Adjacent Level Degeneration: More Complicated Than We Know?

[Harrison]

This is an interesting piece of news from a press release excepted below. I bolded the last line as it has been a concern of mine for years; the fact that the causes of spinal disease continues to be elusive.
_____________________

The scientific paper, co-authored by Ajay Jawahar, MD, Eubulus J. Kerr, MD, David Cavanaugh, MD, Elisa Birdsong, BS, and Pierce D. Nunley, MD, is entitled “Total Disc Arthroplasty Does Not Affect The Incidence of Adjacent Segment Degeneration in Cervical Spine: Results of 93 Patients in Three Prospective Randomized Clinical Trials.” It compared degeneration of adjacent discs in the cervical spine (neck) after fusion surgery with the degeneration rate after total disc replacement.

After a four year study – and contrary to prevalent belief among spine surgeons – these researchers showed the incidence of adjacent disc degeneration was the same for fusion surgery and total disc replacement surgery. In other words, roughly three percent, or three out of every 100 patients will develop some form of disc degeneration after either fusion surgery or artificial disc replacement surgery.

“For years, spine surgeons have believed that there was a lower rate of degeneration in adjacent discs after artificial disc replacement and a higher rate after fusion surgery, because disc replacement allows more flexible movement than fusion surgery,” says Dr. Jawahar. “Now, surgeons and researchers have to revisit the causes of adjacent segment degeneration, knowing that “motion preservation” is only one contributing factor.”

Original link here.

[Rob Wilson]

I have trouble believing that the incidence of adjacent degeneration is only 3% with fusion. Sorry but I have even heard fusion surgeons giving much higher %'s.

[Eskimo]

The 4-year period may not be enough to demonstrate the difference between the two surgeries. 10 years would probably be a more realistic time frame.

The second thing that comes to mind is that DDD is to some extent a natural process that all of us are going through so some of the results may depend on the definition they were using for a degenerated adjacent segment.

Thirdly, I would be more interested in an outcome like neck pain and whether adjacent segment degenerated disc became symptomatic.

Another issue is their sample size is quite small and they are underpowered.

Finally their 3% rate actually seems like a very low rate - that's the equivalent of 0.75%/year for four years. I know one rate I've heard for lumbar fusion is about 3.6%/year or about five times that rate.

[ZorroSF]

The rate of 3 in 100 is very very low considering only half the people in the US who undergo spine surgery come out better off in the end. Still many of those people undergo revision surgery. It's how they came to their conclusion that puzzles me. Most doctors don't perform enough testing to see if adjacent joints are already pain generators prior to operation regardless of fusion or adr. This study indirectly implies it. They also don't study the patient's musculo-skeletal system and the major forms of muscle imbalance in the patient prior to surgery. My guess is that at least half the operations performed those imbalances still exist in the patient many years post op. If the surgery was poorly performed or incorrect then the imbalance will just get exponitially worse adding to adjacent level degeneration, or even worse, thoracic or cervical symptoms.

[Rev. Zen]

This has been a concern for me as well. That is why I have been so determined to try and find an artificial disc with compression capabilities such as the Freedom Lumbar Disc. I feel strongly that this dimension of movement is very crucial in prevetning adjacent disc degeneration (or at the very least minimizing it relative to current alternatives).

My hope is that more options such as the FLD and the, now defunct, DASCOR device will start making their way to us.