Amedica has made its first complex, three-dimensional structures by a 3D printing process called Robotic deposition, or Robocasting which is is a freeform fabrication technique for dense ceramics and composites that is based on layered deposition of highly colloidal slurries. The final products have been confirmed for integrity and validity of the 3D printing method and have been shown to achieve similar theoretical density and microstructure attributed to the traditionally manufactured silicon nitride fusion devices currently in use with advantages in bone fusion, antibacterial behaviour and superior strength.
Source: http://www.medicalplasticsnews.com/news/technology/silicon-nitride-robocasting-medical-applications/