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From Products Liability Law Daily, June 15, 2015

Negligence claims in Zimmer NexGen Knee bellwether case proceed to trial

By Susan Lasser, J.D.

A bellwether patient in the multidistrict litigation relating to a manufacturer’s knee implant devices could proceed with her negligence claims against the manufacturer because genuine issues of fact remained for a factfinder’s resolution, a federal district court in Illinois ruled. However, the patient could not maintain her strict liability claims against the manufacturer. The court also ruled on the admissibility of the testimony of certain of the patient’s experts. The patients in the multidistrict litigation alleged that the femoral and tibial components of the knee implant system were prone to premature loosening, resulting in pain and loss of movement, and, in some cases, necessitated revision surgery (In re: Zimmer NexGen Knee Implant Products Liability Litigation (Batty v. Zimmer, Inc.), June 12, 2015, Pallmeyer, R.).

Background. Kathy Batty’s (Batty) case is the first of three bellwether cases in the multi-district litigation relating to Zimmer, Inc.’s NexGen Flex Knee system. The patient (together with her husband, Thomas Batty) brought suit against Zimmer, Inc., Zimmer Holdings, Inc., and Zimmer Orthopaedic Surgical Products, Inc. (collectively, Zimmer), the manufacturers of the implanted knee replacement devices she received in April 2009 when she had both knees replaced in surgeries 2 weeks apart from one another. Batty’s treating physician implanted a NexGen LPS-Flex Gender Solutions femoral component and a NexGen Stemmed Tibial Component Option in each knee. The implant replaced the top part of the shin bone (the tibia) and the bottom part of the thigh bone (the femur). The design of the LPS Flex implants was an alteration of an existing product, the NexGen Complete Knee Solution (the “Standard” knee). Zimmer intended the new knee to allow patients to achieve higher flexion—i.e., a greater bend of the knee. The Standard knee only permitted flexion up to 130 degrees, but the LPS-Flex advertised a capability “of up to 155 degrees of active flexion.” The knee was intended to allow patients to engage in activities requiring greater flexion, such as squatting and kneeling. Batty’s job as a custodian for the U.S. Postal Service involved such activities. Batty understood that she was getting a knee for “active people.” During her recovery, the highest degree of flexion obtained by Batty that was recorded by her treating physician was 120 degrees in both knees.

Batty began to notice pain in both knees in July 2010. X-rays taken at that visit showed “some radiolucencies” indicating a change in bone densities surrounding the implant. Based on the x-rays, Batty’s treating physician was concerned that she was developing some loosening in the implants. A bone scan indicated this was likely. Batty saw other doctors and another orthopedic surgeon who concluded that her x-rays showed tibial loosening in both knees and that revision surgeries were necessary. He performed the revision surgeries in April and May 2011, implanting a DePuy LCS revision system in each of the patient’s knees. His surgical notes confirmed that both Zimmer tibial components were loose.

The patient filed suit in July 2012, alleging that Zimmer’s negligence in testing and designing the NexGen Flex knee increased the risk of both the femoral and tibial components prematurely loosening. She asserted that even if Zimmer was not negligent in its design and testing of the Flex knee, it was strictly liable for the injuries the knee caused. She also argued that Zimmer negligently failed to warn of the increased risks of loosening and requested compensatory and punitive damages for her injuries.

Experts. Batty presented the testimony of Dr. Thomas Brown and Dr. Joseph Fetto, who opined that the design of the Flex, when used at high degrees of flexion, increased the pressure on the implant, causing both the tibial and femoral components to loosen. Dr. Brown, a well-qualified expert in biomechanical engineering, identified several signature design features that, in his view, increased the risk of implant loosening when the design was used in high flexion, and could have been detected with proper testing. Dr. Fetto, an orthopedic surgeon, also opined that the NexGen Flex’s design increased the risk of aseptic loosening and that Zimmer’s testing was inadequate. Fetto also stated that Zimmer failed to provide adequate warnings about the risk of loosening in high flexion. Zimmer sought to exclude their testimony.

