Assessment of nanOss Bioactive 3D in the Posterolateral Spine

Inclusion Criteria: * At least 21 years of age and skeletally mature. * Symptomatic spinal stenosis secondary to DDD with up to Grade 1 spondylolisthesis at one or two adjacent levels from L2-S1 requiring instrumented PLF surgery. * Completed a minimum of 6 months of non-operative treatment. * Pre-operative objective evidence of primary diagnosis confirmed by appropriate imaging studies (AP, Lateral, Flexion and Extension images and an MRI or CT scan). * Is willing and able to return for post-treatment exams according to the follow-up called for in the protocol. * Is able to review, understand and sign the informed consent document. Exclusion Criteria: * Symptomatic at more than two levels. * Has had previous fusion surgery at the level(s) to be treated (previous discectomy, laminotomy, laminectomy or nucleolysis at the level(s) to be treated \< 6 months ago is ok). * Has \> 11 degrees lumbar scoliosis. * Has \> 40 BMI. * Has \> Grade 1 spondylolisthesis. * Has osteoporosis (T-score of -2.5 or below), osteomalacia, Paget's disease or metabolic bone disease. * Has a disease that significantly inhibits bone healing (e.g., diabetes type 1, renal failure, impaired calcium metabolism). * Has a medical condition that requires or has a history of chronic steroid use (i.e., oral steroids), with the exception of inhaled/nasal corticosteroids steroids or has any medical condition that requires treatment with drugs known to interfere with bone healing. * Has a neurological disease (e.g., Parkinson's disease), a psychosocial disorder (e.g., suicidal, diminished capacity) or has a history of substance abuse which would preclude accurate evaluation or limit the ability to comply with study requirements. * Has either an active infection or infection at the site of surgery * Has a systemic disease (e.g., AIDS, HIV, active hepatitis, tuberculosis) * Has rheumatoid arthritis or other autoimmune disease. * Has spinal tumors. * Has an active malignancy (except non-melanoma skin cancer) or history of any invasive malignancy unless treated and in remission for at least five years. * Has a known sensitivity or allergies to porcine collagen, PEEK, tantalum or titanium. * Has active arachnoiditis. * Has fractures of the epiphyseal plate or fractures for which stabilization of the fracture is not possible. * Is a prisoner. * Is involved in spinal litigation at the treated level(s). * Is participating in another clinical study that would confound Study data. * Is pregnant or is interested in becoming pregnant while participating in the Study.