561- How Cervical Fusion Impacts Adjacent Segment Disease

And really the question was, when you fuse part of the cervical spine, what happens to everything else around it? Mechanically, it's probably pretty obvious.

If you take one or more segments and lock them down, the rest of the cervical spine has to do more work, right? Because the patient's still gonna look down at their phone, they're gonna turn their head while driving, they're gonna look over their shoulder.

So where does all that motion go? Does the segment directly above the fusion start moving more? Does the segment below compensate? Does the whole cervical spine redistribute that motion? And more importantly, does that mechanical compensation help explain when some patients eventually develop what we call adjacent segment disease? Well, that's exactly what the researchers were looking at.

This is a 2026 study titled The effect of single level and multilevel cervical fusion on adjacent segment motion to biomechanical analysis.

Again, we'll drop that link down in the show notes.

And there was a really interesting headline from this paper that a single level fusion did not significantly increase motion at the adjacent segments.

Now, motion is different than load, but as the fusion got longer, especially when they fused three levels, the biomechanics of the remaining cervical spine untouched changed a lot.

And some of that compensation didn't occur immediately next to the fusion.

It occurred several levels away.

And that's probably the most interesting part of this study to me is how adaptable our bodies are.

Now, I want to be super clear on my stance of this right at the beginning.

which is anytime you want to do everything you can to not fuse the spine.

I mean, this is a last ditch effort type of thing.

Obviously, there are occasionally red flags where it's absolutely necessary, myomalacia, et cetera.

But really, this is something where you want to avoid this at all costs.

The load and stress.

I mean, sometimes these studies, I feel like downplay adjacent segment disease.

That's a very real thing.

And I saw in multiple orthopedic groups that I practiced in, As soon as that, it was like a pent-up demand.

As soon as one level fusion happened, it could take five, ten years to get there after the person thought they might need it.

And they were back for a second, third level very, very quickly.

Once that dam breaks, it is really hard to come back from.

So that's really important.

And I think a lot of times patients feel, I heard this all the time, well, I just want to fix the problem.

And it's like...