A comparative MRI study of upper and lower lumbar motion segments in patients with low back pain.

STUDY DESIGN: The study is a prospective cross-sectional study of 514 patients with low back pain and sciatica.

OBJECTIVE: The aim of this study was to assess the relation of various risk factors on upper and lower lumbar levels.

SUMMARY OF BACKGROUND DATA: Various risk factors such as aging, job (physical habits), obesity, and cigarette smoking have been reported to accelerate lumbar degenerative process, possibly to a different extent in upper and lower lumbar spine. Lumbar spine motion segment degenerative process has been radiologically assessed by severity of nucleus pulposus (NP) dislodgement, annular tears, and Modic changes in adjacent end plates.

METHODS: Five hundred and fourteen patients with low back pain of at least 4 weeks duration, aged 18 to 70 years were prospectively enrolled. All underwent thorough neurological assessment and lumbar 1.5 T high-resolution magnetic resonance imaging, being evaluated by independent neurosurgeon and neuroradiologists. NP dislodgement and Modic changes as well as neurological findings were graded. Statistical analysis was performed by analysis of variance, t test, chi, and Fisher exact test.

RESULTS: There were 244 men and 270 women. Sixty-six percent of lower lumbar levels showed NP dislodgement at least in 1 level. Aging had significant association with NP dislodgement, and patients with lower lumbar NP dislodgement had a mean age, 10 years younger than those with upper lumbar NP dislodgement. There was no significant association between sex, body mass index >25 kg/m, and vibratory job either in upper or lower lumbar levels and NP degeneration. Heavy lifting was associated with upper lumbar NP dislodgement while, sedentary and housework were associated with NP dislodgement only in lower lumbar levels. Also cigarette smoking (> or =10 pack/y) and older age (>50 y) were associated only with upper lumbar NP dislodgement. Modic changes correlated only with advanced age (>50 y), and there was no association with body mass index >25, smoking, job habits and sex.

CONCLUSIONS: The study revealed that pathological alteration in vertebral end plates is the same in upper and lower lumbar bony tissues as detected by Modic's criteria, whereas those of intervertebral discs is different regarding spinal level and risk factor.