骨组织修复用生物骨水泥的研究现状及进展

在骨组织修复材料领域,可任意塑形并能在特定条件下快速自固化的生物骨水泥已成为生物医学工程研究的重要内容。该文综述了聚甲酯丙烯酸甲酯、磷酸钙、磷酸镁等生物骨水泥,并介绍了不同生物骨水泥的主要成分、固化机理及目前存在主要问题。     

具有药物缓释功能的磷酸钙骨水泥的研究进展

磷酸钙骨水泥作为一种新型的骨修复材料,以其生物相容性高和易塑形的特点得到了材料界和医学界的广泛关注.利用药物定点缓释,将抗癌或消炎等药物引入磷酸钙骨水泥中,能达到骨修复与冶疗的双重目的.本文综述了具有药物缓释功能的磷酸钙骨水泥的研究进展,包括材料的理化特性和药物缓释机理的研究.研究表明,对不同药物采取合适的包埋技术,并通过调节骨水泥的厚度、药物包埋量等条件可达到药物控制释放的目的.     

高性能化磷酸钙骨水泥的研究进展

磷酸钙骨水泥（CPC）作为一种新型的自固化型骨修复材料,因其具有良好的生物相容性、骨传导性、可降解性及可塑性等优点,受到了国内外众多学者的广泛关注,具有广阔的应用前景。本文从磷酸钙骨水泥高性能化着手,综述了CPC的复合物及其外添加剂的研究成果,并对新型CPC的研制进展做了介绍。     

磷酸钙骨水泥复合材料研究进展

磷酸钙骨水泥以其良好的生物相容性、骨传导性被作为重要的骨修复材料。但其存在固化时间较长、机械性能不足和低塑性等缺点,使其应用受到限制,故需对其进行提高性能研究。本文就近年来磷酸钙骨水泥复合改性的研究做一综述,随着对其改性研究的深入,其性能不断得到提高。     

磷酸钙骨水泥的研究进展

磷酸钙骨水泥(CPC)是一种新型的自固型、非陶瓷型骨水泥,具有良好的生物相容性和骨传导性,有望成为新一代骨替代材料。本文就其固化行为、改性研究、临床应用研究几个方面对CPC综述如下。     

非陶瓷羟基磷灰石人工骨的研究

磷酸钙骨是一种非陶瓷的新型骨修复材料，它是由几种磷酸钙盐组成的混合物，用水调和后呈糊状物，能在人体的环境和温度下自行固化，其成分最终转化为羟基磷灰石，高的生物相容性和能根据缺损部位塑形的特性使其成为研究的热点。本文综述了磷酸钙骨水泥的组成与特性，涉及磷酸钙的制备，骨水泥自行水化硬化的化学变化过程及其生物相容性研究的等的研究进展。     

人工硬组织材料磷酸钙骨水泥制备方法研究

本研究从磷酸钙骨水泥制备方法开始,通过改变磷酸钙骨水泥原料和其制备工艺,用传统水泥工艺法采用骨质原料成功烧制了性能优良的磷酸钙骨水泥。研究了试样组成的配料计算和升温机制。探讨了人工硬组织材料磷酸钙骨水泥制备方法。     

稀土氧化钇改性磷酸钙骨水泥的研究

磷酸钙骨水泥是一种新型的自固化的非陶瓷羟基磷灰石人造骨材料,具有良好的生物相容性、自固化能力、易于塑形、与成骨活性相协调的溶解性能可作为药物、生物活性因子缓释载体等优越的性能。稀土掺杂羟基磷灰石,对羟基磷灰石的合成有促进作用,并且使其具有更稳定的性质。钇的加入有助于羟基磷灰石生物活性的提高。笔者利用钇掺改善羟基磷灰石生物活性作为探讨。其采用氧化钇对磷酸钙骨水泥进行改性研究,考察磷酸钙骨水泥凝结时间、可注射性和孔隙率等基本性能。采用X射线衍射分析骨水泥粉末在水化过程中的变化及其最终产物。采用电镜观察产物的微结构和表面形貌。研究结果表明:钇加入没有影响磷酸钙骨水泥的水化,并且随着钇含量的增加磷酸钙骨水泥的固化体凝结时间逐渐延长,其中氧化钇含量在5%时凝结时间最短;骨水泥浆体的可注射性变大,其中氧化钇含量在1.5%时可注射性最大(壳聚糖溶液)。磷酸钙骨水泥水化最终产物为片状或棒状的羟基磷灰石,其结构呈紧密联系,但表面有较多的孔隙,且随着钇含量的增加孔隙率有增加的趋势。     

