Condition of Approval Study

This prospective, multicenter longitudinal five-year study of X-STOP PEEK implant usage in
LSS patients is designed to supplement pre-market safety and effectiveness data with
information on longer-term device performance in a population of patients with moderately
impaired physical function at preoperative baseline (i.e., an "indicated" population) who
elect to undergo X-STOP PEEK surgery. This post-approval study will enroll 240 patients at up
to 8 clinical sites where all participating spine surgeons have completed a company-sponsored
physician training program. The clinical sites recruited to participate in this study
comprise a geographically diverse mix of academic, referral, and/or community based sites.

Safety and effectiveness data will be assessed at baseline and annually through five (5)
years postoperatively. Office visits will be scheduled preoperatively, and at 6 weeks, 1, 2,
3, 4, and 5 years postoperatively. Clinical/neurological and radiographic examination will be
performed during each office visit. A baseline patient history (including medication usage)
will be taken, and concomitant medications will be recorded at each postoperative follow-up
visit. In addition, patients will be asked to complete the following questionnaires prior to
consultation with their physicians or their staff: Zurich Claudication Questionnaire (ZCQ),
Oswestry Disability Index (ODI), Numeric Rating Scale (NRS), and SF-36 Health Survey. At the
2-, 3-, 4- and 5-year office visit, patients will also be asked two questions assessing the
value of surgery and the overall improvement in the quality of life postoperatively.

The primary study endpoint in this study is treatment success. Secondary endpoints will
include scores from the SF-36, ODI, and NRS, as well as incidence rates of adverse events,
device failures, and secondary surgeries.

Inclusion Criteria:

1. has a baseline score >2.0 in the Physical Function (PF) domain of the Zurich
Claudication Questionnaire

2. is 50 years old or older

3. has leg/buttock/groin pain with or without back pain NOTE: Leg/buttock/groin pain must
be completely relieved when flexed such as when sitting in a chair. If back pain is
also present, it must be partially relieved when flexed.

4. can sit for 50 minutes without pain

5. can walk 50 feet or more

6. has a confirmed diagnosis of neurogenic intermittent claudication secondary to lumbar
spinal stenosis, with X-Ray, MRI and/or CT evidence of thickened ligamentum flavum,
narrowed lateral recess and/or central canal narrowing

7. has completed at least six months of conservative care therapy which may include but
is not limited to physical therapy, bracing, systemic or injected medications

8. has signed a patient informed consent document

9. is physically and mentally willing and able or has a caregiver who can comply with the
postoperative and routinely scheduled clinical and radiographic evaluations

10. lives in the immediate area and has no plans to relocate to another geographic area
before completion of the study or lives outside the immediate area and will comply
with the scheduled postoperative visits with a prearranged and designated physician

Exclusion Criteria:

1. has a baseline score less than or equal to 2.0 in the Physical Function (PF) domain of
the Zurich Claudication Questionnaire

2. cannot sit for 50 minutes

3. cannot walk more than 50 feet

4. has unremitting pain in any spinal position

5. has axial back pain only without leg/buttock/groin pain

6. has a fixed motor deficit

7. has cauda equina syndrome defined as neural compression causing neurogenic bowel
(rectal incontinence) or bladder (bladder retention or incontinence) dysfunction

8. has severe symptomatic lumbar spinal stenosis at more than two levels

9. has significant instability of the lumbar spine, e.g., isthmic spondylolisthesis or
degenerative spondylolisthesis greater than grade 1 (on a scale of 1 to 4)

10. has an ankylosed segment at the affected level(s);

11. has significant scoliosis (Cobb angle is greater than 25 degrees)

12. has an acute fracture of the spinous process or pars interarticularis

13. has sustained pathologic fractures of the vertebrae or multiple fractures of the
vertebrae and /or hips

14. has severe osteoporosis of the spine or hip, defined as bone mineral density (BMD) in
the spine or hip more than 2.5 SD below the mean of adult normals in the presence of
one or more fragility fractures

15. has Paget's disease at the involved segment(s) or metastasis to the vertebrae

16. has had any surgery of the lumbar spine

17. has significant peripheral neuropathy demonstrated by nerve conduction velocity tests

18. has acute denervation secondary to radiculopathy, as shown by EMG

19. has significant peripheral vascular disease characterized by diminished dorsalis pedus
or tibial pulses

20. has extreme obesity as defined by a Body Mass Index (BMI) greater than 40 kg/m2

21. has an active systemic infection or infection localized to the site of implantation

22. has an active systemic disease such as AIDS, HIV, hepatitis, etc.

23. has a medical condition that may interfere with postoperative management and
follow-up, or may result in patient death prior to study completion (e.g., Alzheimer's
disease, unstable cardiac disease, active malignancy)

24. has a recent history of narcotic abuse (i.e., within last 3 years)

25. has a known allergy to titanium,titanium alloy, or polyetheretherketone

26. is immunologically suppressed, or has received or is receiving steroids at any dose
daily for more than one month within the last 12 months

27. is currently involved in a study of another investigational product that may affect
the outcome of this study

28. is pregnant or planning to become pregnant during the study period

29. cannot undergo MRI or tolerate closed MRI scanning.