High Body Mass Index is a Predictor of Lumbar Stenosis: A Retrospective Magnetic Resonance Imaging Study

Background: There are more than 100 million obese American individuals, with number expected to rise. Lumbar stenosis is a neurodegenerative disease causing narrowing of the spinal canal. Little is known about the role of obesity in the pathophysiology of spinal stenosis. Therefore, the purpose of this study was to analyze patient body mass index (BMI) and radiologic measurements of (1) spinal canal width; (2) thickness of ligamentum flavum and (3) spinal canal cross-sectional area at spinal levels of L2-3, L3-4, and L4-5, respectively, to determine whether there exists a correlation between obesity and the development of lumbar spinal stenosis. Methods: Hospital data from January 1, 2016, to December 31, 2021, were used to identify patients who underwent a lumbar MRI to determine the development of radiological lumbar spinal stenosis. Patients older than 17 years and whose BMI's ranged from <20 to >40, who had complete lumbar MRIs, with no preexisting bony pathology, neoplasm, or previous lumbar surgery were included in this study. We assessed the thickness of the ligamentum flavum, width of the spinal canal, and the cross-sectional area of spinal canal at the level of the facet joint. Linear regression models were performed on each assessed variable at each spinal level measured. Results: A significant negative association was found between BMI and spinal canal width at all levels measured (L2-3: B = −0.31, P < 0.001; L3-4: B = −0.29, P < 0.001; L4-5: B = −0.27, P < 0.001). No significant association was found between BMI and thickness of the ligamentum flavum ( P = 0.94 at L2-3; P = 0.70 at L3-4; P = 0.62 at L4-5). Furthermore, no significant association was found between BMI and cross-sectional area of the spinal canal ( P = 0.43 at L2-3; P = 0.55 at L3-4; P = 0.22 at L4-5). Conclusion: This study found that patients with elevated BMI have decreased lumbar spinal canal width and provides new insight into the role of obesity in neurodegenerative diseases. Levels of Evidence: III