Paper number 430

FATIGUE PROPERTIES OF CF/PEEK CORTICAL BONE SCREWS PRODUCED BY COMPOSITE TRANSFER SQUEEZE FORMING (CTSF)

Tognini R.¹, Loher U.², Peter Th.¹, Raschle R., Mayer J.¹, Wintermantel E.¹

1Biocompatible Materials Science and Engineering
Swiss Federal Institute of Technology, ETH Zürich, 8952 Schlieren, Switzerland
2EMPA (Swiss Federal Laboratories for Materials Testing and Research); Dübendorf, Switzerland

Summary

The Composite Transfer Squeeze Forming (CTSF) [10, pp.109-112] allows the processing of high volume fraction composites with thermoplastic matrix. Cortical bone screws (CTSF-3.0) and specially designed screws with a rod-like design (CTSF-3.5) have shown promising mechanical properties. The 3-point bending strength of a 3.0 mm core diameter CTSF-3.0 screw is 700 MPa compared to 900 MPa (F 0.02) for a similar screw made out of commercially pure titanium. For fatigue, the CTSF-screws have shown better performance than Titanium screws, being much less notch sensitive. Compared at 500'000 cycles, Titanium screws achieved approx. 12%, CTSF-3.0 60% and CTSF-3.5 90% of the static load.

Keywords

net-shape processing, composite transfer squeeze forming (CTSF), fastener, screw, PEEK, carbon fibre, implant, translaminar screw fixation.