Medical Professionals

About the Study

Applied Spine Technologies, Inc. has received permission from the FDA to commence a multi-center, randomized, controlled clinical trial to compare posterior dynamic stabilization using the Stabilimax NZ® Dynamic Spine Stabilization System to traditional spinal fusion stabilization to treat degenerative lumbar spinal stenosis.

Study Enrollment Criteria


Inclusion Criteria

Every patient must meet all of the following criteria to be eligible for enrollment in the study.

General Criteria:

  • The greater of the patient’s right and left VAS leg pain score is >= 40mm on a 100mm scale and exceeds the VAS back pain score
  • Zurich Claudication Questionnaire Symptom Severity (SS) score great than 2 on a scale of 1-5
  • Zurich Claudication Questionnaire Physical Function (PF) score greater than or equal to 2 on a scale of 1-4
  • Intermittent neurogenic Claudication as evidenced by the presence of the following symptoms brought on or aggravated by standing, walking or exercising in an erect posture:
    • Discomfort, pain, numbness, weakening, tiredness or heaviness in the thigh or calf
    • Pain, numbness, burning or tingling in the back or buttocks
    • Symptoms are relieved by forward bending, sitting, or lying positions
  • Physician judgment that inadequate pain relief has been obtained after six months of non-surgical management
  • Skeletally mature patients at least 21 years of age
  • Willing to provide written consent for participation and a Health Insurance Portability and Accountability Act (HIPAA) authorization
  • Willing to undergo all study procedures including physical therapy and adhere to the follow-up schedule
  • Patient requires no additional surgical treatment outside the investigational or control at the time of surgery

Radiographic Criteria:

  • Degenerative spinal stenosis of the lumbar spine, defined as the narrowing of the midline sagital spinal canal (central) and/or narrowing between the facet superior articulating process (SAP), the posterior vertebral margin (lateral recess) and the nerve root canal (foraminal)
  • Radiographic confirmation of at least moderate spinal stenosis which narrows the central, lateral, foraminal spinal canal at one or two contiguous levels from L1-S1 that require surgical decompression. Moderate spinal stenosis is defined as 25 percent to 50 percent reduction in lateral/central foramen compared to the adjacent levels, with radiographic confirmation of any one of the following according to the classic definitions provided by Herkowitz¹
    • Evidence of thecal sac and/or cauda equina compression
    • Evidence of nerve root impingement (displacement or compression)by either osseous or non-osseous elements
    • Evidence of hypertrophic facets with canal encroachment
  • Patients can have but are not required to have:
    • Spondylolisthesis, if present, no more than Grade 1 as defined by less than 25 percent vertebral slip forward over the body beneath (Myerding Classification)

Exclusion Criteria

Any and all patients who meet any of the following criteria should not be enrolled in the study.

Surgical Exclusion Criteria:

  • Prior surgery at any lumbar level including the level being treated except for: Lamino/Foraminotomy, Microdiscetomy, IDET and Percutaneous Discectomy
  • Prior surgery at any lumbar level within one year of enrollment
  • No more than one prior surgery at any lumbar level
  • Previous acute trauma at the treated level within two years of enrollment (i.e. fracture or dislocation)

Medical/Neurological Exclusion Criteria:

  • Symptomatic cervical and/or thoracic neurological compromise
  • Significant peripheral neuropathy or acute denervation secondary to radiculopathy caused by conditions other than spinal stenosis (e.g. systemic or autoimmune disorders, infections, acute trauma, etc.)
  • Patients with other neurological pathology that could confound study results (i.e. multiple sclerosis, Lou Gehrig’s Disease/ALS, Guillain-Barre Syndrome)
  • Patients with Cauda Equina Syndrome
  • Peripheral vascular disease requiring intervention (>= 50 percent stenosis of vessel)
  • Active systemic or surgical site infection
  • Any significant medical conditions that would represent a significant increase in surgical risk or interfere with normal healing (e.g. hemophilia or other bleeding disorders)
  • History of psychosocial disorders that could prevent accurate completion of self-reporting assessment scales, including disorders such as: substance abuse or chemical dependency, mood disorders, schizophrenia, anxiety disorders and obsessive compulsive disorder requiring medication to control
  • Women who lactating, pregnant or anticipate becoming pregnant within 24 months post-surgery
  • Patients with insulin-dependent diabetes mellitus
  • Patients who are immunocompromised (having an immune system that has been impaired by disease or treatment) such as but not limited to: Acquired Immunodeficiency Syndrome (AIDS), genetic deficiencies of the complement system, Severe Combined Immunodeficiency Disease and Thymic Hypoplasia
  • Patients who are receiving immunosuppressive therapy
  • Patients who are receiving long-term steroid therapy
  • Patients who have an autoimmune disease such as but not limited to: Sjorgens Syndrome, Rheumatoid Arthritis, Systemic Lupus Erythematosus, Scleroderma, Polymyositis-Dermatomyositis
  • Patients with active hepatitis
  • Malignancy of any type within the last five years

General Exclusion Criteria:

  • Primary diagnosis or discogenic back pain (e.g. torn disc, herniated disc, inflamed or irritated disc, other disc pathology where the patient possesses axial back pain greater than leg pain resulting from degenerative disc disease)
  • Patients contraindicated for MRI
  • Morbid obesity (BMI > 40)
  • Previous known allergy to the materials contained in the Stabilimax NZ®; device including nickel, cobalt, chromium, molybdenum, iron, titanium or Teflon™
  • Participation in another clinical study within four weeks of enrollment
  • Receiving Worker’s Compensation or involved in active litigation relating to his/her spinal condition
  • Patients who are prisoners

Radiographic Criteria:

  • Gross instability, defined as greater than 3mm translational motion on flexion/extension studies
  • Degenerative Spondylolisthesis or retrolisthesis higher than Grade 1 defined by less than 25 percent vertebral slip forward over the body beneath (Myerding).
  • Degenerative scoliosis > 10 degrees at any level in the lumbar spine
  • Lateral listhesis on A-P X-ray
  • Spondylolysis at any level in the lumbar spine
  • Isthmic Spondylolisthesis at any level in the lumbar spine.
  • Spondylolisthesis at more than one lumbar level
  • Metabolic bone disease defined as a DEXA score equal to or below -2.5 T for those patients measured
  • Pathological vertebral fracture
  • Metastases to the spinal vertebrae
  • Paget's disease of the bone
  • Osteomalacia
  • Pars defect or facet fracture preventing pedicle screw fixation
  • Facet arthropathy at the level(s) to be treated is less than Grade 2 and greater than Grade 3 according to the Fujiwara Scale
  • Patients with more than moderate disc degeneration defined as:
    • 66 percent loss of disc height compared to the normal, superior adjacent level; and/or
    • Moderate to severe Osteophyte formation
  • Congenital lumbar spinal stenosis
  • Patient has an estimated interpedicular distance of less than 30mm as measured on preoperative MRIs

Intraoperative Criteria:

  • Patients with inadequate bone quality to support pedicle screw stabilization without supplemental fixation, as determined intra-operatively by the investigator
  • Insufficient interpedicular space to accommodate device implantation
  • Pars defect or facet fracture preventing pedicle screw fixation

1 Herkowitz H., The Lumbar Spine (ed. 2004, Lippincott William & Wilkins)