Funk M J, Litsky A S
Orthopaedic Biomaterials Laboratory, Columbus, Ohio 43210-1128, USA.
Biomaterials. 1998 Sep;19(17):1561-7. doi: 10.1016/s0142-9612(97)00116-6.
Shear tests of the bone-cement interface were performed in vitro using two types of bone cement, standard poly(methyl methacrylate) (PMMA) and a reduced-modulus formulation with poly(butyl methacrylate) beads in a methyl methacrylate matrix (PBMMA). Tests of shear properties were also calculated on cancellous bone and on each cement alone. The tests were done using the Iosipescu shear test method which generates a pure shear force in a zero-moment section of the specimen. With this method, shear properties can be determined at specified locations throughout the specimen. Tests were performed across the entire interface region, specifically in the middle of the region of cement bone interdigitation and at both the bone and cement ends of that region. Ultimate shear strengths and shear moduli were calculated. The shear modulus of the PBMMA is less than 3% that of PMMA. The strength and modulus of cancellous bone had a direct relation to the apparent density of the bone, as did the strength and modulus of the bone-composite interface and the composite region. Strength and modulus were dictated by the bone at the bone-composite interface, and by the cement at the cement composite interface. Through the composite region, the stiffer of the two materials in the composite determined the shear properties. Reduced-modulus bone cement substantially decreases the interfacial shear stresses at the bone-cement interface which should decrease the rate of resorptive bone remodelling at this interface.
使用两种类型的骨水泥在体外进行骨水泥界面的剪切试验，这两种骨水泥分别是标准聚甲基丙烯酸甲酯（PMMA）和一种在甲基丙烯酸甲酯基质中含有聚甲基丙烯酸丁酯珠粒的低模量配方骨水泥（PBMMA）。还对松质骨和每种骨水泥单独进行了剪切性能测试。试验采用Iosipescu剪切试验方法，该方法在试样的零弯矩截面产生纯剪切力。通过这种方法，可以在整个试样的指定位置确定剪切性能。试验在整个界面区域进行，具体是在骨水泥相互交错区域的中部以及该区域的骨端和水泥端。计算了极限剪切强度和剪切模量。PBMMA的剪切模量小于PMMA的3%。松质骨的强度和模量与骨的表观密度直接相关，骨-复合材料界面和复合材料区域的强度和模量也是如此。骨-复合材料界面处的强度和模量由骨决定，水泥-复合材料界面处的强度和模量由水泥决定。在复合材料区域，复合材料中两种材料中较硬的一种决定了剪切性能。低模量骨水泥显著降低了骨水泥界面处的界面剪切应力，这应该会降低该界面处吸收性骨重塑的速率。
