骨形态发生蛋白复合聚(乳酸-羟基乙酸)共聚物／磷酸三钙填充修复兔股骨下段多孔钛周围骨缺损的生物固定效果

Biomechanic results of poly(lactic-co-glycolic acid)/tricalcium phosphate scaffold with bone morphogenetic protein implanted in bone defects peri-porous-titanium in rabbit femur

背景:课题组前期观察了骨形态发生蛋白复合聚(乳酸-羟基乙酸)共聚物/磷酸三钙人工骨作为填充材料植入多孔钛周围的组织学变化,但是对于该材料生物固定多孔钛的特点尚未得知。目的:评估骨形态发生蛋白复合聚(乳酸-羟基乙酸)共聚物/磷酸三钙三维多孔框架材料修复多孔钛周围骨缺损的生物力学特点。设计、时间及地点:随机对照动物实验,于2005-02/2007-09在解放军第四军医大学实验动物中心完成。材料:以负压抽吸法在5×103Pa的压力下将牛骨形态发生蛋白混悬液5mg与聚(乳酸-羟基乙酸)共聚物/磷酸三钙多孔框架复合。新西兰兔36只,随机分为对照组和实验组各18只。方法:于股骨内髁上段0.5cm处制造直径6mm,高为10cm的圆柱状全壁缺损。对照组在羟基磷灰石涂层多孔钛周围填充单纯聚(乳酸-羟基乙酸)共聚物/磷酸三钙材料。实验组在羟基磷灰石涂层多孔钛周围填充复合骨形态发生蛋白的聚(乳酸-羟基乙酸)共聚物/磷酸三钙材料。主要观察指标:填充6,12,24周后取含植入样品的股骨进行生物力学推出测定,测试完毕后标本行扫描电镜观察。结果:所有样品的剪切应力都随时间增长而增大。其中在6,12周实验组剪切应力高于对照组(P<0.05)。扫描电镜观察6周时断裂位置为植入仿生骨-骨界面,金属表面骨组织量较少。12周时断裂面主要发生在植入仿生骨-多孔钛界面或正在重建的编织骨内或编织骨-皮质骨界面。24周时,可以观察到断裂发生在编织骨-皮质骨界面。结论:应用骨形态发生蛋白复合聚(乳酸-羟基乙酸)共聚物/磷酸三钙材料修复多孔钛周围骨缺损,能够更好地固定生物假体。

BACKGROUND： Histological changes in bone morphogenetic protein （BMP） and poly（lactic-co-glycolic acid） （PLGA）/tricalcium phosphate （TCP） artificial bone as furniture have been observed following implanting surrounding the porous titanium. However, the fixation characteristics of this material in the porous titanium are still unclear. OBJECTIVE： To evaluate the biomechanics characteristics of composite material of BMP and PLGA/TCP in repair of bone defects surrounding porous titanium. DESIGN, TIME AND SETFIN： The randomized, controlled, animal study was performed at the Animal Experimental Center, Fourth Military Medical University of Chinese PLA from February 2005 to September 2007. MATERIALS： Using negative pressure aspiration, bovine BMP suspension （5 mg） was compounded with PLGA/TCP at 5×10^3 Pa pressure. A total of 36 New Zealand rabbits were equally and randomly assigned into a control group and an experimental group. METHODS： A circular cylinder-shaped whole-wall defect （6 mm diameter, 10 cm height） was made at 0.5 cm above femoral medial condyle. PLGA/TCP scaffold was filled surrounding the porous titanium in the hydroxyapatite layer in the control group. BMP and PLGA/TCP composite were filled surrounding the porous titanium in the hydroxyapatite layer in the experimental group. MAIN OUTCOME MEASURES： Following 6, 12, 24 weeks of filling, biomechanics of the femur implanted with samples was measured, and samples following test were observed under a scanning electron microscope. RESULTS： Shear stress of all samples increased with the prolonged time. At 6 and 12 weeks, the shear stress was higher in the experimental group than in the control group （P 〈 0.05）. Using the scanning electron microscope, at 6 weeks, the fracture face occurred on the surface implanted with bionic bone-bone, with a few bone tissue volumes on the mental surface. At 12 weeks, fracture face mainly occurred on the interface implanted with bionic bone-porous titanium or reconstituted woven bone or on the interface of woven bone-cortical bone. At 24 weeks, fracture face occurred on the interface of woven bone-cortical bone. CONCLUSION： BMP loaded with PLGA/TCP in repair of bone defects surrounding the porous titanium can better fix the bioprosthesis.