Artificial joints or discs are made in a few different ways, depending on the manufacturer. Which one your doctor chooses depends on preference and what is appropriate for each patient.
Although the surgery generally has a good outcome and patients are satisfied, some prosthesis do break down or cause problems. How this is treated depends on what the problem is and if it is fixable. The options include fixing or replacing the prosthesis, or removing it completely. If the prosthesis is removed completely, chances are the surgeon will fuse, or join together, that section of vertebrae.