Charite and In Motion Artificial Disc

[Researcher]

I read that J&J/Depuy stopped production on the Charite disc in March of this year. I'm having trouble finding current information on the supposed replacement, the In Motion Disc. I'm sure it's out there and probable on SPS, but my eyes are really tired from staring at my monitor for so many hours straight!

I'm not even interested in lumbar discs, but I need to understand the Charite story thoroughly, since it plays a role in my critique of my insurer's policy on ADR.

I also came across the following quote regarding the reason that many Charite discs failed. Any additional insight anyone can offer will be appreciated.

Some experts say the Charite itself is the problem. On October 23, 2006, the Street.com reported that researchers at the University of California at Irvine claim the device maker made a crucial mistake when designing the disc that explains why the replacement surgery has resulted in repeated failures with "catastrophic consequences" for patients.

"They've based their center of rotation on a disc space that is in front of the spinal canal," Dr Charles Rosen, a Cal-Irvine spine surgeon, told the Street.

According to Dr Rosen, the makers overlooked the spine's normal function by creating an "artificial center of rotation" in a space that lies in front of the spinal canal instead of behind it and has compromised the body in the process.

"You have a center of rotation that's normally there, and they falsely impose another," he told the Street. "You can't have two because they will neutralize each other. Something has to give."

"To give," he says, "either the back part of the device breaks or the front part dislocates."

Thanks in advance to my super-knowledgeable SPS friends.

Phil

[KBear]

Nothing scientific here, but I speculate that there were so many failures from it because so many surgeons learned how to do ADR with it (thus lots of guinea pigs received it). We are always hammering in how surgeon's experience is one of the most important ADR factors, well most of them became experienced using this one. Also, it was a hot new idea and I'm sure there were a lot put in people who shouldn't have received one. I'm sure there are many other reasons why, but I'd think these things definitely contributed to it.

[Hooch]

Gday Phil,

You're gonna have a lot of trouble running the de puy charite or it's slightly updated big brother the in motion down as it is still in wide use and has plenty of success. One of the leading surgeons in Australia uses it (fwiw). Personally I wouldn't want one cos of it's wierd arse unrestrained translation. In that article you sent me, Kinematics of Cervical and Lumbar Disc Replacement, they contend that an unconstrained device has an ability to better alter it's centre of rotation to the natural CoR, thereby unloading facets (as compared to a constrained, unrestrained disc like prodisc).

Unconstrained prostheses which have a better capacity for their COR to conform to the natural FSU COR may yet prove to cause less painful facet joint loading.

I could barely even find a mention on the in-motion on the web when I tried either. I'd use that paper as your main source, it exposes the biomechnical insufficiencies of these devices pretty thoroughly.

[Justin]

Phil, here's an article from a friend, The Spine Blogger, about the Charite: Sunday Op Ed Piece - The Big Lebowski.

In Motion™ Artificial Disc

• Here's a link to the In Motion™ Surgical Technique brochure: In Motion™ Artificial Disc Surgical Technique
  
• FDA Premarket Approval, Decision Date 09/05/2007, In Motion Artificial Disc

I hope this helps! Keep up the great work!

[KBear]

I really enjoyed the blog and reading all the comments below it. Very interesting opinions.

[Researcher]

As I expected - great responses - very helpful. That blog made my brain hurt, though! So, J&J stopped Charite production earlier this year. As I understand it, they did not have a recall or "take action". Does this mean that the remaining inventory in the field is available for implant? Are some surgeons still implanting the Charite today?

Where I'm going with all this is that my insurer's anti-ADR policy refers to one study after another related to the Charite. Many of the study results are actually quite good, but they use them to say that ADR is bad (it takes an actuary to be able to do that). I have found numerous other flaws in their anti-ADR policy already. I'm trying to understand if their continued reference to the Charite studies is somewhat irrelevant for policy making if the device is no longer available to patients.

Thanks,

Phil

[Hooch]

Sounds like it's going to be an uphill battle, if they've decreed it 'bad'.

I don't pretend to understand the labyrinth of health care denial that is the US system, but it's been cleared by the FDA ferchrissakes! Whats the problem? Where's this company based, Mexico?

The leading surgeon over here (Matt Scott-Young) moved from Charite to the in-motion, which is the same design but with a few improvements here and there I've been told, mainly operative, the kinematics remain the same. Speaking from common sense of course a surgeon could stick a charite in you, if only it's because it's what he knows and he can reasonably expect a certain success rate. The Charite may have fallen from favour with a number of surgeons, but it's still a proven, medically legitimate prosthesis. Your insurance company is crackers. What will they prescribe for you after denial... leeches?

Good luck man, sorry I can't be of much help.