磷酸钙骨水泥加强骨质疏松性肱骨近端骨折内固定的生物力学研究

Biomechanical evaluation of internal fixation augmented with calcium phosphate cement in treatment of proximal humeral fractures

目的 通过比较注射型磷酸钙骨水泥（CPC）和聚甲基丙烯酸甲酯（PMMA）骨水泥在加强骨质疏松性肱骨近端骨折内固定中的生物力学表现，探讨注射型CPC替代PMMA骨水泥作为肱骨近端骨缺损填充材料的可行性。方法 选择42个甲醛浸泡的老年女性尸体肱骨标本，制作成肱骨近端三部分骨折合并骨缺损模型。模型随机分三组：CPC填充组、PMMA骨水泥填充组和空白对照组，分别对三组标本进行压缩、拉伸及松质骨螺钉轴向拔出试验，测龟极限压缩载荷、极限拉伸载荷及松质骨螺钉初始松动加载力等相关数据。结果 CPC组和PMMA组的最大压缩载荷、拉伸载荷和螺钉松动强度均显著高于空白对照组，差异有统计学意义（P〈0．05）；而CPC组和PMMA组之间差异无统计学意义（P〉0．05）。结论 注射型CPC能够获得与PMMA骨水泥近似的力学强度，可以认为是能够较好替代PMMA骨水泥的生物材料。

Objective To compare injectable calcium phosphate cement （CPC） and polymethyl- methacrylate （PMMA） in their biomechanieal performances in augmenting the fixation for osteoporotie proximal humeral fractures. Methods Forty-two humeral specimens were obtained from aged female corpses soaked in the formaldehyde. They were made models of three-part proximal humeral fracture. The specimens were randomized evenly into CPC group, PMMA group and control group. Biomechanical tests involving compression, stretching and axial pulling-out of cancellous screw were conducted to determine the maximum compression load, tensile load and initial loosening load of screw. Results The values of maximum compression load, tensile load and initial loosening load of screw in CPC and PMMA groups were significantly higher than those in control group （ P 〈 0.05）, and no significant difference was showed between CPC group and PMMA group （ P 〉 0. 05） . Conclusion Since the biomechanieal performances of injectable CPC are similar to those of PMMA, injectable CPC may be used as a fine substitute of PMMA to enhance the internal fixation for osteoporotic proximal humeral fractures.