Magnesium alloy wires as reinforcement in composite intramedullary nails

A promising group of biomaterials assigned for the production of intramedullary nails are composites with a polylactide (PLA) matrix, reinforced with wires made of magnesium alloys and carbon fibres. The paper describes the effect of the composition of magnesium alloy wires, their number and orientation in the composite, as well as their connection with differently directed long carbon fibres, on the mechanical properties and the degradation rate of the obtained intramedullary nails. Among the tested implant prototypes, the best mechanical characteristics and a gradual and uniform course of magnesium alloy wires were exhibited by the PLA+CF1D+MgI composite nails (with a unidirectional orientation of carbon fibres and an axially oriented single Mg alloy wire). The strength of these nails became gradually decreased with the incubation time, which should allow for a gradual loading of the bone. In the case of the PLA with only magnesium alloy wires (without carbon fibres), the increase of the number of wires, on the one hand, stimulates the improvement of the nails' strength, yet on the other hand, a higher content of magnesium alloys in the PLA matrix affects the nails' faster resorption.