Ooms E M, Verdonschot N, Wolke J G C, Van de Wijdeven W, Willems M M M, Schoenmaker M F T, Jansen J A
Department of Biomaterials, College of Dental Science, University Medical Center Nijmegen, P.O. Box 9101, Nijmegen 6500 HB, The Netherlands.
Biomaterials. 2004 Aug;25(17):3887-94. doi: 10.1016/j.biomaterials.2003.10.067.
In this in vitro study we evaluated the initial stability of cementless femoral stems using an injectable calcium phosphate (Ca-P) cement. The cement was not used to form a cement mantle as is routinely done in PMMA cemented prostheses but functioned as an additive to fill the small gaps that exist between a press-fit placed titanium plasma sprayed implant and the bone bed. Six pair of Beagle femora were used in this study. In a random fashion, one femur of each pair was used for placement of a prosthesis without Ca-P cement, the contralateral was used for press-fit placement after injection of the calcium phosphate cement into the intramedullary canal. The reconstructions were placed in a MTS testing machine, tilted 15 degrees in varsus and 15 degrees of endorotation to obtain a physiological load on the femoral head. The load was applied stepwise from zero to a maximum of 100, 250 and 400 N, respectively. At each loading step the load was applied dynamically at a frequency of 1 Hz for 30 min. Between the loading steps, the load was removed for 10 min to allow elastic recovery. The stability of the stems was determined at each loading step with roentgen-stereophotogrammetric analysis. Results showed that with the prostheses without Ca-P cement the most important displacements were movement into varus (max. 818 microm under 400 N) and subsidence (max. 587 microm under 400 N). The displacements showed large variation. After unloading some elastic recovery occurred. In the specimens with Ca-P cement, displacements were negligible. As determined by an F-test the variations found were significantly smaller for the press-fit+Ca-P cement relative to the press-fit prosthesis at all loading steps (p<0.05). A paired t-test revealed significant differences in the mentioned displacements between the press-fit- and press-fit+Ca-P cement prosthesis at a loading with 400 N (P<0.05). On the basis of these results we conclude that the use of Ca-P cement increases the initial stability of press-fit inserted plasma-sprayed femoral prostheses and corrects for the high variability in displacements found with press-fit insertion of these femoral hip prostheses.
在这项体外研究中，我们评估了使用可注射磷酸钙（Ca-P）骨水泥的非骨水泥型股骨柄的初始稳定性。该骨水泥并非像聚甲基丙烯酸甲酯（PMMA）骨水泥固定假体那样用于形成骨水泥套，而是作为一种添加剂，用于填充压配式钛等离子喷涂植入物与骨床之间存在的微小间隙。本研究使用了六对比格犬股骨。以随机方式，每对中的一根股骨用于植入未使用Ca-P骨水泥的假体，对侧股骨则在将磷酸钙骨水泥注入髓腔后进行压配植入。将重建物置于MTS试验机中，内翻倾斜15度，内旋15度，以在股骨头处获得生理负荷。负荷分别从零逐步施加至最大100、250和400 N。在每个加载步骤，负荷以1 Hz的频率动态施加30分钟。在加载步骤之间，去除负荷10分钟以允许弹性恢复。在每个加载步骤通过X线立体摄影测量分析确定柄的稳定性。结果表明，对于未使用Ca-P骨水泥的假体，最重要的位移是内翻移动（400 N下最大818微米）和下沉（400 N下最大587微米）。位移表现出很大的变异性。卸载后发生了一些弹性恢复。在使用Ca-P骨水泥的标本中，位移可忽略不计。通过F检验确定，在所有加载步骤中，相对于压配假体，压配+Ca-P骨水泥的变异性显著更小（p<0.05）。配对t检验显示，在400 N加载时压配假体与压配+Ca-P骨水泥假体之间在上述位移方面存在显著差异（P<0.05）。基于这些结果，我们得出结论，使用Ca-P骨水泥可提高压配插入的等离子喷涂股骨假体的初始稳定性，并纠正这些股骨髋假体压配插入时发现的位移高变异性。
