An MRI-based method to align the compressive loading axis for human cadaveric knees
An MRI-based method to align the compressive loading axis for human cadaveric knees
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DOI：
10.1115/1.2800765
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发表时间：
2007-12-01
影响因子：
1.7
通讯作者：
Hull, M. L.
中科院分区：
文献类型：
--
作者：
Martin, K. J.;Neu, C. P.;Hull, M. L.
对于涉及胫股压缩的研究，需要将胫骨的机械轴与负载轴对齐，以解释结果并确保样本内和样本间负载的可重复性。因此，本研究的目的是（I）开发一种基于磁共振成像（MRI）的对准方法，用于与应用胫股关节压缩的装置一起使用，（2）通过在可以应用胫股关节压缩的装置中对准尸体膝盖来证明该方法的有效性，以及（3）量化与对准方法相关的误差。构建了四自由度可调节装置，以允许尸体膝关节的胫骨的机械轴与施加胫股关节压缩的装置的负载轴的确定和对准。 MRI 用于确定三维骨性标志的位置，定义相对于四自由度装置初始方向的胫骨机械轴。然后计算设备的调整值并将其应用于设备以使胫骨的机械轴与压缩加载装置的轴对齐。为了证明该方法的有效性，将四个尸体膝盖在压缩加载装置中对齐。对于每个尸体膝盖，计算了描述四自由度装置调整之前和之后的胫骨机械轴和装置的负载轴的矢量。四自由度装置调整后，胫骨的机械轴与每个尸体膝关节的装置的负载轴共线。使用蒙特卡罗技术对由于 MR 图像不准确而引入的调整值误差进行量化。平移和旋转调整的精度分别为1.20毫米和0.90度。基于 MR 的对准方法将通过提供明确的加载轴，对使用本文描述的设备进行的胫股压缩研究期间获得的结果进行一致的解释。该对准方法还可以适合于与施加胫股压缩的其他装置一起使用。
There is a need to align the mechanical axis of the tibia with the axis of loading for studies involving tibiofemoral compression to interpret results and to ensure repeatability of loading within and among specimens. Therefore, the objectives of this study were (I) to develop a magnetic resonance imaging (MRI)-based alignment method for use with apparatuses applying tibiofemoral joint compression, (2) to demonstrate the usefulness of the method by aligning cadaveric knees in an apparatus that could apply tibiofemoral joint compression, and (3) to quantify the error associated with the alignment method. A four degree-of-freedom adjustable device was constructed to allow determination and alignment of the mechanical axis of the tibia of cadaveric knee joints with the axis of loading of an apparatus applying tibiofemoral joint compression. MRI was used to determine the locations of bony landmarks in three dimensions defining the mechanical axis of the tibia relative to an initial orientation of the four degree-of-freedom device. Adjustment values of the device were then computed and applied to the device to align the mechanical axis of the tibia with the axis of a compressive loading apparatus. To demonstrate the usefulness of the method, four cadaveric knees were aligned in the compressive loading apparatus. The vectors describing the mechanical axis of the tibia and the loading axis of the apparatus before and after adjustment of the four degree-of-freedom device were computed for each cadaveric knee. After adjustment of the four degree-of-freedom device, the mechanical axis of the tibia was collinear with the loading axis of the apparatus for each cadaveric knee. The errors in the adjustment values introduced by inaccuracies in the MR images were quantified using the Monte Carlo technique. The precisions in the translational and rotational adjustments were 1.20 mm and 0.90 deg respectively. The MR-based alignment method will allow consistent interpretation of results obtained during tibiofemoral compressive studies conducted using the apparatus described in this paper by providing a well-defined loading axis. The alignment method can also be adapted for use with other apparatuses applying tibiofemoral compression.