This project, acquiring an instrument referred to as Biplanar (2D) Fluoroscopy System, aims to accurately measure kinematics. The instrument, currently the most advanced commercially available technology to record human skeletal motion, utilizes specialized software that can translate the measured data into images of high accuracy and resolution. In collaboration with existing computational research capabilities at the institution, the Biplanar (2D) Fuoroscopy System will be mainly used in the Human Dynamics Laboratory, thus stimulating an important expansion in biomechanics research at the home institution, along with the five other collaborating institutions and three clinical centers. The system is expected to be transformative to biomechanics research, both as a direct measurement instrument of previously unreported joint kinematics and as input to state-of-the-art computational models. Moreover, the resulting research is also expected to be comprehensive in the combination of experimental and modeling capabilities (whole-body motion, electromyography and force measurements and musculoskeletal, finite element, and probabilistic modeling). Accurate measurement of kinematics using the instrument should contribute to create scientific advancements in orthopedics and implant design, assistive technologies, understanding injury mechanisms, rehabilitation, and motor control of human movement.

Broader Impacts: The instrument can greatly impact the capability to improve patient outcomes. Given the clinical nature of the proposed work, new biomechanical designs and discoveries could translate into improving the quality of life for those suffering from health injuries. It also contribute to build an exceptional research and education environment for the institution, partner universities and the Rocky Mountain West. The acquired system will provide active learning and research experiences for students in STEM outreach programs, both undergraduate and graduate students, as well as medical students and clinical residents.

Project Report

The accurate measurement of joint motions in the human body is important to understanding the mechanisms of musculoskeletal diseases, improving orthopeadic treatments and developing safe and reliable medical devices. Osteoarthritis affects 17.5 million people in the United States and leads to more than 1 million total joint replacements in the U.S. each year, according to the American Academy of Orthopaedic Surgeons (AAOS). Osteoarthritis and joint replacement affect mobility and influence quality of life for the aging population. Still more patients are impacted by soft tissue injuries. To better diagnose and treat patients with these diseases and injuries, joint motion measurement with sub-mm accuracy is required. The current standard in biomechanical motion tracks reflective markers placed on a subject’s skin. These conventional methods are useful for whole body motion measurement, but they cannot achieve the necessary sub-mm accuracy due to skin motion artifacts. Fluoroscopy or dynamic radiography can measure the motions of bone with x-rays, but are limited by small fields of view and poor measurment accuracy for motions not parallel to the imaging plane. The objective of this Major Research Instrumentation (MRI) project was to realize a high speed stereo radiography system to accurately measure bone and joint motion while subjects perform a variety of activities. By imaging motions in two planes (stereo), the system has demonstrated the ability to track the translation and rotation of bony structures in six degrees of freedom with sub-mm accuracy. Serving as the centerpiece of the Human Dynamics Laboratory at the University of Denver, the system notably has large 16" field-of-view detectors and high-speed cameras which can record motion at speeds as high as 1000 frames/second. The system is configurable for imaging any part of the body, including knee, hip, spine, shoulder, ankle, foot, etc. Further, the system has been integrated with traditional motion capture, force plates and electromyography to develop unique biomechanical datasets combining whole body and local joint motion data with forces and muscle activation. The system has undergone a comprehensive calibration and validation process to ensure function and accuracy, and has been inspected and licensed by the state of Colorado. The realized system is one of five that exist in the United States, with fewer than ten in existence worldwide. The intellectual merit of the stereo radiography system is the unique and transformative orthopaedics research enabled. Measurement of joint motion with this high level of accuracy supports the exploration and discovery of previously unreported joint kinematics; the improved understanding can provide insight into the role of individual structures (e.g. meniscus, ACL ligament), injury mechanisms, rehabilitation and motor control of human movement. Further, the kinematic data has supported the development and validation of computational models of joint mechanics, which play an important role in the design and evaluation of implants and assistive technologies. Since coming online, data collected with the system has led to submission of 1 journal and 5 conference publications. There are currently 7 projects that have received institutional review board (IRB) approval and are underway with support provided by industry, foundation and internal grants. Federal grants proposing to use the system are currently in review. The broader impacts of the stereo radiography system are the benefits the improved understanding of kinematics can have for the research community and longer term to patient outcomes. The system has expanded the capabilities in the Center for Orthopaedic Biomechanics and strengthened the translational environment for research that merges researchers from multiple universities, clinicians and orthopaedic implant manufacturers. The system has already impacted the training and professional development of 2 post-doctoral researchers, 2 medical fellows, 5 graduate and 2 undergraduate students. Further leveraging the system, active learning exercises have been incorporated in multiple courses, including biomechanics, computational biomechanics and medical imaging, and an outreach summer camp (Making of an Engineer). In addition to being disseminated through publication, we have developed an open-source sharing site on that provides details of the system and videos of motions of the knee for educational purposes. For more information, please visit:

National Science Foundation (NSF)
Division of Computer and Network Systems (CNS)
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Rita Rodriguez
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University of Denver
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