A SENSOR-stuffed insole is helping people suffering from balance disorders
stay on their feet. By accurately profiling someone鈥檚 gait, the insole lets
physiotherapists home in on the right treatment鈥攚hich could be anything
from complete 鈥済ait re-education鈥� to a gentle course of t鈥檃i chi.
Balance disorders are a serious problem. Millions of people are thought to be
at risk of falls that could leave them seriously injured or disabled. Among them
are people with neurological disorders such as multiple sclerosis, those who
have lost the sensation in the soles of their feet because of diabetes, and
frail elderly people.
But discovering what makes people wobbly and whether a particular person has
a balance problem is far from clear-cut. Even experienced specialists often
disagree over who鈥檚 at risk. Now Jeff Hausdorff and his team at Harvard Medical
School in Boston have invented a gadget that should settle the arguments.
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The Harvard team has built a sole-shaped device that feeds data from an array
of pressure sensors into a digital memory. Slipped into a patient鈥檚 shoes while
they take a stroll, the gadget records key information about their gait, such as
how long the they take to swing their leg, and the amount this varies from step
to step.
After taking such data from 60 elderly people, Hausdorff monitored them for a
year to see if any of them had a serious fall. He was surprised by what he
found. 鈥淪peed wasn鈥檛 predictive of future falls, and shufflers can be OK,鈥� he
says. 鈥淚t鈥檚 people who have high variability in their gait who are at risk.鈥� So
people who look fairly unstable to their doctors may in fact be fine, and vice
versa.
Hausdorff says his dynamic sensor is ideal for helping reach a diagnosis,
because it鈥檚 able to detect subtle differences in gait caused by different
disorders. 鈥淚f people are falling it鈥檚 for a reason,鈥� he says. 鈥淭here may be an
underlying disease they can be treated for.鈥�
Other groups use different approaches to analyse gait. Lars Oddson and Peter
Meyer at Boston University use a pressure-sensitive platform to record pressure
changes when someone is asked to stand completely still
(快猫短视频, 14 April, p 26).
Meyer says the platform is a better source of data than analysing
the way people walk. 鈥淐ollecting moving data is less practical from a clinical
standpoint.鈥� Their technique can even measure how people react when a rug is
pulled from under them, Meyer says.
Like Hausdorff, Oddson and Meyer find that people who wobble on a timescale
of about a second are more stable than those who wobble more slowly, over
several seconds. 鈥淲e find people who are stiffer over the short period are less
stable over a longer period,鈥� Meyer says.
Both groups say that people who are told they鈥檙e at risk of a fall can help
themselves by doing certain kinds of exercise. Attempting to balance on a very
large rubber ball should help, while Hausdorff recommends a course in t鈥檃i chi.