Department of Orthopaedic Surgery, Hannover Medical School, Anna-von-Borries Str. 1-7, 30625, Hannover, Germany,
Int Orthop. 2013 Dec;37(12):2351-6. doi: 10.1007/s00264-013-2072-5. Epub 2013 Aug 31.
For further development of better bone-preserving implants in total hip arthroplasty (THA), we need to look back and analyse established and clinically approved implants to find out what made them successful. Finite element analysis can help do this by simulating periprosthetic bone remodelling under different conditions. Our aim was thus to establish a numerical model of the cementless straight stem for which good long-term results have been obtained.
We performed a numeric simulation of a cementless straight stem, which has been successfully used in its unaltered form since 1986/1987. We have 20 years of experience with this THA system and implanted it 555 times in 2012. We performed qualitative and quantitative validation using bone density data derived from a prospective dual-energy X-ray absorptiometry (DEXA) investigation.
Bone mass loss converged to 9.25% for the entire femur. No change in bone density was calculated distal to the tip of the prosthesis. Bone mass decreased by 46.2% around the proximal half of the implant and by 7.6% in the diaphysis. The numeric model was in excellent agreement with DEXA data except for the calcar region, where deviation was 67.7%.
The higher deviation in the calcar region is possibly a sign of the complex interactions between the titanium coating on the stem and the surrounding bone. We developed a validated numeric model to simulate bone remodelling for different stem-design modifications. We recommend that new THA implants undergo critical numeric simulation before clinical application.
为了进一步开发更好的全髋关节置换术（THA）中保骨植入物，我们需要回顾和分析已建立并经临床批准的植入物，以找出使其成功的原因。有限元分析可以通过模拟不同条件下的假体周围骨重塑来帮助做到这一点。因此，我们的目的是建立一个已获得良好长期效果的非骨水泥直柄的数值模型。
我们对一种非骨水泥直柄进行了数值模拟，该直柄自 1986/1987 年以来一直以未经改变的形式成功使用。我们对这种 THA 系统有 20 年的经验，2012 年共植入 555 次。我们使用从前瞻性双能 X 射线吸收法（DEXA）研究中得出的骨密度数据进行了定性和定量验证。
整个股骨的骨量损失收敛至 9.25%。在假体尖端远端未计算到骨密度的变化。在植入物近端的一半周围，骨量减少了 46.2%，而在骨干处减少了 7.6%。数值模型与 DEXA 数据非常吻合，除了距骨区，偏差为 67.7%。
距骨区较高的偏差可能是柄上钛涂层与周围骨之间复杂相互作用的迹象。我们开发了一个经过验证的数值模型来模拟不同柄设计修改的骨重塑。我们建议新的 THA 植入物在临床应用前进行严格的数值模拟。
