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Pooka1
08-24-2010, 06:12 AM
In another thread I wrote:


I am trying to understand the state of the art w.r.t. average progression rate. As I first understood our surgeon, he seemed to be saying if my daughter could stay below 50* at maturity, she would avoid fusion for life. I thought he meant that people below 50* at maturity simply don't progress ever. What I have come to learn from when I asked him to clarify is that folks still progress but usually at such a slow rate that they are not likely to need fusion in a normal lifespan.

But I don't think that is accurate after reading the testimonials. What I think we hear is 1* - 2* per year for the average (WIDE variation) sub surgical case that is in the conservative treatment window (~25* - 50*) at maturity. But let's say a kid is at 35* at 15 y.o. and progresses 1* a year. That means they are surgical at age 30 on average. If they are 25* at 15 years old then they are surgical at 40 years old. And assuming a slower progression, it seems that many folks will be surgical by their golden years.

As far as I can tell, all but the smallest curves that are below the conservative treatment range will reach surgical range well within a normal lifespan. And the 10 to 1 adult to adolescent fusion rate is consistent with that. What am I missing?

I think I know what I was missing. I think the 1* - 2* degree a year progression rate is the average rate for folks over 50* AFTER maturity.

I wonder what is know of the average progression rate for folks in the conservative treatment window (~25* - ~45*) after maturity. Whatever it is, it is certain to have a huge variability.

It would be nice for someone to estimate the percentage of AIS cases that are associated with connective tissue disorders given at least some of these cases group away from the average AIS case. It would also be good to scrupulously try to not lump these two groups in these various research articles because each confounds the other if they truly represent distinct groups in terms of average progression rate. This is reason # 5,908,677 why this literature is dicey.

Pooka1
08-24-2010, 06:39 AM
Here's an article...

http://www.ijoonline.com/article.asp?issn=0019-5413;year=2010;volume=44;issue=1;spage=9;epage=13; aulast=Wong


The natural history of adolescent idiopathic scoliosis

Hee-Kit Wong, Ken-Jin Tan
University Spine Center, University Orthopedics, Hand and Reconstructive Microsurgery Cluster, National University Health System, Singapore

There have been great advances in the conservative and surgical treatment for adolescent idiopathic scoliosis in the last few decades. The challenge for the physician is the decision for the optimal time to institute therapy for the individual child. This makes an understanding of the natural history and risk factors for curve progression of significant importance. Reported rates of curve progression vary from 1.6% for skeletally mature children with a small curve magnitude to 68% for skeletally immature children with larger curve magnitudes. Although the patient's age at presentation, the Risser sign, the patient's menarchal status and the magnitude of the curve have been described as risk factors for curve progression, there is evidence that the absolute curve magnitude at presentation may be most predictive of progression in the long term. A curve magnitude of 25 at presentation may be predictive of a greater risk of curve progression. Advances in research may unlock novel predictive factors, which are based on the underlying pathogenesis of this disorder.

Pooka1
08-24-2010, 07:12 AM
From that article (emphasis added):


Curve Progression After Skeletal Maturity


Once the child has attained skeletal maturity, it was generally thought that the curves are less likely to progress. However, this may not always be the case. It is now established that curves due to idiopathic scoliosis do not necessarily stop progressing after skeletal maturity. In a long-term follow-up study of patients with idiopathic scoliosis, Collis and Ponseti found that curves of a larger degree did increase after skeletal maturity. [20] In a separate study with an average follow-up of 40 years, Weinstein and Ponseti also found that a significant number of idiopathic curves increased after skeletal maturity. They reported that in thoracic curves, the Cobb's angle, apical vertebral rotation and the Mehta angle were important prognostic factors. For lumbar curves, the degree of apical vertebral rotation, the Cobb's angle, the direction of the curve and the relationship of the fifth lumbar vertebra to the inter-crest line were of prognostic value. However, they also observed that curves that were less than 30 at skeletal maturity tended not to progress regardless of curve pattern. [21]

Given the varying definitions of curve progression, this suggests that curves with a Cobb's angle of 30 are an important threshold magnitude and may serve as an endpoint for prediction of curve progression rather than predefined units of curve progression quoted in previous studies. In addition, it must be appreciated that the various associated factors and predictions described only apply to the likelihood of a curve progressing in adolescence. They are only averages and correlations and do not allow us to answer the key issue of how much the curve of an individual child is going to progress.

In a recent study, Tan and Wong reported on a group of 279 patients with idiopathic scoliosis detected by school screening, and who were followed-up until skeletal maturity using a 30 Cobb's angle at skeletal maturity as a threshold instead of predefined units of curve progression during shorter periods of growth. They found that an initial Cobb's angle of 25 was the most predictive factor for curve progression to this threshold magnitude. Initial age, gender and pubertal status were less important prognostic factors. [22] When different factors were combined, it was also possible to generate different risk progression profiles [Table 4].

Pooka1
08-24-2010, 07:18 AM
By the way, here's another identifying initial Cobb at the most important prognosticating factor for progression, in agreement with other researchers. This is why the Katz et al. (2010) paper purportedly showing a dose-response in brace wear should have directly addressed the issue when interpreting their results. The groups were relatively small and may have been inadvertently stacked by chance. The researchers need to rule that in or out.

http://journals.lww.com/spinejournal/Abstract/2009/04010/Curve_Progression_in_Idiopathic_Scoliosis_.11.aspx


Conclusion. Initial Cobb angle magnitude is the most important predictor of long-term curve progression and behavior past skeletal maturity. We suggest an initial Cobb angle of 25 as an important threshold magnitude for long-term curve progression. Initial age, gender, and pubertal status were less important prognostic factors in our study.

hdugger
08-24-2010, 08:51 AM
By the way, here's another identifying initial Cobb at the most important prognosticating factor for progression, in agreement with other researchers. This is why the Katz et al. (2010) paper purportedly showing a dose-response in brace wear should have directly addressed the issue when interpreting their results. The groups were relatively small and may have been inadvertently stacked by chance. The researchers need to rule that in or out.

