A Pose-Correction Method for Intraoperative Measurements in Total Hip Surgery

Background & Motivation of the Project:
Precise positioning and alignment of implants and surgical instruments are essential for successful outcomes in orthopedic surgery. This is especially true for minimally invasive procedures, which typically rely on mobile C-arm fluoroscopy for continuous, low-dose real-time assessment throughout the operation. While this imaging technique is popular for its versatility and real-time visualization, it has inherent limitations. These include a small field of view, difficulty in using 2D X-rays to assess complex 3D geometries, parallax and image distortion, and the absence of local scaling parameters—all of which can lead to inaccuracies in fluoroscopy-based assessments. Additionally, these techniques often require capturing the operative anatomy from specific angles through a trial-and-error process, which is highly sensitive to small changes in the position and orientation of the image intensifier, as well as the patient’s positioning and joint angles on the surgical table. Many of these variables are challenging, if not impossible, to control in the fast-paced surgical environment, leading to assessment inaccuracies. Ultimately, these challenges can compromise surgical outcomes, increase the risk of complications or disabilities, and may even result in costly repeat surgeries.

To address these challenges, Torus Biomedical is pioneering an innovative solution called the ConfirMap system. This system integrates seamlessly with the existing mobile fluoroscopy equipment in the operating room and uses advanced algorithms to generate bi-planar long radiographic views and measurements of the operative anatomy. By reconciling bi-planar views of the operative anatomy, the system can estimate the 3D pose and orientation of the anatomies in an approach that is least sensitive to non-idealities of the conventional fluoroscopy-based assessments. In collaboration with a leading spine company in the U.S., a version of the ConfirMap technology tailored for spinal surgery has recently been introduced to the market. Currently, the company is focused on incorporating an AI-enabled automated measurement layer to meet the requirements for use during orthopedic trauma and joint arthroplasty procedures. To support the development of this technology and benchmark its performance against alternative techniques, it’s essential to quantify the impact of intraoperative parameters on specific radiographic outcomes.

Project Objectives:
The proposed research will use computer simulations to study how different imaging and patient positioning factors affect measurements during various stages of minimally invasive hip replacement surgery. We will simulate hip replacement surgery on a group of virtual patients, modeled from CT scans, in a virtual environment. This will allow us to recreate surgical scenarios and generate digitally reconstructed radiographs (DRRs), while accounting for expected variations in the positioning of the imaging equipment, patient posture, and joint angles. As the first objective of the the project, we will use simulated radiographs and ground truth data to assess the accuracy and precision of conventional 2D radiographic measurements for key surgical parameters in total hip arthroplasty, such as cup alignment, leg length, and offset. As the second objective, we will perform the same analysis to evaluate the performance of the ConfirMap system, comparing it to ground truth data from CT scans. We hypothesize that various intraoperative factors can significantly reduce the accuracy and precision of conventional radiographic methods, making them unreliable during hip replacement surgery. In contrast, measuring the performance of the ConfirMap system could demonstrate its potential as a more precise and reliable alternative.

Opportunities for Skill/Career Development:
Through this project, the intern will develop a comprehensive skill set in medical imaging techniques, orthopedic biomechanics, and computer-assisted radiology and surgery. Working closely with the company’s engineering team, clinical collaborators, and academic co-applicants with subject matter expertise in orthopedic medical devices, medical image analysis, and computer vision, the intern will receive valuable mentorship and guidance throughout the project. The intern will gain hands-on experience, from conducting literature reviews to simulating various stages of hip surgery using computer tools. This immersive experience will enhance critical thinking, problem-solving, and collaboration skills as the intern addresses complex technical challenges. Additionally, participating in academic publications resulting from the project will boost the intern’s career development and academic credibility in the field. Overall, this internship offers a unique opportunity to expand knowledge, skills, and professional connections in a dynamic and impactful research environment.

Value for the Company:
This project will assist the company in advancing its core technology by testing, improving, and validating its performance in direct comparison with state-of-the-art methods. The results of the research will significantly aid the company in highlighting the shortcomings of existing techniques while demonstrating the value of its system to clinical users, strategic partners, and stakeholders. Furthermore, the outcomes of the research will be submitted to peer-reviewed scientific and clinical journals for broader dissemination and validation within the research community.