The effect of a spina bifida-defect at the lumbosacral junction on spinopelvic alignments

Abstract

Background: Spina bifida defects, which are mild neurotube defects are commonly found at the lumbosacral junction. The defect which is  associated with micronutrient deficiency (folate) is highly prevalent in impoverished populations; and because the defect occurs early in life, it has the potential to influence pelvic growth and in consequence the pelvic incidence.
Objective: The purpose of this study was to determine whether the presence of a Spina Bifida Occulta (SBO) defect at lumbosacral junction (L5 or S1) has any effect on the pelvic incidence.
Design: Prospective randomized case control study.
Methods: This study enrolled 172 consecutive patients with low back pain patients requiring X-rays of the lumbosacral spine. The X-ray films were screened for spina bifida occulta defect at the lumbosacral junction (L5, S1). Group 1 consisted of those patients with spina bifida occulta defect (SBO-defect) while Group 2 consisted of those without the defect. Measurements of the spino-pelvic parameters were done manually on all the films, followed by calculation of pelvic incidence/lumbar lordosis mismatch (PI-LL+ 10), the primary outcome (or deformity). The means of the two groups were subjected to independent t-test and Pearson Correlation Moment for relationships.
Results: A total of 172 patients were enrolled 88 had SBO-defect (Group 1) and 84 were without defect (Group 2). There were significant differences in the pelvic incidence and the PI-LL+10 mismatch between the two groups, with Group 1 showing higher values (P-value < 0.001). Other spino-pelvic parameters except sacral slope showed significant differences.
Conclusion: The SBO-defect which occurs early in foetal life, appear to cause compensatory pelvic growth with increased pelvic incidence.  Consequently, the sacral orientation and other pelvic measurements become affected.

Key words: Spina-bifida-occulta, Spina-bifida-defect, Spinopelvic-parameters, Pelvic incidence, Pelvic tilt, Sacral slope, Lumbar lordosis, Pelvic-incidence-lumbar-lordosis-mismatch