association of obesity and overweight with disc height and disc herniation in lumbar spine

background & aim: low back pain is the most debilitating condition, and can lead to decreased physical function, compromised quality of life, and psychological distress. several studies has conducted to recognize the risk factors of lbp, but despite of strong relationship between obesity and lbp, the underlying mechanisms are unclear. the aim of this study was to evaluate the relationship between obesity and overweight with disc height and disc bulging at each level and total levels in lumbar vertebra, considering occupational risk factor as a cofounder variable. methods & materials/patients: this is a cross-sectional study on 102 patients with lbp referring to mri department in poursina hospital in rasht. bmi (kg/m2) categories modified for asian populations based on world health organization guidelines were used. disc height and disc herniation were evaluated in sagittal t1, sagittal t2 and axial t2 mri images. we used four risk factors agreed by us-niosh (usa-national institute for occupational safety and health), to evaluate the occupational risk factors. regression test was used for statistical analysis. results: of the 102 patients, 36.3% were men and 63.7% were women. the range of age was 15 to 75 years. results showed that 26.5% of patients had normal bmi, 39.2% were overweight and 34.3% were obese. distribution of levels of occupational risk factor included 36.3% low, 17.6% moderate and 46.1% high. analysis with regression test showed that the relationship between obesity and overweight and disc height was negative at total levels and all levels, unless l5-s1. at l5-s1 level there was no association. there was a positive relationship between obesity and total score of disc herniation at l1-s1. there was no association between overweight and total score at this level. at l1-l2, l2-l3 and l5-s1 there were no association between obesity and overweight and disc herniation and at l3-l4 and l4-l5 there was a negative relationship between obesity and disc herniation. conclusion: our study noted the positive and significant effect of obesity and overweight on disc degenerative changes in lumbar spine. since there is abundant evidence in the literature demonstrating the strong association of disc degeneration on mri with low back pain, prevention and treatment of being overweight or obese must be a public health priority. if successful, such outcomes may lead to the prevention or minimization of the extent and severity of disc degeneration, which in turn may also decrease the risk of developing low back pain and the subsequent need for medical management.