Cilla Myriam, Checa Sara, Duda Georg N
Julius Wolff Institute, Charité - Universitätsmedizin Berlin, Campus - Virchow Klinikum, Augustenburger Platz 1, Institutsgebäude Süd,13353 Berlin, Germany.
Centro Universitario de la Defensa, Academia General Militar, Ctra. Huesca s/n, 50090 Zaragoza, Spain.
J Orthop Res. 2017 Nov;35(11):2534-2544. doi: 10.1002/jor.23540. Epub 2017 Mar 2.
A large number of hip prosthesis with different designs have been developed. However, the influence of hip implant design changes on the strains induced in the bone remains unclear. The purpose of this study is to better understand the mechanics of short stem total hip arthroplasty. Specifically, it investigates whether strain shielding can be avoided by changing implant shape and/or material properties. It is hypothesized that the re-design of existing implant designs can result in further reduction of strain shielding and thus keep bone loss minimal following total hip replacement. Finite element methods were used to compare healthy and implanted models. The local mechanics strains/stresses in the intact and implanted femurs were determined under patient-specific muscle and joint contact forces. Results suggest that small changes in implant geometry and material properties have no major effect on strain shielding. Furthermore, it was found that improvement depends on a dramatic re-design of the original implant design. Whereas the benefit of this strategy of modification of the original geometry of a given short-stemmed hip consists in reduced bone remodeling, care should be taken with regard to long-term bone anchorage and implant fatigue strength. It is also shown that geometrical and material changes have a limited potential in avoiding strain shielding even in short-stemmed implants. Finally, it is suggested that an understanding of the influence of these changes on the strain distribution within the bone can guide in the process of optimizing the current stem designs toward minimal strain shielding effects. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2534-2544, 2017.
已经研发出大量设计各异的髋关节假体。然而，髋关节植入物设计的改变对骨骼中诱导应变的影响仍不明确。本研究的目的是更好地理解短柄全髋关节置换术的力学原理。具体而言，研究能否通过改变植入物形状和/或材料特性来避免应力遮挡。据推测，对现有植入物设计进行重新设计可进一步减少应力遮挡，从而在全髋关节置换术后使骨质流失降至最低。采用有限元方法比较健康模型和植入模型。在患者特定的肌肉和关节接触力作用下，测定完整股骨和植入股骨中的局部力学应变/应力。结果表明，植入物几何形状和材料特性的微小变化对应力遮挡没有重大影响。此外，研究发现改进取决于对原始植入物设计进行大幅重新设计。虽然这种对给定短柄髋关节原始几何形状进行修改的策略的好处在于减少骨重塑，但在长期骨锚固和植入物疲劳强度方面应予以关注。研究还表明，即使在短柄植入物中，几何形状和材料的改变在避免应力遮挡方面的潜力也有限。最后，研究表明，了解这些变化对骨内应变分布的影响可指导当前柄设计朝着最小应力遮挡效应进行优化。© 2017年骨科研究协会。由威利期刊公司出版。《矫形外科研究杂志》35:2534 - 2544，2017年。