Aren't all of these researchers talking about a threshold Cobb (as opposed to the actual Cobb magnitude). I think this threshold of progression (25) is close to the threshold for bracing, so I'd suspect all of the subjects in the bracing study fell above it.

Pooka1
08-24-2010, 09:07 AM
Aren't all of these researchers talking about a threshold Cobb (as opposed to the actual Cobb magnitude). I think this threshold of progression (25) is close to the threshold for bracing, so I'd suspect all of the subjects in the bracing study fell above it.

My point was rather that the magnitude of the curve at the beginning of treatment has been identified as an extremely important variable in trying to predict progression. That is, this is yet another way to restate that larger curves tend to get larger and smaller curves tend to stay smaller. On average. Katz et al. published what purport to be dose-response data (on mostly mature kids) for relatively small subgroups, each with different average hours of brace wear. Just like the results of an important previous bracing study were negated by the identification of unintentional stacking of L versus T curves in the treatment versus observation group respectively, I am saying Katz et al. should have triaged their data for inadvertent stacking of smaller versus larger curves in the various brace wear duration groups identified after the fact.

Ballet Mom
08-24-2010, 09:54 AM
I think I know what I was missing. I think the 1* - 2* degree a year progression rate is the average rate for folks over 50* AFTER maturity.

I wonder what is know of the average progression rate for folks in the conservative treatment window (~25* - ~45*) after maturity. Whatever it is, it is certain to have a huge variability.


The variability is not that huge. There is no doubt some variability between those with 45 degrees and those with 35 degrees and under after maturity.

But for those with a 35 degree curve...none of these 92 patients progressed after maturity for at least sixteen years (except to return to the pre-braced angle, which is to be expected). There is no average progression rate for these patients, at least until in their thirties.

"CONCLUSION: The curves of patients with adolescent idiopathic scoliosis with a moderate or smaller size at maturity did not deteriorate beyond their original curve size at the 16-year follow-up.

Curve progression was related to immaturity."


http://www.ncbi.nlm.nih.gov/pubmed/17873811

hdugger
08-24-2010, 10:05 AM
My point was rather that the magnitude of the curve at the beginning of treatment has been identified as an extremely important variable in trying to predict progression.

Yes, I followed those discussions. I was just saying that that concern, stated in other discussions, didn't seem relevant to the results you cited in *this* discussion, since these papers are emphasizing a threshold of 25 degrees.

On the rest, after a few years on this forum, I see the various interpretations of the scoliosis literature as a kind of Rorschach test - it illuminates the interpreter far more then the research.

Pooka1
08-24-2010, 10:30 AM
Yes, I followed those discussions. I was just saying that that concern, stated in other discussions, didn't seem relevant to the results you cited in *this* discussion, since these papers are emphasizing a threshold of 25 degrees.

Yes that was not on point. I just added it here out of convenience because I found it in the course of working on this thread.


On the rest, after a few years on this forum, I see the various interpretations of the scoliosis literature as a kind of Rorschach test - it illuminates the interpreter far more then the research.

The range of interpretation among lay folks is not really relevant to anything. The range of opinion among researchers in this field and surgeons is what matters but only if they are up on the literature. Some apparently are not.

LindaRacine
08-24-2010, 10:44 AM
Hi Sharon...

I suspect that the magnitude of curve(s) at presentation is important because 25-30 degree curves, which seems to be the size of curves when they're most commonly discovered, are the most successfully braced curves. That is, those kids don't progress to surgery by the time of skeletal maturity. However, as we all know way too well, we don't know if it makes any difference in the long-term outcome.

--Linda

Pooka1
08-24-2010, 10:52 AM
Hi Sharon...

I suspect that the magnitude of curve(s) at presentation is important because 25-30 degree curves, which seems to be the size of curves when they're most commonly discovered, are the most successfully braced curves.

Most successfully braced or most unecessarily treated? This is an open question as far as I can tell.

Don't you think Cobb at presentation is important as a predictor because big curves tend to get bigger and small curves tend to stay smaller? That seems to explain most if not all of its prediction power.


That is, those kids don't progress to surgery by the time of skeletal maturity. However, as we all know way too well, we don't know if it makes any difference in the long-term outcome.

--Linda

I hope some more studies come out on that. I think it will influence the bracing debate depending on how it shakes out. The ratio of adult/adolescent fusions will be relevant as will the average progression rate of curves at the low end of the treatment window in terms of if these folks are reaching surgical range in the out years. Twenty-five or 30* might be an important threshold here.

Ballet Mom
08-24-2010, 11:07 AM
The Daniellson study had both braced and unbraced kids in it. Neither progressed after maturity for sixteen years. (And, in fact, only the non-braced kids progressed to surgery during the study.)

Would I rather have decades of a non-progressing curve with full flexibility and the potential for amazing discoveries in the years ahead should surgery potentially be needed at some point due to multiple pregnancies or age-related deterioration?

Or would I rather not brace and end up with surgery during adolescence and start the clock ticking on my revision surgeries due to age-related deterioration? And perhaps end up with a worse situation due to risks associated with that surgery to have to live with forever.

