2-level Cervical Disc Replacement Comparing Prodisc C SK & Vivo to Mobi-C

The clinical trial is to demonstrate that prodisc C SK and prodisc C Vivo are at least as safe and effective as a similar, currently marketed cervical disc prosthesis to treat symptomatic cervical disc disease (SCDD) in subjects at two contiguous levels from C3 to C7 who are unresponsive to conservative management. Subjects will be randomized in a 2:1 ratio to either the two-level prodisc C SK or prodisc C Vivo device (investigational group) or to the two-level Mobi-C device (control group). Subjects will be followed for at least 2 years and up to 5 years. Subjects will be required to complete subject questionnaires, have X-rays and undergo neurological assessments during the follow up visits as specified in the protocol.