The response of the nucleus pulposus of the lumbar intervertebral discs to functionally loaded positions
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Updated: Jul 14, 2026

An In Vitro Organ Culture Model of the Murine Intervertebral Disc
Published on: April 11, 2017
Lyndsay A Alexander1, Elizabeth Hancock, Ioannis Agouris
1School of Health Sciences, Faculty of Health and Social Care, Robert Gordon University, Garthdee Road, Aberdeen, AB10 7QG, UK. l.a.alexander@rgu.ac.uk
Study Design:
Asymptomatic volunteers underwent magnetic resonance imaging to investigate how different positions affect lumbar intervertebral discs.
Objective:
To quantify sagittal migration of the lumbar nucleus pulposus in 6 functional positions.
Summary Of Background Data:
Previous studies of the intervertebral disc response in the sagittal plane were limited to imaging of recumbent positions. Developments of upright magnetic resonance imaging permit investigation of functional weight-bearing positions.
Methods:
T2-weighted sagittal scans of the L1-L2 to L5-S1 discs were taken of 11 volunteers in standing, sitting (upright, flexed, and in extension), supine, and prone extension. Sagittal migration of the nucleus pulposus was measured (mm) as distance from anterior disc boundary to peak pixel intensity. Lumbar lordosis (Cobb angle) was measured in each position.
Results:
Fifteen comparisons between positions showed significant positional effects (14 at L4-L5, L5-S1, the most mobile segments). Prone extension and supine lying induced significantly less posterior migration than sitting. Flexed and upright sitting, significantly more than standing at L4-L5, as did flexed sitting compared with extended.
Conclusion:
These results support for the first time the validity of clinical assumptions about disc behavior in functional positions: sitting postures may increase risk of posterior derangement, and prone and supine may be therapeutic for symptoms caused by posterior disc displacement.
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