Dennis Douglas A, Komistek Richard D
Department of Biomedical Engineering, University of Tennessee, USA.
Instr Course Lect. 2005;54:207-20.
In a comparison of in vivo knee kinematic patterns of mobile-bearing total knee arthroplasty with thosefrom studies of fixed-bearing total knee arthroplasty and the normal knee, no major differences in the "average" kinematic patterns of fixed- versus mobile-bearing implants was observed. However, there was less AP translation of both the medial and lateral femoral condyles during gait in patients with mobile-bearing implants. This is probably the result of the increased sagittal femorotibial conformity of most mobile-bearing implants, which reduces polyethylene shear stresses and should lessen polyethylene wear rates. In rotating-platform mobile-bearing implants, axial rotation occurs primarily on the inferior surface of the polyethylene bearing instead of on the superior surface, which reduces shear forces on the superior aspect of the polyethylene bearing, thereby lessening wear: Although the average axial rotational values after total knee arthroplasty were limited (< 10 degrees), a significant number of patients exhibited higher magnitudes of rotation (> 20 degrees), which exceeds the rotational limits of most fixed-bearing implants. Rotating-platform mobile-bearing implants may therefore be advantageous in that they can accommodate a wider range of axial rotation without creating excessive polyethylene stresses.
在比较活动平台全膝关节置换术与固定平台全膝关节置换术及正常膝关节的体内膝关节运动学模式时，未观察到固定平台与活动平台植入物“平均”运动学模式存在重大差异。然而，使用活动平台植入物的患者在步态期间股骨内外侧髁的前后平移较少。这可能是由于大多数活动平台植入物矢状面股骨-胫骨贴合度增加，这降低了聚乙烯剪切应力并应降低聚乙烯磨损率。在旋转平台活动平台植入物中，轴向旋转主要发生在聚乙烯衬垫的下表面而非上表面，这减少了聚乙烯衬垫上表面的剪切力，从而减少磨损：尽管全膝关节置换术后的平均轴向旋转值有限（<10度），但相当数量的患者表现出更高的旋转幅度（>20度），这超过了大多数固定平台植入物的旋转极限。因此，旋转平台活动平台植入物可能具有优势，因为它们可以适应更广泛的轴向旋转范围而不会产生过大的聚乙烯应力。
