompatibility and osteointegration of implants placed into a rat tibial defect. Three groups of eight animals each were evaluated by grouting bone graft substitutes into 3-mm holes that were made into the anteromedial tibial metaphysis of rats. Thus, a total of 24 animals was included in this study. Two different formulations varying as to the type of hydroxyapatite were used: Group 1 - nano-hydroxyapatite, Group 2 - micron-hydroxyapatite, with a Group 3 control defect remaining unfilled. Animals of each of the three groups were sacrificed in groups of eight at postoperative week three. Histologic analysis revealed best superior biocompatibility and osteointegration of bone graft substitutes when nanohydroxyapatite was employed. At three weeks, there was more reactive new bone formation in this group when compared to the micron-hydroxyapatite group. The control group showed incomplete closure of the defect. This study suggested that nano-hydroxyapatite may improve upon the bioactivity of bone implant and repair materials. The model scaffold used in this study, poly(propylene fumarate), appeared to provide an osteoconductive pathway by which bone will grow in faster. Clinical implications of the use potential advantages of nano-hydroxyapatite on bone repair and orthopaedic implant design are discussed.     

Choukroun富血小板纤维蛋白在口腔种植骨缺损中的研究与进展

背景：近年来,Choukroun富血小板纤维蛋白作为一种富含自体细胞因子和生长因子的新型生物材料,在口腔种植骨缺损的临床应用中受到了广泛关注。 目的：就富血小板纤维蛋白的实验及临床研究进展进行综述。 方法：由第一作者应用计算机检索PubMed数据库及中国期刊网全文数据库2000-01/2011-12有关富血小板纤维蛋白生物学特性、实验研究以及临床应用等方面的文章,英文检索词为“choukroun’s platelet-rich fibrin,platelet-rich plasma,dental implant,bone defect,GBR”,中文检索词为“富血小板纤维蛋白,富血小板血浆,口腔种植,骨缺损,引导骨再生”。排除重复性研究,共保留30篇文献进行综述。 结果与结论：富血小板纤维蛋白由纤维蛋白网、血小板及粒细胞等组成,是目前较为先进的一种富含成骨作用因子的血液制品。具有制备过程操作简单、不需要添加其他制剂的特点,同时还有效模拟生理状态下血凝块中纤维蛋白的形成,与人体正常血凝块中的纤维蛋白相似,并很好地避免了免疫排斥和交叉感染的发生。在实验研究及临床应用中均显示了很好的促进组织愈合的能力。加之其成本低廉、取材方便等优点,在今后的口腔种植领域将得到越来越多的关注。     

A novel methodology for imaging new bone formation around bioceramic bone substitutes

In this study, Frost's bulk-staining in combination with confocal laser scanning microscopy (CLSM) was used to image and characterize ground sections of undecalcified rat bone tissue with in situ bioceramic implants. This was addressed by bulk staining specimens in alcohol-soluble basic fuchsin dye. The ground sections were imaged using CLSM in the confocal fluorescence mode. Confocal images revealed that the newly formed bone could be clearly distinguished from bone marrow and cortical bone, as well as from the implant material.     

