Ohmori Takaaki, Kabata Tamon, Kajino Yoshitomo, Taga Tadashi, Hasegawa Kazuhiro, Inoue Daisuke, Yamamoto Takashi, Takagi Tomoharu, Yoshitani Junya, Ueno Takuro, Ojima Tomohiro, Tsuchiya Hiroyuki
Department of Orthopedic Surgery, Graduate School of Medical Science, Kanazawa University, Takaramachi13-1, Kanazawa, Ishikawa, Japan.
Department of Orthopedic Surgery, Graduate School of Medical Science, Kanazawa University, Takaramachi13-1, Kanazawa, Ishikawa, Japan.
Knee. 2017 Dec;24(6):1428-1434. doi: 10.1016/j.knee.2017.07.017. Epub 2017 Oct 1.
In TKA, we have used the "projected SEA", which is obtained by projecting the "true SEA" on the distal femoral cutting plane in clinical practice to determine the femoral component rotation. There are no reports examining the accuracy of the "projected SEA". In this study, we investigated the difference between the "true SEA" and "projected SEA".
The present study was a CT-based computer-simulated case series. We evaluated 34 knees without osteoarthritis changes. These patients were selected from the operative schedule prior to THA. We defined the "true SEA" on the 3D model and the "projected SEA" on the cutting plane parallel to the distal femoral axis obtained based on the "true SEA". We changed the cutting angles from 20° flexion to 20° extension, and from five degrees varus to five degrees valgus. We measured the "true SEA angle" and "projected SEA angle" regarding the posterior condylar axis (PCA).
The mean "true SEA angle" was 3.04°±1.34° (0.6-5.0°). The mean "projected SEA angle" was 3.43°±1.58° at 20° flexion, 3.42°±1.56° at 0° flexion, 3.43°±1.52° at 20° extension, 3.39°±1.59° at five degrees valgus, and 3.39°±1.50° at five degrees varus. At each cutting angle, the "projected SEA angle" was significantly larger than the "true SEA angle" (p<0.001). There was no significant difference between any of the "projected SEA angles" (p>0.001).
We found that the true SEA and projected SEA do not differ significantly (0.39°±0.29° [range 0-1.0°]).
在全膝关节置换术（TKA）中，我们在临床实践中使用“投影SEA”，它是通过将“真实SEA”投影到股骨远端截骨平面上获得的，用于确定股骨假体的旋转。目前尚无关于“投影SEA”准确性的报道。在本研究中，我们调查了“真实SEA”与“投影SEA”之间的差异。
本研究是基于CT的计算机模拟病例系列研究。我们评估了34个无骨关节炎改变的膝关节。这些患者是从全髋关节置换术（THA）手术计划中选取的。我们在三维模型上定义了“真实SEA”，并基于“真实SEA”在与股骨远端轴平行的截骨平面上定义了“投影SEA”。我们将截骨角度从屈曲20°改变到伸展20°，以及从内翻5°改变到外翻5°。我们测量了相对于后髁轴（PCA）的“真实SEA角度”和“投影SEA角度”。
“真实SEA角度”的平均值为3.04°±1.34°（0.6 - 5.0°）。在屈曲20°时，“投影SEA角度”的平均值为3.43°±1.58°，在屈曲0°时为3.42°±1.56°，在伸展20°时为3.43°±1.52°，在外翻5°时为3.39°±1.59°，在内翻5°时为3.39°±1.50°。在每个截骨角度，“投影SEA角度”均显著大于“真实SEA角度”（p<0.001）。任何“投影SEA角度”之间均无显著差异（p>0.001）。
我们发现真实SEA与投影SEA之间差异不显著（0.39°±0.29°[范围0 - 1.0°]）。