That is a choice the parents and patients can make themselves...but I certainly know which one I would choose. Obviously some are going to progress even if braced, but that's a risk everyone takes with scoliosis until more is learned about the causes of progression.

hdugger
08-24-2010, 11:15 AM
The range of interpretation among lay folks is not really relevant to anything. The range of opinion among researchers in this field and surgeons is what matters but only if they are up on the literature. Some apparently are not.

Given the quality of the literature, I'm not certain that "being up on it" is of much importance. Because of the lack of quality of the literature, any real scoliosis knowledge lies primarily in the land of anecdotal evidence. I'd trust an alert surgeon's anecdotal knowledge over a researcher who is familiar with the literature but hasn't directly worked with patients.

LindaRacine
08-24-2010, 01:15 PM
Most successfully braced or most unecessarily treated? This is an open question as far as I can tell.


I was referring to success in the short-term. Kids with 30 degree curves usually get great correction if the brace is fitted well. I'm not talking about once brace treatment is discontinued, or success in the long-term.

--Linda

Pooka1
08-24-2010, 01:43 PM
Given the quality of the literature, I'm not certain that "being up on it" is of much importance. Because of the lack of quality of the literature, any real scoliosis knowledge lies primarily in the land of anecdotal evidence. I'd trust an alert surgeon's anecdotal knowledge over a researcher who is familiar with the literature but hasn't directly worked with patients.

In the case of scoliosis bracing, being familiar with the literature is synonymous with realizing how much is unknown still. Claims that more is known than has been shown is to be unfamiliar with the literature.

Pooka1
08-24-2010, 01:44 PM
I was referring to success in the short-term. Kids with 30 degree curves usually get great correction if the brace is fitted well. I'm not talking about once brace treatment is discontinued, or success in the long-term.

--Linda

Ah okay. I see. We need studies on the mid-term and out years for everyone, treated and untreated.

hdugger
08-24-2010, 02:14 PM
In the case of scoliosis bracing, being familiar with the literature is synonymous with realizing how much is unknown still. Claims that more is known than has been shown is to be unfamiliar with the literature.

I'm still not clear why that would be useful.

So, a doctor does a bunch of bracing and has his/her own impressions of the results - seems to work with these kids, not so much with these, and so on and so on. IMO, that working knowledge comprises almost the whole ground of what is known and unknown. The literature contributes very little knowledge, and likely will go on contributing very little knowledge. IMO, what the literature can do is slightly inform the anecdotal knowledge. But it in no way contributes "knowledge."

So, what's "known" lives almost entirely in the anecdotal realm. This discussion keeps coming up with the bracing literature, but it's equally relevant to just about everything concerning scoliosis. What cause PJK, for example, and how can it be avoided? The literature is all over the map - my only hope is that our surgeon can sort it out based on his experience. Should people have physical therapy right after surgery? I think the literature is mute on this topic - have any studies been done? - but doctors seem pretty certain. I'm guessing this comes from some oral history of trial and error which we're not privvy to.

You sometimes discuss the failings in the bracing literature as if it means anything at all about bracing. But, the exact same failings are seen in the research supporting almost every decision related to scoliosis. Either we can rely on the people who actually work with patients every day to sort their way through what they see and draw conclusion about our treatment, or, really, we're just totally sunk. Science - at least the perfect science that you rely on - is almost completely mute and of no help at all.

Pooka1
08-24-2010, 02:55 PM
I'm still not clear why that would be useful.

So, a doctor does a bunch of bracing and has his/her own impressions of the results - seems to work with these kids, not so much with these, and so on and so on. IMO, that working knowledge comprises almost the whole ground of what is known and unknown. The literature contributes very little knowledge, and likely will go on contributing very little knowledge. IMO, what the literature can do is slightly inform the anecdotal knowledge. But it in no way contributes "knowledge."

So, what's "known" lives almost entirely in the anecdotal realm. This discussion keeps coming up with the bracing literature, but it's equally relevant to just about everything concerning scoliosis. What cause PJK, for example, and how can it be avoided? The literature is all over the map - my only hope is that our surgeon can sort it out based on his experience. Should people have physical therapy right after surgery? I think the literature is mute on this topic - have any studies been done? - but doctors seem pretty certain. I'm guessing this comes from some oral history of trial and error which we're not privvy to.

You sometimes discuss the failings in the bracing literature as if it means anything at all about bracing. But, the exact same failings are seen in the research supporting almost every decision related to scoliosis. Either we can rely on the people who actually work with patients every day to sort their way through what they see and draw conclusion about our treatment, or, really, we're just totally sunk. Science - at least the perfect science that you rely on - is almost completely mute and of no help at all.

Anecdote gathered wihtout controls is as useless as the literature without controls. Some surgeons may not accept this.

hdugger
08-24-2010, 05:15 PM
Anecdote gathered wihtout controls is as useless as the literature without controls. Some surgeons may not accept this.

Unless they want to put down their scalpels, they really have no choice. How are they choosing which levels to fuse? Deciding when the sagittal balance is correct? Like it or not, it's not strictly controlled scientific studies which are forming the bases of those decisions. Surgeons are not, as you suggest for bracing studies, dividing their patients by initial curve, marfans symptoms, type of curve, etc and trying out randomly assigned fusion levels across those groups. Instead, they're looking at each individual and figuring out how to precisely align and fuse their spine based largely on anecdotal knowledge and trial and error(!).