异种煅烧骨材料修复骨缺损：特点、优势与问题

文题释义： 拔牙位点保存：当由于各种原因拔除牙齿后,其周围的牙槽骨在前6个月将会发生水平向和垂直向上的严重吸收,导致种植手术时骨量不足,严重影响种植修复的成功率。许多学者建议在彻底拔除牙齿的同时,于拔牙窝内放置骨粉和骨膜进行保护和修复性干预,将会显著减少周围牙槽嵴生理或病理性的骨吸收、阻断周围龈缘和龈乳头的退缩,保存牙槽窝周围软硬组织的高度和形态,并改善新生软硬组织的质量,为后期的种植美学修复创造良好条件。 爬行替代：在具有良好血供的骨损伤区域植入骨移植材料后,将会激活骨再生程序：破骨细胞开始活动,并在植骨材料上进行骨吸收,形成一条条“沟”状缺损,引导骨原细胞进入,随之分化为成骨细胞,成骨细胞分泌大量的类骨质,钙化成骨基质,成熟为骨单位。即在骨移植材料逐渐吸收的部位新生骨组织逐渐形成,充填骨吸收的凹陷。 背景：牙种植区域的牙槽骨骨量不足增加了种植手术难度,植骨材料的出现成功解决了此类难题。在所有单一植骨材料中,异种煅烧骨被广泛用于治疗骨缺损,但单独使用煅烧骨时仍然存在一些缺点。 目的：结合最新的相关研究动态,对异种煅烧骨材料修复骨缺损的相关研究进展作以综述。 方法：第一作者以“calcined bone,xenogeneic bone,bone augmentation,bone substitute”为英文检索词,以“煅烧骨、异种骨、骨增量、骨替代材料”为中文检索词,应用计算机检索 PubMed、维普、万方、知网数据库中1986年1月至2019年11月已发表的相关文献,并进行筛选、归纳与总结,最终纳入69篇相关文献进行综述。 结果与结论：在所有骨移植材料中,异种煅烧骨的结构与人类骨骼相似,具有良好的互连孔性,便于血管因子和骨原细胞进入,为新骨形成提供了通道和支架作用,同时具有良好的生物相容性及一定的降解作用,受到临床医生们的青睐。但其本身仍然存在溶解度较低、吸收缓慢、机械性能较差等不足,这就促使研究者们研发出将煅烧骨与陶瓷、聚合物、骨诱导因子及金属离子等其他材料复合,发挥出所参与材料的优点,从而使复合材料成为骨增量材料的首选。 ORCID: 0000-0002-0313-7462(李芳) 中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程     

Micro-computed tomographic analysis of bone healing subsequent to graft placement

A micro-computed tomographic (muCT) analysis of bone healing subsequent to graft (tri calcium phosphate/TCP) placement in the maxillary sinus prior to dental endosteal implant placement was the focus of the current study. Ten trephined rod shaped human bone cores were obtained three months after the placement of particulate graft material. Using the muCT, samples were evaluated at 6 and 20 mum resolutions. The images exhibited regions of different grey scale (GL) magnitudes for bone and graft allowing a differentiation and quantification of the two sample regions. The GL threshold magnitudes at 20 mum resolution were determined to be less than 235 for organic and fluid, 235-450 for bone, 400-600 for bone and graft, and 600 and above for the graft material. The graft material was integrated with the bone showing the osteoconductivity of the TCP material, the mean bone volume was 25.50 (11.28) ranging from 5.66 to 37.9 and the mean graft volume was 0.42 (0.37) ranging from 0.01 to 1.17. The mean graft to bone volume ratio was 0.015 (0.01) with a range from 0.002 to 0.024. The structural data and observations from two- and three-dimensional images provided a valuable assessment of the graft distribution, its relation to modeling bone and also the anatomy of the healing bone. Thus this study demonstrated the capability to uniquely evaluate the status of healing bone associated with this TCP grafting biomaterial with opportunities for subsequent correlations with histomorphometrical studies and clinical outcomes of these type implant treatments.     

Mechanical basis for bone retention around dental implants

This study, analytically, through finite element analysis, predicts the minimization of crestal bone stress resulting from implant collar surface treatment. A tapered dental implant design with (LL) and without (control, C) laser microgrooving surface treatment are evaluated. The LL implant has the same tapered body design and thread surface treatment as the C implant, but has a 2-mm wide collar that has been laser micromachined with 8 and 12 microm grooves in the lower 1.5 mm to enhance tissue attachment. In vivo animal and human studies previously demonstrated decreased crestal bone loss with the LL implant. Axial and side loading with two different collar/bone interfaces (nonbonded and bonded, to simulate the C and LL surfaces, respectively) are considered. For 80 N side load, the maximum crestal bone distortional stress around C is 91.9 MPa, while the maximum crestal bone stress around LL, 22.6 MPa, is significantly lower. Finite element analysis suggests that stress overload may be responsible for the loss of crestal bone. Attaching bone to the collar with LL is predicted to diminish this effect, benefiting crestal bone retention.     

