Waide V, Cristofolini L, Stolk J, Verdonschot N, Toni A
Laboratorio di Tecnologia Medica, Istituti Ortopedici Rizzoli, Via di Barbiano 1/10, 40136 Bologna, Italy.
Clin Biomech (Bristol). 2003 Jul;18(6):523-36. doi: 10.1016/s0268-0033(03)00072-x.
To determine the load transfer patterns of femurs in the intact, immediate post-operative and long-term (remodelled) post-operative implanted conditions for Lubinus SPII and Müller-Curved cemented hip prostheses, and to examine to what extent remodelling may influence the long-term outcome.
Experimental and finite element (FE) methods were applied to composite femurs under loads representing the heel-strike phase of gait, determining cortical bone and cement strains for the different femur conditions.
The authors previously developed protocols to measure bone and cement strains, and to produce remodelled femur specimens, yet these have not been applied together to compare strain patterns of different femur conditions. The Lubinus SPII is clinically more successful than the Müller-Curved stem, with failure mainly due to aseptic loosening.
Cortical bone strains were determined in intact femurs. Six femurs each were implanted with the two stem types and cortical bone and cement strains were measured. Bone remodelling was recreated using a validated CAD-CAM procedure to remove a layer of proximal cortical bone, replicating a typical scenario found in stable clinical retrievals. Strains were remeasured. FE methods were used to compliment the experiments.
Stress shielding was reduced with remodelling, though bone strains did not return to their intact values, particularly around the calcar. Cement strains increased with remodelling. Differences occurred between the two stems; the Müller-Curved produced a more severe strain transition.
Procedures were successfully combined together to investigate in vitro the performance of two cemented stems, in immediate and long-term post-operative conditions. The increase of cement strains with remodelling is a potential indicator for in vivo cement failure.
The consequences of femoral bone remodelling on the long-term success of joint replacements are not well understood, where remodelling may lead to increased bone and cement stresses.
确定Lubinus SPII和Müller-Curved骨水泥型髋关节假体在完整、术后即刻和长期（重塑后）植入条件下股骨的载荷传递模式，并研究重塑在多大程度上可能影响长期结果。
采用实验和有限元（FE）方法，对代表步态足跟撞击阶段载荷下的复合股骨进行研究，确定不同股骨条件下的皮质骨和骨水泥应变。
作者此前制定了测量骨和骨水泥应变以及制作重塑股骨标本的方案，但尚未将这些方案结合起来比较不同股骨条件下的应变模式。Lubinus SPII在临床上比Müller-Curved柄更成功，失败主要是由于无菌性松动。
测定完整股骨的皮质骨应变。每种假体分别植入6个股骨，测量皮质骨和骨水泥应变。使用经过验证的CAD-CAM程序模拟骨重塑，去除一层近端皮质骨，复制稳定临床翻修中常见的情况。再次测量应变。采用有限元方法辅助实验。
随着重塑，应力遮挡减少，尽管骨应变未恢复到完整值，尤其是在股骨距周围。骨水泥应变随重塑增加。两种柄之间存在差异；Müller-Curved产生的应变过渡更严重。
成功地将各种方法结合起来，在体外研究了两种骨水泥柄在术后即刻和长期条件下的性能。骨水泥应变随重塑增加是体内骨水泥失效的一个潜在指标。
股骨骨重塑对关节置换长期成功的影响尚未完全了解，重塑可能导致骨和骨水泥应力增加。
