Clinical study inclusion and exclusion criteria
| Inclusion criteria | Exclusion criteria |
|---|---|
| Symptomatic degenerative disc unresponsive to nonoperative management for a minimum of 6 mo with imaging studies (eg, radiography, CT, and MRI) verifying L4-L5 or L5-S1 structural abnormalities (eg, disc space collapse, grade 1 degenerative spondylolisthesis, desiccated disc, annular tears, or endplate morphologic changes) | Abnormal pain profile as suggested by 1 or more of the following: nonanatomic pain diagram, ODI >80, and surgeon assessment |
| Aged 20–60 y (inclusive) | ODI <30 |
| Mentally, emotionally, and physically able to understand the procedure; to comply with postoperative care instructions; and to adhere to 2-y follow-up schedule | Provocative discography with non-concordant pain at the operative level |
| Sagittal translation >5 mm at the operative level or above | |
| Symptoms associated with >1 lumbar level | |
| Evidence of grade 2 degenerative spondylolisthesis or greater, any isthmic spondylolisthesis, or arachnoiditis | |
| Radiographic findings of end-stage disc resorption and collapse, prior fracture of lower lumbar spine (eg, endplate sclerosis, endplate irregularities, bone-on-bone collapse, or peripheral rim osteophytes), or degenerative collapse of >3 levels, which—in the opinion of the investigator—prevents the patient from participating in the study | |
| Congenital or acquired structural defect (eg, scoliosis) at the operative level or above | |
| Acute disc herniation with radiculopathy | |
| Clinically significant facet arthrosis or other posterior element lysis or loss at the operative level | |
| Significant leg pain of a radicular or neurogenic claudication nature | |
| Spinal stenosis | |
| Symptoms associated with any neurologic signs | |
| Prior fusion at any lumbar level or laminectomy or discectomy at the operative level | |
| History of any invasive malignancy (except nonmelanoma skin cancer) unless treated with curative intent and there had been no clinical signs or symptoms or malignancy for at least 5 y | |
| Prior radiation to the spine | |
| Systemic disease affecting the spine, including rheumatoid arthritis, autoimmune disease, AIDS, HIV, and hepatitis | |
| Acute or chronic infection (local or systemic) | |
| Using medications or drugs known to potentially interfere with bone or soft-tissue healing (eg, steroids) | |
| Primary osteoporosis or osteopenia (DEXA T score <1.0) or metabolic bone disease | |
| Overweight as indicated by a body mass index ≥30 | |
| Pregnant or interested in becoming pregnant in the next 3 y | |
| Known or suspected allergy to titanium, polyethylene, cobalt, chromium, or molybdenum | |
| Evidence of drug or alcohol abuse | |
| Participation in another clinical trial within 8 wk of the baseline visit and for the duration of this trial | |
| Diabetic patients and patients with a history of implant rejection |
Abbreviations: CT, computed tomography; DEXA, dual-energy x-ray absorptiometry; HIV, human immunodeficiency virus; MRI, magnetic resonance imaging.