Bioresorbable bone graft substitutes of different osteoconductivities: a histologic evaluation of osteointegration of poly(propylene glycol-co-fumaric acid)-based cement implants in rats

Bioresorbable bone graft substitutes may significantly reduce the disadvantages associated with autografts, allografts and other synthetic materials currently used in bone graft procedures. We investigated the biocompatibility and osteointegration of a bioresorbable bone graft substitute made from the unsaturated polyester poly(propylene-glycol-co-fumaric acid), or simply poly(propylene fumarate), PPF, which is crosslinked in the presence of soluble and insoluble calcium filler salts. Four sets of animals each having three groups of 8 were evaluated by grouting bone graft substitutes of varying compositions into 3-mm holes that were made into the anteromedial tibial metaphysis of rats. Four different formulations varying as to the type of soluble salt filler employed were used: set 1--calcium acetate, set 2--calcium gluconate, set 3--calcium propionate, and set 4--control with hydroxapatite, HA, only. Animals of each of the three sets were sacrificed in groups of 8 at postoperative week 1, 3, and 7. Histologic analysis revealed that in vivo biocompatibility and osteointegration of bone graft substitutes was optimal when calcium acetate was employed as a soluble salt filler. Other formulations demonstrated implant surface erosion and disintegration which was ultimately accompanied by an inflammatory response. This study suggested that PPF-based bone graft substitutes can be designed to provide an osteoconductive pathway by which bone will grow in faster because of its capacity to develop controlled porosities in vivo. Immediate applicability of this bone graft substitute, the porosity of which can be tailored for the reconstruction of defects of varying size and quality of the recipient bed, is to defects caused by surgical debridement of infections, previous surgery, tumor removal, trauma, implant revisions and joint fusion. Clinical implications of the relation between developing porosity, resulting osteoconduction, and bone repair in vivo are discussed.     

自体块状皮质骨修复种植区颌骨缺损

文题释义：自体块状皮质骨：自体块状皮质骨具有刚性的板层状结构,毛细血管的含量较低,因此移植后很难维持具有活性的成骨细胞或骨祖细胞,致密的矿化基质导致血管重建和长入的速度相对缓慢,但其空间维持能力强,生物相容性好,其中含有的成骨细胞和生长因子对骨再生起促进作用,是骨移植材料的“金标准”。 Onlay植骨：于两侧下颌外斜线处取长方形皮质骨块,在上颌左侧骨缺损区植入皮质骨块,右侧骨缺损区植骨同期植入种植体。 背景：自体骨有骨传导、骨诱导及骨生成的特性,同时具有良好的生物相容性,移植后无排斥反应。但关于自体骨块移植后的骨块是完全被吸收替代？还是能保留细胞活性长期存留？仍存在争议。 目的：观察皮质骨移植后改建再生过程中的组织学变化。 方法：6只健康比格犬麻醉后拔除两侧上颌前磨牙,并去除颊侧宽约10 mm、长约15 mm、厚度约2 mm的骨板,建立上颌骨缺损模型,在双侧下颌骨体颊侧切取相应大小的块状皮质骨并修整边缘。在上颌骨缺损区移植皮质骨块,一侧为单纯块状皮质骨移植,另一侧在块状皮质骨移植同期植入种植体。分别于骨移植后3,6个月取材,进行大体观测和组织学观察,分析移植骨块的吸收率、移植骨中的细胞存活率。实验方案经大连医科大学动物实验伦理委员会批准。 结果与结论：①大体观察可见移植骨块体积逐渐缩小,边缘圆钝,与基骨结合稳固;②6个月时全部种植体脱落;硬组织磨片可见移植骨块与基骨间存在新生骨连接;6个月时移植骨骨陷窝孔隙率明显低于3个月,移植骨吸收率显著高于3个月(均P < 0.05);③结果说明,块状皮质骨移植后,能够与受植区基骨发生骨结合,其内部的骨细胞部分保持活力,随着愈合期延长,新生骨细胞的比例增加,移植骨块的体积逐渐变小。皮质骨移植同期种植后移植物吸收明显,种植体骨结合不良。 ORCID: 0000-0001-5201-9377(王宁) 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     

