Background: The response to axial physiological pressure due to load transfer to the lumbar spine structures is among the various back pain mechanisms. Understanding the spine adaptation to cumulative compressive forces can influence the choice of personalized treatment strategies.
Aim: To analyze the impact of axial load on the spinal canal's size, intervertebral foramina, ligamenta flava and lumbosacral alignment.
Methods: We assessed 90 patients using three-dimensional isotropic magnetic resonance imaging acquisition in a supine position with or without applying an axial compression load. Anatomical structures were measured in the lumbosacral region from L1 to S1 in lying and axially-loaded magnetic resonance images. A paired t test at α = 0.05 was used to calculate the observed differences.
Results: After axial loading, the dural sac area decreased significantly, by 5.2% on average (4.1%, 6.2%, P < 0.001). The intervertebral foramina decreased by 3.4% (2.7%, 4.1%, P < 0.001), except for L5-S1. Ligamenta flava increased by 3.8% (2.5%, 5.2%, P < 0.001), and the lumbosacral angle increased.
Conclusion: Axial load exacerbates the narrowing of the spinal canal and intervertebral foramina from L1-L2 to L4-L5. Cumulative compressive forces thicken ligamenta flava and exaggerate lumbar lordosis.
Keywords: Axial loading; Diagnosis; Low back pain; Lumbar spine; Magnetic resonance imaging; Musculoskeletal disorder; Spine biomechanics.
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