Advanced Engineering 2018

Zimmer Cleared to Market Unique Composite Hip Implant

16 August 2002

Zimmer has received permission from the United States Food and Drug Administration to market the EPOCH(R) Hip Prosthesis, which, because of its unique combination of materials, closely mimics the bending stiffness of human bone.

""Zimmer uses a composite material approach to addressing the potential problems of stiffness associated with fully porous coated implants,"" said Ray Elliott, Chairman, President and CEO of Zimmer Holdings. ""This product has been in development for more than 10 years and during that time other competing designs have come and gone. We continued to focus on this work because we believe the EPOCH Hip has unique advantages.""

Orthopaedic surgeons have identified implant stiffness as a factor leading to a condition called ""stress shielding,"" where a patient's bone atrophies because it is not allowed to flex and twist due to the rigidity of a hip implant. Zimmer and other competitors have addressed this concern with various materials and design approaches, but the EPOCH Hip's unique design closely approximates the natural bone's bending and stiffness characteristics.

""The EPOCH Hip gives surgeons another powerful tool, particularly in the larger sizes, to address situations where stress shielding is a concern,"" said Elliott.

Due its composite construction, the larger sizes of the EPOCH Hip are 75% less stiff than a comparable cobalt-chromium (a common implant alloy) stem and 50% less stiff than a comparable titanium alloy implant. These implants have a cobalt-chromium alloy core surrounded by a flexible polymer material. The exterior surface is composed of a titanium fiber mesh that is designed to encourage bone ingrowth into tiny openings in the mesh. Smaller sizes of the EPOCH Hip are manufactured from a titanium alloy and have a porous titanium fiber surface, but do not have the polymer middle layer found in the larger sizes.

Zimmer has sold the EPOCH Hip in Europe for approximately eight years. Clinical trials in the United States began in 1994. Patient satisfaction levels in the trial remained very high during a six-year follow-up period following surgery. To date there have been no revisions or implant failures, and all implants showed bone ingrowth into the porous titanium surface.

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