Novel in vivo method for evaluation of healing around implants in bone

A material implanted in bone is always inserted into coagulating blood. Protein and cell interactions during this initial implantation time will govern later healing. Many studies have focused on the tissue surrounding implants. We have developed a method for evaluation of healing around implants in bone by studying cells adhering to the implant surface. Hydrophilic titanium discs were inserted into rat tibiae. Samples were retrieved after 1, 2, 4, and 8 days of implantation and were analyzed by fluorescence microscopy techniques and scanning electron microscopy. Both proliferating and apoptotic cells were found on the surface. Generally, cells closest to the implant surface were nonviable whereas cells in the fibrin network a distance from the surface were viable. Bone morphogenetic protein-2 (BMP-2) is an osteogenic substance. An increase in BMP-2-positive cells was seen during the implantation period, and a population of large BMP-2-positive cells appeared on the surface after 4 days of implantation. The method developed here is a suitable tool for rapid evaluation of the initial healing around implant material.     

A composite graft material containing bone particles and collagen in osteoinduction in mouse.

Demineralized allogenic bone matrices (DABM) and demineralized freeze-dried bone allograft (DFDBA) have been successfully used as bone-graft materials in the treatment of acquired and congenital cranio-maxillofacial defects and in some orthopedic surgery. However, these bone-graft "powders" have many shortcomings. For example, placement of particulate graft material in a hemorrhaging site can result in inadequacies or inaccurate attachment as well as loss of the graft materials. To minimize the inadequacies of powderlike graft materials, xenogenic collagen isolated from human tendon, skin, or bone was added to the bone-graft particles to form a composite spongelike implant. This material is commercially available and consists of 60% collagen and 40% DFDBA (DynaGraft, GenSci Co., Irvine, CA). The goal of this study was to evaluate the characteristics of composite graft implants in the mineralization process in an animal model in comparison with DFDBA powder and pure collagen. Seventy-two Swiss Webster mice were divided into three groups: an experimental group implanted with DynaGraft, two comparison groups implanted with either DFDBA or collagen only. All the graft materials were surgically implanted and inserted into the left thigh muscle. Mice were humanely killed at 1, 2, 3, 4, 6, 8, and 12 weeks. Then the muscle tissues in the vicinity of the implants were excised and processed for histology. Paraffin sections were stained with hematoxylin and eosin (H&E), the Von Kossa method, and Masson's trichrome. Some selected specimens were processed for transmission electron microscopic observation. After 1 week of implantation, the DynaGraft group showed calcium deposition on the collagen material and on the periphery of the DFDBA particles. Increased calcification and bone-forming cells were observed at 4-6 weeks. After 8 weeks, the implant formed a calcified nodule and only heavily mineralized connective tissue was observed at the implanted site. The group implanted with DFDBA powder showed calcification around the particulates. The collagen-sponge control group revealed no calcification or bone formation during the period of implantation. The light microscopic findings were confirmed by electron microscopy. Quantitative radiographic density DynaGraft and DFDBA graft followed sequentially over a period 120 days. It was concluded that a higher rate of calcification and bone formation was produced in the composite graft implant compared to the DFDBA implant. The composite graft material (DynaGraft), which contains both collagen and DFDBA, proved to be more effective for bone formation than particle components alone.     

