Wallis Mechanical Normalization System for Low Back Pain

The purpose of this study is to compare improvement in low back pain with Wallis (interspinous process implant) to exercise and injections.


Eligibility Criteria:
Subjects must meet all inclusion and exclusion criteria listed below for participation in the study.

Inclusion Criteria:

* Ages 18-60; male/female.
* Diagnosis of mild to moderate degenerative disc disease (DDD), which requires:

  * back pain of at least 30/100 as measured on a visual analog scale, with or without leg (radicular) pain; and
  * radiographic confirmation of the following, as determined by computed tomography (CT), magnetic resonance imaging (MRI), discography, plain film, myelography and/or flexion/extension films: up to Modic I changes on MRI, with decreased disc height up to 50% of adjacent level, and no significant osteophytes; with or without a contained disc herniation.
* Candidate for either surgery with Wallis or aggressive conservative management.
* Requires treatment at one or two lumbar levels between L1 and L5.
* Experienced symptoms for at least three months without significant resolution.
* Has undergone a regimen of at least four weeks of anti-inflammatory medication for the current episode of back pain and had exposure to physical therapy.
* Minimum baseline Oswestry score of 30% (15/50).
* Physically and mentally able to comply with the protocol, including ability to read and complete required forms, and willing and able to adhere to the follow-up requirements of the protocol.
* Voluntarily signs the subject informed consent.

Exclusion Criteria:

* Significant neuroforaminal compression requiring discectomy or foraminotomy
* Radiographic evidence of DDD at L5-S1
* Radiographic confirmation of severe facet joint disease or degeneration.
* History of any lumbar disc treatment intended to remove the disc, e.g. surgery, intradiscal electrothermal therapy (IDET), laser or enzymes such as chymopapain.
* Clinically compromised vertebral bodies at the affected level due to current or past trauma, e.g., sustained pathological fracture or multiple fractures of vertebrae.
* Unwilling to comply with 8 weeks of physical therapy.
* Subject refuses to consider epidural or facet injections for leg or back pain.
* Active systemic infection or infection at the operative site
* Osteoporosis. The Simple Calculated Osteoporosis Risk Estimation (SCORE) questionnaire will be used to screen subjects for osteoporosis; subjects whose screening suggests risk will undergo a dual-energy x-ray absorptiometry (DEXA) scan. Subjects will be excluded if the DEXA scan results indicate a T-score equal to or worse than -2.5, in accordance with the World Health Organization definition of osteoporosis.
* Paget's disease, osteomalacia, or any other metabolic bone disease other than osteoporosis, which is addressed above
* Rheumatoid arthritis, lupus, or other autoimmune disease
* AIDS, HIV, or Hepatitis
* Known allergy to titanium, polyetheretherketone, or polyester
* Current pathological lesions, such as tumor
* Congenital lumbar spinal stenosis
* Clinically relevant instability on flexion-extension as determined by the investigator by overlaying films.
* Cauda equina syndrome
* Pregnant at time of enrollment or with plans to become pregnant within the next three years
* Concomitant conditions requiring steroid treatment or prior steroid usage for more than one of the preceding three months
* Diabetes mellitus requiring daily insulin management
* Extreme obesity, as defined by National Institutes of Health (NIH) Clinical Guidelines (body mass index \[BMI\] \> 35)
* Fusion previously performed at the same or an adjacent level; or other instrumented spinal surgery at the operative level.
* Prior participation in study of any experimental spinal implant or treatment
* Pending litigation against a health care professional
* Life expectancy of less than three years
* History of any invasive malignancy (except for non-melanoma skin cancer), unless treated with curative intent and with no clinical signs or symptoms of the malignancy for at least 5 years
* Current or recent history of substance abuse (alcoholism and/or narcotic addiction) requiring intervention
* Spondylolysis
* Translation greater than 2 mm at the symptomatic level
* Significant scoliosis (Cobb angle \> 25 degrees) or scoliosis otherwise requiring surgical correction
* Kyphosis requiring surgical correction