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.