SIB# 376 Spinal Sagittal Balance
The Study: Sagittal balance of the spine
a. “The static sagittal balance of the normal spine is a physiological alignment of the spine in the most efficient manner by the muscular forces.”
b. In the frontal plane, the center of the vertebral column runs through the center of the sacrum.
c. “The pelvic incidence corresponds to the angle between the perpendicular to the upper S1 level passing through its centre and the line connecting this point to the axis of the femoral heads…”
d. There is a relationship between the angle of pelvic incidence and the lumbar lordosis.
e. The 4th and 5th lumbar areas produce about two thirds of the lumbar lordosis which has been previously noted by Jackson.
f. The authors note that as we age there is loss of elasticity of the disc, atrophy in the lumbar extensors, hypertrophy of the facets and bone remodeling. These changes lead to changes in the lumbar lordosis.
g. However, in spines with “harmonious” thoracic and lumbar curves, there is “no tendency for any degeneration based on predisposing mechanical factors.”
h. Sagittal balance is affected by both the cervical lordosis and thoracic kyphosis.
i. “Sagittal balance must be carefully considered before any surgery, limited or not, and especially at the lumbar level and, above all, if the L4-L5-S1 levels (which represent 66% of the lordosis) are included in the fusion.”
j. The authors note that hyperlordosis in the cervical spine can be a result of contraction of the erector muscles in the cervical area.
k. The authors also offer that a reduction in thoracic kyphosis is most often found in “younger subjects because it results from the contraction of erector muscles, which are still strong and efficient.”
l. Sagittal alignment is affected by the pelvic incidence as well as changes in the structure of the spine due to muscular actions, degenerative changes in the soft tissues and remodeling of the boney structures.
In regards to sagittal alignment you must consider pelvic incidence in your evaluation of the spinal structure, along with the effects of muscles, aging and of course gravity.
Reviewer's Comments: Chiropractic is not the only profession that is interested in the alignment of the spine. Spine surgeons are now leading the research in this important area. This is a very complex article and looks at the question of overall sagittal alignment from a point of view that is largely focused on the pelvis. It also has an illustration that gives a good view of the efficiency conus of Dubousset which is basically the amount people sway when standing erect. In short, people with greater sway expend more effort to stand erect. Once again spinal alignment is important. Special Thanks to Dr. Keith Rau for bringing this article (as well as a number of other we have used in the past) to my attention.
Reviewer: Roger Coleman DC
Editor’s Comments: Spine surgeons continue to document the necessity of good sagittal alignment. Their number one tool for evaluating biomechanical alignment is the lateral full spine radiograph. Meanwhile the chiropractic profession continues to eschew the use of radiography and contents itself with manipulating spines for improved intersegmental motion and relief of back pain.
Editor: Mark R. Payne DC
Reference: Le Huec JC, Thompson W, Mohsinaly Y, Barrey C, Faundez A. Sagittal balance of the spine. Eur Spine J. 2019 Sep;28(9):1889-1905. doi: 10.1007/s00586-019-06083-1. Epub 2019 Jul 22.
Link to Abstract: https://www.ncbi.nlm.nih.gov/pubmed/31332569