Clinical Orthopedic Research Center Midden-Nederland, Zeist, the Netherlands; Department of Orthopaedic Surgery, University Medical Center Utrecht, Utrecht, the Netherlands.
Department of Orthopaedic Surgery, University Medical Center Utrecht, Utrecht, the Netherlands.
J Arthroplasty. 2021 Jun;36(6):2184-2188.e1. doi: 10.1016/j.arth.2020.12.055. Epub 2021 Jan 8.
Anterior and posterior pelvic tilt appears to play a role in total hip arthroplasty (THA) stability. When changing from the standing to the sitting position, the pelvis typically rotates posteriorly while the hips flex and this affects the femoro-acetabular positions. This case-control study compares changes in 3-D acetabular cup orientation during functional pelvic tilt between posterior THA dislocations vs stable THAs.
Standing and sitting 3-D cup orientation was compared between fifteen posterior dislocations vs 233 prospectively followed stable THAs. 3-D cup orientation was calculated using previously validated trigonometric algorithms on biplanar radiographs. Those algorithms combine the angles in the three anatomical planes (coronal inclination, transverse version, and sagittal ante-inclination) in the standing position with the change in sagittal pelvic tilt from standing to sitting to calculate the 3-D orientation in the sitting position.
The standing cup orientation of the dislocated THAs was only characterized by a lower coronal inclination (P = .039). Compared with the controls, from standing to sitting, they showed less posterior pelvic tilt (P < .001). This led to a significant lower coronal inclination (P < .001) and sagittal ante-inclination (P < .001) in the sitting position but similar transverse version (P = .366).
Comparing posterior THA dislocations to stable THAs, there is a lower increase of all three orientation angles from standing to sitting. This leads to a decreased sitting coronal inclination and sagittal ante-inclination which may lead to an increased risk of impingement ensued by THA instability. By contrast, the transverse version was not significantly different in both positions. This confirms the importance of biplanar data on functional cup orientation.
Diagnostic, Level III.
骨盆前倾和骨盆后倾似乎在全髋关节置换术（THA）稳定性中发挥作用。当从站立位变为坐位时，骨盆通常向后旋转，同时髋关节屈曲，这会影响股骨髋臼位置。本病例对照研究比较了后脱位性 THA 和稳定 THA 之间功能性骨盆倾斜时髋臼杯三维（3D）方向的变化。
比较了 15 例后脱位和 233 例前瞻性随访的稳定 THA 在站立位和坐位时髋臼杯的 3D 方向。使用之前验证过的基于双平面 X 线片的三角算法来计算髋臼杯的 3D 方向。这些算法将站立位时三个解剖平面（冠状倾斜角、横断倾斜角和矢状前倾角）的角度与站立位到坐位时矢状骨盆倾斜的变化相结合，计算出坐位时的 3D 方向。
脱位性 THA 的站立位髋臼杯方向仅表现为冠状倾斜角较低（P=0.039）。与对照组相比，从站立位到坐位，后倾骨盆倾斜度较小（P<0.001）。这导致在坐位时冠状倾斜角（P<0.001）和矢状前倾角（P<0.001）显著降低，但横断倾斜角（P=0.366）相似。
与稳定的 THA 相比，后脱位性 THA 从站立位到坐位时，所有三个方向角的增加都较低。这导致了坐位冠状倾斜角和矢状前倾角的降低，可能会增加 THA 不稳定导致的撞击风险。相比之下，在两个位置时横断倾斜角没有显著差异。这证实了双平面数据在功能性髋臼杯方向中的重要性。
诊断，III 级。
