Division of Orthopaedics, Department of Trauma and Orthopaedic Surgery, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
Clinic for Anesthesiology and Operative Intensive Care, Albertinen Hospital, Martinistr. 52, 20246, Hamburg, Germany.
Sci Rep. 2023 Jan 25;13(1):1429. doi: 10.1038/s41598-023-28048-7.
In total hip arthroplasty and reconstructive orthopedic surgery, pre-operative digital templating is essential for surgical treatment optimization, risk management, and quality control. Calibration is performed before templating to address magnification effects. Conventional methods including fixed calibration factors, individual marker-based calibration and dual-scale marker methods are not reliable. A novel bi-planar calibration method is described aiming to reduce the error below clinical significance. The bi-planar calibration method requires two conventional orthogonal radiographs and a standard radiopaque marker ball. An algorithm computes the hip plane height parallel to the detector in the antero-posterior radiograph. Foreseeable errors (i.e., patient rotation and misplaced markers or lateral offset) are considered in a correction algorithm. Potential effects of errors are quantified in a standard model. Influence of rotation in lateral radiographs and lateral offset of marker on the calibration factor are quantified. Without correction, patient rotation in the lateral radiograph of 30° results in absolute calibration error of 2.2% with 0 mm offset and 6.5% with 60 mm lateral offset. The error is below the threshold of 1.5% for rotation less than 26° with 0 mm offset and 10° with 60 mm offset. The method is supposed to be reliable in precisely predicting the hip plane and thereby the calibration factor. It may be superior to other methods available. In theory, the method allows correction of clinically relevant rotation of at least 30° and marker displacement without impacting the computed calibration factor.
在全髋关节置换和重建骨科手术中，术前数字化模板对于手术治疗优化、风险管理和质量控制至关重要。在模板制作之前需要进行校准，以解决放大效应问题。传统的方法包括固定的校准因子、基于个体标记的校准和双尺度标记方法都不可靠。本文介绍了一种新的双平面校准方法，旨在将误差降低到临床意义以下。该双平面校准方法需要两张传统的正交射线照片和一个标准的不透射线标记球。一个算法计算与探测器平行的髋关节平面高度在前后射线照片中。校正算法中考虑了可预见的误差（例如患者旋转和标记物错位或外侧偏移）。在标准模型中量化了误差的潜在影响。量化了旋转对侧位射线照片和标记物外侧偏移对校准因子的影响。如果不进行校正，患者在侧位射线照片中旋转 30°会导致绝对校准误差为 2.2%，偏移 0mm 时为 6.5%，偏移 60mm 时为 6.5%。当偏移为 0mm 时，旋转小于 26°且误差小于 1.5%，当偏移为 60mm 时，旋转小于 10°且误差小于 1.5%。该方法可以可靠地精确预测髋关节平面，从而预测校准因子。它可能优于其他可用的方法。从理论上讲，该方法允许校正至少 30°的临床相关旋转和标记物位移，而不会影响计算的校准因子。
