假体表面改性和材料纳米化对骨质疏松骨床中假体骨整合的影响

Effects of surface modification and nanometer material on bone-prosthesis osseointegration in osteoporosis models

背景:羟基磷灰石涂层优化能够改善假体的早期和中期固定效果,但其远期固定效果差强人意。大量研究表明:羟基磷灰石涂层材料纳米化和假体表面改性可提高假体-骨界面的结合情况。但材料纳米化与表面改性和骨整合相关性如何国内外尚未见专门研究。目的:对比骨质疏松条件下材料纳米化与表面改性对两类羟基磷灰石假体骨整合促进作用的差异。设计、时间及地点:随机对照实验,分别于2007-09/12和2008-03/05在中山大学动物实验中心和香港大学医学院矫形外科组织学实验室完成。材料:圆柱形多孔羟基磷灰石假体和光滑表面纳米羟基磷灰石假体由华南理工大学材料学院制作、提供,尺寸为3mm×3mm。方法:将32只5月龄雌性SD大鼠按随机分为4组:假手术+多孔羟基磷灰石组,假手术+光滑表面纳米羟基磷灰石组,骨质疏松+多孔羟基磷灰石组,骨质疏松+光滑表面纳米羟基磷灰石组,每组8只。骨质疏松+多孔羟基磷灰石和骨质疏松+光滑表面纳米羟基磷灰石组大鼠切除卵巢建立绝经后骨质疏松动物模型。在各组大鼠胫骨上段分别植入多孔和光滑表面的羟基磷灰石假体。主要观察指标:12周后处死大鼠,取带假体标本,运用骨组织计量学检测手段,测量假体周围骨的骨量及结合率等指标。结果:①骨质疏松+多孔羟基磷灰石组骨结合率为23.7%,较骨质疏松+光滑表面纳米羟基磷灰石组高16.9%,差异具有显著性意义(P<0.05)。②骨质疏松组在骨整合率上较假手术组显著降低,分别降低30.8%和13.0%。结论:骨质疏松条件下,假体表面结构优化可显著提高假体-骨界面结合程度、促进假体骨整合。光滑表面的纳米羟基磷灰石假体未能发挥纳米级羟基磷灰石的优势;在影响骨整合方面就羟基磷灰石涂层来说,涂层表面改性可能比单纯涂层材料纳米化更重要。

BACKGROUND： Hydroxyapatite （HA） coating can improve the initial and mid-term fixation of prosthesis. However, its long-term stabilization is unsatisfactory. A large number of studies report that nano-HA coating and surface modification of prosthesis can improve the osteointegration at prosthesis-bone interface. Yet, comparative study on osteointegration of nano-materials and surface modification has not been reported. OBJECTIVE： To compare effects of nano-materials and surface modification on osteointegration in osteoporosis （OP） model. DESIGN,TIME AND SETTING： A randomized control experiment was performed in the Animal Experimental Centre of Sun Yat-sun University from September to December 2007 and Histomorphometry Laboratory of the Hong Kong University from March to May 2008, respectively. MATERIALS： Porous HA-coating and surface modified nanometer prostheses sized 3 mm× 3 mm were provided by Department of Materials, South China University of Technology. METHODS： Thirty-two female SD rats, five-month old, were randomly divided into four groups： group A in which rats received sham surgery and was implanted with porous HA, group B in which rats received sham surgery and was implanted with smooth surface nano-HA, group C in which ovariectomized （OVX） rats was implanted with porous HA, and group D in which OVX rats was implanted with smooth surface nano-HA, with eight rats in each group. Rats in group C and D underwent ovariectomy to establish osteoporosis models. Porous and smooth surface HA prostheses were implanted into superior segments of tibia in each group. MAIN OUTCOME MEASURES： At 12 weeks after sacrifice, the bone quantity and osteointegration around the HA implant were observed and the osteointegration at the surface between bone and implant was calculated. RESULTS： （1） Osteointegration rate （OIS） in group C was 23.7%, which was significantly higher than group D 16.9% （P 〈 0.05）. （2） The OIS in the OVX groups was significantly less than sham surgery groups, reducing 30.8% and 13.0%, respectively. CONCLUSION： Surface modification can notably promote osteointegration at implant-bone interface in osteoporosis condition. The smooth surface of nano-HA prothesis fails to take advantage of the benefit of nano-HA. Referring to HA coating, surface modification of coating plays a more important role in promoting osteointegration, compared to coating material.