CFRP replaces UHMWPE in knee implants

Hinges in a newly developed knee replacement technology are made from carbon-fiber reinforced (CFR) polyetheretherketone (PEEK).

Aesculap, a division of healthcare supplier B. Braun Melsungen, is using  PEEK-OPTIMA CFR in its FDA 510k-cleared and CE-Marked EnduRo knee revision system.

Design engineers hope the use of carbon fiber, the same reinforcement that's used in the fuselage of the

The Aesculap EnduRo knee uses PEEK-OPTIMA carbon fiber reinforced polymer in all hinge mechanisms.

Boeing 787 Dreamliner, will overcome the major failure points in knee replacements: dislocation, wear and malpositioning associated with metal components.

"Working with Invibio provided us with both a material and processing solution package that enabled our accelerated time to market requirement," said Ulf Grimm, Aesculap product manager for knee endoprostheses.

Fast market penetration

According to Aesculap, the EnduRo knee has received strong European market reception, gaining a 14% market share in Germany during the first year of availability and with more than 2000 prostheses implanted to date. The first implantation of the EnduRo knee in the United States took place late last year.

In 2010, Millennium Research Group estimated that there were more than 90,000 knee revision surgeries performed in the US and Europe, indicating that some 8% of all knee implant procedures result from failure of the initial knee implant.   A contributing factor to these failures is dislocation, whereby the rotational axis slips out of its guide, requiring total replacement of the implant.

Better wear

CFR PEEK is intended to prevent dislocation compared to traditional hinge mechanism types that use ultra-high-molecular-weight polyethylene (UHMWPE). Invibio, the supplier of PEEK-OPTIMA, says that  CFR provides greater wear and cold flow resistance as well as dimensional stability during the lifetime of the device (greater than 15 years), which aids resistance to dislocation.

Grimm says these are the benefits of using the new composite:

  • Proven biocompatibility and biostability that provides safety and implant longevity,
  • Flexural strength similar to the cortical bone thus reducing stress shielding and improving patient comfort,
  • Excellent wear performance and creep resistance to prevent dislocation,
  • Processing and design flexibility that assists surgery planning and enhances patient mobility, and
  • History of use in FDA approved long term implantable devices for both patient and surgeon reassurance.

In 2011, Invibio Biomaterial Solutions was formed as a wholly owned subsidiary of Victrex plc to focus exclusively on the medical device market.




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