16 year old fusion failing (C-D implants)???

[JScoli91]

Is it possible for a T2-T12 fusion with C-D implants to fail? 16 years after it was done the curve is apparently measuring twice as big as it was when it was freshly corrected.

[Pooka1]

It is possible and has been studied.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4340851/

Conclusions
Deformity progression after posterior spinal fusion does occur after modern segmental instrumentation. Segmental pedicle screw constructs do not prevent deformity progression. Skeletally immature patients with a significant growth potential are at the highest risk for deformity progression. In immature patients, extending the fusion distally to the stable vertebra may minimize deformity progression.

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https://www.hindawi.com/journals/bmri/2018/3247010/

Adolescent idiopathic scoliosis (AIS) is a 3-dimensional deformity of the spine that constitutes the most common type of spinal deformity around puberty. Surgical treatment is usually performed in patients with the curve exceeding 45° to prevent further curve progression and obtain a balanced spine [1]. For some of AIS patients with Lenke 1A and 2A curves, only main thoracic curve needs to be corrected and fused since the flexible lumbar curve can provide postoperative compensation [2–5]. However, some patients may have postoperative coronal decompensation although lumbar curves can improve spontaneously after selective thoracic fusion. Of particular concern is the “adding-on” phenomenon caudal to the fusion, defined as an increase in the number of vertebrae within the distal curve from the first erect radiograph postoperatively to the last follow-up [6]. Distal adding-on could lead to increased coronal decompensation and disc wedging, which in turn could result in degenerative changes later in life and further surgical intervention [7].

Risk factors associated with adding-on have been well documented in previous studies, such as lowest instrumented vertebra (LIV) selection, apical translation, and skeletal maturity [6–10]. Among them, the inappropriate selection of LIV seems to be the major cause [6, 8–10]. In previous literature, nearly 6-7% of AIS patients with adding-on need revision surgery for progressive adding-on [10, 11]. However, few studies have specifically focused on the progression of distal adding-on, which is often accompanied by unsatisfactory clinical outcome and high risk of revision surgery in clinical practice. The purpose of this study is to investigate the natural history of postoperative distal adding-on in AIS patients undergoing selective thoracic fusion and to identify the risk factors related to the progression of this complication.

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Fractional curve pain pattern

https://neupsykey.com/the-importance...ctional-curve/

[titaniumed]

Just looking real quick, they do not mention clamp only constructs. Early C-D systems. The C-D systems eventually evolved using pedicle screws at some point with Medtronics. The first screws in the US were used in Feb 1986. Louisville, I believe

The botton link is excellent, thx for posting Sharon Great ALIF and L5-S1 fusion info Going to take a closer look after Christmas...

Merry Christmas everyone!

Ed

[JScoli91]

I just had a new standing x ray done of my hardware, the first since back in 2004 when it was freshly implanted.

Based off of mri and ct last month they say my hardware is in tact and I am fully fused throughout, but how then is the curve still increasing? It can’t be due to the unfused lumbar curve increasing below it can it? Even if my T curve is fully fused?

I’m so confused

[Pooka1]

I just had a new standing x ray done of my hardware, the first since back in 2004 when it was freshly implanted.

Based off of mri and ct last month they say my hardware is in tact and I am fully fused throughout, but how then is the curve still increasing? It can’t be due to the unfused lumbar curve increasing below it can it? Even if my T curve is fully fused?

I’m so confused

You may have had growth remaining after your surgery and that is what drove the increase. It is called Crankshaft.

J Am Acad Orthop Surg. 2017 Sep;25(9):e185-e193. doi: 10.5435/JAAOS-D-16-00584.
The Crankshaft Phenomenon.
Murphy RF1, Mooney JF 3rd.
Author information
1
From the Department of Orthopaedics, Medical University of South Carolina, Charleston, SC.
Abstract
The crankshaft phenomenon, a progressive rotational and angular spinal deformity that can occur after posterior spinal surgery, has been reported in pediatric patients with idiopathic, congenital, and neuromuscular scoliosis. In the skeletally immature patient, the crankshaft phenomenon is thought to occur secondary to continued growth of the anterior elements of the spine after solid posterior spinal fusion. The condition has also been reported in the setting of newer, so-called growth-friendly posterior distraction-based spinal instrumentation. The clinical evidence of crankshaft phenomenon is often subtle, whereas radiographic findings are usually more apparent. However, objective measurement of radiographic signs may be complicated by instrumentation and postoperative changes. Treatment options for patients with the crankshaft phenomenon are limited; in those with problematic deformity and/or risk of progression, additional surgery may be indicated.

PMID: 28837459 DOI: 10.5435/JAAOS-D-16-00584

[titaniumed]

Its kind of like when you pull on a rope. There will be some stretching that will happen, the harder you pull, the more stretch you get.....Our muscular systems do pull quite hard and bone is not this impervious material that you might think. Materials do move, and clamps will pull into bone over time and hopefully settle.

Even soft steels in an annealed state under 18 rockwell C scale have to be hardened on contact or wear points that exceed just a few hundred pounds of force. Bending will exert several hundred pounds of force on our discs....There have been studies on this.

Bending over and picking up an object off the floor exerts the most force on our lumbar spines. I can post studies if you want to see. This is not a great idea even with a healthy spine, all this does is wear out our discs faster.

