high-tech hip implant for wireless temperature measurements in vivo高科技无线温度测量髋关节植入体内.pdfVIP

High-Tech Hip Implant for Wireless Temperature Measurements In Vivo ¨ Georg Bergmann, Friedmar Graichen*, Jorn Dymke, Antonius Rohlmann, Georg N. Duda, Philipp Damm ´ ¨ Julius Wolff Institute, Charite – Universitatsmedizin Berlin, Berlin, Germany Abstract When walking long distances, hip prostheses heat up due to friction. The influence of articulating materials and lubricating properties of synovia on the final temperatures, as well as any potential biological consequences, are unknown. Such knowledge is essential for optimizing implant materials, identifying patients who are possibly at risk of implant loosening, and proving the concepts of current joint simulators. An instrumented hip implant with telemetric data transfer was developed to measure the implant temperatures in vivo. A clinical study with 100 patients is planned to measure the implant temperatures for different combinations of head and cup materials during walking. This study will answer the question of whether patients with synovia with poor lubricating properties may be at risk for thermally induced bone necrosis and subsequent implant failure. The study will also deliver the different friction properties of various implant materials and prove the significance of wear simulator tests. A clinically successful titanium hip endoprosthesis was modified to house the electronics inside its hollow neck. The electronics are powered by an external induction coil fixed around the joint. A temperature sensor inside the implant triggers a timer circuit, which produces an inductive pulse train with temperature-dependent intervals. This signal is detected by a giant magnetoresistive sensor fixed near the