Department of Mechanical and Materials Engineering, Queen's University, Kingston, ON, Canada.
Int J Comput Assist Radiol Surg. 2012 Mar;7(2):241-8. doi: 10.1007/s11548-011-0641-x. Epub 2011 Jul 8.
Periacetabular osteotomies are a family of surgical procedures used to treat hip dysplasia. In a periacetabular osteotomy, the operating surgeon aims to increase acetabular coverage of the femoral head. The surgical correction has mechanical goals of increasing the stability of the joint and to improving the pressure distribution across the acetabulum. Although it is known that bone will remodel under changing load at the microstructural level, it is unclear whether there is any gross remodeling of the acetabulum or the femoral head in response to the change in loading following a periacetabular osteotomy. This observational study aims to quantify the shape of operative and contralateral hip joint surfaces pre and postoperatively to determine whether there are gross morphological changes in the shape of any of the bony articular surfaces of the joint.
Preoperative and postoperative computed tomography (CT) scans were segmented as triangulated meshes. The bony articular surfaces of these meshes were then isolated. The vertices of these surfaces were fit to spheres and to general ellipsoids and, in the case of the acetabulum, examined in anatomical coordinate frames to look for changes between pre and postoperative segmentations.
Spherical fit results were consistent preoperatively and postoperatively, with small changes in the radii of the spheres of best fit for both operative and nonoperative hips. Ellipsoid fitting showed variations between preoperative and postoperative scans in both eccentricity and orientation.
Because there is no clear evidence of gross articular surface remodeling, periacetabular osteotomy for an adult should be planned with the expectation that the patient's existing articular structure will be preserved.
髋臼周围截骨术是一类用于治疗髋关节发育不良的手术方法。在髋臼周围截骨术中，手术医生的目标是增加股骨头在髋臼中的覆盖面积。手术矫正具有增加关节稳定性和改善髋臼内压力分布的机械目标。虽然已知在微观结构水平上，骨骼会在负载变化下进行重塑，但尚不清楚在髋臼周围截骨术后，负载变化是否会导致髋臼或股骨头发生明显的重塑。本观察性研究旨在定量分析手术髋关节和对侧髋关节关节面的术前和术后形态，以确定关节任何骨性关节面的形状是否存在明显的形态学变化。
对术前和术后的 CT 扫描进行三角网格分割。然后将这些网格的骨性关节面分离出来。对这些表面的顶点进行球体拟合和通用椭球体拟合，如果是髋臼，则在解剖坐标框架中检查，以寻找术前和术后分割之间的变化。
术前和术后的球体拟合结果一致，手术和非手术髋关节的最佳拟合球体半径都有微小变化。椭球体拟合显示术前和术后扫描之间在偏心率和方向上都存在差异。
由于没有明显的关节表面重塑证据，对于成人进行髋臼周围截骨术时，应预期保留患者现有的关节结构。
