A gyroscope-based system for intraoperative measurement of tibia coronal plane alignment in total knee arthroplasty

Coronal plane alignment in total knee arthroplasty (TKA) is an important predictor of clinical outcomes including patient satisfaction and device longevity. Radiography and computer assisted navigation are the two primary technologies currently available to surgeons for intraoperative assessment of alignment; however, neither is particularly well-suited for use in this increasingly high volume procedure. Herein we propose a novel gyroscope-based instrument for intraoperative validation of tibia coronal plane alignment, and provide initial analytical and experimental performance assessments. The gyroscope-based alignment estimate is derived from simplified joint geometry and verified experimentally using a custom tibial trial insert containing a consumer-grade inertial measurement unit (IMU). Average accuracy of the gyroscope-based tibia coronal angle estimate was found to be within ±1° in mechanical leg jig and cadaver testing. These results indicate that the proposed gyroscope-based method shows promise for low cost, accurate intraoperative validation of limb alignment in TKA patients. Integrating IMU technology into the TKA surgical workflow via low-cost instrumentation will enable surgeons to easily validate implant alignment in real time, thereby reducing cost, operating room time, and future revision burden