**6. Revision techniques**

If a CHARITÉ artificial disc were required to be revised, there would be two options available. One approach would be anterior reoperation. This would involve dissecting the retroperitoneal area and dealing with the post-op scarring and hence increased risk of great vessel damage, ureteral damage, and damage to the sympathetic nerves compared to a case without prior dissection and scarring in the retroperitoneal space. A revision allows removal, position adjustment or size change of the CHARITÉ artificial disc. The plastic core would be removed first, and then the metal endplates are separated from the bony endplates by using a chisel between them and levering away from the bone into the disc space. This would allow the placement of another artificial disc in the disc space or the conversion to a fusion. Alternately, a posterior operation with rod-screw stabilization and posterior lateral fusion could be used to fuse the lumbar segment, which would use the CHARITÉ artificial disc as an anterior load share device. As with all surgical decision making, understanding the biomechanical reasoning and etiology of clinical failure is of the utmost importance. In patients with recurring or persistent pain the characterization of the pain generator is often more important than the exact surgical technique used. Radiologic studies such as dynamic A-P and Lat x-ray and multislice CT will aid in understanding failure of the device or progression of the degenerative anatomic changes. Radiologic and provocative studies, including discography, anesthetic or negative discography, nerve root blocks, epidural injections, and facet injections may all be utilized to identify the anatomic site of the pain generator.
