Department of Orthopaedics, Diakonessen Hospital, Utrecht, The Netherlands.
Gait Posture. 2011 Feb;33(2):306-8. doi: 10.1016/j.gaitpost.2010.11.015. Epub 2010 Dec 10.
Relative movement of skin markers to underlying bone limits a valid interpretation of axial femorotibial rotation in noninvasive optoelectronic gait analysis. A distal femoral clamp is a practical solution for thigh marker placement, however, existing devices are still susceptible to measurement errors at increased angles of knee flexion. We developed the Femoral Epicondylar Frame (FEF), which should result in less femoral rotational measurement error due to its anatomic fitting and controlled pressure adjustment. Seven subjects with a total knee replacement in situ, mean age 71 years, mean body mass index 28, were equipped with the frame mounted with a set of tantalum markers. Fluoroscopic data was collected during a step-up motion. A three-dimensional model fitting technique was used to compare the in vivo position and orientation of the frame and the femoral prosthesis component of the prosthesis. The frame rotational measurement error appeared to be linearly dependent on the knee flexion angle. When considering knee flexion angles lower than 40° of flexion, the highest measurement error was 3.3° on average, with an absolute extreme of 6.2°. It is concluded that the accuracy of the FEF is sufficient to evaluate axial knee rotation with optoelectronic gait analysis at group level in clinical studies.
皮肤标记相对于下方骨骼的相对运动限制了非侵入性光电步态分析中对股骨胫轴向旋转的有效解释。股骨远端夹具是大腿标记放置的实用解决方案，但是现有的设备在膝关节弯曲角度增加时仍然容易出现测量误差。我们开发了股骨髁框架（FEF），由于其解剖拟合和受控压力调节，应该会导致股骨旋转测量误差更小。七个原位全膝关节置换的受试者，平均年龄 71 岁，平均体重指数 28，配备了安装有一组钽标记的框架。在台阶运动过程中收集了荧光透视数据。使用三维模型拟合技术比较了框架和假体组件的股骨假体的体内位置和方向。框架的旋转测量误差似乎与膝关节弯曲角度呈线性相关。当考虑膝关节弯曲角度低于 40°时，平均最高测量误差为 3.3°，绝对极限为 6.2°。结论是，FEF 的准确性足以在临床研究中的光电步态分析中评估轴向膝关节旋转。
