Three-Dimensional Morphological Analysis of the Femoral Neck Torsion Angle - An Anatomical Study.

Abstract

Background: The femoral neck torsion angle (FNTA) is a very important but often neglected parameter in assessments of the anatomical morphology of the femoral neck, and it is often confused with the femoral neck anteversion angle (FNAA) in the current literature. Currently, naked eye or two-dimensional literature (2D) visualization method was used in the literature that the measurement method reported, and the measurement parameters and details are not clearly defined. The objection of this research was to establish a three-dimensional (3D) method to measure the FNTA, and to analyse the anatomical and clinical significance of the results. Methods: Computed tomography (CT) data of 200 patients who received a lower extremity CT angiography examination were selected for the three-dimensional CT (3D CT) reconstruction of bilateral femurs by using Mimics software. The 3D axis of the femoral neck was built, and the FNTAs of the isthmus and the basilar part were measured using the “inertia axes” method. SPSS software was used for statistical analyses. Results: 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 differences in the FNTA were 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 increase observed in men (7.87 ± 8.57°) was larger than that in women (4.44 ± 6.23°, p < 0.01). However, no significant differences in the values were observed between sides. According to the correlation analysis, height exerted the greatest effect on the FNTA (r = 0.255, p＜0.001), and the stepwise linear regression analysis produced the following final regression model: Y = -27.685 + 35.134 × HEIGHT (p < 0.001, R2 = 0.095). Conclusions: This study provides a new and reliable 3D method for measuring the FNTA. The method and results provide a methodological foundation and theoretical support for the research and development of internal fixation devices and configurations of the space for an implant designed to treat a femoral neck fracture. And, the optimal opening point of the femoral medullary cavity is recommended to be located at the posterior position of the top of the femoral neck cross-section during hip replacement.

The Oval‐like Cross‐section of Femoral Neck Isthmus in Three‐dimensional Morphological Analysis

“…The “inertia axis” method was used to determine the long and short axes of the FNI cross‐section 20–22 . Two perpendicular lines on the cross‐section of the FNI center on the inertial axes were defined as the long axes and short axes.…”

Accuracy of CT for Measuring Femoral Neck Anteversion in Children With Developmental Dislocation of the Hip Verified Using 3D Printing Technology

“…In 1954, Billing [3]. clearly de ned FNA as the angle between the femoral neck axis and condylar plane (determined by the femoral shaft axis and the femoral condyle axis), which has been widely recognized [4]. With technology progresses, it is found that FNA is closely related to the hip stress and dysplasia, and is critical for the choice of surgical methods [5,6].…”