An additively manufactured locking fixation system for potential application in patient-specific implants

This study introduces a novel technique to implement a locking hole system into AM patient-specific implants without the need of additional post-processing steps such as mechanical machining. This has the potential to decrease the time and cost of manufacturing these implants, providing surgeons with an additional option, that is better suited in cases where the underlying bone is already weakened or bone porosis is an inherent risk. A commercially available locking system was chosen and replicated using high-resolution X-ray CT. A biocompatible material, 316L stainless steel was used to print specimen on a L-PBF machine in different orientations. The specimen were heat treated to tune the mechanical properties to enable the locking system to work. The accuracy of the printed holes was confirmed using a nominal/actual comparison between the original and printed holes. The strength of the system was evaluated by measuring the force needed to push the screw out of the locking plate. The 316L stainless steel samples, when annealed to tailor hardness, performed similarly to the commercial system. This included different build orientations that suggest the locking system can be included in AM implants without the need for additional post-processing steps.