Post-Approval 'Real Conditions of Use' Study

Inclusion Criteria:

1. Radiographic confirmation of at least moderate lumbar stenosis, which narrows the
central spinal canal at one or two contiguous levels from L1-L5 that require surgical
decompression. Moderate stenosis is defined as > 25% reduction of the antero-posterior
dimension compared to the next adjacent normal level, with nerve root crowding
compared to the normal level, as determined by the investigator on computerized
tomography (CT) Scan or MRI. The patient may have, but is not required to have for
inclusion in the study:

- Facet hypertrophy and subarticular recess stenosis at the affected level(s);

- Foraminal stenosis at the affected level(s);

- Up to stable Grade I degenerative spondylolisthesis (Meyerding classification) or
equivalent retrolisthesis as determined by flexion/extension X ray:

(i) For single level disease, there may be up to a stable Grade I
spondylolisthesis or equivalent retrolisthesis at the affected level as
determined on flexion/extension files by the investigator.

(ii) For two level disease, there may be up to a stable Grade I spondylolisthesis or
equivalent retrolisthesis at ONLY ONE of the two contiguous affected levels as
determined on flexion/extension films by the investigator. Patients with up to stable
Grade I spondylolisthesis at two contiguous levels are excluded, but patients with up
to Grade I stable spondylolisthesis at the adjacent level may be included.

(d) Mild lumbar scoliosis (Cobb angle up to 25º)

2. Radiographic confirmation of no angular or translatory instability of the spine at
index or adjacent levels (instability as defined by White & Panjabi: Sagittal plane
translation >4.5mm or 15% or sagittal plane rotation >15° at L1-L2, L2-L3, and L3-L4;
>20° at L4-L5 based on standing flexion/extension X-rays)

3. Visual Analog Scale back pain score of at least 50 mm on a 100 mm scale.

4. Neurogenic claudication as defined by leg/buttocks or groin pain that can be relieved
by flexion such as sitting in a chair.

5. Patient has undergone at least one epidural injection at any prior time point, AND at
least 6 months of prior conservative care without adequate and sustained symptom
relief.

6. Age between 40 to 80 years.

7. Oswestry Low Back Pain Disability Questionnaire score of at least 20/50 (40%).

8. Appropriate candidate for treatment using posterior surgical approach.

9. Psychosocially, mentally, and physically able to fully comply with this protocol,
including adhering to scheduled visits, treatment plan, completing forms, and other
study procedures.

10. Personally signed and dated informed consent document prior to any study-related
procedures indicating that the patient has been informed of all pertinent aspects of
the trial.

Exclusion Criteria:

1. More than two contiguous vertebral levels requiring surgical decompression.

2. Prior surgical procedure that resulted in translatory instability of the lumbar spine
[as defined by White & Panjabi (see 3.4.1 Inclusion Criteria, Item #2)].

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 index level.

5. Radiographically compromised vertebral bodies at any lumbar level(s) caused by current
or past trauma or tumor (e.g., compression fracture).

6. Severe facet hypertrophy that requires extensive bone removal which would cause
instability.

7. Isthmic spondylolisthesis or spondylolysis (pars fracture).

8. Degenerative lumbar scoliosis (Cobb angle of greater than 25°).

9. Disc herniation at any lumbar level requiring surgical intervention.

10. Osteopenia: A screening questionnaire for osteopenia, SCORE (Simple Calculated
Osteoporosis Risk Estimation), will be used to screen patients who require a DEXA
(dual-energy x-ray absorptiometry) bone mineral density measurement. If DEXA is
required*, exclusion will be defined as a DEXA bone density measured T score of ≤ -1.0
(The World Health Organization definition of osteopenia).

11. Back or leg pain of unknown etiology.

12. Axial back pain only, with no leg, buttock, or groin pain.

13. Morbid obesity defined as a body mass index > 40.

14. Pregnant or interested in becoming pregnant in the next three years.

15. Known allergy to titanium, titanium alloys, or MR (magnetic resonance) contrast
agents.

16. Active or chronic infection - systemic or local.

17. Chronically taking medications or any drug known to potentially interfere with
bone/soft tissue healing (e.g., steroids), not including a medrol dose pack.

18. History of significant peripheral neuropathy.

19. Significant peripheral vascular disease (e.g., with diminished dorsalis pedis or
posterior tibial pulses).

20. Unremitting back pain in any position.

21. Uncontrolled diabetes.

22. Known history of Paget's disease, osteomalacia, or any other metabolic bone disease
(excluding osteopenia, which is addressed above).

23. Cauda equina syndrome, defined as neural compression causing neurogenic bowel (rectal
incontinence) or bladder (bladder retention or incontinence) dysfunction.

24. Fixed and complete motor, sensory, or reflex deficit.

25. Rheumatoid arthritis or other autoimmune diseases.

26. Known or documented history of communicable disease, including AIDS, HIV, active
Hepatitis

27. Active malignancy: a patient with a history of any invasive malignancy (except
nonmelanoma skin cancer), unless he/she has been treated with curative intent and
there has been no clinical signs or symptoms of the malignancy for at least five
years. Patients with a primary bony tumor are excluded as well.

28. Prisoner or ward of the state.

29. Subject has a history of substance abuse (e.g., recreational drugs, narcotics, or
alcohol).

30. Subject is currently involved in a study of another investigational product for
similar purpose.

31. Currently seeking or receiving workman's compensation.

32. In active spinal litigation.