Ushio Tetsuro, Mizu-Uchi Hideki, Okazaki Ken, Ma Yuan, Kuwashima Umito, Iwamoto Yukihide
Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, Higashi-ku, Fukuoka, Japan.
J Arthroplasty. 2017 Mar;32(3):1006-1012. doi: 10.1016/j.arth.2016.09.003. Epub 2016 Sep 28.
We evaluated the effect of cutting surface on the anteroposterior (AP) axis of the proximal tibia using a 3-dimensional (3D) bone model to ensure proper tibial rotational alignment in total knee arthroplasty.
3D bone models were reconstructed from the preoperative computed tomography data of 93 Japanese osteoarthritis knees with varus deformity. The AP axis was defined as the perpendicular bisector of the medial and lateral condylar centers in a 3D coordinate system. Bone cutting of the proximal tibia was performed with various tibial posterior slopes (0°, 3°, 7°) to the mechanical axis, and we compared the AP axes before and after bone cutting.
The AP axis before bone cutting crossed a point at about 16% (one-sixth) of the distance from the medial edge of the patellar tendon at its tibial attachment. The AP axis after bone cutting was significantly internally rotated at all posterior slopes: 4.1° at slope 0°, 3.0° at slope 3°, and 2.1° at slope 7°. The percentages of cases with differences of more than 3° or 5° were 66.7% and 34.4% at slope 0°, 53.8% and 24.7% at slope 3°, and 38.3% and 11.8% at slope 7°, respectively.
The AP axis of the proximal tibia may be rotated internally after resection of the proximal tibia in total knee arthroplasty. Hence, surgeons should recognize the effect of changes in the cutting surface on rotational alignment of the proximal tibia.
我们使用三维（3D）骨模型评估了截骨面对胫骨近端前后（AP）轴的影响，以确保全膝关节置换术中胫骨的正确旋转对线。
从93例患有内翻畸形的日本骨关节炎膝关节的术前计算机断层扫描数据重建3D骨模型。AP轴在三维坐标系中定义为内外侧髁中心的垂直平分线。对胫骨近端进行截骨，使其相对于机械轴具有不同的胫骨后倾角度（0°、3°、7°），并比较截骨前后的AP轴。
截骨前AP轴穿过髌腱胫骨附着处内侧边缘距离约16%（六分之一）的一点。在所有后倾角度下，截骨后的AP轴均显著内旋：0°时为4.1°，3°时为3.0°，7°时为2.1°。0°时差异超过3°或5°的病例百分比分别为66.7%和34.4%，3°时为53.8%和24.7%，7°时为38.3%和11.8%。
在全膝关节置换术中，胫骨近端截骨后AP轴可能会向内旋转。因此，外科医生应认识到截骨面变化对胫骨近端旋转对线的影响。
