People wearing prosthetic devices often suffer from the fact that limbs to which these devices attach can swell and and shrink throughout the day due to activity and dietary intake. Fitting the sockets to accommodate for this natural phenomenon could significantly improve the comfort and usability of prostheses. To this end researchers at University of Washington have developed a device that can measure and monitor the fluid volume of limbs inside prosthetic sockets while they’re being worn.

The device consists of electrodes attached to the skin and a processing unit the size of a cigarette pack that records the readings throughout the day. The monitoring system is already being tested in Seattle and San Francisco, and is to be used to test vacuum powered prosthetic sockets that inflate and deflate depending on the current needs of the user.

Researchers are testing the device by asking patients to go through a routine that includes sitting, standing and walking as the device records fluid changes. In the UW lab, Bailey does a series of 90-second exercises while wearing the portable device. Data is transmitted wirelessly to a tablet that displays the changes in his limb size about 15 times a second.

In the near term, researchers hope clinics could go through a similar routine to help track an individual’s swelling and shrinking patterns.

Longer term, researchers want to build a smaller device that patients could wear for a couple of weeks or longer to monitor changes in their limb size as they go about their daily routines.

The hope is that prosthetic limb sockets will become more robust and flexible, accommodating natural changes in swelling without causing discomfort or inconvenience.

This summer the team will work with patients across the U.S. and Canada who use vacuum-suction technology to help keep their residual limbs snug in the sockets and adjust the fit when tissues swell and shrink. Patients say this vacuum can help improve socket comfort and reduce pain, but the technology requires careful maintenance and it can be disruptive when the noisy vacuum turns on.

University of Washington: Pain of artificial legs could be eased by real-time monitoring