The follow up will last 12 months with 2 visits (6 and 12 months after surgery), 2 CT scan slides before inclusion and at 12 months, classical X-rays before inclusion and at 6 and 12 months, questionnaires (visual analogic scale for pain, and quality of life with OSWESTRY and SF36 scales) before inclusion and at 6 and 12 months, and biological exams (CRP/VS, for inflammation) at each visit.