Henckel Johann, Ramesh Angelika, Hothi Harry, Richards Robin, Di Laura Anna, Hart Alister
Royal National Orthopaedic Hospital NHS Trust, Stanmore, United Kingdom.
Department of Mechanical Engineering, University College London, London, United Kingdom.
Front Bioeng Biotechnol. 2023 Apr 28;11:1150061. doi: 10.3389/fbioe.2023.1150061. eCollection 2023.
The placement of acetabular implant components determines the short- and long-term outcomes of total hip replacement (THR) and a number of tools have been developed to assist the surgeon in achieving cup orientation to match the surgical plan. However, the accuracy and precision of 3D-CT for the measurement of acetabular component position and orientation is yet to be established. To investigate this, we compared measurements of cobalt chrome acetabular components implanted into 2 different bony pelvic models between a coordinate measuring Faro arm and 3 different low dose CT images, including 3D-CT, 2D anterior pelvic plane (APP) referenced CT and 2D scanner referenced (SR) CT. Intra-observer differences were assessed using the Intraclass correlation coefficient (ICC). The effect of imaging the pelvis positioned in 3 different orientations within the CT scanner was also assessed. The measured parameters were the angles of inclination and version. 3D-CT measurements were found to closely match the "true values" of the component position measurements, compared with the 2D-CT methods. ICC analysis also showed good agreement between the coordinate measuring arm (CMA) and 3D-CT but poor agreement between the 2D SR method, in the results from two observers. When using the coordinate system of the CT scanner, the measurements consistently produced the greatest error; this method yielded values up to 34° different from the reference digitising arm. However, the difference between the true inclination and version angles and those measured from 3D APP CT was below half a degree in all cases. We concluded that low radiation dose 3D-CT is a validated reference standard for the measurement of acetabular cup orientation.
髋臼植入部件的放置决定了全髋关节置换术（THR）的短期和长期效果，并且已经开发了多种工具来协助外科医生实现髋臼杯的定向，以符合手术计划。然而，三维计算机断层扫描（3D-CT）在测量髋臼部件位置和定向方面的准确性和精确性尚未得到确立。为了对此进行研究，我们比较了植入到两种不同骨盆骨模型中的钴铬合金髋臼部件在坐标测量法如法如臂（Faro arm）与三种不同的低剂量CT图像（包括3D-CT、二维骨盆前平面（APP）参考CT和二维扫描仪参考（SR）CT）之间的测量结果。使用组内相关系数（ICC）评估观察者内部差异。还评估了在CT扫描仪内以三种不同方向放置骨盆进行成像的影响。所测量的参数为倾斜角和扭转角。与二维CT方法相比，发现3D-CT测量结果与部件位置测量的“真实值”密切匹配。ICC分析还表明，在两位观察者的结果中，坐标测量臂（CMA）与3D-CT之间具有良好的一致性，但二维SR方法之间的一致性较差。当使用CT扫描仪的坐标系时，测量结果始终产生最大误差；该方法得出的值与参考数字化臂相差高达34°。然而，在所有情况下，真实倾斜角和扭转角与从三维APP CT测量得到的角度之间的差异均低于半度。我们得出结论，低辐射剂量的3D-CT是测量髋臼杯定向的有效参考标准。
