A Portable Pressure and Force Line Trajectory Measuring System for Unicondylar Knee Arthroplasty

The pressure and force line trajectory of the distal femoral prosthesis relative to the prosthesis gasket are key factors in judging the appropriate position of implants in unicondylar knee arthroplasty (UKA) surgeries, which is critical to the success of UKA surgeries. In this paper, we propose a portable pressure and force line trajectory measurement system, which includes a pressure sensors array, an analog-to-digital converter (ADC), and a microcontroller unit (MCU). Data from twenty sensors is obtained through time-sharing scanning and transmitted to the host computer through the USB interface. We put forward an algorithm to calculate pressure value and fit the force line trajectory for better accuracy. Both the pressure value and force line trajectory are calculated and displayed on the screen of the host computer by developed software in real-time. The experiments results show that the root mean square error of fitting force line trajectory in the experiments is ±0.342mm, which has 63% reduction compared with that in the previous work, and the average pressure value measurement error is 10.03%. Besides, the pressure sensors array, the ADC and the MCU in the system are integrated in a portable handle, which is easier for clinic trial.Clinical Relevance—This system can assist doctors to improve the success rate of unicondylar knee arthroplasty and reduce patient’s pain.