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. This less invasive surgical procedure aims to replace only the medial or lateral compartment yielding faster rehabilitation and better function of the knee. Partial implants have two components, a sliding cap that covers a compartment of the medial/lateral cartilage, which can be found between tibia and femur of the human leg and a fixation device (screw), which is embedded in the bone. Knee hemiarthroplasty and post-surgery time are frequently facing different 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 long-term solutions.
In the CeraKnee project, we are going to develop a pre-industrial ceramic-based implant that significantly inhibits local microbial infections. This can be achieved with nanocoating of raw ceramic feedstock. The antimicrobial powder will be applied for functionalizing different ceramic feedstocks, and 3D-printed for providing long-term antibacterial activity. Additive Manufacturing (AM) is the foremost technology for such implants, finally allowing us to obtain individualized implants for patient-specific bone defects. The antimicrobial activity we will systematically test 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 due to micromotions caused at the bone/implant interface in order to optimize the biotribological surface characteristics of the implant in terms of material composition and 3D-printing process parameters. Since the project aims to provide a complete hemi implant 3D-printed ceramic-based solution, the performance of the 3D-printed alumina, zirconia and an alumina-zirconia mixture will be evaluated as material for the articular cap via biotribological experiments against bovine cartilage.