REFINE Study: A Study In a Novel Interspinous Fusion Device In Subjects With Low Back Pain

Inclusion Criteria: * Subjects enrolled in this study must meet ALL of the following inclusion criteria: 1. Subject must provide written informed consent prior to any clinical study-related procedure. 2. Subject is at least 18 years or older at the time of enrollment, skeletal mature. 3. Subject has 1-2 symptomatic lumbar degenerative disease at adjacent level, T12-S1, with or without grade I spondylolisthesis (confirmed by history and radiographic studies). 4. MRI within 12 months prior to the procedure with at least mild to moderate spinal stenosis at the index treatment level 5. Subject has undergone at least 3 months of non-operative treatment. 6. Subject presents with ZCQ physical function ≥ 2.0 at baseline. 7. Subject reports relief from lumbar flexion and/or sitting. 8. Subject has baseline VAS of back and/or leg pain standing or walking ≥ 50mm. Exclusion Criteria: * Subjects enrolled in this study must NOT meet any of the following exclusion criteria: 1. Subject is unable to provide written informed consent. 2. Subject has had previous lumbar spine surgery at the intended treatment level (e.g., laminectomy or fusion). 3. Subject has a grade II or greater spondylolisthesis on flexion and extension radiographs with 3mm instability. 4. Subject has confirmed or suspected osteoporosis or osteopenia. 5. Subject is enrolled, or intends to participate, in a clinical drug and/or device study (investigational device, investigational drug, new indication for a device or drug, or additional testing beyond standard of care procedures) which could confound the results of this trial as determined by the investigator. 6. Presence of other anatomic or comorbid conditions, or other medical, social, or psychological conditions that, in the investigator's opinion, could limit the subject's ability to participate in the clinical investigation or to comply with follow-up requirements. 7. Subject is pregnant or nursing.