Safety and Effectiveness Study of the TOPS System, a Total Posterior Arthroplasty Implant Designed to Alleviate Pain Resulting From Moderate to Severe Lumbar Stenosis

INCLUSION CRITERIA:

• Moderate to Severe lumbar spinal stenosis at a single level* between L3 - L5, withradiographic confirmation of any one of the following on CT, MRI, plain x-ray ormyelography:

• Evidence of thecal sac and/or cauda equina compression

• Evidence of nerve root impingement by either osseous or non-osseous elements;

• Evidence of hypertrophic facets with canal encroachment Moderate/severe spinalstenosis is further defined radiographically as;

• moderate canal stenosis is a 25-49% reduction in the A/P dimension of the centraland/or lateral foramen when compared to adjacent (cephlad) level

• Severe canal stenosis is defined as 50% or greater reduction in the A/P dimensionof the central and/or lateral foramen when compared to the adjacent (cephlad)level **Patients which require minimal decompressive surgery at an adjacentlevel, may have a laminonotmy or soft tissue resection as long as thedecompression does not compromise the stability of the adjacent segment.

• At least six (6) months of failed, conservative treatment prior to surgery, includingphysical therapy, use of anti-inflammatory medications at maximum specified dosage;administration of epidural/facet injections.

• Age 40-75 years old (male or female).

• Up to one prior surgery without instrumentation implanted at any lumbar vertebrallevel limited to the following:

• IDET,

• laminotomy,

• laminectomy,

• foraminotomy

• Discectomy (that occurred at least three years ago without any reoccurrence ofherniation)

• Lower back pain and/or sciatica with or without spinal claudication.

• VAS leg pain of at least 40/100 at baseline.

• Oswestry Questionnaire score of at least 40/100 at baseline.

EXCLUSION CRITERIA:

• Back or non-radicular leg pain of unknown etiology

• Spondylolisthesis Grade II or higher

• Stenosis caused by an extruded spinal disc fragment

• Lytic spondylolisthesis

• More than one (1) motion segment involved in the degenerative pathology to the extentthat justifies its inclusion in the surgical procedure, unless a decompression alonecan be done at that level without compromising stability.

• Known allergy to titanium and/or polyurethane

• Prior fusion surgery at any lumbar vertebral level with or without instrumentation

• Supplemental interbody support required (e.g., bone graft, spacers, VBRs, or fusioncages)

• Clinically compromised vertebral bodies at the affected level(s) due to any traumatic,neoplastic, metabolic or infectious pathology.

• Scoliosis of greater than ten (10) degrees (both angular and rotational)

• Morbid obesity defined as a body mass index > 40 or a weight more than 100 lbs. overideal body weight. Note: Additional inclusion/exclusion criteria are applied. Please contact Impliant forfurther details.