Spinal fusion works well but there are reports of repeat operations needed at the level above or below the fusion site. Of course the main disadvantage of fusion is the loss of function. That is offset by the primary advantage of fusion: spinal stability.
Other complications after fusion include failure to fuse, fracture, and loosening of any hardware used (screws, plates).
The artificial disc was first used in the early 1960s. Since then technology and design have changed. Improvements in surgical technique have also helped return the use of an artificial disc replacement (ADR) as an option.
The main benefit from an ADR is restored, pain free motion. The nearby bone is preserved with less trauma during the operation. The downside may be in how long the implant lasts. During simulator testing the wear rate for some ADRs was 40 to 50 times less than the usual wear rate for a knee or hip implant.
ADRs don't prevent further disc disease at the level above or below. Researchers aren't sure yet if removing the disc at one level is directly linked with later degeneration at other levels. It may be that nearby levels would deteriorate anyway.