Advanced Manufactured Fused Filament Fabrication 3D Printed Osseointegrated Prosthesis for a Transhumeral Amputation Using Taulman 680 FDA

Presented here is a thermoplastic Fused Filament Fabrication 3D printed osseointegrated upper limb prosthesis for average adult transhumeral amputation with mechanical properties greater than upper limb skeletal bone. The prosthesis is designed with a one step surgical process, large cavities for bone tissue ingrowth for greater stability, made of a polyamide six-based material that has an elastic modulus less than skeletal bone, and can be 3D printed for user-specific sizes if needed. The design is an improvement upon the current two-part osseointegrated prosthetics that are composed of a fixture and abutment. This prosthetic requires two invasive surgeries for implantation and is made of titanium, which has an elastic modulus greater than bone. An elastic modulus greater than bone causes stress shielding and over time can cause loosening of the prosthetic. The material was first characterized to establish how percent infill and layer height affected the strength of a printed part. The results showed unique and unexpected results than what would have been predicted. Tension samples showed a stabilization period before failure, and shear samples had a unique parabola curve instead of a linear trend in data. Mechanical results of the new prosthetic design include maximum tensile pullout force of 6568.33N and 5256.37N in bending in a simulated implantation environment. The prosthesis can also be seated or torqued between 0.50Nm and 4.00Nm before failure occurs for a tight-fitting prosthetic for attachment. The work presented here shows that a 3D printed prosthetic attachment device can be made stronger than bone and how 3D printing can impact the medical field.