Daubert analysis: testimony mostly permitted. The court, assessing Drs. Brown and Fettos’ testimony under a Daubert analysis, denied the implant manufacturer’s motion to exclude Dr. Brown’s testimony, and also denied the request to exclude Dr. Fetto’s testimony, but only with respect to his rebuttal report to Dr. Darryl D’Lima, Zimmer’s expert. Otherwise, the court allowed the exclusion of Dr. Fetto’s testimony. The court found the methodology underlying Dr. Brown’s testimony was reliable and relevant. He relied on peer-reviewed literature and studies to form the basis of his opinions. The court rejected Zimmer’s arguments against the inclusion of Brown’s expert testimony, finding that its criticisms were best raised on cross-examination. Because it decided to admit Dr. Brown’s testimony, the court denied Zimmer’s motion to exclude all testimony relating to tibial loosening.

Dr. Fetto’s testimony was offered to establish that the NexGen Flex implant was defectively designed; that Zimmer inadequately tested the product before bringing it to market; that even with the inadequate testing, the manufacturer was on notice of a design defect and continued to market the high-flex knees; and that Zimmer’s warnings regarding the risk of aseptic loosening were insufficient. He relied on his understanding of the anatomy and kinematics of the knee, his review of published literature regarding total knee arthroplasties, and his review of Zimmer's internal documents and several depositions taken in the case. He criticized the Zimmer knee’s design, specifically the location of the tibial post in Zimmer's high-flex “Posterior Stabilizing” (PS) devices, which he said “forces loading onto the posterior margin of the tibial component” and reduces overall contact area between the femoral and tibial components. He said that the smaller contact area, combined with the higher compressive loads that occur during high flexion, produced a lift-off stress on the front of the tibial component, thereby straining the bond between the tibial component and the tibial bone. The court concluded that Dr. Fetto’s experience qualified him to offer opinions relating to biomechanical engineering and to provide limited evaluations of Finite Element Analysis (FEA) models (a type of computer model); and that he presented a reliable and relevant rebuttal to Dr. D’Lima's FEA model. Thus, the court denied Zimmer’s motion on that point. Although the court found that the remainder of his testimony was relevant, it could not discern any reliable methodology supporting Dr. Fetto’s opinions regarding the design defect, the risk of aseptic loosening, or the adequacy of Zimmer’s testing. The court, therefore, concluded that those opinions had to be excluded. Moreover, the court ruled that his opinions regarding the adequacy of Zimmer’s warnings also should be excluded because they were not based on sufficient facts. The court noted that it was not clear from his testimony that Dr. Fetto actually read the package inserts containing Zimmer’s warnings. The court also excluded his testimony as to the risks of loosening and the adequacy of Zimmer's testing.

Summary judgment. Because material issues of fact remained as to whether the patient achieved high flexion and as to whether the manufacturer acted negligently in its conduct related to the NexGen Flex design, based on Dr. Brown’s testimony critical of the two millimeter bone cut requirement in the knee system’s design, the court denied the knee implant manufacturer’s motion for summary judgment and partial summary judgment with respect to the patient’s negligent design theories based on femoral and tibial loosening, as well as the loss of consortium claim brought by the patient’s husband. Other remaining negligent design theories also could support a finding of liability and remained viable, the court said. In addition, the court granted the manufacturer’s motion for summary judgment on the patient’s claim premised on strict liability because the Pennsylvania Supreme Court, if presented with the issue, would not recognize the claim, according to the district court. The court rejected the patient’s argument that strict liability should attach to medical devices and not to prescription drugs. As to the patient’s failure to warn theory, the court reserved judgment because the question of whether the patient could present evidence associated with this theory was linked to other Daubert motions, which were still pending. The court also declined to rule on the punitive damages claim.

The case is No. 12 C 6279 (MDL No. 2272 (Master Docket No. 11 C 5468)).

Attorneys: Melissa Fry Hague (Anapol Schwartz) for Kathy L. Batty. Andrea R. Pierson (Baker & Daniels LLP), Charles Frederick Webber (Faegre Baker Daniels LLP), and Mark Gebauer (Eckert Seamans Cherin & Mellott LLC) for Zimmer, Inc.

Companies: Zimmer, Inc.

MainStory: TopStory DesignManufacturingNews ExpertEvidenceNews MedicalDevicesNews IllinoisNews PennsylvaniaNews

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