A Prospective, open label, multi-center observational study of patients requiring surgical treatment at one or two (contiguous) cervical spine levels. The primary objectives of the RHINE Cervical Disc study are to: obtain operative data and feedback on surgical instruments and surgical technique; confirm device performance in terms of clinical and radiographic outcomes; confirm device performance in terms of safety and to collect original data to be compared to published reports of the performance of comparable motion-sparing devices, as well as clinical outcomes of fusion devices.