A prosthesis is an artificial replacement of a body part designed to mimic natural form and function. Prosthetic replacements for damaged or degenerated vertebral discs are currently being tested in clinical trials. The disc is a very complicated joint, so the engineering challenge to partially or fully replace a disc is considerable. The “Charité” implant, which is the device pending FDA approval, is designed to perform like the patient’s own disc. The prosthesis is intended to maintain the normal movement between the vertebral bodies and prevent them from collapsing by maintaining the disc space between the bones. Artificial disc surgery can be a substitute for spinal fusion.