3种充填材料应用于绝经后骨质疏松症山羊经皮椎体成形术后椎体的超微结构观察

目的:在山羊骨质疏松症模型上,观察经皮椎体成形术(PVP)中聚甲基丙烯酸甲酯(PMMA)、磷酸钙人工骨(CPC)和复合重组人类骨形态发生蛋白-2(rhBMP-2)的磷酸钙人工骨(rhBMP-2/CPC)3种充填材料充填后椎体的超微结构变化.方法:6～8岁中老年雌性山羊8只,均行双侧卵巢切除术,术后4个月建立骨质疏松症模型.在C形臂X光机监视下,随机选取每只山羊的L2～L6的2节椎体行PVP,分别充填PMMA、CPC和rhBMP-2/CPC,保证每只山羊2节穿刺椎体的充填材料各不相同,术后4个月麻醉动物,活体取出椎体,行扫描电镜观察.结果:8只山羊16个椎体的PVP均成功,3种充填材料分布于椎体内,共出现4个椎体的渗漏.扫描电镜观察:PMMA呈层状黏附于松质骨表面,两者界限明显,PMMA表面有极少量的细胞成分存在,未见骨质长人PMMA和PMMA的降解;CPC呈松散的团状,渗透于骨组织中,与骨组织融合在一起,有新骨组织长入其内部,呈交错连接,无界膜形成,有不规则的互相连通的自然孔隙存在,细胞成分较多,可见CPC吸收;与CPC结构相比,rhBMP-2/CPC细胞成分更为丰富,可见大量成簇的成骨细胞,并可见较成熟的骨小梁形成.结论:rhBMP-2/CPC和CPC均具有降解活性和骨传导活性,优于PMMA.rhBMP-2/CPC还具有诱导成骨活性,可能成为PVP中强化骨质疏松椎体的首选充填材料.

Ultrastructure evaluation of vertebral bodies after percutaneous vertebroplasty with three different filling materials in goats

Aim: To investigate ultrastructure manifestation of vertebral bodies after percutaneous vertebroplasty (PVP) in osteoporotic goats with three different filling materials:polymethylmethacrylate (PMMA), calcium phosphate cement (CPC) and rhBMP-2/CPC. Methods: The bilateral ovaries of the eight goats, 6 to 8 years old, were removed to set up the osteoporotic model. Two vertebral bodies (L_2~L_6) of each goat were selected at random, which were augmented with PMMA, CPC or rhBMP-2/CPC, respectively under fluoroscopic guidance and intravenous anaesthesia. The filling materials were different in two vertebras of each goat. Sixteen vertebral bodies from eight goats were observed under scan electron microscope after four months. Results: PVP was performed successfully in all the sixteen vertebral bodies,and the leakage of cement was found in 5 vertebras. Scan electron microscope results revealed that only few cells could be found at the surface of PMMA.The resorption of PMMA or the new bone formation could not be found. In contrast to PMMA, a seamless contact existed between CPC and bone trabecula, and more cells, new bone formation and resorption of CPC were observed. More osteoblasts and the formation of some mature bone trabeculaes could be found in vertebra filled with rhBMP-2/CPC. Conclusion: The results indicate that CPC and rhBMP-2/CPC are biocompatible and osteoconductive. What is more, the latter might be the best candidate material as a bone substitute in the treatment of osteoporosis with PVP.