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Stroke is the leading cause of long-term disability worldwide. Most stroke survivors experience problems with mobility, which increases their risk of falling. Stroke survivors fall at least 7-times more often than healthy elderly persons—up to 80% fall within the first year—and they fall frequently.

Falls can result in broken bones; damage to soft tissues—muscles, ligaments, or tendons; or head injuries. Breaking a hip is common, especially on the impaired side, and many people cannot get up after they fall.

Injuries and pain caused by frequent falls lead to a fear of falling, so people stay home and walk less, which affects physical health and limits social interactions and community participation.

Current fall management strategies include interventions to improve balance, strength, vision, sensation and proprioception, cognition, and nutrition—including medications to reduce fracture risk. However, these strategies do not reduce the risk of falls after stroke.

Reducing Injuries from Falls


An alternative to preventing a fall is to prevent serious injuries if someone falls. One way to do this is through use of padded hip protectors, usually worn in pockets in specially designed underwear, to cushion the hip. However, the padding is not sufficient to mitigate the forces generated during a fall, and hip protectors can move—so they no longer protect the hip or actually increase the risk of other injuries. They can also be uncomfortable—so people don’t wear them.

Next Steps


In this study, we propose to study active hip protectors—smart airbags, worn unobtrusively and comfortably under clothing, that can inflate to protect the hip when a fall is detected.

We will work with the Wolk airbag (WOLK, The Netherlands), a smart system that was designed to mitigate falls in elderly people. The system can detect when a fall is happening, and deploy the airbags before the person hits the ground. The airbags are reusable, weigh only about 14 ounces, and connect via Bluetooth to a smartphone, which allows monitoring of activity and fall data.

WOLK Airbag
WOLK Airbag

We will work with Wolk, and our collaborator, Dr. Heike Vallery at the University of Delft, to modify the airbag system for stroke survivors and then test the system to see if it reduces injuries when people fall. We will also monitor people’s activity levels using a smartphone app, to see if they are more active when wearing the device, indicating a reduced fear of falling. 

Study Personnel


Arun Jayaraman, PT, PhD (Principal Investigator)
Heike Vallery, Dr-Ing


The contents of this webpage were developed under grants from the National Institute on Disability, Independent Living, and Rehabilitation Research (NIDILRR grant numbers 90RE5014 (2013-2018) and 90REGE0003 (2018-2023). NIDILRR is a Center within the Administration for Community Living (ACL), Department of Health and Human Services (HHS). The contents of this webpage do not necessarily represent the policy of NIDILRR, ACL, or HHS, and you should not assume endorsement by the Federal Government.

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