Investigation of the Simplify® Cervical Artificial Disc

Inclusion Criteria: * Be between 18 and 60 years of age; * Have symptoms of cervical degenerative disc disease (DDD) at one cervical level from C3 to C7 defined as intractable radiculopathy (arm pain and /or a neurological deficit) with or without neck pain or myelopathy due to a single-level abnormality localized to the level of the disc space and radiographic evidence of at least one of the following; 1. Spondylosis (defined by the presence of osteophytes or dark disc) on CT or MRI or; 2. Disc height decreased by ≥ 1 mm when compared to adjacent levels on radiographic film, CT, or MRI or 3. Disc herniation on CT or MRI; * Have at least one of the following radiculopathy or myelopathy symptoms in neck and/or arm; 1. Pain or paresthesias in a specific nerve root distribution from C3 to C7, 2. Decreased muscle strength of at least one level on the 0-5 scale, or 3. Abnormal sensation, including hyperesthesia or hypoesthesia. * Have at least one of the following: 1. At least six weeks of prior conservative treatment (e.g., physical therapy and/or use of anti-inflammatory medications and muscle relaxants at the manufacturer's recommended therapeutic dose); 2. The presence of progressive symptoms (e.g., increasing numbness or tingling) or 3. Signs of nerve root compression. * Have a Neck Disability Index (NDI) greater than or equal to 40 on a scale of 100 (moderate disability); * Be appropriate for treatment using an anterior surgical approach; * Be likely to return for all follow-up visits and * Be willing and able to provide Informed Consent for study participation. Exclusion Criteria: * Marked cervical instability on resting lateral or flexion/ extension X-ray (translation \> 3 mm or \> 11 degrees rotation to that of either adjacent non-treatment level); * Non discogenic neck pain or non discogenic source of symptoms (e.g., tumor, rotator cuff injury, etc.); * Radiographic confirmation of severe facet disease or facet degeneration; * Bridging osteophytes; * Less than 2 degrees of motion at index level; * Prior surgery at the level to be treated, except laminotomy without accompanying facetectomy; * Prior fusion at any cervical level; * More than one neck surgery via anterior approach; * Previous trauma to the C3-C7 levels resulting in compression or bursting; * Documented presence of a free nuclear fragment at cervical levels other than the study level; * Axial neck pain only (no radicular or myelopathy symptoms); * Symptomatic DDD at more than one cervical level; * Severe myelopathy (less than 3/5 muscle strength); * Any paralysis; * Recent history (within previous six months) of chemical or alcohol dependence; * Active systemic infection; * Infection at the site of surgery; * Prior disc space infection or osteomyelitis in the cervical spine; * Any terminal, systemic or autoimmune disease; * Metabolic bone disease (e.g., osteoporosis/osteopenia , gout, osteomalacia, Paget's disease); * Any disease, condition or surgery which might impair healing, such as; 1. Diabetes mellitus requiring daily insulin management, 2. Active malignancy, 3. History of metastatic malignancy. * Current or extended use (\> 6 months) of any drug known to interfere with bone or soft tissue healing; * Known PEEK, ceramic, titanium allergy; * Arachnoiditis; * Significant cervical anatomical deformity at the index level or clinically compromised cervical vertebral bodies at the index level due to current or past trauma (e.g., by radiographic appearance of fracture callus, malunion, or nonunion) or disease (e.g., ankylosing spondylitis, rheumatoid arthritis); * Currently experiencing an episode of major mental illness (psychosis, major affective disorder, or schizophrenia), or manifesting physical symptoms without a diagnosable medical condition to account for the symptoms, which may indicate symptoms of psychological rather than physical origin; * Pregnancy at time of enrollment, or planning to become pregnant, since this would contraindicate surgery ; * Use of spinal stimulator at any cervical level prior to surgery; * Currently a prisoner; * Currently involved in spinal litigation which may influence the subjects reporting of symptoms or * Participation in any other investigational drug, biologic or medical device study within the last 30 days prior to study surgery.