A Trajectory Measurement System And Algorithms For Unicondylar Knee Replacement Surgery

The success of the Unicondylar Knee Arthroplasty (UKA) surgery generally depends on whether the implantation of the single compartment knee prosthesis is appropriate. The trajectory of the femoral prosthesis relative to the gasket is an important factor in judging an appropriate implantation. In this paper we propose an UKA trajectory measurement system which includes the pressure sensors array, the data processing part and transceivers. The data is transmitted wirelessly and displayed on the screen in real-time. The algorithm for determining the maximum pressure point and trajectory fitting is put forward, in which a pressure distribution model with distance as the weight is established. According to this model, the number of the sensors used to calculate the maximum pressure is reduced significantly and the initial solution of the maximum point of pressure is obtained. The surrounding pressure sensors are then used to verify and solve the exact solution of the maximum point of pressure with the basic idea of machine learning. Finally, the improved least squares method is used to fit the trajectory of the maximum points of pressure. From the simulation results, we can find that the computational complexity of the algorithm is reduced and the calculation speed is improved compared with that based on finite element analysis or cubic spline interpolation, which meets the real-time requirement. Moreover, the algorithm in this system is easily to be realized in hardware in future work.