A selective (non-comprehensive) list of some of the more relevant inclusion/exclusion criteria for the study
| Inclusion criteria |
| Age 18–60 y |
| Symptomatic lumbar degenerative disease: magnetic resonance imaging–confirmed disc desiccation, loss of disc height, and bridging osteophytes |
| Symptomatic level L1-2, L2-3, L3-4, or L4-5 |
| Preoperative Oswestry Disability Index score ≥ 30 points |
| Unresponsive to conservative treatment for > 6 mo or presence of progressive neurologic symptoms |
| Willing and able to comply with requirements defined in protocol for duration of study |
| Signed and dated informed consent form |
| Exclusion criteria |
| Prior lumbar fusion surgery at operative level |
| Prior lumbar laminectomy at operative level |
| Prior complete lumbar facetectomy at operative level |
| Prior bilateral retroperitoneal surgery |
| Radiographic signs of significant instability at operative level (> 3-mm translation, > 11° angulation different from adjacent level) |
| Bridging osteophytes or absence of motion < 2° |
| Radiographic confirmation of significant facet joint disease or degeneration |
| Pars defect, facet abnormality, or other compromise of posterior elements |
| Spondylolisthesis (greater than grade 1) |
| Osteopenia, osteoporosis, or osteomalacia to a degree that spinal instrumentation would be contraindicated |
| Body mass index > 40 |
| Active local or systemic infection, including AIDS and hepatitis |