Medical School of Chinese PLA, No. 28, Fuxing Road, Beijing, 100853, China.
Department of Orthopedics, Shijingshan Teaching Hospital of Capital Medical University, Beijing Shijingshan Hospital, No. 24, Shijingshan Road, Beijing, 100043, China.
J Orthop Surg Res. 2020 May 27;15(1):192. doi: 10.1186/s13018-020-01712-8.
The femoral neck torsion angle (FNTA) is an important but often neglected parameter in assessments of the anatomical morphology of the femoral neck, which is often confused with the femoral neck anteversion angle (FNAA) in the current literature. Currently, the measurement methods reported in the literature all adopt the naked eye or two-dimensional (2D) visualization method, and the measurement parameters and details are not clearly defined. The objection of this research was to provide a reliable 3D method for determining the femoral neck axis, to improve the measurement method of the FNTA, and to analyze the anatomical and clinical significance of the results.
Computed tomography (CT) data of 200 patients who received a lower extremity CT angiography examination were selected, and the bilateral femurs were reconstructed with three dimensional CT (3D CT). First, the 3D axis of the femoral neck was built. Second, the long axis of the cross section the femoral neck isthmus (FNI) and femoral neck basilar part (FNB) were confirmed by the "inertia axes" method, and the plane consisting of the long axis of the cross-section and the center of the femoral head was defined as the long axial plane. Third, the coronal plane of the proximal femur was determined through the long axis of the proximal femur and the femoral coronal. Finally, the FNTAs (the angles between the long axial planes and the coronal plane of the proximal femur) of FNI and FNB were measured. The size of FNTA was compared between the sexes and sides and different locations, the correlation between the parameters and age, height, and weight were evaluated.
The difference in FNTA was statistically significant between the isthmus and the basilar part (isthmus 30.58 ± 8.90° vs. basilar part 23.79 ± 3.98°; p < 0.01). Significant difference in the FNTA was observed between the sexes (males 31.99 ± 9.25° vs. females 27.49 ± 7.19°; p < 0.01). The increase in FNTA from the basilar part to the isthmus was 6.79 ± 8.06°, and the male (7.87 ± 8.57°) was greater than the female (4.44 ± 6.23°, p < 0.01). However, no significant difference in the values was observed between sides. Height exerted the greatest effect on the FNTA according to the correlation analysis (r = 0.255, p< 0.001).
This study found a reliable 3D method for the determination of the femoral neck axis improved the measurement method of the FTNTA and made it more accurate and repeatable. The results provided a methodological basis and theoretical support for the research and development of internal fixation device for femoral neck fracture and the spatial configuration of implants in treatment. And the optimal opening point of the femoral medullary cavity was recommended to locate at the posterior position of the top of the femoral neck cross-section during hip replacement.
股骨颈扭转角（FNTA）是评估股骨颈解剖形态的一个重要但常被忽视的参数，在当前文献中常与股骨颈前倾角（FNAA）混淆。目前，文献报道的测量方法均采用肉眼或二维（2D）可视化方法，测量参数和细节不明确。本研究旨在提供一种可靠的确定股骨颈轴的 3D 方法，改进 FNTA 的测量方法，并分析结果的解剖学和临床意义。
选取 200 例行下肢 CT 血管造影检查的患者的 CT 数据，采用三维 CT（3D CT）重建双侧股骨。首先构建股骨颈 3D 轴。其次，采用“惯性轴”法确定股骨颈峡部（FNI）和股骨颈基底（FNB）的横断长轴，并定义包含横断长轴和股骨头中心的平面为长轴平面。然后，通过股骨近端长轴和股骨冠状确定股骨近端的冠状面。最后，测量 FNI 和 FNB 的 FNTAs（长轴平面与股骨近端冠状面之间的角度）。比较男女、左右两侧和不同部位 FNTA 的大小，评价参数与年龄、身高和体重的相关性。
FNI 和 FNB 的 FNTA 差异有统计学意义（FNI 30.58 ± 8.90° vs. FNB 23.79 ± 3.98°；p<0.01）。男女之间 FNTA 差异有统计学意义（男性 31.99 ± 9.25° vs. 女性 27.49 ± 7.19°；p<0.01）。FNTA 从基底到峡部的增加为 6.79 ± 8.06°，男性（7.87 ± 8.57°）大于女性（4.44 ± 6.23°，p<0.01）。但左右两侧之间的数值无明显差异。相关性分析显示，身高对 FNTA 的影响最大（r=0.255，p<0.001）。
本研究找到了一种可靠的确定股骨颈轴的 3D 方法，改进了 FNTA 的测量方法，使其更加准确和可重复。研究结果为股骨颈骨折内固定装置的研究开发和治疗中植入物的空间构型提供了方法学基础和理论支持。并建议在髋关节置换时，推荐将髓腔的最佳开口点定位在股骨颈横断面顶部的后位。
