This study randomizes degenerative spondylolisthesis and/or degenerative disc patients into two groups: one to receive a new ceramic implant and a control group with a more traditional PEEK plastic implant. The procedure uses a single oblique cage in each group. The study will measure and compare pain and disability improvement with the two implanted devices over a period of two years. The fusion status will also be judged with plane x-rays and one CT scan.

Inclusion Criteria:

• Male and female patients age 18-75 years
• Chronic low back pain unresponsive to at least six months of conservative care
• MRI and standing x-ray evidence of Pfirrmann Grade III or greater disc degeneration and/or degenerative or isthmic spondylolisthesis of Grade I or II

Exclusion Criteria:

• Osteoporosis
• Patients with prior failed fusion at the same level
• Degenerative scoliosis
• Degenerative spondylolisthesis greater than Grade II
• Pregnancy
• Psychiatric or mental disease
• Alcoholism (drinking more than 5 units per day)
• Active infection or prior infection at the surgical site
• Active cancer
• Insufficient language skills to complete questionnaires
• Participation in another study
• More than two symptomatic levels that need fusion