Effects of environmental ageing on the static and cyclic bending properties of braided carbon fibre/PEEK bone plates

The use of titanium and steel bone plates to fix fractured limbs can create problems due to stress shielding, bone resorption and subsequent refracture. Here, braided carbon fibre reinforced poly-ether-ether-ketone (CF/PEEK) was evaluated as a possible implant material that could reduce these problems. CF/PEEK bone plates were aged in a simulated body environment for up to 12 weeks and then mechanically tested in 3 and 4-point bending tests. Sample mass increased by around 0.3 wt.%, yet bending stiffness and strength remained unchanged. Scanning Electron Microscopy (SEM) showed no changes in failure modes with age. Braided CF/PEEK shows an excellent resistance to fatigue failure even after prolonged ageing, easily surpassing the fatigue life of commonly used stainless steel alloys such as 316L. In addition, CF/PEEK had half the stiffness of steel for the same static strength, which would reduce stress shielding. Together, the results suggest that CF/PEEK is a highly suitable material for bone plates and should be further investigated for this application.