To implant a complete lumbar disc prosthesis removal of the anterior portion of the annulus fibrosus is required. It is known that the anterior portion of the annulus limits the movement in extension and axial rotation, so removal of this section of the annulus fibrosus will increase the range of movement in extension and axial rotation. As far as the investigators know, this increase in movement ranges has not been measured objectively in alive patients. Also the investigators would like to know if the postoperative prevertebral scar reduces an to what extent these abnormal movement ranges. This could help the investigators to decide when patients should be allowed to regain normal activities and specially, when the patients should be allowed to start working again. The investigators also aim to see if repairing intraoperatively the anterior portion of the annulus has any advantage in the final result achieved, and thus represents an improvement or not in the care of these patients
To implant a complete lumbar disc prosthesis removal of the anterior portion of the annulus fibrosus is required. As the anterior portion of the annulus limits the movement in extension and axial rotation, we would like to know how much increase these two disc movements and also the effect on the postoperative prevertebral scar on the reduction of these abnormal movement ranges. We also aim to see if repairing intraoperatively the anterior portion of the annulus has any advantage in the final result achieved.