Purpose

The purpose of the present study was to assess the kinematical behavior of a multi-radius posterior-stabilized (PS) mobile-bearing (MB) total knee arthroplasty (TKA) during an activity of daily living (Sit-To-Stand—STS) and a high demanding motor task (Deep-Knee-Lunge—DKL) using model-based dynamic RSA. We hypothesized the achievement of medial pivoting movement in both motor tasks due to the congruent geometry of the inlay with the femoral component, which should allow good stability of the medial compartment, and to the high magnitude of rotations guaranteed by the MB on the tibial side.

Methods

Twenty-two randomly selected patients were recruited and prospectively evaluated. The PS MB cemented TKA was implanted with the standard technique (medial parapatellar approach, adjusted mechanical alignment). At minimum 9-month follow-up, patients were examined with model based Dynamic RSA developed in our Institute (BI-STAND DRX 2) during the execution of two motor tasks: STS and DKL. The motion parameters were evaluated using the Grood and Suntay decomposition and the low-point kinematics methods.

Results

In the extension phase of DKL femur performed a greater antero posterior translation of 3.8 mm compared to STS between 0° and 20° of knee flexion (p < 0.05).

Low-point analysis showed a medial pivoting movement in both motor tasks: in 62% of patients during STS and 48% during DKL. Varus-valgus rotations were lower than 1° during all the range-of-motion in both motor tasks without differences.

Conclusions

Medial pivot was partially produced by this multi-radius PS MB TKA with some differences during activity of daily living (STS) and high demanding motor task (DKL).

Level of evidence

IV.

中文翻译：

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多半径后路稳定的可移动式全膝关节置换术在日常生活活动和高要求的运动任务期间部分产生体内内侧枢轴。

目的

本研究的目的是评估在日常生活活动中（坐直站-STS）多半径后路稳定（PS）移动轴承（MB）全膝关节置换术（TKA）的运动学行为以及使用基于模型的动态RSA进行的高难度运动任务（Deep-Knee-Lunge-DKL）。我们假设在两个运动任务中均实现了内侧枢转运动，这是因为嵌体与股骨组件的几何形状一致，这应使内侧腔保持良好的稳定性，并且胫骨侧的MB保证了高旋转度。

方法

招募了22名随机选择的患者并进行了前瞻性评估。PS MB骨水泥化TKA植入了标准技术（内侧pat骨入路，调整后的机械对准）。在至少9个月的随访中，在执行两项运动任务：STS和DKL期间，用我们研究所开发的基于模型的Dynamic RSA（BI-STAND DRX 2）对患者进行了检查。使用Grood和Suntay分解以及低点运动学方法评估了运动参数。

结果

在膝关节屈曲0°和20°之间，与STS相比，在DKL的股骨伸展阶段，股骨的前后后平移更大，为3.8 mm（p  <0.05）。

低点分析显示，在两项运动任务中均发生中枢运动：STS期间62％的患者和DKL期间48％的患者。在两项运动任务的所有运动范围内，内翻-外翻旋转均低于1°，且无差异。

结论

内侧枢轴部分地由这种多半径PS MB TKA产生，在日常生活活动（STS）和高要求运动任务（DKL）期间存在一些差异。

证据水平

IV。