J Korean Soc Spine Surg.  2001 Mar;8(1):46-52.

The Sagittal Balance and Compensatory Mechanisms in Lumbar Spinal Stenosis

• Lee C
• Choi JS
• Kim YC
• Seo SS
• An KC
• Son SD

Abstract

PURPOSE: To evaluate the sagittal alignment and the main factors contributing to sagittal compensatory mechanism in lumbar stenosis.
MATERIALS AND METHODS
63 patients of spinal stenosis surgically treated were evaluated using 14x36 inch standing lateral films. The global sagittal balance was measured with C7 plumb line and hip flexion angle. The thoracic kyphosis, lumbar lordo-sis and pelvic tilting angle were compared to each of normal korean values to find out main factors participating in compensatory mechanism. At last follow-up, at least 6 months after surgery, the changes of sagittal parameters and global balance were evaluated according to the correction amount of pathologic segments angle to understand the compensatory mechanism and its contributing factors.
RESULTS
The C7 plumb line was +3.04 cm(/0.91 SD), thoracic kyphosis 30.0dgree(/12.1), lumbar lordosis 43.1dgree(/14.7) and pelvic tilting angle 21.7dgree(/8.2). All patients except 8 showed global compensation state. The differences compared to normal korean values were 10 dgree of pelvic tilting angle and 2dgreeof thoracic kyphosis. Pelvic tilting angle was more contributing factor of compensatory mechanism than thoracic kyphosis. At last follow up, 14 patients surgically corrected 5dgreeor more showed significant posterior shift of C7 plumb line and increased lumbar lordosis(p<0.05). 11 patients aggravated 5dgree or more showed significant increase of adjacent segment angle to participate in compensatory mechanism(p<0.05).
CONCLUSION
Most lumbar spinal stenosis patients showed compensated sagittal balance state. Adjacent segments and pelvic tilting were thought as main contributing factors of compensation mechanism.

Keyword

Lumbar spine; Stenosis; Sagittal balance; Compensatory mechanism

MeSH Terms

Animals
Compensation and Redress
Constriction, Pathologic
Follow-Up Studies
Hip
Humans
Kyphosis
Lordosis
Spinal Stenosis*

Figure

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  Fig. 1. Angle of incidence(AOI) is sum of pelvic tilting angle and sacral slope.

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  Fig. 2. Results of surgery. Among the total 63 cases, the fused segment’s lordosis angle(FA) was increased at least 5°(group 1) in 14 cases, decreased 5° or more(group 3) in 11 cases. In 38 cases, the changes were less than 5°(group 2).

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  Fig. 3. The changes of sagittal parameters after surgery and follow-up. In group 1, the mean 9.9°increase of pathologic segments angle(d-PS) influenced to other parameters to be more comfortable. But in group 3, the other parameters were worsen especially the non-pathologic segments angle(d-NPS, adjacent segment’s angle) which was statistically significant.

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