This is a single-center, open label, prospective clinical study to assess the clinical application and functional outcomes of symptomatic patients undergoing the Minimally Invasive Lumbar Decompression (MILD™) treatment for lumbar spinal stenosis. In this study, patient-reported outcomes over a 3 month period following treatment will be collected by the investigator. Periodic surveys for each study subject's pain, functional status, quality of life and physical examination will track outcomes following MILD™ treatment.

The Vertos MILD™ devices are used for image-guided Minimally Invasive Lumbar Decompression, referred to as the MILD™ procedure. This percutaneous procedure is performed under fluoroscopic image guidance through a dorsal approach to the spine. Lumbar decompression is performed through the removal of tissue and bone, where indicated. All procedures are conducted in accordance with the product labeling and indications for use. A minimum of ten up to a maximum of twenty-five adult patients will be enrolled and followed for a period of up to 6 months. Patients with symptomatic lumbar spinal stenosis who meet the study enrollment criteria will be offered the MILD™ procedure as an alternative to surgery or continued standard non-surgical medical management.

Inclusion Criteria:

1. Symptomatic lumbar spinal stenosis (LSS) primarily caused by dorsal element hypertrophy.
2. Prior failure of conservative therapy.
3. Radiologic evidence of LSS (L3-L5), Ligamentum flavum > 2.5 mm, confirmed by pre op MRI and/or CT.
4. Central canal cross sectional area < 100mm2.
5. Anterior listhesis < 2 - 3mm.
6. Able to walk at least 10 feet unaided before being limited by pain.
7. Available to complete 12 weeks of follow-up.
8. A signed Informed Consent Form is obtained from the patient.
9. Adults ≥ 18 years of age.

Exclusion Criteria:

1. Prior surgery at intended treatment level.
2. History of recent spinal fractures with concurrent pain symptoms.
3. Disabling back or leg pain from causes other than LSS (e.g. acute compression fracture, metabolic neuropathy, or vascular claudication symptoms, etc.).
4. Significant disk protrusion or osteophyte formation.
5. Excessive facet hypertrophy.
6. Bleeding disorders and/or current use of anti coagulants.
7. Use of acetylsalicylic acid (ASA) and/or non-steroidal anti-inflammatory drug (NSAID) within 5 days of treatment.
8. Epidural steroids within prior three weeks.
9. Inability of the patient to lie prone for any reason with anesthesia support (e.g. chronic obstructive pulmonary disease (COPD), obesity, etc.).
10. Any potential wound healing pathologies that may compromise outcomes, including: diabetes, excessive smoking history, cancer, connective tissue diseases, recent spine radiation and severe COPD.
11. Dementia and/or inability to give informed consent.
12. Pregnancy.

Period of collection from enrollment through end of study (Month 6).

Small pilot series with short follow-up. Procedure experience of investigator limited. Minimal information available regarding appropriate patient selection, thus patient pool confined to complex cases wait-listed for more aggressive laminectomy.