Thursday, December 18, 2008

Okay kids, squeaky hips are in again - solving an unconscionable mystery....

[Click on Post Title for Link to External Article]

It's always great to hear from an old friend, isn't it? Especially when they produce squeaky sounds as they approach you! In case, you missed my blog from earlier this year (because you were reading random pie charts and "nice" stuff written by bloggers placing ads of the companies they were writing about)...

Anyway, in May we all found out that Stryker had been providing hip replacements with added functionality - total, unassailable, humiliation to it's customers (no, not the Doctors getting cushy payments, free breakfasts, golf games etc.) - the patients that had to walk around with them.

As you walked with your brand, spanking hips, they would jingle or squeak nicely. Well, around the holidays if you are dressing up as Santa, that must come in handy - or hippy?.

Long story short, thanks to
George Bushthe Supreme CourtRiegelpre-emption, Stryker has walked away, let's say, without having to squeak.

What happened after the news article came out seems to be a total mystery. With a highly ineffective Congress and Judicial System failing to hold companies responsible for grave errors that have put patients through extreme trouble, this doesn't surprise me.

After all, not doing what you are supposed to, or get paid for is the hallmark of...

Oh well.

The Analysis

What is intriguing is, that Stephen B. Murphy, MD is hoping to acquit most hip implants minus one - and which one that is, is anyone's guess.

Back in May, I had alluded to the material properties of the implants and had urged some testing. In fact, I said that the displaced or replaced hips (about 7% of all hip implants had to be replaced thanks to the squeaky joy) and do some fatigue analysis on them.

It turns out the material is probably the culprit.

If you read the rather confusing article on, Dr. Murphy points to the specific stem material as the culprit.

If you want a good introductory article on hip replacements, go to:

If you want a good image, go to:

(Thank you guys).

"ceramic components mounted on a beta titanium alloy stem causes the squeaks"

To briefly recap, hip replacements are not new, so please do not accept any feigned innocence on new products. This is a tried and tested product line.

Dr. Murphy's study (which I have not read and vetted yet - I will report back later) claims that when a specific type of alloy, known as the "beta titanium alloys" that contain molybdenum, zirconium and iron are used, alongside ceramic heads, you get this problem.

This should be a slam dunk.

The study looks more like a literature review, but I am sure it is sufficient to indicate probable cause. My theories on the failure still hold:

1. There is a new material. If the FDA where to actually act and examine if the implant material was appropriately tested, I am sure short-falls will be noticed. The very presence of the squeaking in 7% of the products, the apparent attempts to "silence" the patients, not the hips, and a continuing fogging of whatever happened after the news came out in May should be a clear indicator.

When a company endeavors to introduce a new product line with a new material, shouldn't the IDE contain extensive data on material testing and properties, rather than just biocompatability?

2. Take a look at this study:

It points to several factors including "component design and engineering", patient selection and other decisive factors. Like I said, not such a mystery - the science or engineering. I would bet that if you reviewed the squeaky hips, "marketing requirements" would stand out as winner.

Whenever you have "marketing" drive "innovation" and product design, this type of result should not be surprising. After all, ages ago, I almost worked for one, and then did work for another where "marketing" aka MBA jockeys with little to no knowledge or concern for medical device efficacy were driving design. Where those products went, how innovative they have been since that point would be a child's guess.

3. Prove it - A good finite element model can produce enough information on impingement, transcendental friction, long-term wear, fatigue, and so on.

A good motion analysis will produce data on what happens in inaccurate placement. It could also indicate how much error the surgeon is indeed allowed in placement. It's fundamental kinematics that I am sure is well within the analytical prowess of today's software applications.

4. I said this before, and I will say it again - get those replaced, squeaky hips. Study them. It is so easy to do fundamental image comparison and analysis to reproduce the "altered" states of the failing hips thoroughly.

5. Be honest, for heaven's sake. When you print those brochures about saving people's lives - mean it! If you can't stand by one word of your "mission" or "vision" statement, why bother?

Well, this hip story is not over. I am going to try and access the paper, and find out more about the study itself. If you come across this blog and know something about other studies, please let me know.

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