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PEEK Compound Replaces Titanium in Surgical Head Restraint Systems

03 June 2008

To solve material incompatibility problems in a surgical head restraint used during brain surgery, Performance Plastics (PPL), Cincinnati, Ohio used an RTP Company PEEK-based compound as a titanium replacement which met all the complex requirements of the device.

Incompatibility problems can arise when head restraints are made from magnetic materials. They can distort magnetic resonance (MR) brain scans. Computer tomography (CT) images become unrecognizable when magnetic components are employed. Titanium, although non-magnetic, can produce undesirable heat and be cost prohibitive to manufacture. The challenge was to find a viable alternative.

PPL worked with RTP Company on converting the head restraint assembly to plastic. Size limitations of the device and the high loads applied to it during surgery required a high strength-to-weight ratio. In addition to meeting the mechanical criteria, sterilization necessitated a chemically resistant material that could withstand high temperatures.

""A big hurdle with this application was that we needed a compound that was more highly modified than standard VICTREX PEEK grades because the head restraint system is composed of large parts with long flow lengths,"" said Ken Kelly, Engineering Manager at PPL. ""We asked the engineers at RTP Company to assist by optimizing the fibre loadings because of their superior additive technologies.""

RTP Company customized an RTP 2200 polyetheretherketone (PEEK) high flow carbon fiber reinforced compound. The material exhibits a tensile strength of 40,000 psi (276 MPa) and flexural modulus of 5.4 psi x 10E6 (37,233 MPa), meeting the stiffness and creep resistance requirements critical for titanium replacement while optimizing the fibre loadings for improved flow. The compound handles the extreme temperatures and harsh conditions of autoclave and gamma radiation sterilization.