Epidemiology, etiology, diagnostic evaluation, and treatment of low back pain.

Low back pain affects a minority of individuals over 65 years of age. Four years after the onset of sciatica, the number of individuals working is independent of their workers' compensation status. A complex interaction of metalloproteinases, cytokines, chondrocytes, and macrophages are necessary for the resorption of herniated intervertebral discs. Positional magnetic resonance imaging in the seated extended posture identifies foraminal narrowing that is not visualized with conventional magnetic resonance studies. Compression associated with cauda equina syndrome must be reversed within 48 hours to preserve neurologic function. The gene for transforming growth factor can be transferred to intervertebral discs, resulting in increased proteogylcan production in a rabbit animal model. An aerobic exercise program is as effective as more expensive exercise programs in the treatment of chronic low back pain. Complementary therapies, willow bark and magnets, have marginal benefit for low back pain. Surgical intervention results in improved function for spinal stenosis patients.