MIS MiLIF Versus Open

Inclusion Criteria: * Patient is between 18 and 75 years of age * Patient is scheduled for an elective spinal lumbar interbody single level fusion * Patient is a candidate for posterior unilateral lumbar fusion through a midline incision * Indication for surgery and dominant symptom of chronic low back and/or leg pain * Diagnosis of one or more of the following: * Primary symptomatic degenerative disc disease confirmed with appropriate imaging studies and/or positive lumbar discography * Spondylolisthesis Grade I/II * The affected motion segment reside in L2-S1 and are adjacent segments * Patient, or authorized representative, signs a written Informed Consent form to participate in the study, prior to any study mandated determinations or procedure. Exclusion Criteria: * Patient has a known fracture in the lumbar spine * Patient has systemic infection or evidence of any surgical site infection (superficial or organ space) * Patient has compromised immune system or autoimmune disease (WBC\<4000 or \>20,000) * Patient has uncontrolled diabetes * Patient has a known malignancy * Prior lumbar fusion attempt; prior laminectomy and/or discectomy are allowed * Known medical or anatomical condition that would preclude a posterior lumbar fusion using metallic instrumentation (e.g., severe osteopenia) * Patient with a planned placement of an electric bone stimulator * Patient with a planned placement of indwelling epidural catheter for a long term pain management * Patient is pregnant or wishes to become pregnant during the length of the study participation * Patient is currently in litigation * Patient is not likely to comply with the follow-up evaluation schedule * Patient is participating in a clinical trial of another investigational drug or device.