REPETITIVE motion injuries are one of the fastest growing causes of lost time to business and industry, not to mention their impact on worker health and morale. The orthopedic surgery these injuries sometimes necessitate is costly and painful. The therapy and orthopedic implants associated with degenerative bone and muscle diseases and acute injuries are also costly, and in the case of implants, the initial cost may not be the final cost if and when the implant needs to be replaced.|
Computational models of joint anatomy and function can help doctors and physical therapists understand trauma from repetitive stress, degenerative diseases such as osteoarthritis, and acute injuries. Models of prosthetic joint implants can provide surgeons and biomechanical engineers with the analytical tools to improve the life-span of implants and increase patient comfort.1
With such purposes in mind, the Laboratory embarked about three years ago on a mission to model the whole human hand at high resolution. The challenge is that most biological structures are dauntingly complex, and the hand is no exception. The human wrist alone has eight bones, and the rest of the hand has 19 more, to say nothing of soft tissues--ligaments, tendons, muscles, and nerves--and the interactions among them.
More recently, the Laboratory's Computational Biomechanics Group within the Institute for Scientific Computing Research (ISCR) narrowed the mission to a computational model focusing on the dynamics of specific bones and joints that are often associated with injury or damage. The group also undertook a closely related endeavor: creating a computational model of prosthetic joint implants, initially for the thumb.
In light of the complexity of these models and the need for very high accuracy, it is appropriate that a facility like LLNL--which offers powerful computational resources, an understanding of complex engineering systems, and multidisciplinary expertise--take on these tasks. It is also significant that the work is being done collaboratively through the ISCR and draws on experts from the Laboratory (particularly the Mechanical Engineering Department), academia, medicine, and industry (see the box below). The NIKE3D modeling code, for example, which was developed at the Laboratory to address engineering problems involving dynamic deformations, such as the response of bridges to large earthquakes,2 is now being used as part of our collaborative joint modeling work.
Each person's bones differ in shape and size. Our models are based on the detailed anatomy of individual people. We start with high-resolution data obtained from computed tomography or magnetic resonance imaging, as shown in the illustrations below. Images from a single hand scan involve several gigabytes of raw data, and the models developed from them are highly complex--thus the need for powerful computers.
Focusing on the Hand and Knee
Collaborators in Biomechanics Modeling
ISCR biomechanics research is collaborative in the broadest sense. At Livermore, we work with experts in computer vision, mechanical and electrical engineering, nondestructive evaluation, health care technology, health services, and with visiting scholars and students. Partners outside the Laboratory include:
University of California, Berkeley
University of California, San Francisco
University of California, Davis
University of California, Santa Cruz
University of New Mexico
Institute for Math and Computer Science, Hamburg, Germany
G. W. Long Hansen's Disease Center
Louisiana State University Medical Center
Massachusetts General Hospital
Children's Hospital, San Diego
ArthroMotion/Avanta Orthopedics, Inc.
Orthopedic Biomechanics Institute
National Highway Traffic Safety Administration
Wright Medical, Inc.
XYZ Scientific Applications, Inc.
Key Words: biomechanical modeling, finite-element modeling, Institute for Scientific Computing Research (ISCR), NIKE3D, prosthetic point implants.
1. Modeling the Biomechanics of Human Joints and Prosthetic Implants, UCRL-TB-118601 Rev. 1, Lawrence Livermore National Laboratory, Livermore, CA (1995).
2. Energy & Technology Review, UCRL-52000-95-9/10 (September/October 1995) is devoted to a series of articles on computational mechanical modeling, including NIKE3D.
3. For more information on finite-element modeling using massively parallel processors, see "Frontiers of Research in Advanced Computations," Science & Technology Review, UCRL-52000-96-7 (July 1996), pp. 4-11.