I suspect that surgeons are pretty comfortable with the "informed intuition" that forms the basis of most scoliosis decisions. Or they'd find some more "known" area of science to settle into. And I also suspect that they feel that they "know" these things (levels to fuse, etc) just as well as they "know" whether to brace or not, even though their knowledge is not largely based on rigorous scientific studies.

Pooka1
08-24-2010, 06:02 PM
Well, with surgery, they get feedback in the form of patient data. For example, if they choose a lowest instrumented level using Method A, they will quickly amass data on if that method produces stability and balance going forward. This doesn't mean that there is only one "best" approach only that there is at least one.

One potential problem here is the pediatric guys who I don't think follow patients out past 18 but rather hand them off. These guys have to keep data themselves on their patients and analyze it. I think they all do this. And they have to confer with colleagues on their data, usually at meetings.

In the case of bracing, they can't know in principle if most of their braced patients weren't unnecessarily braced. As someone said recently, the actual successes are swamped out by the apparent successes of curves that wouldn't have progressed anyway. This appears to be the majority of braced kids.

All they can note is the bracing failures but even in those cases, they really don't have any handle on compliance nor do they necessarily spot all connective tissue patients. So many of those "failures" are only apparent and might just be artifacts of compliance and condition.

So with bracing, they are dealing with a huge false positive rate and also a false negative rate. Bracing is simply NOT like surgery where you can document all results and therefore have a much better sense of what's what, albeit entirely empirically. There is no comparison that I can see in terms of knowing outside controlled studies.

LindaRacine
08-24-2010, 08:17 PM
There's a basic problem with the way kids with scoliosis are treated is that the vast majority are treated by pediatricians, who do not see them after around the age of 18.

Pooka1
08-24-2010, 08:36 PM
There's a basic problem with the way kids with scoliosis are treated is that the vast majority are treated by pediatricians, who do not see them after around the age of 18.

Excellent point. ;)

hdugger
08-25-2010, 12:12 PM
So with bracing, they are dealing with a huge false positive rate and also a false negative rate. Bracing is simply NOT like surgery where you can document all results and therefore have a much better sense of what's what, albeit entirely empirically. There is no comparison that I can see in terms of knowing outside controlled studies.

I'm just saying that their method of "knowing" is the same in both cases - they do something on an individual and they look at the results. That's in contrast to the idea that "knowing" is only available through controlled research studies. Were that the case, surgeons couldn't "know" anything.

As to seeing the results, it's somewhat similar to bracing in that they see the immediate results of the surgery but don't have a clear sense of how their surgical choices map to long-term life quality. How did their particular choice of fusion level/method turn out 5 (or even 2) years down the road? I suspect they don't know enough about that, even anecdotally, and I'm certain they don't know it through well-controlled scientific studies.

So, to draw the parallel

- surgeons don't know whether bracing maps to patients final curve when the brace is removed (the important outcome for bracing)
- surgeons don't know how their choice of levels fused (or any other surgical decision) maps to quality of life (the important outcome for surgery)

In both cases, they have no solid research to guide their most critical decisions.

LindaRacine
08-25-2010, 01:40 PM
I'm just saying that their method of "knowing" is the same in both cases - they do something on an individual and they look at the results. That's in contrast to the idea that "knowing" is only available through controlled research studies. Were that the case, surgeons couldn't "know" anything.

As to seeing the results, it's somewhat similar to bracing in that they see the immediate results of the surgery but don't have a clear sense of how their surgical choices map to long-term life quality. How did their particular choice of fusion level/method turn out 5 (or even 2) years down the road? I suspect they don't know enough about that, even anecdotally, and I'm certain they don't know it through well-controlled scientific studies.

So, to draw the parallel

- surgeons don't know whether bracing maps to patients final curve when the brace is removed (the important outcome for bracing)
- surgeons don't know how their choice of levels fused (or any other surgical decision) maps to quality of life (the important outcome for surgery)

In both cases, they have no solid research to guide their most critical decisions.

For the most part, I agree with this. But, non-pediatric surgeons have been doing some (though not enough) long-term followup on surgical patients. As far as I know, no one other than the Swedish group has done any long-term peds followup (surgical or non-surgical).

--Linda

hdugger
08-25-2010, 03:28 PM
My sense is that the major weakness in scoliosis surgery research isn't the lack of long-term follow-up (although that's pretty bad!), but the lack of a meaningful outcome measure.

<rant on>

Surgeons tend to fall back on the Cobb angle, I assume because it's so gosh-darned easy to measure. But just reading this forum, I've seen very little correlation between Cobb angle and quality of life in adult patients. Although the Cobb angle seems to be pretty good for measuring outcome in kids, it just seems to fall apart completely for adults. There has to be some better way of getting a complete picture of an adult - how are they balanced, overall? did their initial complaints resolve? did they end up with new pains? are they able to get back to what they used to do? The survey measures just don't seem accurate or complete enough. There needs to be some combination of actually *looking* at them and judging their overall balance, and then some set of physical tests they try to complete. Without that, you're stuck judging outcome from a single number which really says nothing at all about the things you're interested in.

<rant over>

Pooka1
08-25-2010, 08:19 PM
I'm just saying that their method of "knowing" is the same in both cases - they do something on an individual and they look at the results. That's in contrast to the idea that "knowing" is only available through controlled research studies. Were that the case, surgeons couldn't "know" anything.

No I think there is a real difference here. Surgeons have a certain small number of "methods" for doing different things (like identifying the lowest instrumented vertebrae) and then someone like Lenke can amass huge numbers of patients in a short time who were fused with that method. He knows the results (balance) very soon afterwards but can't know about things like pseudoarthroses right away. Things like adjacent level disease down the road are not complete black boxes; something is known about how low or high you fuse, balance and intrinsic bone properties drive the likelihood of that outcome.


