Two recent federal cases illustrate important Daubert principles in the medical device context.

In Fuesting v. Zimmer Inc., 2009 WL 174163 (C.D. Ill., 1/26/09), the U.S. District Court for the Central District of Illinois, in an opinion by Chief Judge Michael P. McCuskey, found inadmissible plaintiff’s expert witness testimony that his knee implant failed due to alleged oxidation caused by the method Zimmer used to sterilize the product.  In contrast, in Jaske v. Zimmer Inc., 2009 WL 150946 (N.D. Ill., 1/20/09), the Northern District of Illinois reversed an earlier decision to exclude two expert witnesses for the plaintiff. On a motion for reconsideration, the court ruled that plaintiff can present testimony from two experts in polymer science as to why his prosthetic knee, manufactured by defendant Zimmer, allegedly failed.

Fuesting alleged he received the Zimmer-made implant in 1994. In 2001, he began experiencing pain in the knee, and his doctor removed the prosthesis in November of that year. Fuesting sued, alleging that Zimmer’s sterilization of the prosthesis by gamma irradiation in air (GIA) rendered it defective. At trial, his expert witness, Dr. Pugh, testified that GIA caused the prosthesis to oxidize and delaminate, resulting in premature failure. A jury returned a verdict for plaintiff, but the Seventh Circuit vacated the judgment after finding that Pugh’s testimony did not meet the requirements for admissibility of expert testimony under Fed. R. Evid. 702 and the standards set forth in Daubert.

Under Rule 702 and the Daubert standard, expert testimony must be both relevant and reliable. The district court must act as a “gatekeeper” making a preliminary assessment of the reasoning or methodology underlying the testimony. Daubert factors include: (1) whether the scientific theory can be and has been tested; (2) whether the theory has been subjected to peer review and publication; (3) the theory’s known or potential rate of error when applied; and (4) whether the technique or theory has been ‘generally accepted’ in the scientific community.

On remand, Fuesting proffered the testimony of a second expert witness, Dr. Rose. But the trial court found that Dr. Rose had not bridged the analytical gap between accepted principles and his complex conclusions. He had not, and could not, show that the prosthesis failed because of the sterilization method used. To bridge the gap, rhe expert needed to show, with respect to Fuesting’s implant in particular, what quantum of each variable is required to set the alleged causal chain reaction in motion. That is, the causation opinion must be specific to the plaintiff, and each chain in the causal link must be supported by adequate science. Gaps included how much radiation does it take to cause oxidation, and to what degree? How much oxidation must occur to render polyethylene more susceptible to delamination? And once polyethylene becomes more susceptible to delamination, how then does oxidation affect delamination? Are all forms of polyethylene, including that used by Zimmer (which the company claims to be oxidation-resistant), susceptible to delamination? What effect, if any, does implantation into the human body have on the rate of oxidation?

The expert testimony as to defect also failed. Oxidation can occur in implants sterilized by any method. However, plaintiff’s expert did not know of any peer-reviewed studies or articles that compared oxidation rates for implants sterilized by GIA to those sterilized through other methods. While the prosthesis showed significant oxidation when it was tested, that testing occurred more than six years after the knee joint was explanted, and plaintiff failed to account for oxidation that may have occurred after the joint was removed.

Having granted Zimmer’s motion to exclude the expert testimony, the court had no alternative but to also grant the company’s motion for summary judgment.

In Jaske, Plaintiff had his left knee replaced with a prosthesis to alleviate recurring pain. When the prosthesis allegedly failed, he filed suit against the manufacturer. Last year, the district court granted defendant’s motion to exclude the testimony of two of plaintiff’s experts in polymer science, who, while qualified to offer some opinions, used a test as the basis for their opinions that was not reliable. (A Fourier Transform Infrared Spectroscopy (“FTIR”)). Plaintiff moved for reconsideration.

The court had determined that the proffered testimony was unreliable for two reasons. First, the results of the FTIR test may have been skewed because lipids and proteins from Jaske’s body had permeated the product. And, second, even if the test results were accurate, they did not determine when the oxidation took place. Originally, plaintiff offered nothing but a naked expert opinion on this issue. On reconsideration, plaintiff presented new evidence that any biological material present would absorb the infrared spectrum used in the FTIR at a different frequency than oxidized polyethylene, and that the FTIR is the accepted standard of the American Society of Testing and Manufacturing for this purpose.

The court had also originally noted that the FTIR test measured the amount of oxidation present in the prosthesis only at the time the test was conducted. It did not provide historical readings. Plaintiff clarified that his experts developed their theory independent of the test results. Instead of relying on the FTIR results to arrive at their theory, they said, the FTIR simply provided support for it. In other words, the results of the FTIR are merely consistent with the theory. The theory that gamma irradiation sterilization in air causes oxidation has been recognized, asserted plaintiff, for some time in the scientific community.

This second case demonstrates one of the potential dangers of the Daubert challenge: if the court is going to give plaintiff a second bite of the apple, the Daubert motion turns into a roadmap for the plaintiff on what holes to fix.  See our post on reasons why you might not file a credible motion.