Jaramaz Branislav, Eckman Kort
The Western Pennsylvania Hospital, Pittsburgh, Pennsylvania, USA.
Med Image Comput Comput Assist Interv. 2006;9(Pt 2):653-61. doi: 10.1007/11866763_80.
Measurements of cup alignment after total hip replacement (THR) surgery are typically performed on postoperative pelvic radiographs. Radiographic measurement of cup orientation depends on the position and orientation of the pelvis on the X-ray table, and its variability could introduce significant measurement errors. We have developed a tool to accurately measure 3D implant orientation from postoperative antero-posterior radiographs by registering to preoperative CT scans. The purpose of this study is to experimentally and clinically validate the automatic CT/X-ray matching algorithm by comparing the X-ray based measurements of cup orientation with direct 3D measurements from postoperative CT scans. The mean measurement errors (+/- stdev) found in this study were 0.4 degrees +/-0.8 degrees for abduction and 0.6 degrees +/- 0.8 degrees for version. In addition, radiographic pelvic orientation measurements demonstrated a wide range of inter-subject variability, with pelvic flexion ranging from -5.9 degrees to 11.2 degrees.
全髋关节置换术（THR）后髋臼假体对线的测量通常在术后骨盆X线片上进行。髋臼假体方向的X线测量取决于骨盆在X线检查台上的位置和方向，其变异性可能会引入显著的测量误差。我们开发了一种工具，通过与术前CT扫描进行配准，从术后前后位X线片中准确测量三维植入物方向。本研究的目的是通过将基于X线的髋臼假体方向测量与术后CT扫描的直接三维测量进行比较，对自动CT/X线匹配算法进行实验和临床验证。本研究中发现的平均测量误差（±标准差）外展为0.4°±0.8°，前倾角为0.6°±0.8°。此外，X线骨盆方向测量显示受试者间存在广泛的变异性，骨盆屈曲范围为-5.9°至11.2°。
