The phenomenon of accelerated adjacent segment degeneration is still debated by spine specialists worldwide. We are of the belief that it does exist. This phenomenon can best be described by the fact that fusing one or two levels will lead to increased stress at the remaining adjacent levels, the remaining motion segments will have to take up and accommodate the remaining motion of the spine, these adjacent levels will then tend to age and degenerate faster because of the resultant increased load and stress.
On a more controversial note, many spinal arthroplasty surgeons propose that by performing a disc replacement and restoring motion to a diseased spinal segment, this reconstructed spinal motion segment will offload the stress to the adjacent levels and actually lower the risk of onset of accelerated adjacent segment degeneration. The spine is a mobile structure and motion will occur at the places of least resistance and stiffness, if motion can be restored by a disc replacement then this will lead to reduced stresses at other more degenerated parts of the spine.
An illustrated example of accelerated adjacent level degeneration.
One such patient is shown courtesy of Dr. Raymond Yip.