The biomechanical behavior of 3D printed human femoral bones based on generic and patient-specific geometries

Abstract

Background: Bone is a highly complex composite material which makes it hard to fnd appropriate artifcial surro�gates for patient-specifc biomechanical testing. Despite various options of commercially available bones with generic geometries, these are either biomechanically not very realistic or rather expensive. Methods: In this work, additive manufacturing was used for the fabrication of artifcial femoral bones. These were based on CT images of four diferent commercially available femoral bone surrogates and three human bones with varying bone density. The models were 3D printed using a low-budget fused deposition modeling (FDM) 3D printer and PLA flament. The infll density was mechanically calibrated and varying cortical thickness was used. Compression tests of proximal femora simulating stance were performed and the biomechanical behavior concerning ultimate force, spring stifness, and fracture pattern were evaluated as well as compared to the results of commercial and cadaveric bones. Results: Regarding the ultimate forces and spring stifness, the 3D printed analogs showed mechanical behavior closer to their real counterparts than the commercially available polyurethan-based surrogates. Furthermore, the increase in ultimate force with increasing bone density observed in human femoral bones could be reproduced well. Also, the fracture patterns observed match well with fracture patterns observed in human hip injuries. Conclusion: Consequently, the methods presented here show to be a promising alternative for artifcial generic surrogates concerning femoral strength testing. The manufacturing is straightforward, cheap, and patient-specifc geometries are possible. Keywords: 3D printing, Fused-deposition modeling (FDM), Biomechanical testing, Femur