Automated 3D geometric reasoning in Computer Assisted joint reconstructive surgery

Abstract

Computer Assisted Orthopedic Surgery (CAOS) employing information and computer graphics technologies for preoperative planning, intraoperative navigation, and for guiding or performing surgical interventions, has received very little attention for bone tumor surgery applications. We have developed a CAOS system called OrthoSYS, driven by geometric reasoning algorithms to visualize tumor size, shape, and plan for resection according to the tumor's spread, starting from a 3D model reconstructed from CT images. Anatomical landmarks on bone are automatically identified and labeled, useful for registering patient model with virtual model during surgery and also as a reference for tumor resection and prosthesis positioning. The thickness of bone stock remaining after tumor resection is automatically analyzed to choose the best modular stem and fix the prosthesis. A method for prosthesis components selection using fuzzy logic has been developed to assist the surgeons. The medial axis of the long bones and anatomical landmarks are used for positioning the prosthesis in virtual planning and verification in the intraoperative stage. A set of anatomical metrics have been developed to measure the effectiveness of the prosthetic replacement of bone.