Kessler Oliver, Dürselen Lutz, Banks Scott, Mannel Henrich, Marin Frédéric
Scientific Affairs, Stryker Europe, Thalwil, Switzerland.
Clin Biomech (Bristol). 2007 Jan;22(1):52-8. doi: 10.1016/j.clinbiomech.2006.07.011. Epub 2006 Oct 9.
It is known that in vivo kinematics after total knee replacement is influenced by the design of the implant. The goal of this study was to show that the sagittal curvature of two different knee prostheses differing in geometric design predicts their in vivo motion behavior.
Three-dimensional tibio-femoral displacements of two prosthesis designs (single radius vs. dual radius) were measured during knee extension under weight bearing conditions by in vivo video fluoroscopy. Finite helical axes were computed to represent the tibio-femoral motions. Angular deviation alpha and the spatial localization deviation delta were used to characterize the motions. Angular deviation is the angle between each incremental finite helical axis and the medio-lateral axis of the femoral component of the prosthesis. The spatial localization deviation is the distance between each finite helical axis and the center of the femoral component of the prosthesis. Statistical comparisons were performed using the median and the interquartile range of the angular deviation and the spatial localization deviation.
The single-radius design showed finite helical axes concentrated at a single axis near to the medio-lateral axis of the femoral component. The angular and spatial localization deviation of the dual radius design were larger compared to the single radius design, exhibiting finite helical axes varying between two axes.
Video fluoroscopy in combination with finite helical axis analysis proved to be suitable methods to evaluate the in vivo kinematical behavior of total knee arthroplasty, which can be useful for implant designers. Knowledge of in vivo kinematics can also provide surgeons with more background information about the total knee arthroplasty models they implant.
已知全膝关节置换术后的体内运动学受植入物设计的影响。本研究的目的是表明，两种几何设计不同的膝关节假体的矢状曲率可预测其体内运动行为。
在负重条件下膝关节伸展过程中，通过体内视频荧光透视法测量两种假体设计（单半径与双半径）的三维胫股位移。计算有限螺旋轴以表示胫股运动。使用角偏差α和空间定位偏差δ来表征运动。角偏差是每个增量有限螺旋轴与假体股骨组件的内外侧轴之间的夹角。空间定位偏差是每个有限螺旋轴与假体股骨组件中心之间的距离。使用角偏差和空间定位偏差的中位数和四分位间距进行统计比较。
单半径设计显示有限螺旋轴集中在靠近股骨组件内外侧轴的单个轴上。与单半径设计相比，双半径设计的角偏差和空间定位偏差更大，其有限螺旋轴在两个轴之间变化。
视频荧光透视法与有限螺旋轴分析相结合被证明是评估全膝关节置换术体内运动学行为的合适方法，这对植入物设计者可能有用。体内运动学知识还可为外科医生提供有关他们植入的全膝关节置换术模型的更多背景信息。
