Assessing Superion Clinical Endpoints vs. Decompression

STUDY DESIGN:This study is a prospective, multi-center, randomized controlled "Conditions of
Use" clinical trial comparing the Superion® IDS to open, direct decompression in the
treatment of subjects aged 45 or older suffering from moderate symptoms of neurogenic
intermittent claudication secondary to a confirmed diagnosis of moderate LSS at one or two
contiguous levels from L1 to L5, i.e. from the L1-L2 level to the L4-L5 level. A maximum of
20 investigative sites in the U.S. will enroll subjects into the trial using a 1:1
randomization assignment. Enrollment will include 358 subjects (152 per arm, plus 18% to
account for lost to follow-up). An investigative site is defined as a facility or facilities
in the same general geographic location if they are under the control of a local
Institutional Review Board (IRB).

After implantation of the Superion® IDS or performance of the direct decompression, each
Investigator will be permitted to provide a postoperative care regimen based on the
subject's specific need. The regimen may include, but need not be limited to: medications, a
corset or brace, acupuncture, traction, physical therapy, chiropractic treatment, use of a
TENS unit and massage therapy. The type and amount of the postoperative care will be
collected.

At each follow-up visit through 60 months, subjects will be interviewed to determine if they
have experienced adverse events (AEs) since the previous follow-up visit. A neurological
assessment will be performed for all patients at baseline and all follow-up visits. All
subjects will be required to complete ZCQ, ODI, VAS, EQ-5D and the VertiFlex® Patient
Satisfaction questionnaires to evaluate disability, function, pain, quality of life and
satisfaction at each follow-up visit. Subjects are also required to complete a VAS
questionnaire to evaluate pain status at discharge.

The potential impact of spinal injections/nerve blocks use on the ZCQ was evaluated based on
review of the medical literature. As these are potentially confounding of the ZCQ outcomes,
epidural steroid injections or nerve block procedures at the treated level(s) will be deemed
failures. Further, rhizotomy procedures at the treated level(s) will be deemed failures.

With respect to spinal cord stimulators, because the use of a permanent implant would
require a surgical procedure, this will be deemed a device failure.

Radiographic evaluations will be performed at discharge, and at each scheduled follow-up
visit and prior to any re-operations, in accordance with the Radiographic Evaluation
Protocol. The Investigator may also obtain x-rays at unscheduled visits or to assess adverse
events, if clinically indicated.

Inclusion Criteria:

1. Male or female subjects ≥ 45 years of age.

2. Persistent leg/buttock/groin pain, with or without back pain that is consistently
relieved by flexion activities (example: sitting or bending over a shopping cart).

3. Subjects who have been symptomatic and undergoing conservative care treatment for at
least 6 months, without relief.

4. Diagnosis of degenerative spinal stenosis of the lumbar spine, defined as the
narrowing of the midline sagittal spinal canal (central) and/or narrowing between the
facet superior articulating process (SAP), the posterior vertebral margin (lateral
access), and the nerve root canal (foraminal).

5. Radiographic confirmation of at least moderate spinal stenosis which narrows the
central, lateral, or foraminal spinal canal at one or two contiguous levels from
L1-L5. Moderate spinal stenosis is defined as ≤50% reduction in lateral/central
foramen.

6. Must present with moderately impaired Physical Function (PF) defined as a score of ≥
2.0 of the Zurich Claudication Questionnaire (ZCQ).

7. Subjects who are able to give voluntary, written informed consent to participate in
this clinical investigation and from whom consent has been obtained.

8. Subjects, who, in the opinion of the Clinical Investigator, are able to understand
this clinical investigation, cooperate with the investigational procedures and are
willing to return for all the required post-treatment follow-ups.

- Note: In Criteria #5, all imaging used to confirm LSS should be completed within
4 weeks prior to enrollment. Radiographic confirmation of LSS may include MRI
and/or CT.

Exclusion Criteria:

1. Axial back pain only.

2. Fixed motor deficit in lower extremity(ies).

3. Diagnosis of lumbar spinal stenosis which, if the patient were randomized to the
Superion arm, would not require any direct neural decompression or surgical
intervention other than that required to implant the Superion® device or if
randomized to the direct decompression arm, would not require a decompression
procedure which would create significant instability requiring spinal fusion, with or
without instrumentation.

4. Unremitting pain in any spinal position.

5. Significant peripheral neuropathy or acute denervation secondary to radiculopathy.

6. Lumbar spinal stenosis at more than two levels determined pre-operatively to require
surgical intervention.

7. Significant instability of the lumbar spine as defined by ≥ 3mm translation or ≥ 5°
angulation through flexion/extension films.

8. Sustained pathologic fractures of the vertebrae or multiple fractures of the
vertebrae and/or hips.

9. Spondylolisthesis or degenerative spondylolisthesis greater than grade 1 (on a scale
of 1-4).

10. Spondylosis (pars fracture) at the treatment level(s).

11. Degenerative lumbar scoliosis with a Cobb angle of > 10° at treatment level.

12. Osteoporosis, defined as a DEXA bone density measurement T score ≤ -2.5.

13. Morbid obesity, defined as Body Mass Index (BMI) >40kg/m2.

14. Significant peripheral vascular disease (diminished dorsalis pedis or tibial pulses).

15. Prior surgery of the lumbar spine at the treatment level(s).

16. Cauda equina syndrome (defined as neural compression causing neurogenic bowel or
bladder dysfunction).

17. Active (systemic, or local in disc or spine) infection at time of surgery.

18. Active systemic disease such as AIDS, HIV, hepatitis, etc.

19. Paget's disease at involved segment or metastasis to the vertebrae, osteomalacia, or
other metabolic bone disease.

20. Currently undergoing immunosuppressive therapy or long-term steroid use.

21. Known allergy to titanium or titanium alloys.

22. Tumor in the spine or a malignant tumor except for basal cell carcinoma.

23. Known or suspected history of alcohol and/or drug abuse.

24. Prisoner or transient.

25. Life expectancy less than two years.

26. Any significant psychological disturbance, psychotic or neurotic, that could impair
the consent process or ability to complete subject self-report questionnaires.

27. Involved in pending litigation of the spine or worker's compensation related to the
back.

28. Enrolled in the treatment phase of another drug or device clinical investigation
(currently within past 30 days).

29. Congenital defect of the spine.

30. Pregnant or lactating.

31. Any condition that, in the opinion of the Investigator, would affect the patient's
welfare or outcome of the clinical trial.