Armiger Robert S, Armand Mehran, Lepisto Jyri, Minhas Davneet, Tallroth Kaj, Mears Simon C, Waites Matthew D, Taylor Russell H
Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland 20723, USA.
Comput Aided Surg. 2007 Jul;12(4):215-24. doi: 10.3109/10929080701541855.
Periacetabular osteotomy (PAO) is intended to treat a painful dysplastic hip. Manual radiological angle measurements are used to diagnose dysplasia and to define regions of insufficient femoral head coverage for planning PAO. No method has yet been described that recalculates radiological angles as the acetabular bone fragment is reoriented. In this study, we propose a technique for computationally measuring the radiological angles from a joint contact surface model segmented from CT-scan data. Using oblique image slices, we selected the lateral and medial edge of the acetabulum lunate to form a closed, continuous, 3D curve. The joint surface is generated by interpolating the curve, and the radiological angles are measured directly using the 3D surface. This technique was evaluated using CT data for both normal and dysplastic hips. Manual measurements made by three independent observers showed minor discrepancies between the manual observations and the computerized technique. Inter-observer error (mean difference +/- standard deviation) was 0.04 +/- 3.53 degrees for Observer 1; -0.46 +/- 3.13 degrees for Observer 2; and 0.42 +/- 2.73 degrees for Observer 3. The measurement error for the proposed computer method was -1.30 +/- 3.30 degrees . The computerized technique demonstrates sufficient accuracy compared to manual techniques, making it suitable for planning and intraoperative evaluation of radiological metrics for periacetabular osteotomy.
髋臼周围截骨术（PAO）旨在治疗疼痛性髋关节发育不良。手动放射学角度测量用于诊断发育不良，并确定股骨头覆盖不足的区域，以规划PAO。目前尚未有方法能够在髋臼骨块重新定位时重新计算放射学角度。在本研究中，我们提出了一种从CT扫描数据分割出的关节接触面模型中计算测量放射学角度的技术。利用倾斜图像切片，我们选择髋臼月状面的外侧和内侧边缘以形成一条封闭、连续的三维曲线。通过对该曲线进行插值生成关节面，并直接使用三维表面测量放射学角度。使用正常和发育不良髋关节的CT数据对该技术进行了评估。由三名独立观察者进行的手动测量显示，手动观察与计算机技术之间存在微小差异。观察者间误差（平均差异±标准差）：观察者1为0.04±3.53度；观察者2为-0.46±3.13度；观察者3为0.42±2.73度。所提出的计算机方法的测量误差为-1.30±3.30度。与手动技术相比，计算机技术显示出足够的准确性，使其适用于髋臼周围截骨术放射学指标的规划和术中评估。
