Ebramzadeh Edward, Sangiorgio Sophia N, Longjohn Donald B, Buhari Cyrus F, Dorr Lawrence D
Biomechanics Laboratory, Los Angeles Orthopaedic Hospital/University of California at Los Angeles, Los Angeles, CA 90007-2697, USA.
J Bone Joint Surg Am. 2004 Jan;86(1):106-15. doi: 10.2106/00004623-200401000-00016.
The optimum surface roughness of cemented femoral stems used for total hip replacement is a subject of controversy. While rougher surfaces provide stronger cement adhesion, it has been hypothesized that polished, tapered, noncollared stems settle into the cement mantle, providing improved stability. However, the effects of surface finish on the stability of straight, cemented stems tapered only in the coronal plane are not known.
Using composite model femora, we assessed the initial stability of a straight, cemented femoral stem as a function of surface roughness, the presence or absence of a collar, stem size, and the resultant cement thickness under simulated walking and stair-climbing loads. Otherwise identical stems were manufactured with polished or rough surfaces, with or without a collar, in two different sizes. We isolated these three variables and compared their relative contributions to the motion at the stem-cement interface throughout cyclic loading. We defined three indicators of stability: per-cycle motion, rate of migration, and final migration.
Surface roughness had a greater influence on per-cycle motions than did the presence or absence of a collar or cement thickness. Specifically, in the medial-lateral direction, per-cycle motion of polished stems was 43 micro m greater than that of rough stems (p < 0.01). None of the per-cycle motions decreased over the 77,000 load cycles. In contrast, with all stems, the rate of migration decreased over the course of cyclic loading, but the rate of migration of the polished stems was greater than that of the rough stems. Final migrations of the stems over the course of loading were generally distal, medial, and into retroversion. Compared with rough stems, polished stems had 8 to 18 micro m more axial migration (p < 0.001), 48 micro m more anterior-posterior migration (p < 0.001), and 0.4 degrees more rotational migration (p = 0.01).
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The results indicated that, for cemented, straight femoral stems tapered only in the coronal plane, a rough surface offers the advantage of less per-cycle motion. These results may apply to widely used cemented stem designs based on the profile of the original Charnley femoral component, which has approximately parallel anterior and posterior aspects.
用于全髋关节置换的骨水泥型股骨柄的最佳表面粗糙度是一个存在争议的话题。虽然更粗糙的表面能提供更强的骨水泥附着力，但据推测，经过抛光、呈锥形且无领圈的股骨柄会嵌入骨水泥壳中，从而提供更好的稳定性。然而，表面光洁度对仅在冠状面呈锥形的直柄骨水泥型股骨柄稳定性的影响尚不清楚。
我们使用复合模型股骨，评估了直柄骨水泥型股骨柄在模拟行走和爬楼梯负荷下的初始稳定性，将其作为表面粗糙度、有无领圈、柄的尺寸以及由此产生的骨水泥厚度的函数。制造了表面抛光或粗糙、有或无领圈、两种不同尺寸的其他方面均相同的股骨柄。我们分离出这三个变量，并比较它们在整个循环加载过程中对柄 - 骨水泥界面运动的相对贡献。我们定义了三个稳定性指标：每周期运动、迁移率和最终迁移量。
表面粗糙度对每周期运动的影响比对有无领圈或骨水泥厚度的影响更大。具体而言，在内侧 - 外侧方向上，抛光柄的每周期运动比粗糙柄大43微米（P < 0.01）。在77,000次加载循环中，所有每周期运动均未降低。相比之下，对于所有股骨柄，迁移率在循环加载过程中均下降，但抛光柄的迁移率大于粗糙柄。在加载过程中，股骨柄的最终迁移通常是向远侧、内侧和进入后倾方向。与粗糙柄相比，抛光柄的轴向迁移多8至18微米（P < 0.001），前后迁移多48微米（P < 0.001），旋转迁移多0.4度（P = 0.01）。
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结果表明，对于仅在冠状面呈锥形的直柄骨水泥型股骨柄，粗糙表面具有每周期运动较少的优势。这些结果可能适用于基于原始Charnley股骨部件轮廓的广泛使用的骨水泥柄设计，该部件的前后方面大致平行。
