A-MAV™ Anterior Motion Segment Replacement

Inclusion Criteria: * Has back and/or radicular pain with degeneration of the disc as confirmed by patient history, physical examination, and radiographic studies with one or more of the following factors: * instability as defined by \> 5° angulation * osteophyte formation of facet joints or vertebral endplates * decreased disc height, on average by \>2mm, relative to the next adjacent vertebral segment * scarring/thickening of ligamentum flavum, annulus fibrosis, or facet joint capsule * herniated nucleus pulposus * facet joint degeneration/changes * vacuum phenomenon * Has single-level symptomatic degenerative involvement from L4-S1 requiring surgical treatment * Has intact facet joints at the involved vertebral levels documented by CT and/or MRI * Has preop Oswestry score≥30 * Has preop back pain score ≥8 * Age 18 to 70 yrs, inclusive and is skeletally mature * Has not responded to non-operative treatment for 6 mos * If child-bearing potential, patient is non-pregnant, non-nursing, and agrees not to become pregnant for 1 yr after surgery * Is willing and able to comply with the study plan and sign the Patient Informed Consent Form Exclusion Criteria: * Has primary diagnosis of a spinal disorder other than DDD at involved level * Had previous anterior lumbar spinal surgery at involved level * Had previous posterior lumbar spinal fusion surgical procedure at involved level * Had prior posterior lumbar surgery resulting in significant muscle/ligament morbidity, not including facet saving techniques * Requires surgical intervention at more than 1 lumbar level * Has severe pathology of facet joints of involved vertebral bodies * Has facet arthritis or any posterior element insufficiency * Has spondylolisthesis * Has mid-sagittal stenosis of \<8mm, based on remaining canal diameter * Has rotatory scoliosis at involved level * Has lumbar scoliosis with \>11° sagittal plane deformity * Had previous trauma to L4, L5, or S1 levels in compression or burst * Meets any of the following criteria: Previous diagnosis of osteoporosis, osteopenia, or osteomalacia; postmenopausal Non-Black female over 60 yrs of age and weighs less than 140 pounds; postmenopausal female that has sustained a non-traumatic hip, spine or wrist fracture; male over age 60 that has sustained a non-traumatic hip or spine fracture. If Yes to any of these, a DEXA scan is required. If level of BMD is -3.5 or lower or -2.5 or lower with vertebral crush fracture, the patient is excluded * Had previous lumbar spinal fusion at adjacent level * Bone growth stimulator use in spine * Has obesity defined by BMI greater than or equal to 40 * Has arachnoiditis * Has a non-contained or extruded herniated nucleus pulposus with acute nerve root compression * Has condition that requires postop medications that interfere with bone metabolism, such as chronic steroid use or prolonged use of non-steroidal anti-inflammatory drugs, excluding routine perioperative, non-steroidal anti-inflammatory drugs. Does not include low dose aspirin for prophylactic anticoagulation * Has overt or active bacterial infection, either local or systemic and/or potential for bacteremia * Has presence or prior history of malignancy (except for basal cell carcinoma of skin) * Has documented metal allergy, titanium alloy intolerance or cobalt-chrome-molybdenum alloy * Is mentally incompetent. If questionable, obtain psych consult * Has a Waddell Signs of Inorganic Behavior score of 3 or greater * Has chronic or acute renal and/or hepatic failure or prior history of renal and/or hepatic parenchymal disease * Is prisoner * Is pregnant * Is an alcohol and/or drug abuser as defined by currently undergoing treatment for alcohol and/or drug abuse * Has history of autoimmune disease * Has received treatment with an investigational therapy within 30 days prior to implantation surgery or treatment is planned during 24 months following the implantation surgery * Has history of any endocrine or metabolic disorder known to affect osteogenesis * Has any disease that would preclude accurate clinical evaluation