Zhang Yu, Xu Hockin H K
Paffenbarger Research Center, American Dental Association Foundation, National Institute of Standards and Technology, 100 Bureau Drive Stop 8546, Gaithersburg, Maryland 20899-8546, USA.
J Biomed Mater Res A. 2005 Dec 15;75(4):832-40. doi: 10.1002/jbm.a.30461.
Approximately a million bone grafts are performed each year in the United States, and this number is expected to increase rapidly as the population ages. Calcium phosphate cement (CPC) can intimately adapt to the bone cavity and harden to form resorbable hydroxyapatite with excellent osteoconductivity and bone-replacement capability. The objective of this study was to develop a strong CPC using synergistic reinforcement via suture fibers and chitosan, and to determine the fiber strength-CPC composite strength relationship. Biopolymer chitosan and cut suture filaments were randomly mixed into CPC. Both suture filaments and composite were immersed in a physiological solution. After 1-day immersion, cement flexural strengths (mean +/- SD; n = 6) were: (2.7 +/- 0.8) MPa for CPC control; (11.2 +/- 1.0) MPa for CPC-chitosan; (17.7 +/- 4.4) MPa for CPC-fiber composite; and (40.5 +/- 5.8) MPa for CPC-chitosan-fiber composite. They are significantly different from each other (Tukey's at 0.95). The strength increase from chitosan and fiber together in CPC was much more than that from either fiber or chitosan alone. The composite strength became (9.8 +/- 0.6) MPa at 35-day immersion and (4.2 +/- 0.7) MPa at 119 days, comparable to reported strengths for sintered porous hydroxyapatite implants and cancellous bone. After suture fiber dissolution, long macropore channels were formed in CPC suitable for cell migration and tissue ingrowth. A semiempirical relationship between suture fiber strength S(F) and composite strength S(C) were obtained: S(C) = 14.1 + 0.047 S(F), with R = 0.92. In summary, this study achieved substantial synergistic effects by combining random suture filaments and chitosan in CPC. This may help extend the use of the moldable, in situ hardening hydroxyapatite to moderate stress-bearing orthopedic applications. The long macropore channels in CPC should be advantageous for cell infiltration and bone ingrowth than conventional random pores and spherical pores.
在美国，每年大约进行一百万例骨移植手术，并且随着人口老龄化，这一数字预计将迅速增加。磷酸钙骨水泥（CPC）能够紧密贴合骨腔并硬化形成具有优异骨传导性和骨替代能力的可吸收羟基磷灰石。本研究的目的是通过缝线纤维和壳聚糖的协同增强作用开发一种高强度的CPC，并确定纤维强度与CPC复合材料强度之间的关系。将生物聚合物壳聚糖和切断的缝线细丝随机混入CPC中。缝线细丝和复合材料均浸入生理溶液中。浸泡1天后，骨水泥的抗弯强度（平均值±标准差；n = 6）分别为：CPC对照组为（2.7±0.8）MPa；CPC-壳聚糖组为（11.2±1.0）MPa；CPC-纤维复合材料组为（17.7±4.4）MPa；CPC-壳聚糖-纤维复合材料组为（40.5±5.8）MPa。它们彼此之间有显著差异（Tukey检验，置信度为0.95）。壳聚糖和纤维共同作用使CPC强度的增加远大于单独使用纤维或壳聚糖时强度的增加。复合材料在浸泡35天时强度变为（9.8±0.6）MPa，在浸泡119天时变为（4.2±0.7）MPa，与报道的烧结多孔羟基磷灰石植入物和松质骨的强度相当。缝线纤维溶解后，CPC中形成了适合细胞迁移和组织长入的长形大孔通道。得到了缝线纤维强度S(F)与复合材料强度S(C)之间的半经验关系：S(C) = 14.1 + 0.047 S(F)，相关系数R = 0.92。总之，本研究通过在CPC中结合随机缝线细丝和壳聚糖实现了显著的协同效应。这可能有助于将可模塑的原位硬化羟基磷灰石的应用扩展到承受中等应力的骨科应用中。与传统的随机孔和球形孔相比，CPC中的长形大孔通道对细胞浸润和骨长入应该更有利。
