Hospital for Special Surgery, 535 East 70th Street, New York, NY 10021, USA.
Clin Orthop Relat Res. 2013 Jan;471(1):76-85. doi: 10.1007/s11999-012-2530-1.
Rotating-platform TKA, although purported to have superior kinematics, has shown no clinical advantages over those of fixed-bearing TKA. Our design-matched retrieval study aimed to investigate if differences in bearing wear damage exist between fixed- and mobile-bearing TKAs with similar condylar geometry.
QUESTIONS/PURPOSES: We asked whether (1) the rotating platform's more conforming tibiofemoral articulation would be associated with less severe damage; (2) the location of damage and wear would be similar on the tibiofemoral or backside surfaces of two contemporary designs with similar condylar geometry; and (3) the combined damage and deformation measured as thickness would differ between the two designs.
We performed damage grading and damage mapping on 25 rotating-platform and 17 fixed-bearing inserts. The patient demographic data from each of these cohorts were comparable. Inserts were also laser-scanned from which we obtained thicknesses, and inferior surface three-dimensional scans, from which we determined dimensional changes.
Rotating-platform and fixed-bearing inserts had similar tibiofemoral damage scores. However, the scores on the inferior surface of rotating platforms were greater, often as a result of third-body debris scratching observed on both damage mapping and three-dimensional scans. The extent of damage as a function of surface area was greater for rotating platforms, consistent with the greater tibiofemoral conformity. Dimensional changes on the inferior surfaces of the fixed bearing followed loading areas of the knee. However, no differences were seen in the thicknesses between fixed- and rotating-platform bearings.
The increased total damage score on the rotating platform, coupled with increased surface area damaged and the propensity for third-body debris, indicates no damage advantage to this mobile-bearing design.
旋转平台 TKA 虽然据称具有优越的运动学性能，但在临床方面并未优于固定平台 TKA。我们的设计匹配检索研究旨在调查具有相似髁几何形状的固定和活动平台 TKA 之间是否存在轴承磨损损伤的差异。
问题/目的：我们想知道（1）旋转平台更符合的胫股关节是否会与更严重的损伤相关；（2）在具有相似髁几何形状的两种现代设计的胫股或后侧表面上，损伤和磨损的位置是否相似；（3）作为厚度测量的组合损伤和变形是否会在两种设计之间有所不同。
我们对 25 个旋转平台和 17 个固定平台植入物进行了损伤分级和损伤绘图。这些队列中的每个患者的人口统计学数据都是可比的。我们还对植入物进行了激光扫描，从中获得了厚度，并对下表面进行了三维扫描，从中确定了尺寸变化。
旋转平台和固定平台植入物的胫股损伤评分相似。然而，旋转平台的下表面评分更高，通常是由于在损伤绘图和三维扫描中观察到的第三体碎屑刮擦所致。随着胫股吻合度的增加，旋转平台的损伤程度与表面积成比例增加。固定平台下表面的尺寸变化遵循膝关节的负荷区域。然而，在固定和旋转平台轴承之间没有观察到厚度差异。
旋转平台上增加的总损伤评分，加上增加的损伤表面积和第三体碎屑的倾向，表明这种活动平台设计没有任何优势。
