Walking in new shoes with Parkinson's Disease

UD researcers help patients improve gait
April 3, 2013
A tester models an early prototype of the PDShoe. SOURCE UNIVERSITY OF DELAWARE

Parkinson's Disease robs patients of control. The disease can make it difficult to hold a glass, but it can also affect the way a person walks.

Some people with Parkinson's disease feel like their feet are glued to the ground; their brains fail to get the signal that one foot has landed on the ground and it's time to move the other. They fail to lift the second foot, sometimes slowing the pace of walking to a stop, explained Ingrid Pretzer-Aboff, UD assistant professor of nursing.

University of Delaware researchers are developing a shoe that will help patients with this problem, called freezing of gait, to walk more easily and stay active.

“The shoe is designed with three sensors on the foot. As you walk, the sensors at the heel, ball, and toe detect what phase of the gait you are in; this triggers a vibratory sensation,” says Sunil Agrawal, UD professor of mechanical engineering. The vibrations in the shoe signal the patient to move the foot, and it helps them walk more evenly, he said.

It's called the PDShoe and researchers say it shows promise in helping people who have gait-related symptoms.

Kyle Winfree, a doctoral student in UD’s Biomechanics and Movement Science program, said the researchers, including Agrawal and Ingrid Pretzer-Aboff, hypothesize that the sense of pressure may be diminished in Parkinson's patients.

“The basic sense of touch can be impaired, so detecting foot contact isn't as strong in Parkinson's patients,” Winfree said, meaning when a patient places his foot on the floor, it doesn't signal the body to move the trailing foot because the brain isn't sure the first foot is on the ground.

“Another hypothesis is that the vibrations in the shoe might act as a tactile cue to help synchronize the person's steps,” said Pretzer-Aboff.

The shoe is built using a common beach shoe, made of flexible mesh on top with a rubberized sole. But, the shoe is not meant to be worn on the beach, Winfree said.

It is slipped on, then the control electronics are attached to an elastic band placed around the person's ankle. Two small disk-shaped vibrators are placed against the feet. These are turned on as the person’s foot touches the ground.

So far, 80 patients have tested the new device. The group has been working on the project for three years and soon will be seeking volunteers to test the newest version of the shoe.

The PDShoe was developed with support from a University of Delaware Research Foundation grant and the U.S.-India Science and Technology Endowment Fund. Researchers are collaborating with the Parkinson’s community in Delaware and the neurology and physiotherapy faculty at the All India Institute of Medical Sciences in New Delhi to pilot test the PDShoe.

Agrawal told the story of one woman whose life was changed by the PDShoe. “She previously fell often and had particular difficulty navigating turns and crowds,” he said. “The shoe broadened her world – she was actually able to get out of the house and take a train to the institute to participate in the study.”

While the shoe cannot cure Parkinson’s, it could go a long way to help the more than 1 million Americans living with the disease enjoy a better quality of life, Pretzer-Aboff said.

“We are happy with the results of our first tests, and we want to move forward and work with people to improve their gait,” Pretzer-Aboff said. “There are many uses for the shoe. We hope to help those with Parkinson's certainly, but also others with balance problems.”

To view the University of Delaware research video on the PDShoe, go to For more information or to sign up as a volunteer in the Newark-based study, contact Dr. Ingrid Pretzer-Aboff at

What is Parkinson's

Nearly one million people in the United States are living with Parkinson's disease. The cause is unknown, and although there is no cure, there are treatment options such as medication and surgery to manage its symptoms. April is Parkinson's Disease Awareness month, designed to increase understanding of the disease and the people who suffer from it.

According to the Parkinson's Disease Foundation, the disease is caused by malfunctioning neurons in the brain. These nerve cells produce dopamine, a chemical that sends messages within the brain to control movement and coordination. As these cells die, a Parkinson's patient  can no longer control movement.

Primary motor signs of Parkinson’s disease include the following:

• tremor of the hands, arms, legs, jaw and face

• bradykinesia or slowness of movement

• rigidity or stiffness of the limbs and trunk

• postural instability or impaired balance and coordination

Parkinson's affects middle-aged and older Americans, but early-onset Parkinson's has been known to affect those as young as 30, including actor Michael J. Fox, who was diagnosed in 1991.

The foundation reports research published in the Jan. 8, 2013 issue of "Proceedings of the National Academy of the Sciences," reported Parkinson's Disease could be linked to pesticide use.

Scientists found a pesticide called benomyl, which was used in agriculture for 30 years, interfered with crucial enzymes in the brains of laboratory animals, causing serious health problems. The pesticide was banned in 2001 by the U.S. Environmental Protection Agency.

For more information and research on Parkinson's Disease, go to