Turner A W L, Gillies R M, Sekel R, Morris P, Bruce W, Walsh W R
Orthopaedic Research Laboratories, University of New South Wales, Prince of Wales Hospital, L2 South Wing, Edmund Blacket Bldg, High St, Randwick, Sydney NSW 2031, Australia.
J Orthop Res. 2005 Jul;23(4):705-12. doi: 10.1016/j.orthres.2005.02.002. Epub 2005 Mar 23.
Femoral periprosthetic bone loss following total hip replacement is often associated with stress shielding. Extensive bone resorption may lead to implant or bone failure and complicate revision surgery. In this study, an existing strain-adaptive bone remodelling theory was modified and combined with anatomic three-dimensional finite element models to predict alterations in periprosthetic apparent density. The theory incorporated an equivalent strain stimulus and joint and muscle forces from 45% of the gait cycle. Remodelling was simulated for three femoral components with different design philosophies: cobalt-chrome alloy, two-thirds proximally coated; titanium alloy, one-third proximally coated; and a composite of cobalt-chrome surrounded by polyaryletherketone, fully coated. Theoretical bone density changes correlated significantly with clinical densitometry measurements (DEXA) after 2 years across the Gruen zones (R2>0.67, p<0.02), with average differences of less than 5.4%. The results suggest that a large proportion of adaptive bone remodelling changes seen clinically with these implants may be explained by a consistent theory incorporating a purely mechanical stimulus. This theory could be applied to pre-clinical testing of new implants, investigation of design modifications, and patient-specific implant selection.
全髋关节置换术后股骨假体周围骨丢失通常与应力遮挡有关。广泛的骨吸收可能导致植入物或骨失效，并使翻修手术复杂化。在本研究中，对现有的应变适应性骨重塑理论进行了修改，并与解剖学三维有限元模型相结合，以预测假体周围表观密度的变化。该理论纳入了等效应变刺激以及来自步态周期45%的关节和肌肉力。对三种具有不同设计理念的股骨部件进行了重塑模拟：钴铬合金，近端三分之二涂层；钛合金，近端三分之一涂层；以及聚芳醚酮包围的钴铬复合材料，全涂层。理论骨密度变化与2年后Gruen区域的临床骨密度测量（DEXA）显著相关（R2>0.67，p<0.02），平均差异小于5.4%。结果表明，临床上这些植入物所见的大部分适应性骨重塑变化可以用一个包含纯机械刺激的一致理论来解释。该理论可应用于新植入物的临床前测试、设计修改研究以及患者特异性植入物选择。
