Choi Donok, Park Youngbae, Yoon Yong-San, Masri Bassam A
Department of Mechanical Engineering, KAIST, Daejeon, 305-701, Republic of Korea.
Clin Biomech (Bristol). 2010 Jan;25(1):50-5. doi: 10.1016/j.clinbiomech.2009.08.008.
Cemented stems with various surface roughnesses are used in total hip arthroplasty. However, it is not clear how the surface roughness of the stem affects the longevity of the implant. In this study, we investigated the effect of the stem roughness on the micromotion at the bone-cement and cement-implant interface and investigated cracks in the cement layer through in vitro measurement.
Stems with the same shape and material but with different surface roughness (polished with Ra=0.05 microm and matte-finished with Ra=0.83 microm) were tested to measure the interface micromotion using custom-made sensors. The stems were implanted in five paired cadaver femurs and cyclic loading was applied to the femoral head to measure the interface micromotion. After loading, we measured the crack length and calculated the crack length density at the cement layer.
The difference in the interface micromotion between the polished stem and the rough stem was not significant except at the distal region of the cement-bone interface. More cracks were found at the distal region of the polished stem than at the rough stem. The magnitude of the cement crack length density did not correlate with the interface micromotion.
The results showed that the difference in the roughness between the polished and matte finishes did not significantly affect the micromotion and crack of the interface. However, more cement wear particles were expected in the matte-finished stem.
全髋关节置换术中使用了具有不同表面粗糙度的骨水泥型股骨柄。然而，股骨柄的表面粗糙度如何影响植入物的使用寿命尚不清楚。在本研究中，我们通过体外测量研究了股骨柄粗糙度对骨水泥与骨水泥-植入物界面微动的影响，并研究了骨水泥层中的裂纹。
使用定制传感器对形状和材料相同但表面粗糙度不同（抛光至Ra = 0.05微米和磨砂处理至Ra = 0.83微米）的股骨柄进行测试，以测量界面微动。将股骨柄植入五对尸体股骨中，并对股骨头施加循环载荷以测量界面微动。加载后，我们测量了裂纹长度并计算了骨水泥层的裂纹长度密度。
除了在骨水泥-骨界面的远端区域外，抛光股骨柄和粗糙股骨柄之间的界面微动差异不显著。在抛光股骨柄的远端区域发现的裂纹比粗糙股骨柄更多。骨水泥裂纹长度密度的大小与界面微动无关。
结果表明，抛光和磨砂表面粗糙度的差异对界面的微动和裂纹没有显著影响。然而，预计磨砂处理的股骨柄中会产生更多的骨水泥磨损颗粒。