As to seeing the results, it's somewhat similar to bracing in that they see the immediate results of the surgery but don't have a clear sense of how their surgical choices map to long-term life quality. How did their particular choice of fusion level/method turn out 5 (or even 2) years down the road? I suspect they don't know enough about that, even anecdotally, and I'm certain they don't know it through well-controlled scientific studies.

I think folks who do a million surgeries like Lenke and Bridwell know more about the particulars than you think. And they are publishing them, albeit relatively slowly. Surgery, because the outcome seems to be largely driven by variables under the surgeon's control like how to select LIV, is more tractable because you can simply hit it with so many patients while holding other variables constant that an empirical answer emerges in a given, well-defined surgical scenario. You can take a million 60* Lenke Type 2b curves and chose one method for something and see what happens.

With bracing, there are too many variables not under the surgeon's control and known huge false positive rates that are in principle not identifiable empirically. And then there is the unknowable false negative rate which I suspect exists but may not. It seems very few things can be held constant while varying others in bracing studies.


So, to draw the parallel

- surgeons don't know whether bracing maps to patients final curve when the brace is removed (the important outcome for bracing)
- surgeons don't know how their choice of levels fused (or any other surgical decision) maps to quality of life (the important outcome for surgery)

In both cases, they have no solid research to guide their most critical decisions.

Again, I think more is known about surgical outcomes than you think. For example I think they know good balance in all planes usually maps to a good result radiographically and quality of life-wise and in the long term, at least for T fusions. Equally, they know fusing into the lumbar with H rods can be problematic. Pedicle screws aim in part to solve those problems. It is a constant honing and perfecting using the previous generation instrumentation. Surgery, unlike bracing, is a very long process of perfecting past technique and constantly seeking to build a better mouse trap. Although of course it started some where out of nowhere but that was a long time ago and it has gotten down the road in many ways. And disastrous techniques are identified and abandoned.

In contrast, we see bracing going off in new directions (e.g., Spinecor) because there is no there there to build on because of the huge false positive and potential false negative rates. It is intrinsically harder to study than surgery because you don't really have a clear shot at holding at least some variables constant while varying one. The combination of patient plus brace seems far wider than the combination of patient plus fusion with kids. The results of bracing are all over the map and known to be incorrect at times whereas the fusions in kids tend to group pretty well and positively, at least in the short to mid term. Adult fusion is more all over the map but still probably groups more positively than bracing when correcting for false positives in the bracing.

hdugger
08-25-2010, 08:47 PM
We're really just trying to pin down the definition of "known." So, when you say:

"Again, I think more is known about surgical outcomes than you think. For example I think they know good balance in all planes usually maps to a good result radiographically and quality of life-wise and in the long term, at least for T fusions. Equally, they know fusing into the lumbar with H rods can be problematic. Pedicle screws aim in part to solve those problems. It is a constant honing and perfecting using the previous generation instrumentation."

you're talking about knowing as a kind of trial-and-error anecdotal process, guided mostly by surgeon's shared experience and informed intuition.

That's really all I'm getting at. It's *all* that kind of knowledge - none of it is what anyone would call clearly researched and replicated.

I understand your "black box" argument about bracing, but I'd suggest that surgeons are tracking their bracing results intuitively in a way that isn't represented in the literature, in much the same way that they track their surgical results. I suspect it's that shared intuition that serves as the basis of knowledge about the kinds of patients who benefit from bracing. So, although they don't understand the inner workings of the box, they do see into it well enough to recognize the kinds of patients who aren't benefiting from bracing. If it were entirely a black box, they'd be bracing every patient who comes in.

I'm not necessarily pro-bracing (nor necessarily pro-surgery :)), but I don't think the arguments against it involves the lack of clear scientific proof. There isn't clear scientific proof for any of this stuff.

Pooka1
08-25-2010, 09:39 PM
I understand your "black box" argument about bracing, but I'd suggest that surgeons are tracking their bracing results intuitively in a way that isn't represented in the literature, in much the same way that they track their surgical results. I suspect it's that shared intuition that serves as the basis of knowledge about the kinds of patients who benefit from bracing. So, although they don't understand the inner workings of the box, they do see into it well enough to recognize the kinds of patients who aren't benefiting from bracing. If it were entirely a black box, they'd be bracing every patient who comes in.


No, intuition about what works and doesn't work about bracing is not useful because there is no way in principle to intuit when you have a huge false positive and potential false negative rate and no way to figure out when a patient is in one of those categories. This is where intuition is known to fail a person. It can't be used. There can never be even empirical (true) data in this situation.

Intuition is much less important in surgery now that there is a huge mass of empirical data on the relatively few methods and combinations of methods to skin the cat. And because it builds on itself.

I guess that is the point... bracing relies on intuition which must fail in that particular case and surgery relies on tons of empirical data where you can hold some things constant while varying others. Because of this, surgery is simply more tractable and therefore more can be known outside controlled studies.

Ballet Mom
08-25-2010, 09:39 PM
I understand your "black box" argument about bracing, but I'd suggest that surgeons are tracking their bracing results intuitively in a way that isn't represented in the literature, in much the same way that they track their surgical results. I suspect it's that shared intuition that serves as the basis of knowledge about the kinds of patients who benefit from bracing. So, although they don't understand the inner workings of the box, they do see into it well enough to recognize the kinds of patients who aren't benefiting from bracing. If it were entirely a black box, they'd be bracing every patient who comes in.