多孔羟基磷灰石与富血小板血浆和纤维蛋白胶复合修复骨缺损

背景：自体骨移植是治疗骨缺损的最理想方法,但来源有限,供区有一定的并发症,所以寻找自体骨的替代材料一直是骨科学领域的研究方向。 目的：观察珊瑚多孔羟基磷灰石、富血小板血浆和纤维蛋白胶复合物修复骨缺损的效果。 方法：在新西兰大白兔双侧前臂桡骨中段截骨1.5 cm制成骨缺损模型,随机分为3组,实验组植入珊瑚多孔羟基磷灰石、富血小板血浆和纤维蛋白胶复合物,对照组植入自体骨,空白对照组未植入任何物质。 结果与结论：①X射线：实验组术后12周时骨缺损基本修复,塑性完全,愈合过程与对照组同步;空白对照组骨缺损无明显变化。②组织病理学：实验组与对照组术后12周时骨缺损基本修复,出现成熟板层骨及哈佛氏管;空白对照组仅见大量成纤维细胞增生,未见骨质形成。③生物力学：术后2周时实验组最大扭矩和抗扭刚度优于对照组(P < 0.05),术后12周时两组最大扭矩和抗扭刚度差异无显著性意义。表明珊瑚多孔羟基磷灰石、富血小板血浆和纤维蛋白胶复合物具有促骨质愈合的作用,甚至在术后早期修复骨缺损的效果优于自体骨。     

应用浓缩生长因子行上颌窦内提升后种植体周围骨变化

背景：许多实验和临床研究报道不使用植骨材料而单纯采用患者静脉血、可吸收胶原海绵、富纤维蛋白凝块等均可促进新骨形成,那么只移植浓缩生长因子在上颌窦内提升中是否也能有效地促进骨再生？目的：以浓缩生长因子作为移植材料行上颌窦内提升,观察种植体周围骨水平的改变。方法：纳入26例患者,其中男14例,女12例,年龄35-73岁,均以自体浓缩生长因子作为移植材料行上颌窦内提升,同期植入Astra Tech种植体。按随访时间分为6-12个月组、13-18个月组与18个月以上组,按术前剩余牙槽骨高度分为≤5 mm组、5-7 mm组与≥7 mm组,按术后上颌窦提升高度分为≤2 mm组、2.0-3.0 mm组与≥3 mm组,随访观察种植体存留率与边缘骨水平变化。结果与结论：共植入种植体44 枚,修复后随访6-18个月,43枚种植体修复成功,种植体存留率为98%。不同随访时间组间近、远中边缘骨水平改变比较差异无显著性意义,显示以浓缩生长因子作为移植材料行上颌窦内提升在随访6-18个月内能形成良好骨结合。不同剩余牙槽骨高度组间的近、远中边缘骨水平改变比较差异无显著性意义,不同窦底提升高度组间的近、远中边缘骨水平改变比较差异无显著性意义,说明剩余牙槽骨高度与上颌窦提升高度对种植体周骨组织形成无明显影响。表明在上颌窦内提升时使用浓缩生长因子移植材料同期植入种植体存留率高,种植体周围牙槽骨稳定,长期效果有待进一步观察。 中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程     

低结晶性碳酸磷灰石团块骨移植材料的合成及性能

背景：作为优良的生物吸收性骨移植材料,碳酸磷灰石团块通常通过烧结过程来制备,然而,烧结过程中造成的碳酸含量流失将导致其生物吸收性明显下降,低于生体骨,从而影响新骨的生成。 目的：合成低结晶性碳酸磷灰石团块作为骨移植材料并研究其性能。 方法：通过氢氧化钙团块的碳酸化生成碳酸钙团块,浸泡在60 ℃、1 mol/L磷酸二氢铵盐溶液中1-14 d,并对各样本通过径向抗拉强度测试进行生物力学性能分析,通过X射线衍射分析、红外吸收光谱测定、扫描电子显微镜观察与碳酸含量、钙磷元素测定等进行理化性能分析。 结果与结论：结果发现,经过磷酸二氢铵盐溶液处理14 d后,碳酸钙已几乎完全转化成为结晶度较低的B型碳酸磷灰石;最终生成物的径向抗拉强度值为(10.27±1.08) MPa,满足骨缺损移植材料的机械强度要求;其碳酸含量为(4.80±0.50)%,与生体骨的碳酸含量极其接近;钙磷摩尔比为1.63±0.01,提示为贫钙型碳酸磷灰石。结果证实,实验将碳酸钙团块浸泡在60 ℃,1 mol/L的磷酸二氢铵盐溶液中,成功合成了具有足够强度的低结晶性B型碳酸磷灰石团块,方法简单可行。     

