Schwartz Zvi, Raz Perry, Zhao Ge, Barak Yael, Tauber Michael, Yao Hai, Boyan Barbara D
Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, 315 Ferst Drive N.W., Atlanta, GA 30332-0363, USA.
J Bone Joint Surg Am. 2008 Nov;90(11):2485-98. doi: 10.2106/JBJS.G.00499.
Titanium implants that have been grit-blasted and acid-etched to produce a rough microtopography support more bone integration than do smooth-surfaced implants. In vitro studies have suggested that this is due to a stimulatory effect on osteoblasts. It is not known if grit-blasted and acid-etched Ti6Al4V implants also stimulate osteoblasts and increase bone formation clinically. In this study, we examined the effects of micrometer-scale-structured Ti6Al4V surfaces on cell responses in vitro and on tissue responses in vivo.
Ti6Al4V disks were either machined to produce smooth surfaces with an average roughness (Ra) of 0.2 microm or grit-blasted, resulting in an Ra of 2.0, 3.0, or 3.3 microm. Human osteoblast-like cells were cultured on the disks and on tissue culture polystyrene. The cell number, markers of osteoblast differentiation, and levels of local factors in the conditioned media were determined at confluence. In addition, Ti6Al4V pedicle screws with smooth or rough surfaces were implanted into the L4 and L5 vertebrae of fifteen two-year-old sheep. Osteointegration was evaluated at twelve weeks with histomorphometry and on the basis of removal torque.
The cell numbers on the Ti6Al4V surfaces were lower than those on the tissue culture polystyrene; the effect was greatest on the roughest surface. The alkaline-phosphatase-specific activity of cell lysates was decreased in a surface-dependent manner, whereas osteocalcin, prostaglandin E(2), transforming growth factor-beta1, and osteoprotegerin levels were higher on the rough surfaces. Bone-implant contact was greater around the rough-surfaced Ti6Al4V screws, and the torque needed to remove the rough screws from the bone was more than twice that required to remove the smooth screws.
Increased micrometer-scale surface roughness increases osteoblast differentiation and local factor production in vitro, which may contribute to increased bone formation and osteointegration in vivo. There was a correlation between in vitro and in vivo observations, indicating that the use of screws with rough surfaces will result in better bone-implant contact and implant stability.
经过喷砂和酸蚀处理以产生粗糙微观形貌的钛植入物比表面光滑的植入物能支持更多的骨整合。体外研究表明，这是由于对成骨细胞的刺激作用。尚不清楚喷砂和酸蚀的Ti6Al4V植入物在临床上是否也能刺激成骨细胞并增加骨形成。在本研究中，我们研究了微米级结构的Ti6Al4V表面对体外细胞反应和体内组织反应的影响。
将Ti6Al4V圆盘加工成平均粗糙度（Ra）为0.2微米的光滑表面，或进行喷砂处理，使其Ra分别为2.0、3.0或3.3微米。将人成骨样细胞培养在圆盘和组织培养聚苯乙烯上。在汇合时测定细胞数量、成骨细胞分化标志物以及条件培养基中局部因子的水平。此外，将表面光滑或粗糙的Ti6Al4V椎弓根螺钉植入15只两岁绵羊的L4和L5椎骨中。在12周时通过组织形态计量学和去除扭矩评估骨整合情况。
Ti6Al4V表面的细胞数量低于组织培养聚苯乙烯上的细胞数量；在最粗糙的表面上这种影响最大。细胞裂解物的碱性磷酸酶特异性活性以表面依赖性方式降低，而在粗糙表面上骨钙素、前列腺素E(2)、转化生长因子-β1和骨保护素水平较高。粗糙表面的Ti6Al4V螺钉周围的骨-植入物接触更大，从骨中取出粗糙螺钉所需的扭矩是取出光滑螺钉所需扭矩的两倍多。
微米级表面粗糙度的增加会增加体外成骨细胞的分化和局部因子的产生，这可能有助于体内骨形成和骨整合的增加。体外和体内观察结果之间存在相关性，表明使用表面粗糙的螺钉将导致更好的骨-植入物接触和植入物稳定性。
