New Member introduction - Robustness of M6C ?

[drewrad]

Annapurna, I raised your issue with Dr. Zeegers today. We talked for about an hour over the phone. He agrees with you, however, I would love to hear your opinion of the disc he prefers which is the Activ L. Do you know it? Please, I'd like to hear you discuss it. If it was you, I'm assuming you would use the Activ L product before an M 6, correct?

[dieter]

Thank you so much for your information and comments.

Yes, ADR still seems to stay open for ACDF but I rather have a lasting device than a second operation.
I personally judge the operation itself to be the higher risk component than the choice between ADR or ACDF especially when the advantage of the ADR vs ACDF has not been proven statistically significant.

When I read it correctly there is basically only one or two way to conduct ACDF. But there are about 10 different ADR devices on the market each with its own unique mechanics and risks.

A thought that keeps on coming back to me is: How can a doctor or patient take the right decision if the expected advantages are not proven statistically significant? Sure there is more to a decision than statistics but when I make a decision I want proof that it is lasting, if possible, for ever.


Best wishes Dieter

[annapurna]

Drewrad,
Before I answer your question, I have to say that neither Laura nor I are medical professional in the slightest. If a doctor told you your foot was connected to your wrist and we told you it wasn't, I'd trust them and not us.

Strictly from an engineering standpoint, the Activ-L design is simpler. It fails to mimic the loading in a natural spine and tends to put more load on the facets and the connective tissue and musculature. On the other hand, there are relatively few ways it can fail, outside of poor selection, poor placement and subsidence, which can take down any ADR. Wear of plastics is fairly well understood and we have pretty good models to go from bench tests to reality. That doesn't mean we've got a good handle on x bench test cycles yielded y grams of material loss which means z many years of life but experience is much clearer to put those piece together into what to expect for long-term performance.

That said, just because the disk is less likely to fail doesn't mean that it's the best thing for someone's spine. I'm speaking out against the M6 because I'm concerned that the rush to the new design is going to land people in trouble if they fail to check on it regularly. I can't really say if I'd prefer to have the Activ-L in my back or get the M6 and plan on regular flexion-extension x-rays for the rest of my life. Both approaches are reasonable. I wouldn't accept an M6, though, if I didn't plan for some kind of regular monitoring.

Richard and I have spoken about the M6 and he brings up a completely different, but valid concern. The simpler ADR designs have fewer pieces and a tendency to "scrub" those surfaces during movement. Biofilms can still form but there would seem to be much less tendency on an Active-L design compared to a M6 design. I simply can't answer to the degree that this should factor into your decision. That's well beyond my knowledge and I'd effectively be parroting what I learned from a trusted (and possibly trustworthy) source. It is something for you to be aware of, though.

[annapurna]

Originally Posted by dieter

A thought that keeps on coming back to me is: How can a doctor or patient take the right decision if the expected advantages are not proven statistically significant? Sure there is more to a decision than statistics but when I make a decision I want proof that it is lasting, if possible, for ever.

As of a couple of years ago, the only statistically significant determiners of ADR success was the patient condition and the surgeon's skill. Type of ADR used wasn't significant in any way. There might be new data but it's unlikely as that data would have been discussed extensively here.

[bwink23]

Well, sure the M6 is a complex design. It's intended to replace a complex piece a tissue, based on how a series of complex biomechanical systems work harmoniously to balance out the entire spine and keep those nagging aches, pains, spasms to a minimum. Giving the spine a part that acts more like a hip joint while the other corresponding parts to the spinal machine act very differently to me isn't desirable. You can use the complex design as a deterrent to M6 use....if you don't mind risking long term damage to the other structures that must take on more loads in reaction to the weak link in the chain. How would technology ever advance if we we always took the short and easy? What I'm saying is the conservative approach may not be as conservative as you think.

[Stonewall_Boris]

Harrison, Annapurna,

If the M6 designed and manufactured in California were to be an eligible disc replacement in the US as I understand it you would not support the design. Is that the case?

[drewrad]

Another thing Dr. Zeeger told me yesterday is that the Activ L is not 'out of the box' like the M6 and thus the Activ L is tailor specific to the individual's need.

Obviously there are a variety of M6s for a variety of body types, however, the Activ L sounds like it is more 'special order' for unique needs as well as the 'big and tall' guy or the guy(or woman) with unique bone needs.

[dieter]

To me the last paragraph at the following Web Site (burtonreport.com/InfSpine/SurgArtificialDiscs.htm) reflects the situation with respect to ADR pretty much the way I summed it up for myself although the article seems to be already a few years old.
"Artificial Discs" and "Editorial: Artificial Discs"

Best wishes Dieter

[Harrison]

Originally Posted by Stonewall_Boris

Harrison, Annapurna,

If the M6 designed and manufactured in California were to be an eligible disc replacement in the US as I understand it you would not support the design. Is that the case?

Yes, as I've mentioned. I am concerned about long term reliability; number of materials; total number of components.

In general, "less is more." Less is generally safer. This also relates to failure analysis study results. I'll defer to Jim & Laura on that, though they've already commented in spades on this subject.

That said, I am so happy that people are getting their lives back with ANY technology. We all face the same risks and we are all in this together. Peace and good health to all of us!

[Harrison]

Drew, I recall talking to Zeegers years ago about the customization attributes of the Activ L. At the same show, I also talked to the mfrs -- I liked the myriad configurations for surgeons to choose the best sizes and footprints to the individual patient. Zeegers had a huge influence on that design if I recall correctly.

That highly flexible config option was born out of necessity to minimize complications like subsidence and HO.

Dieter, danke für die Referenz. Ich hoffe, dass alles gut ist.