Disc replacements for the spine are not far off, but actual bone replacement isn't ready yet. Only about a dozen spine centers around the United States are using disc replacements and only discs in the low back or lumbar spine are being replaced at this time.

However, some say it's only a matter of time before a similar device is ready for use in the neck. Right now studies are being done on cadavers. These are spines preserved for study after death. Scientists at the Orthopaedic Biomechanics Lab in San Francisco studied the use of a special ball-and-socket implant design for the cervical spine (neck).

The results were very good in terms of restoring disc height and neck motion. The disc replacement gave the cadavers normal motion in all directions. Future studies will look at the amount of load put on the discs and joints above and below the implant.