磷酸铋作为磷酸钙骨水泥的显影剂及其对材料性能的影响

以部分结晶磷酸钙-磷酸氢钙体系骨水泥为研究对象,探讨了添加磷酸铋作为显影剂对磷酸钙骨水泥的显影性能、凝结时间、流变性、可注射性能、抗压强度、相组成和显微结构的影响.结果表明:添加磷酸铋能显著增强磷酸钙骨水泥的显影性能,当添加磷酸铋达到9%以上时,骨水泥获得了明显的显影效果.添加磷酸铋使磷酸钙骨水泥粘度下降,可注射性显著提高,抗压强度增大,凝结时间延长.但磷酸铋加入量大于12%时会使材料强度下降,综合考虑,加人9%左右的磷酸铋较为合适.磷酸铋有望成为一种新的磷酸钙骨水泥显影剂.     

磷酸钙骨水泥的临床应用与研究进展

磷酸钙骨水泥是一种新型的自固型、非陶瓷型骨水泥。它克服了钙磷陶瓷脆性大、塑型困难、不能降解等缺点,有良好的生物相容性、可降解性和骨传导能力,且可任意成型,反应不生热,使用方便,临床上用于非负重部位骨缺损的修复、松质骨螺钉加固、药物或生物因子载体等领域。本文对近年来CPC的临床应用与研究进展进行了综述。     

磷酸钙骨水泥的合成与改进

利用沉淀法,以碳酸钙和磷酸为原料,合成出了粒径小,分布均匀的磷酸钙粉末。进一步探讨了pH值对合成产率的影响。结果表明,在pH=6～7的中性环境中更有利于磷酸钙的合成,磷酸钙骨水泥的速凝调和液选取磷酸二氢钠,获得了很好的快速凝固效果。对合成粉末进行X射线衍射并对凝固后的骨水泥进行显微硬度测量,证实了粉末具有较高的纯度且凝固成品硬度符合使用要求。     

硅酸钙类骨水泥改性研究进展

硅酸钙类骨水泥材料具有良好的自固化性能，能够作为硬组织修复材料对缺损的骨和牙进行填充和修复，但是由于其力学性能不足、固化时间长等缺点限制了其在临床上的应用范围。该文主要综述了硅酸钙粉体的制备方法及硅酸钙类骨水泥的力学强度、凝结时间、可注射性、降解及生物相容性等，并提出今后的研究重点是利用各体系骨水泥间的性能互补关系，将硅酸钙类骨水泥与其他体系骨水泥进行交叉复合，有望获得综合性能优良的无机复合骨水泥。     

HEMA‐Modified Expandable P(MMA‐AA) Bone Cement with Dual Water Absorption Networks

Although the shrinkage of polymethyl methacrylate (PMMA) bone cement has been tackled by the poly(methyl methacrylate‐co‐acrylic acid) [P(MMA‐AA)] bone cement due to the expandable P(MMA‐AA) copolymer in the solid phase, the hydrophobicity of PMMA and its solidification restrict simulated body fluid (SBF) diffusion and expansion properties. In this research, hydroxyethyl methacrylate (HEMA)‐modified P(MMA‐AA) bone cement (HMBC) is obtained by introducing HEMA into the liquid phase of P(MMA‐AA) bone cement. It is assumed that the dual water absorption networks can promote the SBF absorption capacity, thus resulting in the increased expansion behavior. The results demonstrate that the introduction of HEMA improves the hydrophilicity of the bulk. SBF absorption efficiency and swelling efficiency are promoted in the primary step of expansion. The porous structure of HMBC contributes to the increased SBF absorption and swelling in the second step of expansion behavior. Meanwhile, the remarkable absorption ratio and expansion ratio reach 88.5% and 97.4%, respectively. Furthermore, enhanced biocompatibility and osteogenesis activity provide HMBC as a promising biomaterial in the clinical setting.     

Clay Nanotube/Poly(methyl methacrylate) Bone Cement Composites with Sustained Antibiotic Release

Orthopedic‐grade PMMA bone cement, admixed with prophylactic antibiotics, is widely used in hip and knee replacement surgery. There is a critical need to improve its structural integrity and to control antibiotic release. In this study, clay nanotubes are loaded with the antibiotic gentamicin sulfate and the cement is doped with 5–8 wt% nanotubes. The halloysite nanotubes isolate the drug from the cement monomers and serve as nanocontainers for sustained release of the antibiotic. Gentamicin‐loaded clay nanotubes admixed in PMMA cement provide sustained release up to 300–400 h and with enhanced release at cement cracks. The PMMA/halloysite/gentamicin composite tensile strength does not deteriorate as compared with pure cement and its adhesion to bone is significantly increased.

