Weight-bearing MRI of the lumbosacral spine: Difference between supine and weight bearing positions and additional value in patients with low back pain

Abstract

© JOURNAL OF THE MEDICAL ASSOCIATION OF THAILAND | 2020. Objective: To study the difference of magnetic resonance imaging (MRI) parameters of the lumbosacral spine between weight-bearing and supine positions, and evaluate whether there is additional value in patients with low back pain. Materials and Methods: Eight-six patients with low back pain with or without leg pain who underwent MRI of the lumbosacral spine in weight-bearing and supine positions were included in the present retrospective study. The patients’ characteristics and MRI parameters were measured. The data were analyzed to find significant differences between these two positions. Results: MRI parameters which significantly increased in weight-bearing position compared to supine position (p<0.05) included lumbar lordotic angle, lumbosacral angle, presence of spondylolisthesis (at L4/L5 level), and presence of nerve root compression (at L3/L4, L4/L5, and L5/S1 levels). Parameters or findings that significantly decreased were spinal canal diameter (at L2/L3, L4/L5, and L5/S1 levels), and intervertebral disk height (at L2/L3, L4/L5, and L5/S1 levels). Older age group (mean age of 54.3 years versus 45.6 years as younger group) showed a significant change in number of nerve root compression. Forty-three percent of patients with radiating symptom showed a changed number of nerve root compression but this was not statistically significant. Conclusion: Multiple MRI parameters of the lumbosacral spine show significant change in weight-bearing compared to supine position. Increased presence of spondylolisthesis and nerve root compression might be beneficial in patients with radiating symptom unexplained by conventional MR studies in supine position. Older age group showed a significant change in number of nerve root compression.