Magnetic resonance imaging of the lumbar spine: findings in female subjects from administrative and nursing professions.

STUDY DESIGN: Cross-sectional magnetic resonance imaging (MRI) study.

OBJECTIVE: To find out whether different patterns of lumbar disc degeneration related to different physical work types (static vs. dynamic) can be found.

SUMMARY OF BACKGROUND DATA: The association of lumbar disc degeneration with physical workload as well as the association of disc degeneration with low back pain (LBP) has been debated controversially. Nevertheless, many of the mainly invasive treatment concepts are based on disc degeneration models.

METHODS: An MRI study was performed in female subjects aged 45 to 62 years with persistent LBP and in age-matched controls. Subjects (n = 109) were selected from nursing and administrative professions. A questionnaire was used to assess the subjects' exposure to physical workplace factors. Disc degeneration, disc herniation, nerve root compromise, high intensity zones, endplate changes, and facet joint osteoarthritis were evaluated based on sagittal T1- and T2-weighted as well as axial T2-weighted images.

RESULTS: The two occupational groups could clearly be distinguished by the physical workplace factors: administrative work was associated with predominantly sitting postures whereas nursing work was associated with frequent walking, pushing, pulling, and lifting. Except for endplate (Modic) changes at L5-S1, MRI findings did not differ between the four groups, namely, nurses and secretaries with and without LBP. When analyzing the MRI findings within the two vocational groups, nerve root compromise and endplate changes in the lower lumbar spine were found to be significant (P < 0.05) risk factors for LBP. Disc degeneration, disc herniation, nerve root compromise, and facet joint osteoarthritis were present in more than 50% of the intervertebral spaces studied.

CONCLUSIONS: These findings give evidence that in subjects performing nonheavy work, patterns of lumbar disc degeneration are not associated with the job type and characteristic physical loadings.