Effects of spine loading in a patient with post-decompression lumbar disc herniation: observations using an open weight-bearing MRI

Our objective was to use an open weight-bearing MRI to identify the effects of different loading conditions on the inter-vertebral anatomy of the lumbar spine in a post-discectomy recurrent lumbar disc herniation patient.

A 43-year-old male with a left-sided L5-S1 post-decompression re-herniation underwent MR imaging in three spine-loading conditions: (1) supine, (2) weight-bearing on standing (WB), and (3) WB with 10 % of body mass axial loading (WB + AL) (5 % through each shoulder). A segmentation-based proprietary software was used to calculate and compare linear dimensions, angles and cross sections across the lumbar spine.

The L5 vertebrae showed a 4.6 mm posterior shift at L5-S1 in the supine position that changed to an anterior translation >2.0 mm on WB. The spinal canal sagittal thickness at L5-S1 reduced from supine to WB and WB + AL (13.4, 10.6, 9.5 mm) with corresponding increases of 2.4 and 3.5 mm in the L5-S1 disc protrusion with WB and WB + AL, respectively. Change from supine to WB and WB + AL altered the L5-S1 disc heights (10.2, 8.6, 7.0 mm), left L5-S1 foramen heights (12.9, 11.8, 10.9 mm), L5-S1 segmental angles (10.3°, 2.8°, 4.3°), sacral angles (38.5°, 38.3°, 40.3°), L1–L3–L5 angles (161.4°, 157.1°, 155.1°), and the dural sac cross sectional areas (149, 130, 131 mm²). Notably, the adjacent L4–L5 segment demonstrated a retro-listhesis >2.3 mm on WB.

We observed that with weight-bearing, measurements indicative of spinal canal narrowing could be detected. These findings suggest that further research is warranted to determine the potential utility of weight-bearing MRI in clinical decision-making.