I think you're absolutely right hdugger. When my daughter was diagnosed with a 35 degree curve, I thought the surgeon was nuts to have prescribed her a Charleston Bending Brace after I read the research studies on it. The TLSO braces worn continuously clearly get better results on larger curves than the nighttime braces and 35 degrees was the maximum size of curve recommended for this brace.

But in retrospect, I think the surgeon was simply highly skilled and attuned to my daughter's physical traits. He knew she was very thin, and was a ballerina and therefore likely very flexible, which he probably could figure out in the exam anyway, and he encouraged her to continue with the ballet. He also told me it was the brace he would use on his daughter if she had scoliosis, so he had obviously had good experience with it, at least for kids with the same physical attributes, and felt it had a good risk/reward trade-off.

Ballet Mom
08-25-2010, 09:41 PM
For the most part, I agree with this. But, non-pediatric surgeons have been doing some (though not enough) long-term followup on surgical patients. As far as I know, no one other than the Swedish group has done any long-term peds followup (surgical or non-surgical).
--Linda

I think it's amazing the research studies that are relied on for scoliosis. I know it must be terribly difficult to get the numbers of patients needed for a good study, but when you realize that the progression numbers for those patients in the great Weinstein/Poncetti study "Curve Progression in Idiopathic Scoliosis" for those with thoracic curves from 50 to 75 degrees is based on eleven patients, it makes me wince. Surely they could be doing more studies following more patients over time to see how they do, both those who choose surgery and those who don't.

Thank goodness for the Swedes!

hdugger
08-25-2010, 10:16 PM
Because of this, surgery is simply more tractable and therefore more can be known outside controlled studies.

I'm going to leave this at "agree to disagree." I don't believe surgeons "know" any more about the outcome (in terms of quality of life) of adult surgery then they "know" about bracing in children, and I'd trust their intuition equally in both cases.

Pooka1
08-25-2010, 10:17 PM
I'm going to leave this at "agree to disagree." I don't believe surgeons "know" any more about the outcome (in terms of quality of life) of adult surgery then they "know" about bracing in children, and I'd trust their intuition equally in both cases.

Okay but what would you say about what surgeons know about fusion in adolescents? Would you say more or less is known about that compared to bracing?

hdugger
08-25-2010, 10:22 PM
But in retrospect, I think the surgeon was simply highly skilled and attuned to my daughter's physical traits. He knew she was very thin, and was a ballerina and therefore likely very flexible, which he probably could figure out in the exam anyway, and he encouraged her to continue with the ballet. He also told me it was the brace he would use on his daughter if she had scoliosis, so he had obviously had good experience with it, at least for kids with the same physical attributes, and felt it had a good risk/reward trade-off.

Yes, exactly. I think that's the thing about informed intuition (ala the "Blink" book). As a surgeon who sees patients, you have this huge amount of information coming in all the time. Even if you don't track it empirically, you track it subconsciously. So, you just kind of "know" things which can't be parsed out scientifically.

Hence the importance of finding a really, really good doctor. A good doctor who's paying attention is just going to intuit stuff that makes sense of everything they've seen and read. I'd run like hell from anyone who was relying on the research to make decisions. With the way the research disagrees with itself, they'd be changing their surgical decisions mid-surgery. :)

hdugger
08-25-2010, 10:33 PM
Okay but what would you say about what surgeons know about fusion in adolescents? Would you say more or less is known about that compared to bracing?

We haven't really had a pediatric surgeon, so I'm not sure I'd know.

But . . . given the outcome points of the two treatments, I think I'd say they know equally little.

So, the outcome point of bracing is to hold a curve until the end of the growth spurt. Pediatric surgeons are actually there for their point, so I'd guess that they have some sense about what kinds of braces work for what kinds of patients.

The outcome point for surgery is quite different. Its goal is to provide long-term quality of life. (I'm throwing this out there, you're welcome to disagree.) Given that outcome, I'd say that pediatric surgeons don't have much sense about how the surgical decisions they made affect that long-term quality of life. I'm not arguing that they don't know that surgery itself is effective - I think that case has been clearly made. I'm saying that they don't know how the *specific* surgical decisions they make turn out in the long-run.

For adult patients, it's even more of a crap shoot. I've seen lots of people on this forum come out of surgery with terrific correction but terrible pain. I have no idea how a surgeon of adult patients can "know" much of anything.

hdugger
08-25-2010, 10:43 PM
As an example of the crap shoot - I've been focusing on PJK (because I believe my son is at some risk of it.) Have you read that literature? They might as well be picking causes out of a hat. One study says hooks, the other says screws, and another says mixed. One thinks its the gender, another thinks it's the age. If *one* of those studies is correct, I wish it would stand up and announce itself, because I can't make heads or tails of it.

But . . . if I just follow the stories of everyone going in for surgery who sounds a bit like my son, the pattern I see is that people with kyphosis (whether with scoliosis or not) going into surgery almost always come out with some kind of neck problem. Maybe that's an anomaly over the last year on the two forums I participate on, but that's the data I'm pulling out. So, that's how I'm making sense of the research. I'm paying attention to what I see, and I'm looking at my son, and I'm asking "Is he like the people that end up with that problem." Only after that do I see if the research confirms that at all.

I suspect his surgeon is doing the same thing. He may be reading the research, but I can't imagine he's relying on it. Mostly he's relying on what he's seen and what he's heard. I can only help its gelling in his head better than it is in mine.

