Table 1 Inclusion and exclusion criteria.

Age greater than 20 years and less than 65 years

Back pain of greater than 6-month duration

Has telephone and willing to complete telephone interviews

Ability to communicate in English

Physician diagnosis of discogenic back pain

One or two level disc degeneration on MRI scan

Leg pain greater than back pain

Pregnant

Instability on lumbar flexion-extension radiographs (if done)

Motor deficit on physical examination

Abnormal electrodiagnostic studies (if done)

Lumbar spinal stenosis requiring a laminectomy.

Prior lumbar fusion or multilevel laminectomy

Spondylolisthesis of more than 25% (>grade I)

Inflammatory spondyloarthropathy

Spinal malignancy or infection

Severe co-morbid illness that would contraindicate surgery or result in major functional decline

Developmental spine deformities or vertebral fractures

Disc protrusion or extrusion on imaging with either:

Nerve root compression or displacement, or pain radiating below the knee