Comparative evaluation of sparse and minimal data point cloud registration: A study on tibiofemoral bones

An accurate bone registration is a crucial step in Computer-assisted Orthopaedic Surgery (CAOS) to estimate the relationship between a preoperative patient's bone model and the actual position during surgery. A-mode ultrasound and motion capture system is a new promising non-invasive technique to determine the bone's 3D pose. The main challenge with such a system is the sparsity of the measurement; it could trap the optimization, which minimizes the registration error, in the local minima. In this paper, we aim to find the registration algorithm that could provide enough surgical navigation accuracy. Several registration algorithms were compared using Monte Carlo simulations. The number of points and placement sensitivity were also investigated while keeping the practical aspect of the system. With 15 points, Unscented Kalman Filter (UKF)-based registration with 6D similarity vector showed superior to the other examined algorithms in minimizing the transformation error. In terms of balancing the accuracy and the equipment availability, the simulation showed that points needed to be dispersedly placed; 15 points were sufficient to register the femur, but 20 points were required to register the tibia. Beyond this number, the registration error hardly improved and will therefore be used to base our number of sensors on.