多孔碳酸化羟基磷灰石水泥植入修复兔包容性骨缺损的力学分析

背景：采用发泡剂成孔技术，制成了有知识产权的新型骨修复材料多孔碳酸化羟基磷灰石，既保留了碳酸化羟基磷灰石骨水泥原位固化性能等所有的优点，同时又形成多孔结构。 目的：通过动物实验观察新型的骨修复材料多孔碳酸化羟基磷灰石水泥修复骨缺损的力学效果。 方法：30只新西兰大白兔，手术组25只在双侧股骨髁制备直径为5.5 mm、深12 mm的骨缺损动物模型，左侧植入多孔碳酸化羟基磷灰石骨水泥为实验组，右侧植入碳酸化羟基磷灰石骨水泥为对照组。非手术组5只，用于正常力学对照。将多孔碳酸化羟基磷灰石骨水泥和碳酸化羟基磷灰石骨水泥试件经模仿体液浸泡，检测力学强度。同时在手术组背肌内分别植入多孔碳酸化羟基磷灰石骨水泥和碳酸化羟基磷灰石骨水泥标准试件。分别于术后2，4，8，12，16周分批处死动物，进行试件骨内和肌内植入的力学实验分析和试件在模仿体液中浸泡后的抗压强度测试。 结果与结论：多孔碳酸化羟基磷灰石骨水泥：2周时的骨内力学强度较低，4周时降到最低，8周时接近正常松质骨强度，12周时超过正常松质骨强度，16周时恢复到正常松质骨水平。碳酸化羟基磷灰石骨水泥：2周时骨内植入强度较多孔碳酸化羟基磷灰石骨水泥略高，4周时有所降低，8，12，16周时略升高，但是始终低于正常松质骨的强度。多孔碳酸化羟基磷灰石骨水泥和碳酸化羟基磷灰石骨水泥在SBF中浸泡的抗压强度变化不大。试件植入肌内后抗压强度变化非常显著。结果表明，多孔碳酸化羟基磷灰石水泥具有原位固化性能和一定的力学支撑作用，能作为自体骨移植的一种替代物修复骨缺损。 关键词：多孔碳酸化羟基磷灰石水泥；骨缺损；生物活性材料；兔；生物力学 doi:10.3969/j.issn.1673-8225.2010.16.003

Biomechanical evaluation of repairing rabbit cancellous bone defect by implanting porous carbonated hydroxyapatite cement

BACKGROUND: A new material of porous carbonated hydroxyapatite cement (PCHC) is discovered using foaming technique. The new material characterizes original solidification and forms porous structure. OBJECTIVE: To investigate the biomechanical effect of PCHC on repairing cancellous bone defect. METHODS: Among 30 New Land rabbits, 25 ones were considered as surgery group, whose bilateral condyles of femur was used to establish bone defect model (5.5 mm diameter and 12 mm depth). PCHC was implanted into the left side, which was considered as the experimental group, and carbonated hydroxyapatite cement (CHC) was implanted into the right side, which was considered as the control group. Another 5 rabbits were used as normal mechanical control group. Both PCHC and CHC were dip in simulated body fluid (SBF) to test mechanical intension. PCHC and CHC were then implanted into muscles of back in the surgery group. Rabbits were sacrificed after 2, 4, 8, 12, and 16 weeks postoperatively. Mechanical analysis was tested following intra-bone and intramuscular implantation, and compressive strength was then tested following dipping into SBF. RESULTS AND CONCLUSION: PCHC: Intra-bone mechanical strength was lower at 2 weeks, the lowest at 4 weeks, but then closed to intension of normal cancellated bone at 8 weeks, higher than normal cancellated bone at 12 weeks, and recovered to the level of normal cancellated bone at 16 weeks. CHC: Intra-bone strength was higher than that of PCHC at 2 weeks, decreased at 4 weeks, gradually increased at 8, 12, and 16 weeks, but still lower than intension of normal cancellated bone. Compressive strength of both PCHC and CHC was not changed following dipping in SBF; however, compressive strength was changed remarkably following intramuscular implantation. The results demonstrated that PCHC characterized by immobilization in situ and mechanical supporting. Thus it could be used for one kind of bone substitute material to repair the bone defect.