Why are doctors trying to replace discs in the back or neck rather than just fusing them together as they used to do?
When someone has degenerating discs in the back or neck, this can cause severe pain and restrict their ability to move and participate in daily activities. Fusion, taking some bone usually from the hip and fusing it to the affected area, is often done to help remedy the situation.

Fusion, although successful in many cases, does have drawbacks. The joining of the bones limits movement as the area is no longer able to bend and move freely. As well, doctors have found that patients who have had fusion can end up having to have repeat surgery at the discs right above or below.

Using a prosthesis, a replacement, is an attempt to mimic the movement of the back or neck, improving the outcome.