Fig 1.
Examples of spinal curvature evaluation methods.
Methods of evaluating the sagittal spinal curvature in 2D images: (a) Modified Cobb method (left); (b) TRALL method (middle); (c) Posterior tangents (right).
Fig 2.
The spinal curve assessment framework.
The spinal curve assessment framework steps (shown from left to right): the first 3 steps (on the left, colored blue) are spinal canal segmentation steps—seed point, fast growing morphological region and active object segmentation. The fourth step (middle, purple) is curve extraction. The next curve model (5th step from the left, yellow) is created and finally model comparison (right, green).
Fig 3.
The spinal curve characteristics measurements.
Schematic of the curve's characteristics measurements showing the vertebrae. The spinal canal centerline is presented as a wide gray line. The curve endings are marked as points A (cranial curve ending) and B (caudal curve ending), and the lordosis peak is marked by point P. The projections of each point on the Z and Y axes are also drawn as Az, Bz, Pz, and Ay, By, Py, respectively.
Fig 4.
Spine Model Curve (black line) is composed from various curves (colored lines) of healthy individuals shown in 3 different views: a 3D view (left), coronal plane (center), and the sagittal plane (right). As described, the coordinates are scaled by the vertical distance between the superior end plate of the sacrum and the inferior end plate of T12.
Table 1.
Comparison of lordosis curve parameters between males and females (two-tailed t-test).
Fig 5.
Male population curves, 3-D view.
The graph on the left is scaled to the axes proportions; the graph on the right is freely scaled to arbitrary proportions for a better view of the curve shape. Each line represents a curve sample. The solid black line in the middle is the model curve. The coordinates are scaled by the vertical distance between the superior end plate of the sacrum and the inferior end plate of T12.
Fig 6.
Males population curve 2-D view.
Male population curve 2-D views: sagittal (top) and coronal (bottom) planes. The coordinates are scaled by the vertical distance between the superior end plate of the sacrum and the inferior end plate of T12.
Fig 7.
Female population curves, 3-D view.
The graph on the left is scaled to the axes proportions; the graph on the right is freely scaled to arbitrary proportions for a better view of the curve shape. Each line represents a curve sample. The solid black line in the middle is the model curve. The coordinates are scaled by the vertical distance between the superior end plate of the sacrum and the inferior end plate of T12.
Fig 8.
Female population curves, 2-D view.
Female population curve 2-D view: sagittal (top) and coronal (bottom) planes. The graphs on the left are scaled to the axes proportions; the graphs on the right are freely scaled to arbitrary proportions for a better view of the curve shape. Each line represents a curve sample. The coordinates are scaled by the vertical distance between the superior end plate of the sacrum and the inferior end plate of T12.
Table 2.
Model comparison: Comparison of curve shape on the sagittal plane (Y axis = dorsal-ventral) between males and females.
Table 3.
Model comparison: Comparison of curve shapes on the coronal plane (X-axis = lateral-lateral) between males and females.
Fig 9.
Models of male population vs. female population.
Graphical comparison of the sagittal plane of the curve shape between male and female populations: black line—general population; blue line—male population; red line—female population. Squares denote locations of significant differences (p < 0.05) between the curves. The graph is scaled to arbitrary proportions for a better view of curve differences.