Measuring femoral neck torsion angle using femoral neck oblique axial computed tomography reconstruction

et al. 2020

J Orthop Surg Res

Background: 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. Methods: 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. 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 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).

Section: Discussionmentioning

confidence: 99%

Three-dimensional morphological analysis of the femoral neck torsion angle—an anatomical study

et al. 2020

J Orthop Surg Res

“…In the early stage, the axis of the femoral neck was determined by the anteroposterior and lateral centerline of X-ray or two-dimensional CT, but both methods were affected by the femoral position during fluoroscopy, and the axis was ultimately two-dimensional [3,4] . Nakanishi and Yin [5,21] searched for the layers including both the femoral head and the femoral neck on coronal slices of 3D CT images, and they defined the connecting line between the femoral head center and the femoral neck isthmic center as the femoral neck axis. However, this method was also affected by the spatial position of the femur.…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2020

Preprint

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.

“…Nakanishi and Yin [5,23] searched for the layers including both the femoral head and the femoral neck on coronal slices of 3D CT images, and they defined the connecting line between the femoral head center and the femoral neck isthmic center as the femoral neck axis. However, this method was also affected by the spatial position of the femur.…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2020

Preprint

Background: 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.Methods: 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.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 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). Conclusions: This study found a reliable 3D method for the determination of the femoral neck axis improved the measurement method of the FNTA 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.