Implanted wireless sensing for monitoring joint replacements

Post-operative failures of joint replacement can only be detected by MRI after 50 microns of displaced positioning. Surgeons need to be alerted of failure earlier, while this displacement is as small as 10 microns. This document details the specifications of an implanted wireless sensor system, which utilises cylindrical wireless, externally powered sensors implanted within orthopaedic knee replacements, to monitor health complications over time. The wireless sensor uses an electromagnetic wave to measure the distance from the sensor to the bottom plate of the knee replacement. This distance is monitored regularly via an external reader device which reports the data and any complications to the clinician. This system allows wireless, non-invasive monitoring of the health of the implant, to eliminate the need for invasive procedures such as surgery. This initial implementation is designed specifically for knee replacements, but can be applied in the future for other joint replacements. This document will support the development of a prototype for the implanted wireless sensor system, along with further testing and final implementation.