van Loon C J, Kyriazopoulos A, Verdonschot N, de Waal Malefijt M C, Huiskes R, Buma P
Department of Orthopaedics, University Hospital Nijmegen, The Netherlands.
Clin Orthop Relat Res. 2000 Sep(378):282-9. doi: 10.1097/00003086-200009000-00039.
Although stemmed femoral components often are used in revision total knee arthroplasty, no quantitative comparison of the relative stability of a femoral component with and without a stem has been performed previously. A radiostereophotogrammetric analysis was performed to determine the influence of stem extension on mechanical stability in a laboratory experiment. In addition, the contribution of impacted morselized bone graft used for reconstruction of bone defects to stability was determined. Ten fresh frozen distal femoral specimens, of which the bone mineral density was measured, were prepared to fit a cemented femoral component with an uncemented stem. A cyclic axial load of 750 N was applied to the medial part of the femoral component. The loading test was repeated after creation of a standard, unicondylar, uncontained medial bone defect, after reconstruction of the defect with impacted morselized bone graft, after disconnecting the stem from the component, and after removal of the morselized bone graft. A significant difference was found in rotation and translation of the femoral component with the stem and after its functional removal. The femoral component rotated significantly into varus and internal rotation, and the tip of the stem translated significantly laterally after disconnection of the stem. A linear correlation between bone mineral density in the femoral neck and the radiostereophotogrammetric motion data was absent, but a bone mineral density threshold level of 0.55 g/cm2 was present, below which stability decreased considerably. Morselized bone graft provided only a minor contribution to stability compared with a stem.
尽管带柄股骨部件常用于全膝关节置换翻修手术，但此前尚未对带柄和不带柄股骨部件的相对稳定性进行定量比较。在一项实验室实验中，进行了放射立体摄影测量分析，以确定柄的延长对机械稳定性的影响。此外，还确定了用于骨缺损重建的打压植骨碎骨对稳定性的贡献。制备了10个新鲜冷冻的股骨远端标本，测量其骨密度，以适配一个带非骨水泥柄的骨水泥股骨部件。对股骨部件的内侧部分施加750 N的周期性轴向载荷。在制造标准的单髁、非包容性内侧骨缺损后、用打压植骨碎骨重建缺损后、将柄与部件分离后以及移除植骨碎骨后，重复进行加载测试。发现带柄股骨部件及其功能移除后在旋转和平移方面存在显著差异。柄分离后，股骨部件显著内翻并内旋，柄尖显著向外平移。股骨颈骨密度与放射立体摄影测量运动数据之间不存在线性相关性，但存在一个0.55 g/cm²的骨密度阈值水平，低于该水平稳定性会显著下降。与柄相比，植骨碎骨对稳定性的贡献较小。
