Department of Mechanical Engineering, Indian Institute of Technology, Kharagpur, Kharagpur, 721 302 West Bengal, India.
Ann Biomed Eng. 2010 Jun;38(6):2107-20. doi: 10.1007/s10439-010-0007-5. Epub 2010 Mar 23.
It is hypothesized that changes in stem length and implant-bone interfacial conditions would affect the mechanical environment within the uncemented resurfaced femur, thereby influencing potential short- and long-term failure mechanisms. This study is aimed at investigating the influence of changes in implant-bone interfacial conditions and stem length on eventual failure, using 3D FE models integrated with bone remodeling simulations. Musculoskeletal forces corresponding to normal walking and stair climbing were used as applied loading conditions. Sliding micromotions of 26-72 microm at the implant-bone interfaces for both the stem designs suggest bone ingrowth on the coated surface of the implant was likely. The initial risk of femoral neck fracture was less for the uncemented designs as compared to the cemented designs, irrespective of interfacial conditions and variation in stem length. For the uncemented variety, shortening the stem length provided only slight advantages (5%) with regard to strain shielding and bone remodeling. However, bone resorption was considerably higher when fully bonded interfaces were simulated. It may, therefore, be concluded that cementless fixation seems to be a viable alternative to cemented fixation, provided sufficient initial fixation and secondary stability through bone ingrowth into the coated surface of the implant can be achieved.
有人假设，柄长度和植入物-骨界面条件的变化会影响非骨水泥表面股骨的力学环境，从而影响潜在的短期和长期失效机制。本研究旨在通过整合骨骼重塑模拟的三维有限元模型，研究植入物-骨界面条件和柄长度变化对最终失效的影响。正常行走和爬楼梯时的肌肉骨骼力被用作应用的加载条件。对于两种柄设计，界面处的滑动微运动为 26-72μm，这表明涂层表面上的植入物可能发生了骨长入。与骨水泥固定设计相比，无论界面条件和柄长度如何变化，非骨水泥固定设计的股骨颈骨折初始风险都较低。对于非骨水泥设计，缩短柄长度仅在应变屏蔽和骨骼重塑方面提供了略微的优势（5%）。然而，当模拟完全结合界面时，骨吸收量要高得多。因此，可以得出结论，只要能够实现足够的初始固定和通过骨长入到植入物的涂层表面获得的二次稳定性，非骨水泥固定似乎是骨水泥固定的可行替代方案。
