Hirata Masanobu, Nakashima Yasuharu, Hara Daisuke, Kanazawa Masayuki, Kohno Yusuke, Yoshimoto Kensei, Iwamoto Yukihide
Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan.
Int Orthop. 2015 Apr;39(4):645-51. doi: 10.1007/s00264-014-2538-0. Epub 2014 Sep 25.
Compared to medial femoral offset (MFO), the role of anterior femoral offset (AFO) on range of motion (ROM) in total hip arthroplasty (THA) has not been fully examined. We therefore defined AFO as the anterior distance from the centre of the femoral head to the proximal femoral axis in the sagittal plane and determined the optimal AFO required for ROM needed for activities of daily living using a computer-simulated THA model.
Various AFOs were obtained by changing stem anteversion (stem-AV) and stem tilt in the sagittal plane (stem-tilt) using a CT-based simulation software. The required ROM was defined as: flexion ≥ 110°, internal rotation at 90° flexion (IR) ≥ 30°, external rotation (ER) ≥ 30°, and extension ≥ 30°, and we determined AFO and MFO to satisfy required ROM.
AFO was positively correlated with stem-AV and anterior stem-tilt. MFO was negatively correlated with stem-AV and not influenced by stem-tilt. Flexion and IR increased with both increased AFO and MFO, whereas extension and ER decreased with increased AFO. A smoothing spline curve showed the optimal AFO and MFO for required ROM to be from 15 mm to 25 mm on average and more than 32.1 mm, respectively.
This is the first study to show that AFO directly influenced ROM in THA. Optimal AFO as well as MFO should be reconstructed to achieve sufficient ROM.
与股骨内侧偏移（MFO）相比，全髋关节置换术（THA）中股骨前侧偏移（AFO）对活动范围（ROM）的作用尚未得到充分研究。因此，我们将AFO定义为矢状面中股骨头中心到股骨近端轴线的前侧距离，并使用计算机模拟THA模型确定日常生活活动所需ROM所需的最佳AFO。
使用基于CT的模拟软件，通过改变矢状面中的柄前倾（柄-AV）和柄倾斜（柄倾斜）来获得各种AFO。所需的ROM定义为：屈曲≥110°，90°屈曲时的内旋（IR）≥30°，外旋（ER）≥30°，伸展≥30°，我们确定AFO和MFO以满足所需的ROM。
AFO与柄-AV和柄前倾斜呈正相关。MFO与柄-AV呈负相关，且不受柄倾斜的影响。屈曲和IR随AFO和MFO的增加而增加，而伸展和ER随AFO的增加而减少。平滑样条曲线显示，所需ROM的最佳AFO和MFO平均分别为15 mm至25 mm和超过32.1 mm。
这是第一项表明AFO直接影响THA中ROM的研究。应重建最佳AFO以及MFO以实现足够的ROM。
