Silicon Nitride: Promising Improvements in Patient Value through Reduced Infection and Improved Osseointegration

Revision surgeries due to infection and failed osseointegration represent a significant burden across implantable biomaterial applications, including joint arthroplasty, spinal fusion, and dental restoration. Patients particularly suffer due to pain, secondary disease, loss of mobility, inability to work, and risk of further harm during revisions due to implant failure. Development of novel functional materials is one potential solution to reduce incidence of these implant failure modes. Silicon nitride, when employed as a monolithic device, coating, or composite inclusion, offers a potential to increase patient value through several routes. Due to its low atomic number constituents, it presents as radiotranslucent on X-ray radiographs, which allows the care provider to easily assess a device’s position while being able to clearly see tissue adjacent to and also behind the device. Artifact-free images are obtained under MRI due to the material’s low magnetic susceptibility. Further, favorable surface chemistry and elution of silicic acid are thought to be responsible for observed enhancements to bone cell activity upon exposure to silicon nitride. Clinically, spinal fusions have occurred in significantly shorter periods of time with silicon nitride devices relative those made from conventional biomaterials. Finally, silicon nitride has demonstrated an inherent ability to resist biofilm formation when challenged with a variety of orthopedically relevant bacteria. This is thought to be a consequence of its passive surface properties and local elution of ammonia at the implant-tissue interface. Imaging samples along with data from pre-clinical and clinical studies are presented to illustrate these biomaterial properties and provide context for a discussion of silicon nitride’s potential to drive improvements in morbidity, frequency of revision surgeries, and acceleration of desired outcomes, all of which strongly influence different aspects of value for patients, providers, and care organizations.