How come some curves come back after surgery?

[albsmom]

Hi-
Sorry if there's a thread out there for this; I looked but didn't see anything. I have seen on a couple of postings where it looks like the person posting has had surgery but the curve came back. Why does this happen? Is it because the fusion is not performed low/high enough? I would just hate to think anyone would go through such a big operation and then have the curve come back. I will definitely ask this question next time I see my specialist at Hopkins, but would like to hear firsthand from anyone who has had this experience. Thanks.

[ddr]

That's a good question. I was wondering the same thing. It reminds me of when I had braces put on as an adult and when they came off my teeth went back to the way they were.
dd

[discombobulated]

Hi Albsmom & Ddr,

A curve returning can result from a few different things that I'm aware of:

1. The spine above or below the fused verebrae begins to curve
Sometimes a new curve develops with no warning at all. But for people who start with two or more curves, sometimes surgeons take a calculated risk (with their patient's consent) in the hope of preserving as much spinal flexibility as possible. In this case, they fuse the first curve that developed (the "structural curve") while leaving a second, smaller curve (the "compensatory curve") unfused. The idea is that the comp. curve developed in response to the first curve, to balance the spine, & once the structural curve is fused, the comp. one should sort itself out. Quite often, this works out fine, but sometimes the compensatory curve continues to worsen & eventually requires an extension of the fusion. This latter scenario happened to me, but I'm not sure how common it is.

2. The fused spine continues to grow (I think this is the way this one works):
This is a small but distinct risk for young fusion patients, who have a lot of growing to do. When a fusion is done, the growth plates in between the vertebrae are removed...but it only takes the surgeon to miss a small amount of cells for the spine to continue growing. Even a small amount of growth can result in the bone not fusing properly, & as the spine grows more, it has no place else to go but to curve out to the side again (since it's anchored top & bottom to the instrumentation). I think that with improvements in instrumentation, where the rods are secured to each vertebra, this risk is somewhat less these days....but present, nonetheless.

3. The bone fails to fuse solidly in one or more areas (aka. pseudoarthrosis)
To the best of my knowledge, pseudoarthrosis doesn't routinely cause the spine to curve again, but it can do. For example, when it occurs in areas where pivotal anchor pieces of instrumentation are placed or occurs over a large area, the instrumentation can become loose & allow the spine to curve. Pseudoarthrosis can also cause things like rod breakage. It's probably the most common of fusion surgery complications, though you can reduce the odds - e.g., by quitting smoking, getting regular weight-bearing exercise, etc.. Unfortunately, conditions like obesity, osteopaenia, osteoporosis, diabetes, & malnutrition can greatly increase the odds.


I hope this helps some. I've probably missed some cause/s, though, lol.

Best wishes.