Table 1

Study Inclusion and Exclusion Criteria.

Inclusion Criteria
 • Age 18-69 years;
 • Symptomatic cervical degenerative disc disease in one or two levels between C3-C7 with:

  • ◦ Myelopathy or myeloradiculopathy and/or

  • ◦ Decreased muscle strength and/or

  • ◦ Abnormal sensation and/or abnormal reflexes;

 • Deficit confirmed by CT, MRI, or X-ray;
 • NDI Score of > 30/100;
 • Unresponsive to non-operative treatment for at least 6 weeks or presence of progressive symptoms or signs of nerve root/spinal cord compression despite continued non-operative treatment;
 • No prior surgical procedures at the operative level and no prior fusions at any cervical level;
 • Physically and mentally able and willing to comply with the protocol;
 • Signed informed consent;
 • Willingness to discontinue all use of non-steroidal anti-inflammatory drugs (NSAIDs) from one week before surgery until 3 months after surgery;
Exclusion Criteria
 • More than two vertebral levels requiring treatment;
 • Immobile levels between C1 and C7 from any cause;
 • Any prior surgery at the operative level or any prior fusion at any cervical level;
 • Disc height less than 3 mm;
 • T-score less than -1.5 (osteoporosis evaluation);
 • Paget's disease, osteomalacia, or any other metabolic bone disease other than osteoporosis;
 • Active infection of surgical site or history of or anticipated treatment for systemic infection including HIV and/or Hepatitis C;
 • Active malignancy: a history of any invasive malignancy (except non-melanoma skin cancer), unless treated with curative intent with no clinical signs or symptoms of malignancy in the past 5 years;
 • Marked instability of the cervical spine on resting lateral or flexion-extension radiographs;
 • Known allergy to device materials including cobalt, chromium, molybdenum, or polyethylene;
 • Segmental kyphosis of greater than 11° at treatment or adjacent levels;
 • Rheumatoid arthritis, lupus, or other autoimmune disease;
 • Any diseases or conditions that would preclude accurate clinical evaluation;
 • Daily, high-dose oral and/or inhaled steroids or a history of chronic use of high dose steroids;
 • Morbid obesity (BMI > 40);
 • Use of any other investigational drug or medical device within 30 days prior to surgery;
 • Pending litigation relating to spinal injury (worker's compensation not included);
 • Smoking more than one pack of cigarettes per day;
 • Reported to have a mental illness or belonging to a vulnerable population.