微弧氧化/电化学沉积钙磷涂层纯钛种植体的骨内植入

背景：近年来已有对微弧氧化/电化学沉积技术制备涂层在材料性能方面的相关报道,但对这种材料植入体内的性能研究较少见。 目的：观察纯钛种植体经微弧氧化/电化学沉积处理后的骨结合和新骨形成情况。 方法：通过微弧氧化/电化学沉积方法在纯钛上制备含钙磷元素的涂层,然后将该种植体和纯钛种植体分别植入羊两侧胫骨种植窝内,于动物处死前15,5 d分别进行注射四环素进行四环素标记。术后4,12周分别进行X射线、扫描电镜及激光共聚焦观察。 结果与结论：两侧X射线表现相似,种植体周围均无明显阴影,骨小梁排列和骨质密度与宿主骨基本一致。术后4周时,在电镜下可观察到两组种植体和骨组织之间均有间隙,部分见骨性结合;术后12周时,微弧氧化/电化学沉积种植体组可形成新骨,并且新骨与种植体和原来骨组织结合紧密,涂层与钛基体没有明显间隙,纯钛种植体组也可见新骨生成,但可看到明显裂隙。激光共聚焦观察显示,微弧氧化/电化学沉积种植体组双标记带间距离及骨矿化沉积率均高于纯钛种植体组(P < 0.05)。表明微弧氧化/电化学沉积处理可增强纯钛种植体的骨结合能力及新骨形成。     

复合硫酸钙-脱钙骨基质人工骨聚甲基丙烯酸甲酯骨水泥的理化性能

背景：临床研究表明,聚甲基丙烯酸甲酯骨水泥的生物活性较差,不太适合单独用于经皮椎体成形。 目的：探索一种能满足经皮椎体成形填充材料理化要求的具备生物活性的多孔复合材料。 方法：将碳酸氢钠、硫酸钙-脱钙骨基质颗粒粉末和聚甲基丙烯酸甲酯骨水泥按不同质量比例(1∶40∶60,0∶40∶60,   1∶0∶100)混合构成A、B、C 3种复合材料。检测各种复合物凝固时间、聚合温度、抗稀散性及成型材料的抗压性,以扫描电镜观察其超微结构。 结果与结论：A、B组与C组材料的凝固时间、聚合温度、抗压强度比较差异有显著性意义,但均符合经皮椎体成形填充材料基本要求,抗稀散性均良好。扫描电镜示A组结合较B、C组材料疏松,材料内部孔隙较多。提示复合材料A具有良好的理化性能,能满足作为经皮椎体成形填充材料的基本条件,且具备较好的孔隙结构,可以进一步研究其组织相容性、可降解性、骨传导性及骨诱导性等生物学性能。     

