Initial mechanical properties of phosphate-glass fibre-reinforced rods for use as resorbable intramedullary nails

This paper investigates the use of novel phosphate- glass fibre-reinforced rods as resorbable intramedullary nails. Random and unidirectional fibres were moulded into composite rods by forging at ∼100 °C. Rods produced using non-woven random mats (RM) showed little improvement in mechanical strength over the unreinforced polylactic acid (PLA) rods. This was suggested to be due to the breakdown of the fibres during the manufacturing process; the length of the fibres decreased from 10-mm (initial) to ∼1.2 mm. Modulus and stiffness values for P50 RM rods were higher than those for the PLA rods which could be due to the orientation of the fibres during the rod manufacture process. Rods produced using long fibres parallel to the length of the rod displayed superior mechanical properties, not only against the PLA rods but also cortical bone. Maximum flexural, shear and compressive strengths were 242, 87 and 400 MPa, respectively. A flexural modulus of 25 GPa was achieved, with shear and compressive stiffness values of 6 and 21.5 kN mm ^-1, respectively. These unidirectionally reinforced phosphate glass fibre PLA composites have huge potential to be used as IM fixation devices.