Inclusion Criteria:

1. At least moderate lumbar stenosis from L1-L5, at one or two contiguous levels, confirmed by MRI or CT, with up to Grade I spondylolisthesis.
2. Radiographic confirmation of no angular or translatory instability of the spine at index or adjacent levels.
3. VAS back pain score of at least 50mm on a 100mm scale.
4. Neurogenic claudication as defined by leg/buttocks or groin pain that can be relieved by flexion.
5. At least one epidural injection at any prior timepoint, and at least 6 months of prior conservative care without adequate and sustained symptom relief.
6. 40 to 80 years of age.
7. Minimum baseline Oswestry score of 40% (20/50).
8. Appropriate candidate for treatment using posterior surgical approach.

Exclusion Criteria:

1. More than two vertebral levels requiring surgical decompression.
2. Prior surgical procedure resulting in translatory instability of the lumbar spine.
3. More than one surgical procedure at any combination of lumbar levels.
4. Prior fusion, implantation of a total disc replacement, complete laminectomy, or implantation of an interspinous process device at any lumbar level.
5. Radiographically compromised vertebral body at any lumbar level caused by current or past trauma or tumor.
6. Severe facet hypertrophy requiring extensive bone removal which would cause instability.
7. Isthmic spondylolisthesis or spondylolysis (pars fracture).
8. Degenerative lumbar scoliosis (Cobb angle >25°).
9. Lumbar disc herniation requiring surgical intervention.
10. S.C.O.R.E. ≤6 suggestion of osteopenia or osteoporosis risk confirmed by DEXA T-score equal to or worse than -1.0.
11. Back or leg pain of unknown etiology.
12. Axial back pain only, with no leg, buttock or groin pain.
13. Morbid obesity as defined by BMI >40.
14. Pregnant or interested in becoming pregnant in the next three years.
15. Known allergy to titanium, titanium alloys or MR contrast agents.
16. Active or chronic infection - systemic or local.
17. Chronic use of medications or any drug known to potentially interfere with bone/soft tissue healing (e.g. steroids), not including Medrol DosePak.
18. History of significant peripheral neuropathy.
19. Significant peripheral vascular disease.
20. Unremitting back pain in any position.
21. Uncontrolled diabetes.
22. Known history of Paget's disease, osteomalacia, or any other metabolic bone disease.
23. Cauda equina syndrome.
24. Fixed and complete motor, sensory, or reflex deficit.
25. Rheumatoid arthritis or other autoimmune disease.
26. History of AIDS, HIV or active Hepatitis.
27. History of invasive malignancy (except non-melanoma skin cancer) within at least five years.
28. History of substance abuse.
29. Current involvement in a study of another investigational product for similar purpose.
30. Currently seeking or receiving workman's compensation.