The association between the sagittal femoral stem alignment and the resulting femoral head centre in total hip arthroplasty
The association between the sagittal femoral stem alignment and the resulting femoral head centre in total hip arthroplasty
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DOI：
10.1007/s00264-010-1047-z
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发表时间：
2011-07-01
影响因子：
2.7
通讯作者：
Tohtz, Stephan
中科院分区：
文献类型：
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作者：
Mueller, Michael;Crucius, Dirk;Tohtz, Stephan
充分的股骨柄对线对于全髋关节置换术（THA）的成功至关重要，以避免脱位和撞击。到目前为止，尚未充分研究的一个因素是股骨柄在矢状面中的倾斜，这对股骨头中心的位置有影响，因此也对假体扭转有影响。我们的目的是使用3D-CT评估THA患者的矢状位股骨柄位置，并开发一个数学几何模型来模拟矢状位股骨柄倾斜与对功能前倾的影响之间的功能相关性。30例THA患者接受了CT扫描。通过CT数据的三维重建，确定股骨/假体轴向、扭转和矢状倾斜。根据股骨和假体轴的位置，测量旋转（rAV）（手术调整）和功能（取决于矢状倾斜）前倾（fAV）。还使用欧拉角进行了三维坐标转换，以推导矢状位股骨柄倾斜和相应的前倾影响之间的几何相关性。平均rAV为8A度（-11.6至26 A度），fAV为18 A度（6.2至37 A度），差值为10A度（8.8至18 A度）。股骨柄向股骨轴前倾的平均角度为5.2A度（0.7 - 9A度）。单独测量的参数反映在几何模型中。根据矢状面偏离的程度，对扭转的影响明显。例如，以15 A度前倾角植入股骨柄，向前矢状倾斜2度，导致fAV为20 A度。证实了矢状位股骨柄对线与对fAV的影响之间存在明确的相关性。因此，外科医生预期的旋转前倾可能在功能上显著不同。这可能会增加脱位或撞击的风险。因此，在撞击和脱位诊断的背景下，应考虑假体的矢状倾斜。在这方面，我们建议对股骨柄对线进行3D分析。
Adequate stem alignment is essential for the success of Total Hip Arthroplasty (THA) to avoid dislocation and impingement. One factor that has not been sufficiently investigated so far is the stem tilting in the sagittal plane, which has an influence on the position of the centre of the femoral head and thus also on prosthesis torsion. We aimed to evaluate sagittal stem position using 3D-CTs in patients with THA and to develop a mathematical-geometrical model to simulate the functional correlation between sagittal stem tilting and the influence on functional anteversion. Thirty patients with THA underwent a CT-scan. By 3D-reconstruction of the CT-data, femoral-/prosthesis-axis, torsion and sagittal tilt were determined. In accordance with the position of the femoral and prosthesis axes, the rotatory (rAV) (surgically adjusted) and functional (depending on sagittal tilt) anteversion (fAV) was measured. A three dimentional-coordinate transformation was also performed using the Euler-angles to derive a mathematical-geometrical correlation between sagittal stem tilting and corresponding influence on anteversion. The mean rAV was 8A degrees (-11.6 - 26A degrees), the fAV 18A degrees (6.2 - 37A degrees), and the difference 10A degrees (8.8 - 18A degrees). The mean degree of stem tilting was 5.2A degrees (0.7 - 9A degrees) anterior towards the femoral axis. The individually measured parameters are reflected in the mathematical-geometrical model. Depending on the extent of the sagittal deviation, a clear influence on the torsion emerges. For example, a stem implanted at a 15A degrees anteverted angle with a sagittal tilt by two degrees towards anterior results in a fAV of 20A degrees. A clear association between the sagittal stem alignment and the impact on the fAV was demonstrated. Hence, the rotatory anteversion intended by the surgeon may be functionally significantly different. This might pose an increased risk of dislocation or impingement. The sagittal tilt of the prosthesis should therefore be considered in the context of impingement and dislocation diagnosis. In this respect, we recommend a 3D-analysis of stem alignment.