M6®-C Artificial Cervical Disc Two-Level IDE Pivotal Study

Prospective, concurrently controlled, multi-center study to evaluate the safety and effectiveness of the Spinal Kinetics M6-C™ artificial cervical disc compared to anterior cervical discectomy and fusion (ACDF) for the treatment of contiguous two-level symptomatic cervical radiculopathy at vertebral levels from C3 to C7 with or without spinal cord compression.

Patients will be concurrently enrolled in the M6-C treatment group and the ACDF control group. Patients should have failed at least six weeks of conservative treatment or demonstrate progressive symptoms despite continued non-operative treatment. For the study, 263 patients will undergo either a two-level cervical artificial disc procedure, or an instrumented (ACDF) procedure as per site group assignment. Patients will be evaluated clinically, radiographically, and via the collection of patient-reported outcomes at 6 Weeks, 3 Months, 6 Months, 12 Months and 24 Months. The primary endpoint is Overall Success at 24 Months.

Eligibility Criteria:
Inclusion Criteria:

* Diagnosis of degenerative cervical radiculopathy with or without spinal cord compression requiring surgical treatment at two contiguous levels from C3 to C7 demonstrated by signs and/or symptoms of disc herniation and/or osteophyte formation (e.g. neck and/or arm pain, radiculopathy, etc.) and is confirmed by patient history and radiographic studies (e.g. MRI, CT, x-rays, etc.)
* Inadequate response to conservative medical care over a period of at least 6 weeks or have the presence of progressive symptoms or signs of nerve root/spinal cord compression in the face of continued non-operative management
* Neck Disability Index score of ≥ 30% (raw score of ≥ 15/50)
* Neck or arm pain Visual Analog Scale Score ≥ 4 on a scale of 0 to 10
* Willing and able to comply with the requirements of the protocol including follow-up requirements
* Willing and able to sign a study specific informed consent
* Skeletally mature and at least 18 years old but not older than 75 years old

Exclusion Criteria:

* More than two cervical levels requiring surgery, or two non-contiguous levels requiring surgery
* Previous anterior cervical spine surgery
* Axial neck pain as the solitary symptom
* Previous posterior cervical spine surgery (such as a posterior element decompression) that destabilizes the cervical spine
* Advanced cervical anatomical deformity (such as ankylosing spondylitis, scoliosis) at either of the operative levels or adjacent levels
* Symptomatic facet arthrosis
* Less than four degrees of motion in flexion/extension at either of the index levels
* Instability as evidenced by subluxation greater than 3 millimeters at either of the index or adjacent levels as indicated on flexion/extension x-rays.
* Advanced degenerative changes (e.g., spondylosis) at either of the index vertebral levels as evidenced by bridging osteophytes, central disc height less than 4 millimeters and/or \< 50% of the adjacent normal intervertebral disc, or kyphotic deformity \> 11 degrees on neutral x-rays
* Severe cervical myelopathy (i.e., Nurick's Classification greater than 2)
* Active systemic infection or infection at the operative site
* Co-morbid medical conditions of the spine or upper extremities that may affect the cervical spine neurological and/or pain assessment
* Metabolic bone disease such as osteoporosis that contradicts spinal surgery
* History of an osteoporotic fracture of the spine, hip or wrist
* History of an endocrine or metabolic disorder (e.g. Paget's disease) known to affect bone and mineral metabolism
* Taking medications that may interfere with bony/soft tissue healing including chronic steroid use
* Known allergy to titanium, stainless steels, polyurethane, polyethylene, or ethylene oxide residuals
* Fibromyalgia, Rheumatoid Arthritis (or other autoimmune disease), or a systemic disorder such as HIV or acute hepatitis B or C.
* Insulin dependent diabetes
* Medical condition (e.g., unstable cardiac disease, cancer) that may result in patient death or have an effect on outcomes prior to study completion
* Pregnant, or intend to become pregnant, during the course of the study
* Severe obesity (Body Mass Index greater than 45)
* Physical or mental condition (e.g. psychiatric disorder, senile dementia, Alzheimer's disease, alcohol or drug addiction) that would interfere with patient self-assessment of function, pain or quality of life.
* Involved in current or pending spinal litigation where permanent disability benefits are being sought.
* Incarcerated at time of study enrollment
* Current participation in other investigational study.