Ballet Mom
08-25-2010, 10:48 PM
From my reading of PJK, I think it's the people with some kyphosis who, due to the strength of the new hardware systems, are able to obtain "too great" a correction. The change in the kyphotic curve is too drastic and leads to neck problems. Hopefully their use of hooks at the top of the fusion will help.

But what do I know....I could be completely wrong!

Ballet Mom
08-26-2010, 12:50 PM
As an example of the crap shoot - I've been focusing on PJK (because I believe my son is at some risk of it.) Have you read that literature? They might as well be picking causes out of a hat. One study says hooks, the other says screws, and another says mixed. One thinks its the gender, another thinks it's the age. If *one* of those studies is correct, I wish it would stand up and announce itself, because I can't make heads or tails of it.


You're right hdugger. I just found a research study that absolutely rejects what I just said in the post above.


a larger magnitude of kyphosis both before surgery and at final follow-up tended to be associated with the development of PJK. A comparison of those patients who developed PJK with those who did not is contained in Table 6 . Those patients that developed PJK had a lower kyphosis percentage correction compared with those patients that did not develop PJK.

Also:


There was no apparent correlation of proximal anchor type (hook or screw) with the development of PJK

(Operative Management of Scheuermann's Kyphosis in 78 Patients: Results
http://www.medscape.com/viewarticle/566467_3 )

It really is a crap shoot. This study says that 39% of their studied fusions developed PJK (most cases are not that big a problem) ...so there's something going on with the new hardware that these surgeons are searching around to solve.


The prevalence of PJK at 7.8 years postoperation was 39% (62/161 patients).

This study thinks the risks are: Older age at surgery >55 years (vs. < or =55 years) and combined anterior and posterior spinal fusion (vs. posterior only) demonstrated significantly higher PJK prevalence.

(Proximal junctional kyphosis in adult spinal deformity after segmental posterior spinal instrumentation and fusion: minimum five-year follow-up.
http://www.ncbi.nlm.nih.gov/pubmed/18794759 )

So what the heck? You're right, every study seems to contradict the other. At least the surgeons are hunting around trying to find the causes and solutions.

hdugger
08-26-2010, 01:08 PM
Yeah, it would be almost funny if it didn't actually matter.

And the likely cause that Linda suggests - that PJK is often the result of surgeons choosing the wrong level - is unlikely to undergo scientific scrutiny. I don't think I've ever seen a study examining what might be considered "surgical misjudgements" for scoliosis surgery and their long-term effects.

Ballet Mom
08-26-2010, 01:22 PM
Yeah, it would be almost funny if it didn't actually matter.

And the likely cause that Linda suggests - that PJK is often the result of surgeons choosing the wrong level - is unlikely to undergo scientific scrutiny. I don't think I've ever seen a study examining what might be considered "surgical misjudgements" for scoliosis surgery and their long-term effects.

Lol! No and I doubt you will either! That's what revision surgery is for. :)

Pooka1
08-26-2010, 02:00 PM
And the likely cause that Linda suggests - that PJK is often the result of surgeons choosing the wrong level - is unlikely to undergo scientific scrutiny.

Well, if by "wrong" level you mean surgeons trying to save levels and not just fusing the entire way up the thorax then maybe that is correct. Maybe it is a joint risk determination between the patient and surgeon about how much chance they will take by not fusing up to T1. If so then it might be analogous to the trade-off at the distal end where surgeons want to go as short as possible for the sake of preserving flexibility but then they might miss fusing some of the structural curve. If folks just threw their hands up and said, "Fuse the entire length down to S1" then there would be no adjacent level disease at the distal end. The risk would be ZERO.

Also, it may be the case that no matter what a surgeon does, the intrinsic bone issues will not allow a successful fusion with any conceivable combination of instrumentation and choice of levels. It may be some folks are just SOL. That would not then be the surgeon's fault, yes? I'm just concerned that a "shoot the messenger" note might creep into this discussion and I want to head it off.

hdugger
08-26-2010, 02:40 PM
Well, if by "wrong" level you mean surgeons trying to save levels and not just fusing the entire way up the thorax then maybe that is correct. Maybe it is a joint risk determination between the patient and surgeon about how much chance they will take by not fusing up to T1. If so then it might be analogous to the trade-off at the distal end where surgeons want to go as short as possible for the sake of preserving flexibility but then they might miss fusing some of the structural curve. If folks just threw their hands up and said, "Fuse the entire length down to S1" then there would be no adjacent level disease at the distal end. The risk would be ZERO.

I'll leave it to Linda to correct, but my sense is that she meant "the wrong vertebra" and not just "a conservative strategy."

If I can make any sense of the literature, it seems as if the problem shows up within the first two years. I'm hard-pressed to imagine a conservative strategy which only protects you for a few years at most.

Pooka1
08-26-2010, 02:57 PM
I'll leave it to Linda to correct, but my sense is that she meant "the wrong vertebra" and not just "a conservative strategy."

I'll look forward to what she says but I can't imagine how "wrong vertebra" could possibly mean anything different than going short when they should have gone longer. I mean the only other choice for "wrong vertebra" is to miss the curve which I assume never happens. So the choices are go long and lose more flexibility or gamble and go shorter.


If I can make any sense of the literature, it seems as if the problem shows up within the first two years. I'm hard-pressed to imagine a conservative strategy which only protects you for a few years at most.

