Kamath Jagannath, Danda Raja Shekar, Jayasheelan Nikil, Singh Rohit
Professor, Department of Orthopaedics, Kasturba Medical College, Manipal University , Mangalore, Karnataka, India .
Senior Resident, Department of Orthopaedics, Kasturba Medical College, Manipal University , Mangalore, Karnataka, India .
J Clin Diagn Res. 2016 Jun;10(6):RC11-3. doi: 10.7860/JCDR/2016/17324.8042. Epub 2016 Jun 1.
Various methods of measuring mechanical axis deviation of lower limb have been described including radiographic and CT scanogram, intraoperative fluoroscopy with the use of an electrocautery cord. These methods determine the mechanical axis in a supine, non-weight bearing position. Although long cassette standing radiographic view is used for the purpose but is not available at most centres. A dynamic method of determining the mechanical axis in a weight bearing position was devised in this study.
The aim of the study was to describe a simpler and newer method in quantifying the mechanical axis deviation in places where full length cassettes for standing X rays are not available.
A pilot study was conducted on 15 patients. The deviation from the mechanical axis was measured using a manually operated, hydraulic mechanism based, elevating scissor lift table. Patient was asked to stand erect over the elevating lift table with both patellae facing forward and C-arm image intensifier was positioned horizontally. Radiological markers were tied to a radio-opaque thread and placed at the centre of head of the femur and another at the centre of the tibio-talar joint. C-arm views of the hip, ankle and knee joint were taken to confirm the correct position of the marker by varying the height of the lift table.
The mechanical axis deviation values were recorded by measuring distance between the centre of the knee and radio-opaque thread in cm. This was measured in each case both clinically and from the image on the monitor. The two values were found to be statistically same. Pain was measured on VAS. Mechanical axis deviation values and VAS score were found to be positively significantly correlated.
This technique is dynamic, unique and accurate as compared to other methods for assessing mechanical axis deviation in a weight bearing position.
已经描述了多种测量下肢机械轴偏差的方法，包括放射照相和CT扫描图、使用电灼线的术中透视。这些方法在仰卧、非负重位置确定机械轴。虽然长暗盒站立位放射照片可用于此目的，但大多数中心都没有。本研究设计了一种在负重位置确定机械轴的动态方法。
本研究的目的是描述一种更简单、更新的方法，用于在没有用于站立位X线检查的全长暗盒的地方量化机械轴偏差。
对15例患者进行了一项初步研究。使用基于手动操作的液压机构的升降剪式升降台测量与机械轴的偏差。要求患者双髌骨向前站立在升降台上，C形臂影像增强器水平放置。将放射性标记物系在不透射线的线上，放置在股骨头部中心，另一个放置在胫距关节中心。通过改变升降台高度，拍摄髋关节、踝关节和膝关节的C形臂图像，以确认标记物的正确位置。
通过测量膝关节中心与不透射线线之间的距离（以厘米为单位）记录机械轴偏差值。在每种情况下，都从临床和监视器上的图像进行测量。发现这两个值在统计学上相同。使用视觉模拟评分法（VAS）测量疼痛。发现机械轴偏差值与VAS评分呈显著正相关。
与其他在负重位置评估机械轴偏差的方法相比，该技术具有动态、独特和准确的特点。
