This project is being undertaken by Alloyed to develop and promote innovation for orthopaedic implants. This is achieved through a dual approach of new alloy development and structural functionality, with specific consideration of lattices enabled by additive manufacturing (AM).
The high stiffness of currently adopted implant materials and cage structures can result in stress shielding and excessive bone resorption and prevent effective bone formation.
Alloyed carried out a 3-month sheep in-vivo study to determine the effects of implant cage stiffness on bone ingrowth with due consideration of improving both material stiffness and the structure of the implant cage.
Alloyed’s strut implants were shown to promote bone ingrowth.
Increase strength / modulus ratio
Lower absolute modulus
Higher fatigue resistance
Higher fracture stresses than vertebrae
Pores to promote both colonization and vascularization
Improve AM processability
Alloyed designed and built a series of lattice geometries to optimize mechanical properties and biological response of the new alloys.
Larger pores with thick struts > better mechanical properties (fatigue)
Smaller pores with thin struts > better biological properties (cell adhesion)
Three alloys have been identified for further atomization, characterization and performance evaluation with AM for optimal balance.
Voronoi lattices with different strut thicknesses.
Mechanical testing was carried out to assess lattice performance with respect to key design variables and their impact on performance.
A higher relative density leads to greater strength and stiffness. The modality and distribution of the pores did not influence the strength/stiffness ratio. Lattices with minimum angle of 10 degrees and maximum of 90 degrees (most isotropic) had the best strength-stiffness ratio.
A series of new alloys were designed using Alloyed’s computational ABD® platform
These alloys showed improved absolute Young’s Modulus and strength/stiffness ratios
Alloyed designed a series lattice topologies and demonstrated their printability
Lattices showed high potential for targeted mechanical and biological response