Predictability of Acetabular Component Angular Change with Postural Shift from Standing to Sitting Position
Predictability of Acetabular Component Angular Change with Postural Shift from Standing to Sitting Position
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DOI：
10.2106/jbjs.m.00765
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发表时间：
2014-06-18
影响因子：
5.3
通讯作者：
Wan, Zhinian
中科院分区：
文献类型：
--
作者：
Kanawade, Vaibhav;Dorr, Lawrence D.;Wan, Zhinian
背景：全髋关节置换术中髋臼组件的角度随着身体姿势的变化而变化，这种变化会影响稳定性和磨损。我们试图将术中倾斜角和前倾角与患者从站立到坐姿的角度变化联系起来，并确定这些变化是否可预测。方法：85例患者（85髋）行全髋关节置换术前后分别行站立和坐位矢状（侧位）脊柱骨盆x线片。在这些x线片上测量脊柱和骨盆倾斜。手术时髋臼倾斜和前倾的角度在坐位时发生改变。每位患者根据脊柱/骨盆的僵硬度进行分类，通过测量站立和坐姿之间骶骨后或骨盆倾斜的变化来测量。矢状杯位置（称为前倾）的变化幅度与骨盆的刚度分类相关。实验幻影模型再现术中倾斜和前倾的可能组合，并根据骨盆倾斜将它们与矢状前倾相关联。结果：骨盆僵硬度正常，随着站立到坐姿的变化，骨盆后倾20°~ 35°。站立时髋臼杯前倾平均为29.6度+/- 8.4度（95%可信区间[CI] = 13.1度至46度），坐着时为54.6度+/- 10.2度（95% CI = 44.4度至64.8度）。僵硬的骨盆比正常僵硬的骨盆倾斜平均少4度，比术后坐姿的过度活动的骨盆倾斜平均少13度。幻影模型显示，可以通过测量术前骶骨/骨盆倾斜从站立到坐姿的变化程度来预测前倾。结论：坐位时的前倾会导致髋臼杯更加垂直，从而导致髋关节不稳定，尤其是脱位和边缘负荷磨损。仰卧冠状杯倾角>= 50度，>= 25度的患者和骨盆活动过度的患者存在风险。在体位改变过程中盆腔的空间位置会造成手术杯放置的术后后果。
Background: The angles of the acetabular component of a total hip replacement change with body postural changes, and this change can affect stability and wear. We sought to correlate the intraoperative angles of inclination and anteversion of the cup with the changes in these angles when patients moved from standing to sitting and determine if these changes were predictable.Methods: Eighty-five patients (eighty-five hips) had sagittal (lateral) spinopelvic radiographs made while they were standing and while they were sitting before and after undergoing total hip replacement. The spinosacral tilt and the pelvic tilt were measured on these radiographs. The angles of acetabular inclination and anteversion achieved at surgery changed during sitting. Each patient was classified according to the stiffness of the spine/pelvis as measured by the change in posterior sacral or pelvic tilt between the standing and sitting positions. The magnitude of change of the sagittal cup position (termed ante-inclination) was correlated to the stiffness classification of the pelvis. An experimental phantom model reproduced possible combinations of intraoperative inclination and anteversion and correlated them to sagittal ante-inclination according to pelvic tilt.Results: The pelves with normal stiffness tilted posteriorly 20 degrees to 35 degrees with the postural change from standing to sitting. Ante-inclination of the acetabular cup averaged 29.6 degrees +/- 8.4 degrees (95% confidence interval [CI] = 13.1 degrees to 46 degrees) with standing and 54.6 degrees+/- 10.2 degrees(95% CI = 44.4 degrees to 64.8 degrees) with sitting. The stiff pelves had a mean of 4 degrees less tilt than those with normal stiffness and 13 degrees less than the hypermobile pelves with the postoperative sitting position. The phantom model showed ante-inclination could be predicted by measuring the preoperative degrees of change in sacral/pelvic tilt from standing to sitting.Conclusions: Ante-inclination during sitting results in a more vertical acetabular cup, which can result in hip instability, especially drop-out dislocation, and edge-loading wear. Patients with supine coronal cup inclination of >= 50 degrees and anteversion of >= 25 degrees and those with a hypermobile pelvis are at risk. It is the pelvic spatial position during postural change that creates the postoperative consequences of the surgical cup placement.