Dynamic morphometric changes in degenerative lumbar spondylolisthesis: A pilot study of upright magnetic resonance imaging

•Degenerative lumbar spondylolisthesis (DLS) is more symptomatic in upright posture.•Conventional MRI is underestimating the severity of neural compression in DLS.•The open MRI can acquire images in the most symptomatic posture in DLS patients.•In DLS, the height of the lateral recess is reduced by 50% in the standing posture.•The cross-sectional area of the thecal sac is reduced by 30% in standing posture.