Graduate engineers design a 'smart' ankle brace to reduce falls of the elderly

By Kendall Madden

One in three individuals over the age of 65 will fall in the next year. One fall in 200 will result in a broken hip. One-half of seniors who break a hip never regain their full degree of mobility, and one-quarter die within six months. Falls account for $26 billion in medical costs each year.

Graduate engineering students working with Thomas Andriacchi, professor of mechanical engineering and orthopedic surgery, recently developed a "smart" ankle brace for the elderly to correct imbalances and prevent falling. The Stanford Biodesign Innovation Program sponsored the interdisciplinary project.

Students Tim Ramsey, Ryan McDonnell, Buzzy Bonneau, Tejas Mazmudar, Jeremy Dittmer and Surag Mantri started working on the project during Winter Quarter 2005 as part of a two-quarter course, Medical Device Design, taught by Andriacchi. On the first day of class, students heard from researchers about critical technological needs in the health care industry. Professor Paul Yock (Medicine and, by courtesy, Mechanical Engineering) and Ken Martin (Biodesign) proposed the need for a device to reduce falls in the elderly.

"The ability to detect and prevent falls would not only cause a significant cost savings in health care, but would greatly improve the comfort and lifestyle of this growing segment of the population [the elderly]," wrote the research team in a comprehensive 89-page report they compiled for their project.

Falls among the elderly are often due to decreasing proprioceptionthe awareness of your body's relationship to its surroundings. Studies have found that sensitivity to foot position declines as people age. The researchers conceived that a device that could help simulate this lost sensitivity could help individuals maintain their balance without relying on cumbersome support devices, such as walkers, or ineffective devices, such as canes.

Their invention is an ankle brace containing a smart chip that continuously monitors the roll of the ankle. If the chip detects a roll that is greater than normal, it provides a correctional vibration. This vibration helps the wearer change position or shift balance to avoid a fall in much the same way that sensory nerves provide correctional feedback to the brain.

"The development of the device is still at a preliminary stage and more testing, research and funds need to be invested before commercialization is possible," said Surag Mantri, a bioengineering master's student working on the project. His team hopes that the brace will eventually become available to all people over the age of 65, but they plan to target high-risk groups first: diabetics with peripheral neuropathy, Parkinson's patients and people with high degrees of proprioceptive loss.

Kendall Madden is a science-writing intern at Stanford News Service.