Mechanical and biological behaviour of additive manufactured biomimetic biodegradable orthopaedic cortical screws

Purpose The complications caused by metallic orthopaedic bone screws like stress-shielding effect, screw loosening, screw migration, higher density difference, painful reoperation and revision surgery for screw extraction can be overcome with the bioabsorbable bone screws. This study aims to use additive manufacturing (AM) technology to fabricate orthopaedic biodegradable cortical screws to reduce the bone-screw-related-complications. Design/methodology/approach The fused filament fabrication technology (FFFT)-based AM technique is used to fabricate orthopaedic cortical screws. The influence of various process parameters like infill pattern, infill percentage, layer height, wall thickness and different biological solutions were observed on the compressive strength and degradation behaviour of cortical screws. Findings The porous lattice structures in cortical screws using the rapid prototyping technique were found to be better as porous screws can enhance bone growth and accelerate the osseointegration process with sufficient mechanical strength. The compressive strength and degradation rate of the screw is highly dependent on process parameters used during the fabrication of the screw. The compressive strength of screw is inversely proportional to the degradation rate of the cortical screw. Research limitations/implications The present study is focused on cortical screws. Further different orthopaedic screws can be modified with the use of different rapid prototyping techniques. Originality/value The use of rapid prototyping techniques for patient-specific bone screw designs is scantly reported. This study uses FFFT-based AM technique to fabricate various infill patterns and porosity of cortical screws to enhance the design of orthopaedic cortical screws.

Automated summary

This study used additive manufacturing technology to fabricate orthopaedic biodegradable cortical screws and observed the influence of various process parameters on their compressive strength and degradation behavior. The findings showed that porous screws enhance bone growth and osseointegration with sufficient mechanical strength. The compressive strength of the screw is inversely proportional to its degradation rate.