The Implant Biomechanics Laboratory of the J. Vernon Luck, Sr., M.D. Orthopaedic Research Center, 2400 South Flower Street, Los Angeles Orthopaedic Hospital-UCLA, Los Angeles, CA 90007-2697, USA.
J Biomech. 2011 Jan 4;44(1):22-7. doi: 10.1016/j.jbiomech.2010.08.017. Epub 2010 Sep 15.
In this study, the in vitro fixation of four otherwise identical double-tapered stem-types, varying only in surface finish (polished or matte) and proximal stem geometry (with or without flanges) were compared under two conditions. First, four specimens of each stem type were tested with initially bonded stem-cement interfaces, representing early post-operative conditions. Then, simulating conditions a few weeks to months later, stems were implanted in unused synthetic femurs, with a thin layer coating the stem to prevent stem-cement adhesion. Per-cycle motions were measured at both cement interfaces throughout loading. Overall, surface finish had the smallest relative effect on fixation compared to flanges. Flanges increased axial fixation by 22 μm per-cycle, regardless of surface finish (P=0.01). Further, all stems moved under dynamic load at the stem-cement interface during the first few cycles of loading, even without a thin film. The results indicate that flanges have a greater effect on fixation than surface finish, and therefore adverse findings about matte surfaces should not necessarily apply to all double-tapered stems. Specifically, dorsal flanges enhance the stability of a tapered cemented femoral stem, regardless of surface finish.
在这项研究中，比较了四种相同的双锥形柄类型的体外固定情况，这些柄仅在表面处理（抛光或磨砂）和近端柄几何形状（有或没有法兰）上有所不同。在两种情况下进行了测试。首先，每种柄类型的四个样本最初都具有粘合的柄-水泥界面，代表术后早期的情况。然后，模拟几周到几个月后的情况，将柄植入未使用的合成股骨中，在柄上涂有一层薄涂层以防止柄-水泥粘连。在加载过程中，在两个水泥界面处测量每个周期的运动。总的来说，与法兰相比，表面处理对固定的影响最小。无论表面处理如何，法兰都会使每个周期的轴向固定增加 22μm（P=0.01）。此外，在加载的前几个周期中，即使没有薄膜，所有柄在柄-水泥界面处也会在动态负载下移动。结果表明，法兰对固定的影响大于表面处理，因此关于磨砂表面的不利发现不一定适用于所有双锥形柄。具体来说，背侧法兰增强了锥形水泥股骨柄的稳定性，而与表面处理无关。
