Valeo OL Interbody Fusion Devices for Posterior Lumbar Interbody Fusion SNAP Trial

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