The arc of lumbar spinal lordosis before surgery and at the last follow-up examination + Image on uncompressed MRI: lumbar spinal stenosis position on uncompressed MRI, area and degree of fibrosis of multifidus muscle at the site of preoperative stenosis, classification of central stenosis according to author Schizas, degree of stenosis disc degeneration at the location of spinal canal narrowing, classification of causes of lumbar spinal stenosis. Evaluate the role of axial loading MRI: Clinical manifestations on axial loaded MRI.