Global spinal alignment method
A method of planning the correction of spinal deformations of a subject, by performing segmentation on a three dimensional image of the subject's spine in its erect neutral position, such that the positions and orientations of the vertebrae in a region of interest are characterized. Parameters relating to the alignment and position of the vertebrae are derived from the segmentation, followed by determining whether the parameters fall within an acceptable range desired for the spine of the subject. If not within the acceptable range, an alignment optimization is performed on the vertebrae to bring the parameters within the acceptable range, to reduce the spinal deformations of the subject's spine. The alignment optimization is performed by taking into consideration limitations arising from the dynamic range of motion of the vertebrae as determined by analyzing images of the subject's spine, while the subject is in positions of maximum bending.
1. A method of planning the correction of spinal deformations of a subject, comprising:
performing segmentation of at least one three-dimensional image of the subject's spine in its erect neutral position, such that positions and orientations of at least some vertebrae in a region of interest of the spine are characterized;
calculating spinal parameters from the segmentation that relate to an alignment and position of at least one vertebra in the region of interest;
determining a dynamic range of motion of the at least one vertebra by analyzing at least one two- or three-dimensional image of the subject's spine in a position of bending of the subject; and
when the spinal parameters do not fall within a predetermined acceptable range desired to optimize a global balance of the subject, identifying alignment changes of the at least one vertebra in the region of interest of the spine which would result in bringing the spinal parameters within the acceptable range, to reduce the spinal deformations of the subject's spine,
wherein the identified alignment changes of the at least one vertebra are such that an allowable motion of the at least one vertebra will not extend beyond the dynamic range of motion of the at least one vertebra.
2. The method of claim 1 , wherein the identified alignment changes are based on at least in part on biomechanical considerations over the entire length of the subject's spine.
3. The method of claim 1 , wherein the spinal parameters relate to at least some mutual angles, projections and linear positions generated by the vertebrae in the region of interest.
4. The method of claim 1 , wherein the determining as to whether the spinal parameters fall within the predetermined acceptable range is performed either automatically by image processing, or by manual measurement on images, or based on medical personnel judgment or experience.
5. The method of claim 1 , wherein the positions of bending of the subject comprise at least one of bending in a first lateral direction, bending in a second lateral direction opposite the first lateral direction, bending in flexion, bending in extension, and rotation.
6. The method of claim 1 , wherein the identified alignment changes comprise at least one of an optimization to generate a straightened spinal alignment in a coronal plane and an optimization of the spinal alignment in a sagittal plane.
7. The method of claim 1 , wherein the identified alignment changes involve manipulation of sagittal parameters according to a procedure which generates a sagittal vertical axis offset of less than a predetermined value.
8. The method of claim 1 , wherein the determining the dynamic range of motion of the at least one vertebra is performed by determining an extent of rotation of the at least one vertebra under bending around at least one of its axial, lateral and AP axes.
9. The method of claim 1 , wherein the at least one two- or three-dimensional image of the subject's spine in positions of bending is obtained from at least one of (i) a two-dimensional X-ray image of the subject or (ii) a two-dimensional image derived from a three-dimensional image set of the subject, in which the dynamic range of motion of the at least one vertebra is determined by matching corresponding vertebrae from the two dimensional image with those from the three-dimensional image set.
10. The method of claim 1 , wherein the identified alignment changes comprise a virtual adjustment of the at least one three-dimensional image of the subject's spine according to predetermined values of at least one of (i) spino-pelvic parameters and (ii) a level of compensatory mechanisms of the subject's spine.
11. The method of claim 1 , wherein the at least one three-dimensional image of the subject's spine in its erect neutral position is derived by conversion of three-dimensional image data of the subject's spine in a supine or prone position.
12. The method of claim 1 , further comprising the step of calculating a shape of at least one fusion rod to maintain at least the vertebrae in the region of interest of the spine in an optimized alignment pose.
13. The method of claim 1 , further comprising the step of defining a surgical correction of at least one vertebra to achieve the identified alignment change.
14. The method of claim 1 , wherein the vertebrae in the region of interest of the spine are spinal segments comprising a number of adjoining vertebrae.
15. The method of claim 1 , wherein when the identified alignment changes are such that the motion achieved of the at least one vertebra exceeds the dynamic range of motion of the at least one vertebra, surgical intervention on at least the at least one vertebra is indicated.
16. A method of planning the correction of spinal deformations of a subject, comprising:
obtaining three-dimensional images of the subject's spine in its erect neutral position;
obtaining additional two-dimensional images of the subject's spine in positions of full bending achieved by the subject;
obtaining at least one parameter quantizing a limit of at least one of translational and orientational motion of at least one vertebra of the subject's spine in the positions of full bending; and
determining an adjustment of a virtual orientation and position of the at least one vertebra in the three-dimensional images according to a procedure for reducing spinal deformations that are apparent in the three-dimensional images of the subject's spine,
wherein the determined adjustment does not require a translational or orientational motion of the at least one vertebra that would exceed the at least one parameter.
17. The method of claim 16 , wherein the positions of full bending comprise at least one of bending in a first lateral direction, bending in a second lateral direction opposite the first later direction, bending in flexion, bending in extension, and rotation.
18. The method of claim 16 , wherein the procedure which reduces spinal deformations that are apparent in the three-dimensional images of the subject's spine comprises at least one of (i) an optimization to generate a straightened spinal alignment in a coronal plane, (ii) an optimization of the spinal alignment in a sagittal plane, and (iii) manipulation of sagittal parameters according to a procedure which generates a sagittal vertical axis offset of less than a predetermined value.
19. The method of claim 16 , wherein the at least one parameter is the extent of at least one of axial, AP, or lateral rotation of a vertebra.
20. The method of claim 16 , wherein the three-dimensional images of the subject's spine in its erect neutral position are derived by a conversion of three-dimensional image data of the subject's spine in a supine or prone position, taking into account any changes which would occur in an orientation and position of the at least one vertebra, as the spine of the subject would become upright and hence weight bearing.
21. A method of planning the correction of spinal deformations of a subject, comprising:
performing segmentation of at least one three-dimensional image of the subject's spine in its erect neutral position, such that positions and orientations of at least some vertebrae in a region of interest of the spine are characterized;
calculating spinal parameters from the segmentation that relate to an alignment and position of at least one vertebra in the region of interest;
determining a dynamic range of motion of the at least one vertebra by analyzing at least one two- or three-dimensional image of the subject's spine in a position of bending of the subject; and
when the spinal parameters do not fall within a predetermined acceptable range desired to optimize a global balance of the subject, identifying at least one alignment change of the at least one vertebrae which would result in bringing the spinal parameters within the acceptable range, to reduce the spinal deformations of the subject's spine,
wherein when the identified at least one alignment change of the at least one vertebra is such that a motion achieved for the at least one vertebra would exceed the dynamic range of motion of the at least one vertebra, a surgical intervention on at least the at least one vertebra is indicated.