Ohmori Takaaki, Kabata Tamon, Kajino Yoshitomo, Taga Tadashi, Inoue Daisuke, Yamamoto Takashi, Takagi Tomoharu, Yoshitani Junya, Ueno Takuro, Tsuchiya Hiroyuki
Department of Orthopedic Surgery, Graduate School of Medical Science, Kanazawa University, Kanazawa, Ishikawa, Japan.
Department of Orthopedic Surgery, Graduate School of Medical Science, Kanazawa University, Kanazawa, Ishikawa, Japan.
Knee. 2018 Jan;25(1):15-24. doi: 10.1016/j.knee.2017.11.008. Epub 2018 Jan 12.
The "grand-piano sign" is a well-known indicator of proper rotational femoral alignment. We investigated changes in the shape of the femoral anterior cutting plane by changing the rotational alignment, anterior portion depth, and cutting plane flexion angle.
We simulated various cutting planes after cutting the anterior portion of the femur next to the distal femoral osteotomy in 50 patients with varus knee and also a femoral anterior osteotomy with four degree (S group) and seven degree (T group) flexion angles regarding the mechanical axis. We defined the final cutting plane as the farthest position that we could reach without making a notch and the precutting plane as two millimeters anterior from the final cutting plane. The simulated resection plane was rotated to produce external and internal rotation angles of 0°, three degrees, and five degrees relative to the surgical transepicondylar axis (SEA). We investigated medial and lateral portions of the femoral anterior cutting plane length ratio (M/L).
When we cut parallel to SEA, M/L was 0.67±0.09 and 0.62±0.12 in the T and S groups, respectively. M/L was approximately 0.8 and 0.5 with five degree internal and external rotations, respectively (P<0.01). On comparing final cutting and precutting planes, there were no significant differences in M/L without five degree external rotation in the T group and no significant difference in any case in the S group (P>0.01).
The ideal M/L of the femoral anterior cutting plane was 0.62-0.67. M/L did not change with a precutting plane in almost all rotational patterns.
“三角钢琴征”是股骨旋转对线良好的一个著名指标。我们通过改变旋转对线、前部深度和截骨平面屈曲角度，研究了股骨前侧截骨平面形状的变化。
我们对50例膝内翻患者在股骨远端截骨旁截除股骨前部后模拟了各种截骨平面，还模拟了相对于机械轴有4度（S组）和7度（T组）屈曲角度的股骨前截骨。我们将最终截骨平面定义为在不形成切口的情况下能够到达的最远位置，将预截骨平面定义为距最终截骨平面前方2毫米处。将模拟的截骨平面旋转，以产生相对于手术髁间轴（SEA）的0°、3°和5°的外旋和内旋角度。我们研究了股骨前截骨平面内侧和外侧部分的长度比（M/L）。
当我们平行于SEA截骨时，T组和S组的M/L分别为0.67±0.09和0.62±0.12。在5°内旋和外旋时，M/L分别约为0.8和0.5（P<0.01）。比较最终截骨平面和预截骨平面时，T组在无5°外旋时M/L无显著差异，S组在任何情况下均无显著差异（P>0.01）。
股骨前截骨平面的理想M/L为0.62 - 0.67。在几乎所有旋转模式下，M/L在预截骨平面时均无变化。
