Source: s3://data.kl3m.ai/documents/govinfo/USCOURTS/USCOURTS-azd-2_09-cv-00485/USCOURTS-azd-2_09-cv-00485-0/pdf.json

Nature of Suit Code: 365
Nature of Suit: Personal Injury - Product Liability
Cause of Action: 28:1332 Diversity-Product Liability

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NOT FOR PUBLICATION

IN THE UNITED STATES DISTRICT COURT

FOR THE DISTRICT OF ARIZONA

John Pearson; Stephanie Pearson, 

Plaintiffs, 

vs.

Wright Medical Technology, Inc., 

Defendant. 

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No. CV-09-0485-PHX-FJM

ORDER

The court has before it defendant’s motion for summary judgment and motion to strike

the testimony of Lester Hendrickson, Ph.D. (doc. 44), plaintiffs’ response (doc. 46), and

defendant’s reply (doc. 50). 

This is a products liability action involving the PROFEMUR® total hip replacement

system, a prosthetic hip implant manufactured and sold by defendant Wright Medical

Technology, Inc. On April 9, 2007, plaintiff John Pearson underwent left hip replacement

surgery, during which the PROFEMUR® prosthetic hip was implanted. The PROFEMUR®

implant is comprised of three separate components that are assembled together during

surgery: the femoral head, the modular neck, and the femoral stem. The allegedly defective

component at issue in this litigation, the modular neck, is manufactured from a titanium alloy

and is designed to be inserted directly into the metal femoral stem. On June 26, 2008, the

modular neck of plaintiff’s PROFEMUR® implant cracked and required replacement.

Case 2:09-cv-00485-FJM Document 53 Filed 07/22/10 Page 1 of 5
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Plaintiffs filed this action against Wright Medical Technology, alleging that the hip implant

was defectively designed and/or manufactured. 

A manufacturer is strictly liable for injuries caused by use of any product that was in

a “defective condition and unreasonably dangerous.” Dart v. Wiebe Mfg., Inc., 147 Ariz.

242, 244, 709 P.2d 876, 878 (1985) (quoting Restatement (Second) of Torts § 402A (1965)).

To establish a prima facie case of strict products liability, a plaintiff must show that, when

the product left the defendant’s control, it was in a defective condition that made it

unreasonably dangerous, and that the defect was the proximate cause of the plaintiff’s

injuries. Jimenez v. Sears, Roebuck & Co., 183 Ariz. 399, 402, 904 P.2d 861, 864 (1995).

Defendant now moves to strike the testimony of plaintiffs’ expert witness, metallurgist

Lester Hendrickson, Ph.D., contending that his opinions are neither relevant nor reliable. It

also seeks summary judgment, arguing that without Dr. Hendrickson’s testimony, plaintiffs

cannot establish their claim. 

The Federal Rules of Evidence allow expert testimony that will assist a trier of fact

in understanding the evidence or in determining a fact in issue, so long as “(1) the testimony

is based upon sufficient facts or data, (2) the testimony is the product of reliable principles

and methods, and (3) the witness has applied the principles and methods reliably to the facts

of the case.” Fed. R. Evid. 702. Under the framework developed in Daubert v. Merrell Dow

Pharm., Inc., 509 U.S. 579, 113 S. Ct. 2786 (1993), trial courts must serve as gatekeepers to

ensure that proffered testimony is both relevant and reliable. Id. at 597, 113 S. Ct. at 2799.

The test of reliability is “flexible.” Id. at 594, 113 S. Ct. at 2797. We may consider factors

such as (a) whether the theory or technique can or has been tested; (b) whether it has been

subjected to peer review and publication; (c) the known or potential rate of error; (d) the

existence and maintenance of standards controlling the technique’s operation; and (d) its

general acceptance within the scientific community. Id. at 593-94, 113 S. Ct at 2796-97.

The role of the courts in reviewing proposed expert testimony is “to make certain that an

expert, whether basing testimony upon professional studies or personal experience, employs

in the courtroom the same level of intellectual rigor that characterizes the practice of an

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expert in the relevant field.” Kumho Tire Co. v. Carmichael, 526 U.S. 137, 152, 119 S. Ct.

1167, 1176 (1999). “Our task, then, is to analyze not what the experts say, but what basis

they have for saying it.” Daubert v. Merrell Dow Pharm., Inc., 43 F.3d 1311, 1316 (9th Cir.

1995) (Daubert II). 