     

Interaction of Acrylic Bone Cement with Bone Structure

The resistivity of the products resulting from the interaction between acrylic cement and bone or bone marrow was measured. The dependence of the resistivity on the aging time is discussed. The results indicate that, for the products of the interaction between the cement and bone, the resistivity decreases with increasing time up to 15 days, increases to its probable maximum value after 45 days, and then decreases with increasing time up to 8 weeks. Also, the resistivity of the products of the interaction between the cement and bone marrow suggests a maximum value after 45 days. It is concluded that the variation of resistivity with the aging time is due to formation of a bond between the cement and bone or bone marrow, and that this bond is not perfect. Moreover, it was found that the resistivity of the samples is influenced by the polymerization process of the cement.     

Control of Crystallinity of Hydrated Products in a Calcium Phosphate Cement

A novel calcium phosphate cement (CPC) was prepared by dry-mechanochemical rout in this work. With the different crystallinity, the CPC showed the different degradation ratio after setting. The degradation ratio of CPC was characterized by the calcium ion-dissolving ratio in deionized water after different soaking time. With the increment of crystallinity, the setting times of CPC were prolonged, and the different mechanical property of CPC were obtained. This novel CPC was supposed to match the new bone ingrowth in vivo and have the potential application in orthopedic surgery for filling non-load-bearing bone defects.     

Preparation of Clay/PMMA Nanocomposites with Intercalated or Exfoliated Structure for Bone Cement Synthesis

Summary: Clay/PMMA nanocomposites were prepared by melt blending of an organically modified MMT with PMMA under various process conditions. The MMT clay was initially cation exchanged with octadecylammonium to enhance its hydrophobicity and to expand the interlamellar space of the silicate plates. PMMA was then inserted into the inter‐lamellar space of the modified clay by melt blending at an elevated temperature. The effects of blending temperature, blending time, and clay/PMMA compositions on the level of expansion and homogenization were investigated. Composites with intercalated and/or exfoliated clay structure were obtained depending upon the process conditions, as confirmed by XRD diffractometry. The thermal decomposition temperature (T_d) and glass transition temperature (T_g) of the composites were determined, respectively, by TGA and DSC analyses. Marked improvements, up to 35 °C, of the thermal stability (T_d) with respect to pure PMMA were achieved for many of the composite samples. The T_g of the composites, however, does not increase accordingly. Furthermore, a novel type of bone cement was synthesized by applying the clay/PMMA nanocomposites as a substitute for PMMA in a typical formulation. These bone cements demonstrated much higher impact strength and better cell compatibility than the surgical Simplex P cement. Therefore, the bone cements with clay/PMMA nanocomposites meet the requirement for the architectural design of orthopedic surgery.

TEM images of an OA‐clay/PMMA composite.     

Rapid Self-Expansion Behavior of the PMMA-Based Bone Cement with P(MMA-AA)-GO Nano-Units

The volume shrinkage of polymethylmethacrylate (PMMA) bone cement is typically addressed by incorporating additives into the matrix. However, the maximum water absorption and swelling capacity of the composite bone cement are not sufficiently improved due to its rapid solidification. In this work, poly(methyl methacrylate-acrylic acid)-grafted graphene oxide [P(MMA-AA)-GO] nano-units with the microsphere-lamellar structure are synthesized, and then P(MMA-AA)-GO bone cement (PGBC) is fabricated. The rate of absorption and swelling of PGBC are significantly promoted by the microsphere–lamellar structure of P(MMA-AA)-GO nano-units, achieving maximum absorption and swelling capacity of PGBC before its solidification. PGBC 4 exhibits the maximum equilibrium simulate body fluid (SBF) absorption ratio and equilibrium swelling ratio of 90.2% ± 1.7% and 92.5% ± 4.5%, respectively. Interestingly, the maximum compression strength of the composite before immersion is also observed in PGBC 4 with a value of 77.2 ± 1.1 MPa. The enhanced compression strength of PGBC overcomes the bottleneck of the decreased compression strength resulting from the enhanced absorption behavior. Therefore, PGBC with rapid self-expansion behavior and improved mechanical properties can not only reduce the injection volume to avoid leakage in the clinic but also provide sufficient mechanical support, which has promising application potential in the clinical setting.