Inclusion criteria
| Age between 18 and 60 years |
| Evidence of degenerative disc disease at either L4–5 or L5-S1 (only 1 level) with radiographic evidence (CT, MRI, plain film, flexion/extension films, myelography, discography, and so on) of mild to moderate osteophyte formation of vertebral endplates, loss of disc height >2 mm when compared with adjacent level, herniated nucleus pulposus, loss of water content on MRI (black disc on T2-weighted image), or vacuum phenomenon |
| History of back and/or radicular pain that is severe, ongoing, and recurrent |
| At least 6 months of prior conservative therapy for discogenic back pain and/or prior nucleolysis, nucleoplasty, discectomy, or laminotomy (without accompanying facetotomy) at study treatment level |
| ODI showing moderate disability |
| VAS showing moderate disability |
Abbreviations: CT, computed tomography; MRI, magnetic resonance imaging.