Beta-TCP bone graft substitutes in a bilateral rabbit tibial defect model

The use of artificial bone graft substitutes has increased as the surgical applications widen and the availability of allograft bone decreases. The ideal graft substitute should reabsorb with time to allow and encourage new bone formation whilst maintaining its properties as an osteoconductive scaffold until it is no longer required. A potential disadvantage of some synthetic substitutes is their long dissolution time. Beta-tricalcium phosphates (beta-TCPs) have some advantages when compared to hydroxyapatite (HA), when used as a filler, in that it is more rapidly reabsorbed. Three commercially available and clinically used beta-TCP bone graft substitutes with the same chemistry (Vitoss, Osferion, Chronos) but with varying macro and microscopic characteristics were investigated using a bilateral tibial metaphyseal defect model in New Zealand white rabbits. When placed into tibial defects all three materials performed similarly in terms of mechanical properties of the healing defects. A decrease in properties was found at 12 weeks where implant resorption was nearly achieved while remodelling of the anteromedial cortex had yet to be completed. All materials were osteoconductive and supported new bone formation while implant resorption with time differed between materials. Vitoss resorbed faster than the other materials and is likely to differences in particle geometry, pore structure and interconnectivity.     

Developing porosity of poly(propylene glycol-co-fumaric acid) bone graft substitutes and the effect on osteointegration: a preliminary histology study in rats

Bioresorbable bone graft substitutes could eliminate disadvantages associated with the use of autografts, allografts and other synthetic materials. We investigated a bioresorbable bone graft substitute made from the unsaturated polyester poly(propylene fumarate) which is crosslinked in the presence of soluble and insoluble calcium filler salts. This compact bone graft substitute material develops porosity in vivo by leaching of the soluble filler salts. In attempt to develop materials whose in vivo porosity can be designed such that implant degradation would occur at a rate that remains supportive of the overall structural integrity of the repairing defect site, we studied the early tissue response upon implantation in a bony defect. Three grout formulations of varying solubilities using slightly soluble hydroxyapatite (HA) and soluble calcium acetate (CA) were evaluated in 3 mm holes made in the anteromedial tibial metaphysis of 200 g Sprague Dawley rats (n = 16 per formulation for a total of 48 animals). Grout formulations cured in situ. Animals from each formulation were sacrificed in groups of 8 at 4 days and 3 weeks postoperatively. Histologic analysis of the healing process revealed improved in vivo osteointegration of bone graft substitutes when a higher loading of calcium acetate was employed. All formulations maintained implant integrity and did not provoke sustained inflammatory responses. This study suggested that the presence of a soluble salt permits in vivo development of porosity of a poly(propylene fumarate) based bone graft substitute material.     

Hyaline cartilage regeneration by combined therapy of microfracture and long-term bone morphogenetic protein-2 delivery

Microfracture of cartilage induces migration of bone-marrow-derived mesenchymal stem cells. However, this treatment often results in fibrocartilage regeneration. Growth factors such as bone morphogenetic protein (BMP)-2 induce the differentiation of bone-marrow-derived mesenchymal stem cells into chondrocytes, which can be used for hyaline cartilage regeneration. Here, we tested the hypothesis that long-term delivery of BMP-2 to cartilage defects subjected to microfracture results in regeneration of high-quality hyaline-like cartilage, as opposed to short-term delivery of BMP-2 or no BMP-2 delivery. Heparin-conjugated fibrin (HCF) and normal fibrin were used as carriers for the long- and short-term delivery of BMP-2, respectively. Rabbit articular cartilage defects were treated with microfracture combined with one of the following: no treatment, fibrin, short-term delivery of BMP-2, HCF, or long-term delivery of BMP-2. Eight weeks after treatment, histological analysis revealed that the long-term delivery of BMP-2 group (microfracture + HCF + BMP-2) showed the most staining with alcian blue. A biochemical assay, real-time polymerase chain reaction assay and Western blot analysis all revealed that the long-term delivery of BMP-2 group had the highest glucosaminoglycan content as well as the highest expression level of collagen type II. Taken together, the long-term delivery of BMP-2 to cartilage defects subjected to microfracture resulted in regeneration of hyaline-like cartilage, as opposed to short-term delivery or no BMP-2 delivery. Therefore, this method could be more convenient for hyaline cartilage regeneration than autologous chondrocyte implantation due to its less invasive nature and lack of cell implantation.