Not sure I'm following but the conservative strategies (i.e., not accepting risk) at least at the distal end protect the patients for EVER. There is no disc below an SI fusion. Perhaps it is the same with the top at T1 although maybe the cervical vertebra can kyphose (verb?) when T1 is included.

hdugger
08-26-2010, 03:09 PM
I'll look forward to what she says but I can't imagine how "wrong vertebra" could possibly mean anything different than going short when they should have gone longer. I mean the only other choice for "wrong vertebra" is to miss the curve which I assume never happens. So the choices are go long and lose more flexibility or gamble and go shorter.

In the example she gave, it sounded like they missed the curve and didn't include the correct proximal end. But, again, I'm just remembering what I recall.

I'm not sure exactly what flexibility they'd hope to retain in the thoracic spine, but I'm not sure a vertebrae or two one way or the other is going to make much difference.




Not sure I'm following but the conservative strategies (i.e., not accepting risk) at least at the distal end protect the patients for EVER. There is no disc below an SI fusion. Perhaps it is the same with the top at T1 although maybe the cervical vertebra can kyphose (verb?) when T1 is included.

Sorry, I flipped the definition of conservative :)

I meant that, if it was a decision to spare a vertebrae in order to preserve flexibility, that seems like an odd trade off if you pay the price in PJK within at most a few years. I assume that the "spared" lumbar vertebrae last a little longer than that.

And, yes, as far as I can make out, the PJK can go up into the cervical vertebra. So, you can see why, as the parent of a kid whose curve starts at T2, I'd be pretty concerned about how they'd deal with PJK if he ends up with it. Fuse the neck? Sounds pretty bad to me.

hdugger
08-26-2010, 03:16 PM
This isn't exactly the right post - there's one I remember where she addressed it more generally - but this is kind of what I recall Linda saying:

http://www.scoliosis.org/forum/showpost.php?p=100600&postcount=10

you can scroll up a little to get the context.

Pooka1
08-26-2010, 03:24 PM
This isn't exactly the right post - there's one I remember where she addressed it more generally - but this is kind of what I recall Linda saying:

http://www.scoliosis.org/forum/showpost.php?p=100600&postcount=10

you can scroll up a little to get the context.

Okay Linda will dope slap me but I think adjacent level disease at the distal end is caused by not fusing part of the structural curve and(or) not achieving good balance. Additionally, if the distal end is in the lumbar then adjacent level disease may not be preventable no matter what you do because of the state of the art w.r.t. lumbar fusions.

Not sure what causes adjacent level disease at the proximal end.

I think what Linda means by wrong is that they didn't fuse high enough to avoid the kyphosis. They took a risk by going shorter.

At he distal end, adjacent level disease can be avoided completely by fusing to S1.

LindaRacine
08-26-2010, 09:28 PM
Adjacent level disease can be caused by many things, but I think the one thing the best surgeons will tell you is true is that if the wrong level is selected, leaving the vertebrae below the lowest instrumented vertebrae or the vertebrae above the highest instrumented vertebrae, in a non-horizontal position, leaves the patient more vulnerable to ALD. I think it also can be caused by choosing a top vertebrae that is at a level vulnerable to the forces in the sagittal plane. For example, I think that patients who need to be fused starting at around L1 are usually actually started at T10 or T11 to avoid this problem.

I'm far from being an expert on the subject, and have actually read relatively little of the literature, so as always, I suggest that patients (or parents) follow the advice of qualified professionals.

--Linda

Pooka1
08-27-2010, 07:09 AM
Thanks, Linda.

So in both cases you mention, leaving a tilted vertebra and not stabilizing an area that is not structural but vulnerable to sagittal forces, isn't that the trade-off I spoke off? Isn't that trading a risk of ALD for increased flexibility?

All of these decisions seem to reduce to reducing risk of further problems by going longer versus taking a risk to preserve flexibility. I can imagine some folks who have a high risk of developing ALD below a fusion to just go ahead and fuse a final 2 or 3 vertebrae to reduce the risk to exactly zero. Or maybe the difference in flexibility is so large with leaving L4, L5 and S1 unfused such that many patients will opt to take a risk of ALD and not fuse them.

In reading testimonials, it seems some pediatric guys will only go to L3 on some double major curves in kids whereas an adult surgeon might go lower on an adult patient with similar curves. So maybe there is a big difference in flexibility fusing to L3 versus L5 or S1. In kids, some times this risk pays off and sometimes it doesn't. There were three cases I can think of where only fusing the top curve and stopping at T12 or L1 did not seem to work (at least in the short term) but I have to believe it works sometimes or else surgeons would never chance it. That seems to clearly be a case of accepting large risk for the big reward of a flexible lumbar.

Hopefully the surgeon can accurately convey the risk of various issues when deciding to go shorter versus longer so hte patient can make an informed decision.

jrnyc
08-27-2010, 02:31 PM
hi Sharon
i think there is a very big difference in flexibility between fusing to L3 vs/sacrum or lower!! i would LOVE to only need fusion to L3 or even L5!! but i need fusion to pelvis! Dr Lonner told me there is little difference between fusing to sacrum vs/pelvis...but fusing to L3 is much better for flexibility than fusing lower!! thus, most surgeons try to fuse children only to L levels so they have the flexibility when young...

have a great wkend...

jess

LindaRacine
08-27-2010, 11:13 PM
Thanks, Linda.

So in both cases you mention, leaving a tilted vertebra and not stabilizing an area that is not structural but vulnerable to sagittal forces, isn't that the trade-off I spoke off? Isn't that trading a risk of ALD for increased flexibility?


Yes, I guess that's correct. In adults, at least with the surgeons I work with the most, there's very little talk about preserving motion segments. I'm sure it comes up occasionally, probably mostly when a patient has the concern. I'm sure it's more of an issue with kids.

--Linda