Comparison of Artificial Disc Implants in Cervical Disc Arthroplasty

Comparison of Unconstrained and Semi-constrained Artificial Disc Implants Used in Cervical Disc Arthroplasty

This study will comprehensively evaluate the outcomes and endpoints of these two different FDA-approved artificial disc implants used to treat cervical spondylotic myelopathy and/or radiculopathy today: Biomet Zimmer Mobi-C and Nuvasive Simplify. Both implants are structurally different with the Nuvasive Simplify implementing a three-piece design with two endplates and a semi-constrained mobile core while the Biomet Zimmer Mobi-C implements an unconstrained three piece design. Subjects will be age-matched and randomly assigned to either implant with informed consent. All subjects will undergo a variety of assessments that evaluate neck disability, quality of life, pain, physiological outcome (radiographic assessments), and neck range-of motion before and after their procedure. One baseline testing will be conducted along with three post-operation visits (three months, six months, and one year) in accordance to standard follow-up procedure. Thus, the duration of participation in the study will be approximately one and a half years.

In cases where surgery is indicated, treatment for cervical spondylotic myelopathy and/or radiculopathy (typically caused by disc herniation or degenerative disc disease) has traditionally been performed by a procedure known as anterior cervical discectomy and fusion (ACDF) to treat a damaged disc in the neck area of the spine. However, medical advancement in this field has allowed for a new procedure often referred to as cervical arthroplasty that implements artificial disc implantation. These implants mimic the function and structure of discs by cushioning the neck's vertebral bones instead of fusing them and providing flexibility for head movements. The emergence of different artificial disc implants that are structurally and mechanistically different calls for a comparative analysis that evaluates performance across a comprehensive set of patient outcomes.

This study will comprehensively evaluate the outcomes and endpoints of these two different FDA-approved artificial disc implants used to treat cervical spondylotic myelopathy and/or radiculopathy today: Biomet Zimmer Mobi-C and Nuvasive Simplify. Both implants are structurally different with the Nuvasive Simplify implementing a three-piece design with two endplates and a semi-constrained mobile core while the Biomet Zimmer Mobi-C implements an unconstrained three piece design. Subjects will be age-matched and randomly assigned to either implant with informed consent. All subjects will undergo a variety of assessments that evaluate neck disability, quality of life, pain, physiological outcome (radiographic assessments), and neck range-of motion before and after their procedure. One baseline testing will be conducted along with three post-operation visits (three months, six months, and one year) in accordance to standard follow-up procedure. Thus, the duration of participation in the study will be approximately one and a half years.

This study has significant implications in better assessing the overall efficacy of cervical arthroplasty while providing insight to the differences in outcomes based on the artificial disc implanted. Findings can also contribute to characterizing the advantages and disadvantages of both implants to aid surgeons in making more informed and personalized treatment recommendations according to the needs of the patient.

Inclusion Criteria:

• Patient is skeletally mature and between 18 to 60 years of age
• Experiences cervical spondylotic myelopathy and/or radiculopathy typically caused by disc herniation or degenerative disc disease at a single level between C3 to C7
• Is unresponsive to at least six weeks of non-surgical conservative care
• Has the intention of undergoing cervical arthroplasty for their chief complaint
• Signed informed consent form

Exclusion Criteria:

• Patient has had prior cervical spine surgery
• Has more than two diseased levels requiring surgery
• Has a known allergy to a metal alloy or polyethylene
• Is morbidly obese
• Has active local or system infection
• Has any circumstances or conditions such that their ability to provide informed consent comply with follow-up requirements, or provide self-assessments is compromised (eg: psychiatric disorders, chronic alcohol or substance abuse, etc.)