Clinical Trial Comparing Decompression With and Without Coflex™ Interlaminar Technology Treating Lumbar Spinal Stenosis

Inclusion Criteria:

1. Radiographic confirmation of clinical symptoms of at least moderate degenerative spinal stenosis, with constriction of the central spinal canal of one or two adjacent segments in the region L3 to L5 with the need for decompression.

   If necessary additional decompression in the adjacent segment(s) may be performed avoiding any instability in the affected segment.

   In addition the following may exist (but is not obligatory):

   • hypertrophy of the facet joints and subarticular recessus stenosis in the relevant segment or
   • stenosis of the foramen in the relevant segment
   • and/or stable retrolisthesis up to grade I verified by flexion-/extension X-ray films.
2. Radiographic confirmation of no translatory instability in the main segment as well as in adjacent segments (dynamic translatory instability ≤ 3 mm).
3. VAS back pain score of at least 50 mm on a 100 mm scale (for acute back pain or a period of at least 3 month of back pain before the onset of leg pain).
4. Minimum of 3 months conservative therapy without improvement of symptoms.
5. Age >40 years.
6. Oswestry Low Back Pain Disability Questionnaire score of at least 18/45 (40%) for German sites or 20/50 (40%) for the US sites (The question about sexual life will be excluded).
7. Suitability of the patient for a posterior surgery procedure.
8. Mental and physical ability of patient to follow the protocol according to compliance to time schedule, treatment plan, fill in of CRF pages and further study procedures.
9. Personally signed informed consent form before the start of any study related procedures.

Exclusion Criteria

Any of the following will exclude a subject from the study:

1. Preceding fusion or decompression surgery of the lumbar spine or preceding nucleotomy of the segments of concern (also if nucleotomy becomes necessary during surgery).
2. Radiographically confirmed damage of the vertebral body in the segment of concern in the lumbar spine (e.g. osteoporotic compression fracture or because of tumors)
3. Isthmic and degenerative spondylolisthesis (anterolisthesis; retrolisthesis > grade I) or spondylolysis (Pars fracture).
4. Degenerative lumbar scoliosis (> 25°).
5. Adipositas (obesity). Defined as a body mass index >40.
6. Pregnancy, or wish to get pregnant during the course of the study.
7. Known allergy for titanium and titanium alloys.
8. Fluoride infections - both systemic and local.
9. History of severe peripheral neuropathy.
10. Significant peripheral vascular disease (claudication intermittens ≥ stage 2b).
11. M. Paget or osteomalacia or other metabolic bone disorders.
12. Cauda equina syndrome.
13. Communicating diseases, including HIV, active hepatitis
14. Patients who are lawfully kept in an institution.
15. Subjects who, in the opinion of the investigator, will be inappropriate for inclusion into this clinical trial or will not comply with requirements of the study.
16. Subjects who participated in a clinical observation or therapy with X-ray during the last 10 years.
17. Subjects who participate(d) in another clinical trial (within the last 4 weeks) that might influence the safety and effectiveness assessment of this trial.