Two-level Exclusion Criteria

Subjects were not permitted to enroll in the Mobi-C® trial if they met any of the following exclusion criteria.

  1. Reported to have an active systemic infection or infection at the operative site.
  2. Reported to have a history of or anticipated treatment for active systemic infection, including HIV or Hepatitis C.
  3. More than one immobile vertebral level between C1 to C7 from any cause including but not limited to congenital abnormalities and osteoarthritic “spontaneous” fusions.
  4. Previous trauma to the C3 to C7 levels resulting in significant bony or disco-ligamentous cervical spine injury.
  5. Reported to have had any prior spine surgery at the operative level.
  6. Reported to have had a prior cervical fusion procedure at any level.
  7. Axial neck pain in the absence of other symptoms of radiculopathy or myeloradiculopathy justifying the need for surgical intervention.
  8. Disc height less than 3 mm as measured from the center of the disc in a neutral position and disc height less than 20% of the anterior-posterior width of the inferior vertebral body.
  9. Radiographic confirmation of severe facet joint disease or degeneration.
  10. Reported to have an increased risk of osteoporosis/osteopenia. This was defined as a T-score less than (worse than) -1.5 on a previous or required Hologic Sahara or dual energy X-ray absorptiometry (DEXA) scan. All subjects that met one or more of the following were to undergo a Hologic Sahara or DEXA scan as part of the trial enrollment procedures:
    • Females 50 years and older;
    • Females who were post-menopausal or post-hysterectomy with oophorectomy;
    • Subjects taking bisphosphonate medication for the treatment of osteoporosis; and/or
    • Subjects with history of chronic use of high dose steroids. High dose steroid use is defined as part of Exclusion Criterion #22.
    • All females less than 50 years of age, and all males, who had not had a Hologic Sahara or DEXA scan within six months of surgery, were screened for osteoporosis using the Simple Calculated Osteoporosis Risk Estimation (SCORE) questionnaire. Subjects whose screening suggests increased risk (SCORE greater than 6) were to undergo a Hologic Sahara or DEXA scan as part of the trial enrollment procedures.
  11. Reported to have Paget’s disease, osteomalacia or any other metabolic bone disease other than osteoporosis, which is addressed above.
  12. Reported active malignancy that included a history of any invasive malignancy (except non-melanoma skin cancer), unless the subject had been treated with curative intent and there had been no clinical signs or symptoms of the malignancy for at least five years.
  13. Symptomatic DDD or significant cervical spondylosis at more than two-levels.
  14. Spondylolysis.
  15. Marked cervical instability on resting lateral or flexion-extension radiographs demonstrated by:
    • Translation ≥ 3.5 mm, and/or
    • Greater than 11° angular difference to that of either adjacent level.
  16. Known allergy to cobalt, chromium, molybdenum or polyethylene.
  17. Segmental angulation of greater than 11° at treatment or adjacent levels.
  18. Reported pregnancy or nursing at time of enrollment, or with plans to become pregnant within the next three years.
  19. Reported to have rheumatoid arthritis, lupus, or other autoimmune disease that affect the musculoskeletal system.
  20. Congenital bony and/or spinal cord abnormalities that affect spinal stability.
  21. Reported to have diseases or conditions that would preclude accurate clinical evaluation (e.g. neuromuscular disorders).
  22. Reported concomitant conditions requiring daily, high-dose oral and/or inhaled steroids. High dose steroid use is defined as:
    • Daily, chronic use of oral steroids of 5 mg/day or greater.
    • Daily, chronic use of inhaled corticosteroids (at least twice per day).
    • Use of short-term (less than 10 days) oral steroids at a daily dose greater than 40 mg within one month of the trial procedure.
  23. Reported to have current or recent history of substance abuse (alcoholism and/or narcotic addiction) requiring intervention.
  24. Clinically Severe Obesity, as defined by National Institutes of Health (NIH) Clinical Guidelines Body Mass Index (BMI) > 40).
  25. Reported use of any other investigational drug or medical device within the last 30 days prior to surgery.
  26. Evidence of symptomatic moderate to severe facet joint degeneration or disease where the investigator felt this was a major contributor to the subject’s pain as diagnosed by injection and imaging.
  27. Reported to be taking medications known to potentially interfere with bone/soft tissue healing (e.g., high-dose oral and/or inhaled steroids, immunosuppressant medication, chemotherapeutic agents). High dose steroid use is defined as part of Exclusion Criterion #22.
  28. Reported to have pending personal litigation relating to spinal injury (worker’s compensation was not an exclusion).
  29. Reported to have a current history of heavy smoking (more than one pack of cigarettes per day).
  30. Anticipated or potential relocation greater than 50 miles that may interfere with completion of follow-up examinations.
  31. Reported to have mental illness or belonged to a vulnerable population, as determined by the investigator (e.g., prisoner or developmentally disabled),that would compromise ability to provide informed consent or compliance with follow-up requirements.
  32. Reported to have an uncontrolled seizure disorder.
  33. Reported to have taken epidural steroids within 14 days prior to surgery.