Clinical study to evaluate the safety and effectiveness of the Aesculap Activ-L？ artificial disc in the treatment of degenerative disc disease

The study proposed is a prospective, randomized, single-masked, controlled, multi-center clinical trial consisting of an estimated 414 subjects with single-level DDD of the lumbar spine (L4/L5, or L5/S1) who have failed to improve with conservative treatment for at least six months prior to enrollment. After enrollment, subjects will be randomized in a 2:1 ratio to either the Activ-L Disc (investigational device) or the control (Charité or ProDisc-L). Radiographic endpoints will be evaluated by an independent reviewer at an imaging core laboratory. Each subject will be followed for 5 years post-treatment.The safety and effectiveness of the Activ-L Artificial Disc for treatment of single-level degenerative disc disease of the lumbar spine will be equivalent to Charité？ Artificial Disc [DePuy Spine] or ProDisc-L？ Total Disc Replacement [Synthes Spine] at 24 months.Current Controlled Trials NCT00589797.Lower back pain is a leading cause of physician patients report back pain annually in the U.S. Conservative treatment ultimately fails in over 4.5 million patients, and of these, some 500,000 undergo surgery of the lumbar spine, of which 200,000 are fusions [1-5].One of the primary causes of lower back pain is degeneration of the intervertebral disc. Disc degeneration may result in rupture or herniation, spinal instability, articular facet syndrome, or painful impingement on the nerves enclosed in the spinal visits in the United States, second only to the common cold. The resultant pain may also lead to significant disability.Spinal fusion effectively eliminates the motion segment between two vertebrae by use of a bone graft, thereby providing improved stability and decreased pain. The success rate in spinal fusion has proven highly variable; averaging approximately 60 to 70% [2]. The use of internal fixation generally increases the fusion rate but also increases the stiffness of the fused area. This may lead to increased stress on the adjacent nonfused segments and, in