Disc and nerve root findings on lumbar MRI with straightened vs flexed hips and knees—pilot study

Objective: To compare disc and nerve root findings, image quality, and pain between supine lumbar MRI positions with straightened vs flexed hips and knees. Methods: In this prospective pilot study, 14 adults with sciatica or suspected lumbar radiculopathy underwent MRI supine with their hips and knees flexed and then straightened. For each position, two experienced radiologists assessed disc contour, location/size of disc herniation, nerve root affection, image quality, image evaluation difficulty, and sagittal angles between the vertebral bodies at each disc level L3-S1. Patients scored pain (0–10) after MRI in each position. We compared MRI assessments and mean pain scores (t-test, log-transformation) between the two positions. Results: We found no clear difference in disc bulges, disc herniation, nerve root affection, image quality, or image evaluation difficulty between MRI with straightened vs flexed knees/hips. Herniation size differed ≤ 0.6 mm between the two positions. Sagittal angles between neighboring vertebral bodies differed ≤3.8°. Mean pain score after MRI with straightened vs flexed knees/hips was 4.64 vs 3.29 (p = 0.005). Conclusion: In this pilot study, supine lumbar MRI with straightened vs flexed hips/knees showed similar disc and nerve root findings. The straightened position appeared more painful. Advances in knowledge: In previous studies, spondylolisthesis increased on supine MRI with straightened vs flexed lower limbs, but corresponding data on disc findings were lacking. In this pilot study, supine lumbar MRI with straightened rather than flexed hips and knees was more painful and did not improve the diagnosis of disc or nerve root findings.publishedVersio