This is a controlled study with two group of equal size: one group is treated by discectomy and arthrodesis and the other by discectomy and prosthesis/ The criteria for the inclusion of the patients are: clinical radiculopathy and/or myelopathy due to a cervical disk disease (disk herniation or osteophytosis), lack of effect of the medical treatment, CT scan or MRI showing a compression of roots and/or spinal cord.