My DePuy Hip Recall
In law, interrogatories (also known as requests for further information) are a formal set of written questions propounded by one litigant and required to be answered by an adversary, in order to clarify matters of fact and help to determine in advance what facts will be presented at any trial in the case.
I will focus only on the interrogatory re the replay of the entire testimony of Magnus Fleet who you might recall is the project engineer who was responsible for the initial design and development of the ASR which was to be a competitor to resurfacing products in Europe. This interrogatory was obviously key to the plaintiffs case so they played the full video tape (he was located in England) for the jury. The Plaintiff is doing the questioning here.
Magnus Fleet had no prior experience with hips in any way shape or form as was mentioned in the opening remarks/ introduction to this case which I covered in a previous post so I won't repeat all of that. Suffice it to say, he was working in the automotive industry for 15 years looking at failure mode analysis for breaks. Similar process of risk assessment he claimed but different subject matter. He was really an expert in the process of risk mitigation analysis .
It was established that the obligation of the engineer was to ensure safety by anticipating the way in which the product would be used in the market and then define the product by:
- identifying the risk
- designing out risk in the new hip
- instituting some guards in place to protect against risk
- providing warnings if there was remaining risk.
- Primary and secondary fixation (lack of bony ingrowth to secure the placement) to prevent loosening of the implant/movement in the acetabulum (they used the Duraloc hip as a proxy as there weren't any monoblocks on the market at the time but they all agreed on the design team, the Duraloc experience which had been published in papers was the best model to use as a proxy.)
- instructions to the physicians
- revision surgery potential- categorized as an extreme event and rated an 8 on a scale of 10
- Causes of failure from metal debris to cause lack of bony ingrowth: This was not investigated by the group in this report because the risk of that was estimated at "almost never."
- excessive wear of the bearing surface
Conversation then proceeded to the adequacy of using the Duraloc as a "model" since it was a modular system and not a monoblock. In the modular system, you could insert a shell of poly between the cup and the ball but that was not the case with a monoblock system like the ASR. (Seemed as though the defense was getting at whether the Duraloc was the right model.)
(excerpts from transcripts)
Attorney: Was there any analysis of Edge wear?
Attorney: Was there any analysis of rim ware?
Attorney: Was there any analysis of debris resulting from placement at different angles?
MF: No because generally surgeons did not implant things at high inclinations/angles at the time.
(The attorney proceeded to demonstrate all of the "new" features of this hip and asked why they were only testing things that had evidence of being done in the past with different procedures and hips.)
Attorney: Given the history looking back, do you think the group failed to identify one or more failure modes?
MF: I think with hindsight , you can look back and we did not get them all....I'm not sure we identified all of the reasons for failure....I think we got all of the ones we could have identified at the time with the information we had.
Attorney: I would like you to look at this paragraph in your design document and confirm that is something that needed to be tested:
"the likelihood of wear and osteolysis will be reduced with wear resistant metal-on-metal bearing surfaces."
This was a performance target correct when the cup interacted with the head? the ASR had to be at least as good as the existing depuy MoM designs?
MF: yes, .
Attorney: How was that done?
MF: We used the Ultima MOM and Unltimet MoM hip as the baseline. We did not know that the placement would vary widely from 45 degrees.
Attorney: did you think it might vary to 65 degrees? Back in 2003, Dr Schmalzride published a paper showing the range of inclination between 35-65 degrees. Wasn't he apart of your design team?
Attorney: were you not aware of the fact that the Durloc model wasn't always fully seated [positioned exactly as directed?]
Mf: I don't recall
Attorney: Wasn't it true that from the date of the design in early 2000-2008, Depuy had no idea of the acceptable range was for placement of the ASR?
MF: I think we got some evidence that 55 was the angle which caused metal debris
Attorney: I didn't ask that. If I tell you that every single person who testified in this case agreed that from 2003-2007, Depuy did not know the acceptable range of the angle placement, would you disagree ?
MF: I don't know whether they said or did not say that.
Attorney: You previously testified that Depuy determined an acceptable range for placement in 2003. is that your testimony?
MF: uh huh
Attorney: is that your testimony?
MF: I don't recall. I'm saying when we designed this, we had a 45 degree target.
Attorney: You never determined an acceptable range did you in 2003?
Attorney: Can you cite any single study where depuy tested 55 degree fixation since that was known to be ok?
Attorney: You were advertising that " Our design was reducing metal wear." correct?
MF: Yes, it was big part of our marketing effort
Attorney: Were you aware that one of the engineers who ran simulation tests found the following with the smaller Pinnacle: "varying diametrical clearance has shown the trend of the smaller the clearance, the lower the wear although it is not statistically significant?
MF: That is one of her conclusions
Attorney: I am asking you for the existence of affirmative evidence, evidence of some test done prior to marketing the ASR, that affirmatively concludes that reduction in clearance will significantly reduce wear for any size other than 54?
MF: I am not aware of anything else.
Attorney: Was this information conveyed to the surgeons?
MF: We were specifically clear on every aspect of the tests and we did not hide anything.
Attorney: What I am trying to understand is that in 2005 when the product was rolled out to the US, had Depuy determined through testing what the safe level of Cr and Co ions were?
MF: I am not aware of one
Attorney: In 2007, that was the first time you were aware of the relationship between excessive wear and blood ion levels right?
MF: That is my recollection
Part Two continued in next post on litigation