8:02 a.m., Dec. 16, 2008----More than 700,000 Americans experience a stroke each year, and many are left with abnormal gait patterns afterwards. A subject-specific walking simulation under development at the University of Delaware may soon make it possible for tailored treatment programs to be developed for stroke patients with gait abnormalities.

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The work is supported by a five-year, $1.6 million grant from the National Institutes of Health to collaborate with Simbios, the Center for Physics-based Simulation of Biological Structures, at Stanford University.

Simbios provides infrastructure, software, and training to help biomedical researchers understand biological form and function as they create novel drugs, synthetic tissues, medical devices and surgical interventions.

Led by Jill Higginson, assistant professor of mechanical engineering at the University of Delaware, the study will use open-source software available through Simbios to investigate the relationships among altered muscle morphology, muscle activation, and muscle coordination during walking after stroke.

The UD team also includes Thomas Buchanan, professor of mechanical engineering and deputy dean in the College of Engineering; Stuart Binder-Macleod, chairperson of the Department of Physical Therapy and Edward L. Ratledge Professor of Physical Therapy; and Darcy Reisman, assistant professor of physical therapy, as well as several graduate students and postdoctoral researchers.

“One of the things we want to determine,” says Higginson, “is whether reductions in muscle force and joint torque following stroke are the result of muscle atrophy or impaired activation -- in other words, does the problem lie in the muscle itself or in the message being sent to the muscle from the brain?”

The researchers will gather data using a variety of experimental measurements, including MRI, strength testing, twitch interpolation techniques, and gait analysis.

They will then apply the Simbios toolkit (www.simtk.org) to develop simulations based on the data collected from subjects.

Higginson explains that models have traditionally been built using parameters based on healthy adult male subjects. “The problem is that we're not sure whether the conclusions we're drawing are applicable to an impaired population,” she says. “Our ultimate quest is to determine what factors are limiting gait speed so that appropriate rehabilitation strategies can be designed for these patients.”

“As we augment the open-source simulation software with data specific to our subjects, we'll post it, creating a global community for this work,” she continues. “In addition, we'll get expert feedback on the use of the software from the team at Stanford.”

The findings of the new study will also be applied to other ongoing work in gait retraining at the University of Delaware. “We're very excited about this work,” Higginson says. “We expect these simulations to lead to customized clinical treatments.”

Article by Diane Kukich