"Shock-absorbing" ADRs: Spinal Kinetics' M6 and NuVasive's NeoDisc

[Tyler]

Hello everyone,

I'm a candidate for 2-level ADR at C5-6 and C6-7 and have been looking into two very different new discs that claim to provide shock-absorbing capability similar to that of the natural discs:

> M6-C (Titanium endplates surround central artificial nucleus and fibrous core; made by Spinal Kinetics) - used in Europe at Stenum (Ritter-Lang), in the UK (Nick Boeree), Spain (Pablo Clavel) and other locations
Spinal Kinetics

> NeoDisc (Compressible silicone disc within polyester sleeve; made by NuVasive) - just completed a clinical trial in the U.S., used in Brazil (Luis Pimenta) and elsewhere
NeoDisc - Conditions & Treatments

Would really appreciate any feedback from folks who have had these or know about them. Thanks!

Best,
Tyler

[Tyler]

It looks like the NeoDisc is radically different from almost all of the traditional implants in that it has no keels or other fixtures to lock it to the adjacent vertebral endplates.

From the animal studies, it appears that the polyester sleeve eventually induces what is called "fibrous tissue ingrowth." Presumably this would be easier to get out in the case of a revision but I wonder how it's movement, durability and other attributes compare to the more traditional ADRs.

U.S. Clinical Study completed Spring 2010

Photos showing tissue ingrowth:
http://www.ellisdev.co.uk/neodisc2.jpg

[Rev. Zen]

The NeoDisc is similiar to the DASCOR device that did not make it out of clinical trials. I am a major proponent of this technology. I would have liked to have been considered for the NeoDisc, however, I do not meet the criteria.

I think shock absorption is a key element that many ADR devices have neglected. It is my opinion that the lack of shock absorpotion will only increase the rate at which adjacent discs degenerate.

[Maddie]

Tyler, you've taught me something today. Perhaps I missed it during the surgery process, but I didn't know that the mesh is designed to grow into the bone. I wondered about that a time or two.

I sure hope that it doesn't break down after a few decades Thanks for the help.

[annapurna]

Way back when, there was thought that shock absorption was a lesser consideration for the cervical spine due to the smaller weight on it. I've never spent the time to do the calculation but I wondered at the time if the lower load was offset by the smaller size so the pressure was in the same range. If you see some resistance to the concept, it could stem from that belief.

Just based on opinion, it does look like the connection to bone is going to be weaker for the Neodisc compared to a fixed endplate ADR design. You're relying on the longterm strength of the fabric rather than a pair of static bonded surfaces.

As are active person from your description, there was a poster a short while ago that questioned the M6 disk and the possibility of gas bubble formation when ascending from a SCUBA dive. I don't know that you'd care, but if it has any applicability to you, you might want to search up his post and responses.

[Tyler]

It looks as if NeoDisc may be designed to promote fibrous tissue in-growth.
It seems like this could end up as heterotopic ossification (development of bony tissue outside of existing bones) - or auto-fusion.

So one question is whether it tends to up as a fusion and, if so, would it be better to have a strong fusion in the first place...?

On the other hand, and maybe this applies well to you Maddie, it could turn out to be beneficial to allow bone to develop in gradually if it's going to do so based on an individual patient's and disc's physiology. And with metal allergies, I'm assuming you might have had problems with the cages that would have been used in fusion via ACDF.

Since I haven't been able to find out much about NeoDisc in publications, I'm hoping to learn more from experts like Dr. P. and others.

[JKDE302]

I wish i could get thhis pro-disc taken out my neck and have a neo disc or m6 put in...

[Harrison]

JK,

We discussed the reported (alleged) failures of the NeoDisc trial on another topic. Sorry you feel that way -- is your cervical spine hurting? Reactive arthritis under control? Any way, pls update us on your post-op outcome topic when you have some time, it's here:

http://www.adrsupport.org/forums/f47...prodisc-10557/

Hope you get better -- you've been suffering for years...

[jss]

Originally Posted by Tyler

It looks as if NeoDisc may be designed to promote fibrous tissue in-growth.
It seems like this could end up as heterotopic ossification (development of bony tissue outside of existing bones) - or auto-fusion.

So one question is whether it tends to up as a fusion and, if so, would it be better to have a strong fusion in the first place...?

Tyler, that is an excellent question; and I wish I knew the answer. I have a pair of M6s courtesy of Dr Clavel at the Barcelona Spine Center in Spain in Nov '09. To mitigate autofusion, he spreads a "bone wax" around the ends of the vertebral bodies around the implants that impede the osteoblasts from spreading calcium salts into the intervertebral space and forming an "autofusion". I know that Dr Bertagnoli in Germany does the same thing. Perhaps this is standard practice with ADR? I don't know. Perhaps someone that has a NeoDisc could inform us if their surgeon did the same thing?

In the eight months since surgery I've managed to run in excess of 1500 miles and bike almost 1000 (and will be competing in the Hotter'n Hell 100 mile bicycle race in three weeks) with no problems. I can still turn my head the same (a little further) as I could at my post-surgical checkup, and I can still look up to see the road when cruising down the bike path on the bicycle. I haven't had an x-ray in eight months, but am satisfied that up to this point that an autofusion hasn't occurred.

I don't know if that experience is typical, but my experience is that whatever goop they spread to mitigate autofusion has appeared to work (at least on me). Will it work on you? I don't know.

[Harrison]

For an interesting topic on bone wax, this one is actually four years old -- but it's important:

Bone Spur/Osteophyte Removal: Cure Worse Than The Disease?

If someone could look into this further (e.g., updated information) that would be very helpful.