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

摘要

Pelvic fracture reduction surgery (PFRS) has always been one of the most challenging procedures in trauma orthopedics. Excellent preoperative planning is crucial for surgery, especially with the increasingly mature robot-assisted surgical systems. However, current preoperative reduction planning heavily relies on surgeons’ experience. This paper proposes an automatic preoperative planning framework for PFRS. Firstly, an enlarged RRT <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^\ast$</tex-math> </inline-formula> (ERRT <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\ast)$</tex-math> </inline-formula> algorithm is proposed to search feasible paths, which adopts a synchronized exploration and asynchronous adjustment strategy in 6D space to change the position and orientation of fragments during the reduction process. Secondly, a collision detection method based on surface point cloud is proposed to improve the safety of the reduction path by taking into account the actual volume of fragments. Finally, a post-processing method combining path shortening (PS) algorithm and cubic spline interpolation is proposed to optimize and smooth the reduction path. The clinical case simulation results show that the ERRT <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^\ast$</tex-math> </inline-formula> algorithm can find a feasible reduction path within a few seconds ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$&lt;$</tex-math> </inline-formula> 10s), and the length of the path is reduced by an average of 11.11% with the PS algorithm. Furthermore, repeated experimental results demonstrate that the method has good consistency. The proposed preoperative planning method can serve as a powerful tool to provide references for surgeons and also provide a quantitative basis for robot-assisted PFRS. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —This work addresses the challenge of automating preoperative planning for pelvic fracture reduction surgery, specifically in determining the target reduction pose and operative path for repositioning the fragment. The motion of the fragment is decoupled into translation along a point and rotation through the coordinate system of that point to quantify the difference between the initial pose and target pose and determine the planning requirements. An enlarged RRT <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^\ast$</tex-math> </inline-formula> algorithm based on six-dimensional generalized coordinates is proposed, combined with an efficient collision avoidance algorithm, to quickly find a safe and feasible reduction operation path. The proposed planning method not only provides guidance to physicians but also establishes a basis for robot-assisted fracture reduction surgery.