Study to Investigate the Performance of Cervical Arthroplasty for the Treatment of Cervical Degenerative Disc Disease

The purpose of the study is to evaluate the performance of the Discover cervical Artificial disc in the treatment of degenerative disc disease in one level of the cervical spine.

The protocol underwent 3 amendments, the last of which (02APR2009) changed the study design from a randomized to a non-randomized and non-comparative clinical trial. All of the subjects were enrolled under the randomized design with the exception of the last subject. This study is not applicable per FDAA Title VIII, Section 801 due to the final trial design. However, results are submitted to clinicaltrials.gov due to the majority of study data being collected under a randomized (FDAA Title VIII, Section 801 applicable) trial design

Eligibility Criteria:
Inclusion Criteria:

* Male or female subjects, aged between 18 and 65 years inclusive.
* Subjects who are able to give voluntary, written informed consent to participate in this clinical investigation and from whom consent has been obtained.
* Subjects who, in the opinion of the Clinical Investigator, are able to understand this clinical investigation, co-operate with the investigational procedures and are willing to return to the hospital for all the required post-operative follow-ups.
* Objective evidence of cervical disc disease in one vertebral level between C3-C7 defined as one or more of the following:

  * Shoulder and/or arm pain in a radicular distribution resulting from herniated disc or bony osteophytes (Consistent w diagnostic imaging including Axial CT, CT Myelogram, MRI and/or plain films)
  * Subjects with myeloradiculopathy resulting from mild spinal cord compression and nerve root impingement
* Unresponsive to documented non-surgical management for ≥ 6 weeks and/or presents with progressive symptoms of nerve root or spinal cord compression in the face of continued non-surgical management (e.g., physical therapy, medication therapy, corticosteroid injections, etc.)
* Minimum Neck Disability Index score of ≥30 % (15/50 points)

Exclusion Criteria:

* Subjects who, in the opinion of the Clinical Investigator, have an existing condition that would compromise their participation and follow-up in this clinical investigation.
* Subjects who are pregnant, lactating or wishes to become pregnant within the duration of the study.
* Subjects who are known drug or alcohol abusers or with psychological disorders that could affect follow-up care or treatment outcomes.
* Subjects who have participated in a clinical investigation with an investigational product in the last 30 days.
* Subjects who are currently involved in any injury litigation claims.
* Subjects with significant degeneration at more than one cervical level (e.g. DISH, ankylosing spondylitis, congenital abnormality, rheumatoid arthritis)
* Subjects who have had any prior surgery at the level to be treated (subjects with a prior Laminotomy at the level to be treated may be included in the study)
* Subjects who have marked cervical instability on lateral or flexion/extension x-rays defined as translation ≥3mm and/or ≥11 degrees of rotational difference to either adjacent level
* Subjects who have presence of systemic infection or infection at the site of surgery
* Subjects who have been diagnosed with malignancy
* Subjects who have been diagnosed with a condition or require postoperative medication(s) that may interfere with bony/soft tissue healing
* Subjects who have been diagnosed with Osteoporosis, Osteopenia, other metabolic bone disease or endocrine disorder known to affect osteogenesis.
* Subjects with pre-existing neurological abnormalities other than deficits produced from the spinal lesion (e.g., MS, Parkinson's, CVA, diabetic neuropathy, peripheral neuropathy).
* Subjects with morbid obesity defined as a BMI of ≥40, or more than 100 lbs (45.4kg) over ideal weight.
* Subjects with any known allergy to titanium metal, polyethylene, metal alloy or carbon fibre reinforced polymer
* Subjects who have had prior fusion surgery at any level(s) (C1-T1)
* Subjects with kyphosis \>-15 degrees evaluated using the Cobb angle measurement
* Subjects with Significant cervical degenerative disease characterized by bridging anterior osteophytes, significant loss of disc space height (3mm or less), sclerotic facets, large posterior osteophytes, autofusion of other cervical levels, and degenerative retrolisthesis. Spinal diseases such as DISH, ankylosing spondylitis, congenital abnormality, and rheumatoid arthritis, should also be excluded
* Subjects undergoing treatment with a bone growth stimulator, which cannot be discontinued prior to enrollment in the study.
* Significant kyphotic deformity or significant reversal of lordosis.