Rods regardless of type of material will stretch and move some....Our rods are in a annealed soft state and not hardened. Our hardware is also designed to move....which aids in the fusion process. Otherwise, they would simply increase size of our hardware.

Metals in general are actually soft materials when you think about it....I was on the top floor of the World Trade Center 45 years ago, the towers swayed back and forth around 6 feet. You would think with all that steel that there would be no movement but thats not the case. We are kind of like that in a sense. May we never forget.

Bone has a harder outside shell, with a softer honeycomb inside core. Corticle bone, Cancellous bone. Its an interesting material to have to work with.

I hope this helped some even if it is a crappy physics and material science explaination.

Ed

[JScoli91]

Pooka1, from what I was reading about the crankshaft phenomenon it sounds like it’s pretty rare for girls fused after the age of 10 and happens more comment in girls fused below the age of ten and boys fused below the age of 13. However, my rib hump that I had before my original fusion has come back whereas after fusion in the immediate years to follow it had disappeared. I would assume this would lend itself towards a crankshaft scenario where the posterior vertebral elements were fused but the anterior elements continued to grow and hence rotate.

[LindaRacine]

I just had a new standing x ray done of my hardware, the first since back in 2004 when it was freshly implanted.

Based off of mri and ct last month they say my hardware is in tact and I am fully fused throughout, but how then is the curve still increasing? It can’t be due to the unfused lumbar curve increasing below it can it? Even if my T curve is fully fused?

I’m so confused

The standing xrays you're getting are actually pretty useless, as they don't show your lumbar spine. If I were you, I wouldn't let anyone do any more spine xrays on me until you can find someone who can do 36" full spine radiographs from the front/back (A/P or P/A) and from the side (lateral).

With that said, I don't think it's of any real importance that your curve has increased, as that's probably not what is causing your pain. It's not uncommon for C-D constructs to allow one's curves to increase from their original post-surgery position. The newer, pedicle screw constructs are better at holding the curve(s).

Sharon... Although it's probably similar, I suspect most specialists would not call this crankshaft.

--Linda

[LindaRacine]

Pooka1, from what I was reading about the crankshaft phenomenon it sounds like it’s pretty rare for girls fused after the age of 10 and happens more comment in girls fused below the age of ten and boys fused below the age of 13. However, my rib hump that I had before my original fusion has come back whereas after fusion in the immediate years to follow it had disappeared. I would assume this would lend itself towards a crankshaft scenario where the posterior vertebral elements were fused but the anterior elements continued to grow and hence rotate.

Your rib hump reappearing is a side effect of your curve increasing.

[Pooka1]

Sharon... Although it's probably similar, I suspect most specialists would not call this crankshaft.

--Linda

Okay.

.

.

[JScoli91]

The standing xrays you're getting are actually pretty useless, as they don't show your lumbar spine. If I were you, I wouldn't let anyone do any more spine xrays on me until you can find someone who can do 36" full spine radiographs from the front/back (A/P or P/A) and from the side (lateral).

I was surprised that when I reminded them the point of the xrays was to check in on my scoliosis curves that they did the T spine x ray separate from the L spine x ray. They overlap by 2 vertebrae or so but aren’t on a single x ray together.

With that said, I don't think it's of any real importance that your curve has increased, as that's probably not what is causing your pain. It's not uncommon for C-D constructs to allow one's curves to increase from their original post-surgery position. The newer, pedicle screw constructs are better at holding

So if I were to have my lumbar curve fused, the newer hardware would do a better job at preventing the curve from progressing even once fused and attached to hardware? I guess in now seeing the thoracic curve continued to curve despite being fused I would hate to fuse the lumbar only to have it correct and then continue to curve. I know the changes in my thoracic spine have nothing to do with my pain and it’s origins, I’m just surprised it has professed so far from its original correction after only 16 years.

[LindaRacine]

I was surprised that when I reminded them the point of the xrays was to check in on my scoliosis curves that they did the T spine x ray separate from the L spine x ray. They overlap by 2 vertebrae or so but aren’t on a single x ray together.



So if I were to have my lumbar curve fused, the newer hardware would do a better job at preventing the curve from progressing even once fused and attached to hardware? I guess in now seeing the thoracic curve continued to curve despite being fused I would hate to fuse the lumbar only to have it correct and then continue to curve. I know the changes in my thoracic spine have nothing to do with my pain and it’s origins, I’m just surprised it has professed so far from its original correction after only 16 years.

You'd have to talk to your surgeon, but the new implants may have zero impact on your thoracic curve. Depending on what the actual issue is with your thoracic curve, and what surgery (if any) you choose, anchoring the thoracic implants to the lumbar implants might slow or stop the thoracic construct from rotating. With that said, it's possible that the thoracic spine already stopped rotating. It's possible that the rotation occurred mostly in the early years, and as the fusion became more solid, it slowed down or stopped. Since you don't have any xrays taken during the gap years, it's impossible to know for sure.

--Linda

[LindaRacine]

Okay.

.

.

I see why one would think of crankshaft, but crankshaft is caused by growth in the front of the spine when growth in the back of the spine is arrested by surgery. Because of her age, it's unlikely that Jscoli had a lot of growth in the front of her spine after surgery. Since there's no xrays for the 15 years following surgery, we can't know if the rotation occurred in the first year or two after surgery, or over the entire 15 years.