Inclusion Criteria:

• is at least 18 years of age and skeletally mature
• must have symptomatic single level degenerative disc disease at L4/5 requiring surgical treatment
• must have completed a minimum of six months of unsuccessful conservative, non-operative care
• must have discogenic back pain with or without leg pain
• must show radiographic confirmation using plain films, MRI, CT, myelogram or discography of one of the following: decreased disc height when compared to the adjacent level, contained herniated nucleus, or vacuum phenomenon (dark disc)
• must score at least 40% on the Oswestry Disability Index
• must score at least 4 on a 10cm Visual Analog Scale for back pain
• is able to comply with the protocol's follow-up schedule
• must understand and sign the informed consent document

Exclusion Criteria:

• symptomatic DDD at more than one level
• previous fusion at any lumbar level (discectomy, laminectomy/laminotomy, IDET, or nucleolysis performed > 6 months ago are permitted)
• clinically compromised vertebral bodies, at the affected level due to previous trauma, i.e., compression or burst fracture
• pars defect
• involved vertebral endplate dimensionally smaller than 34.5 mm in the medial-lateral direction and/or 27 mm in the anterior-posterior direction
• disc height less than 5 mm at the target level
• bony stenosis
• lytic spondylolisthesis, spondylolisthesis greater than 3mm
• lumbar scoliosis greater than 11 degrees.
• osteoporosis, osteopenia, osteomalacia, Paget's disease or metabolic bone disease
• Schmorl's nodes, an incomplete annulus, or endplates that are not intact
• spinal tumors
• symptomatic facet joint disease
• free fragment herniation confirmed radiographically
• isolated radicular compression syndrome, especially due to a disc herniation
• arachnoiditis
• active infection or surgical site infection
• is using any medication known to interfere with bone/soft tissue healing
• rheumatoid arthritis or other autoimmune disease
• systemic disease such as AIDS, HIV, hepatitis
• morbid obesity defined as body mass index (BMI) >40 or a weight more than 100 lbs over ideal body weight
• psychosocial disorders that would preclude accurate evaluation or has a history of substance abuse
• active malignancy except non-melanoma skin cancer; history of any invasive malignancy unless treated and in remission for at least five years
• documented allergies to metal or plastic; i.e., cobalt, chromium, molybdenum, polyethylene, titanium or polyetheretherketone
• pregnancy, or interested in becoming pregnant within the next two years
• prisoner
• involvement in an investigational drug or device study within 30 days