3D-printed ceramic-based partial Implants for knee hemiarthroplasty

Cartilage or meniscal injuries, which can result from trauma or joint deformity, lead to a change in the distribution of load in the joints and consequently cause osteoarthritis. These patients might benefit from hemiarthroplasty using partial implants as a less invasive surgical procedure yielding faster rehabilitation. Knee arthroplasty and post-surgery time frequently facing various problems, e.g., failure mechanisms at the implant/cartilage interface and revision operations mainly induced by infection, bone resorption, and implant loosening. As the number of patients with cartilage injuries increases, there is a need for alternative partial implant materials that would enable better joint movement and offer a long-term solution. In the proposed CeraKnee project, we aim to develop a pre-industrial ceramic-based implant material that significantly inhibits local microbial infections. This will be achieved with nanocoating of raw ceramic powder and 3D-printed onto an additive high-density zirconia-alumina mixture to provide long-term antibacterial activity. Additive Manufacturing (AM) is the leading technology for such implants, finally allowing individualized implants for patient-specific bone defects. The antimicrobial activity will be systematically tested in vitro, determining the optimal therapeutic window for the nano-additive amount. To close the innovation circle, we will also determine the long-term wear behavior at the bone/implant interface, considering biotribological surface characteristics to optimize. The development of such materials for partial implants involves several steps and validation procedures. The project CeraKnee will end at Technology Readiness Level TRL 4 " Technology validated in lab", since the preparation of surface modified powder with silver nanoadditive still requires technology development of this novel concepts. Optimization of 3D-printing process parameters for manufacturing zirconia-alumina macroporous structures and tribological investigations was performed only on the metal implant and bovine cartilage samples. To sum up, the combination of various advanced technologies such as additive manufacturing and ultrapure nanoparticle technology will allow the development of innovative material constructs for making a step towards ideal implants for cartilage reconstruction. The consortium is highly complementary, involving a company in 3D-printing technology and four research partners with expertise in materials development and processing, cell-material interface optimization, and in vitro biological characterization. Moreover, this way of manufacturing implant materials opens the door to eliminating sensitive production devices such as clean rooms and the abandonment of chemicals. In this manner, resources can be spared, and toxic waste could be significantly reduced.