Post Market Observational Trial for the PerQdisc Nucleus Replacement Device

Inclusion Criteria: * Patient is skeletally mature and between 21 and 60 years of age. * Patient has Degenerative Disc Disease (DDD) at one or more levels between L1 and S1 but must have a single level identified as the pain generator. * Patient has adequate disc height (6mm) at the level to be treated * Patient is not responsive to conservative, non-surgical treatment for back pain. * Patient has signed the approved Informed Consent Form. Exclusion Criteria: * Patient has less than 6 mm of disc height. * Patient has had prior lumbar spine surgery (nucleoplasty at non-index level is considered acceptable). * Patient has had spinal fusion in the lumbar or thoracic intervertebral spaces. Cervical fusion is allowed as long as there are no neurologic deficits in the lower extremities. * Patient has spondyloarthropathy or other spondylolisthesis greater than 2 mm. * Patient has congenital moderate or severe spinal stenosis or epidural lipomatosis. * Patient has significant facet disease. Significant is defined as pain improvement of 80% or more following image-guided medial branch blocks of the target level according to Spine Intervention Society (SIS) guidelines (diagnostic, contrast controlled). * Patient has any known active malignancy. * Patient has previously undergone or currently on immunosuppressive therapy. Steroids used to treat inflammation are allowed. * Patient has active or local systemic infection. * Patient has been diagnosed with hepatitis, rheumatoid arthritis, lupus erythematosus, or other autoimmune disease including Acquired Immune Deficiency Syndrome (AIDS), AIDS related Complex (ARC), and Human Immunodeficiency Virus (HIV). * Patient has diabetes mellitus (Type 1 or 2) requiring daily insulin management. * Patient has osteopenia of the spine (T-score of -1.0 or lower). A Bone Densiometry (DEXA) scan should be performed to rule out patients considered at risk for osteopenia. * Patient has morbid obesity defined as a Body Mass Index (BMI) more than 40 or a weight of more than 45 kg (100 lbs.) over ideal body weight. * Patient has a known allergy to silicone or barium sulfate. * Patient has a significant disc herniation at the level to be treated. Significant is defined as a large extruded herniation that creates a risk for expulsion. * Patient has a significant Schmorl's node in the level to be treated. Significant is defined as a large, rectangular or irregular shaped node that has an associated active inflammatory process (Modic I changes). * Patient has motion of less than 3 degrees on pre-operative lateral flexion/extension radiographs. * Protrusion of the 20A Imaging Balloon up to or beyond the outer margin of the vertebra during the imaging steps. * Patient has a violated endplate as determined by imaging balloons during fluoroscopy. * Patient has a disc space that is too narrow for implantation.