Defendant first argues that Dr. Hendrickson’s expert testimony should be excluded

as irrelevant and unreliable because it was based on his incorrect assumption that Mr.

Pearson received a traditional, non-modular hip implant during his April 9, 2007 surgery,

when in fact he had received a modular device, consisting of three separate components.

Defendant believes that this distinction is critical because, by assuming that the implant was

a single-piece device, Dr. Hendrickson failed to consider the possibility that the implant

cracked due to “fretting.” 

Fretting is a metallurgical phenomenon that occurs at metal-to-metal contact areas

placed under load stress and subjected to motion. DSOF ¶ 16. During surgery, the

PROFEMUR® neck is inserted into the femoral stem, resulting in a metal-to-metal interface.

The surgically implanted device is then repeatedly subjected to force and movement when

the patient ambulates. According to defendant, the development and progression of fretting

is affected by patient weight and activity level, surgical technique, patient bone structure, and

biochemical issues, but is unrelated to the manufacturing process. Motion at 6. Defendant

argues that because Dr. Hendrickson believed that Mr. Pearson received a single-piece

implant with no metal-to-metal contact, he incorrectly concluded that fretting was not

possible. Defendant contends that Dr. Hendrickson’s opinion is therefore irrelevant and

inadmissible. 

Dr. Hendrickson opined that the subject implant failed due to a premature fatigue

fracture resulting from a manufacturing defect. He observed through visual inspection and

the use of a scanning electron microscope (“SEM”) numerous microcracks on the surface of

the implant stem. He stated that such surface cracks act as stress concentrations and crack

initiation sites, and are known to cause fatigue fractures. He opined that these microcracks

“could only be present due to a manufacturing defect,” PSOF, ex. 1, ¶ 10, and that “the first

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phase of the fracture process is effectively manufactured into the stem.” DSOF, ex. G at 5.

Dr. Hendrickson acknowledged that he incorrectly identified the model of the

defective prosthetic, but stated that he would have reached the same conclusions even if he

had understood that the prosthesis was a modular implant with metal-to-metal contact. He

explained that he rejected fretting as the cause of the failed prosthetic because none of the

indices of fretting, including linear wear markings, debris, or pitting, was observed during

his inspection.

Defendant presents the rebuttal report of expert Brad James, Ph.D., who opined that

the subject implant exhibited no evidence of manufacturing defects. His report includes

photographs of the surface of the cracked implant neck, purportedly showing debris, pitting

and linear wear, thereby establishing that fretting had occurred. This conflicting evidence,

however, demonstrates that a genuine issue of material fact remains for trial. It does not

establish as a matter of law that plaintiffs’ claim is without merit. 

Defendant also contends that Dr. Hendrickson’s opinions are unreliable because they

are not based on any scientifically valid methodology. Defendant argues that Dr.

Hendrickson did not review any manufacturing or design history records, or performance

specifications, and contends that he knows nothing about the manufacturing process or the

condition of the device when it left defendant’s control. 

Evidence is admissible under Daubert if there is an accepted scientific method for

making a reliable measurement, even if the evidentiary significance of the measurement can

be disputed. Daubert, 509 U.S. at 595, 113 S. Ct. at 2797 (“The focus, of course, must be

solely on principles and methodology, not on the conclusions that they generate.”). 

Although defendant criticizes Dr. Hendrickson’s methodology as not demonstrating

scientific reliability, both parties’ experts employed the same techniques in evaluating the

failed implant. Both experts conducted a non-destructive analysis using visual and scanning

electron microscope (SEM)-based inspection, and energy dispersive spectroscopy. Dr. James

concluded that “[n]o defects were observed on the fracture surface that could have contributed

to fatigue crack initiation and growth,” and that “[e]xamination of the outside surface of the

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neck showed clear evidence of fretting.” DSOF, ex. K at 6. Dr. Hendrickson opined, on the

other hand, that he observed microcracks near the fracture origin and concluded, based on his

educational background and experience of more than thirty-five years analyzing failed

consumer products, including artificial hips and prosthetic implants, that these microcracks

are evidence of a manufacturing defect. DSOF, ex. G at 5. 

We are satisfied that Dr. Hendrickson’s opinion, while certainly subject to challenge,

is based on valid principles and is sufficiently probative to assist the trier of fact in evaluating

the issues presented in this case. 

Accordingly, IT IS ORDERED DENYING defendant’s motion for summary

judgment and DENYING defendant’s motion to strike expert testimony (doc. 44).

DATED this 22nd day of July, 2010.

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