The study is designed to evaluate the safety and effectiveness of the CHARITE Artificial Disc compared to anterior lumbar interbody fusion for treatment of degenerative disc disease at one level of the lumbar spine (either L4/L5 or L5/S1).

Treatments for disc degeneration have historically included conservative modalities, such as rest, heat, electrotherapy, physical therapy, and analgesics to surgery. Currently, there are two main surgical techniques for treatment of disc degeneration: (1) nucleotomy or diskectomy, i.e., excision of part or all of the degenerated disc, which is typically performed for treatment of radicular syndrome in the case of disc herniation; and (2) spinal fusion, i.e., grafting bone between the vertebrae adjacent to the degenerated disc to eliminate articulation at the damaged segment, which is typically performed for treatment of degeneration together with instability and reduction of the intervertebral space. Rigid internal fixation may also be used to promote fusion.

The CHARITÉ Artificial Disc is designed to provide a new therapeutic option for treatment of degenerative disc disease as an alternative to spinal fusion to preserve function in the lumbar vertebral region. Each institution participating in the study was to treat the first 5 consecutive study participants with the CHARITE to as it involves a modification to the technique used for anterior fusion. Data will be collected on these "training" cases but will not be included in the comparison with the control (fusion) treatment.

Comparison: Outcomes for patients treated with the CHARITÉ Artificial Disc will be compared to outcomes for patients treated with anterior lumbar interbody fusion.

Inclusion Criteria:

• 18 to 60 years of age inclusive
• symptomatic degenerative disc disease confirmed by provocative discogram
• single level disease L4/L5 or L5/S1
• leg or back pain without nerve root compression
• VAS pain score >= 40
• Oswestry Disability Index score >= 30
• six months prior conservative treatment
• appropriate for anterior surgical approach

Exclusion Criteria:

• previous lumbar or thoracic fusion
• other spinal surgery at target level
• symptomatic multiple level degeneration
• non-contained or extruded nucleus pulposus
• compression or burst at L4, L5, or S1 due to trauma
• mid-sagittal stenosis < 8mm
• osteoporosis, osteopenia, or other metabolic bone disease of the spine
• spondylolisthesis > 3mm, scoliosis > 11 degrees
• facet joint arthrosis
• isthmic spondylolisthesis
• positive straight leg raise for radiculopathy