Computer-Assisted Automatic Preoperative Path Planning Method for Pelvic Fracture Reduction Surgery Based on Enlarged RRT* Algorithm

Pelvic fracture reduction surgery (PFRS) has alwaysbeen one of the most challenging procedures in trauma ortho-pedics. Excellent preoperative planning is crucial for surgery,especially with the increasingly mature robot-assisted surgi-cal systems. However, current preoperative reduction planningheavily relies on surgeons' experience. This paper proposes anautomatic preoperative planning framework for PFRS. Firstly,an enlarged RRT & lowast;(ERRT & lowast;)algorithm is proposed to searchfeasible paths, which adopts a synchronized exploration and asyn-chronous adjustment strategy in 6D space to change the positionand orientation of fragments during the reduction process. Sec-ondly, a collision detection method based on surface point cloud isproposed to improve the safety of the reduction path by takinginto account the actual volume of fragments. Finally, a post-processing method combining path shortening (PS) algorithmand cubic spline interpolation is proposed to optimize and smooththe reduction path. The clinical case simulation results show thatthe ERRT & lowast;algorithm can find a feasible reduction path withina few seconds (<10s), and the length of the path is reducedby an average of 11.11% with the PS algorithm. Furthermore,repeated experimental results demonstrate that the method hasgood consistency. The proposed preoperative planning methodcan serve as a powerful tool to provide references for surgeonsand also provide a quantitative basis for robot-assisted PFRS. Note to Practitioners-This work addresses the challenge ofautomating preoperative planning for pelvic fracture reductionsurgery, specifically in determining the target reduction pose andoperative path for repositioning the fragment. The motion of thefragment is decoupled into translation along a point and rotationthrough the coordinate system of that point to quantify thedifference between the initial pose and target pose and determinethe planning requirements. An enlarged RRT & lowast;algorithm basedon six-dimensional generalized coordinates is proposed, combinedwith an efficient collision avoidance algorithm, to quickly finda safe and feasible reduction operation path. The proposedplanning method not only provides guidance to physicians butalso establishes a basis for robot-assisted fracture reductionsurgery.