Researchers at the University of Wisconsin-Madison have developed a wearable device that can non-invasively measure tendon tension when wearers are engaged in physical activity. The technology could help researchers to measure and understand the forces that act on muscles during movement. These data are useful for scientists designing treatments and prostheses for patients with gait disorders. Measuring tendon tension could also indicate whether an injured tendon has healed sufficiently to allow for normal activity.
“Currently, wearables can measure our movement, but do not provide information on the muscle forces that generate the movement,” said Darryl Thelen, a researcher involved in the study.
To address this, the researchers developed a new way to measure tension in muscle tendons. The technique involves placing a small wearable on the skin over a tendon. The device lightly taps the tendon approximately 50 times per second, initiating waves that travel along the tendon. Two miniature accelerometers measure the wave speed along the tendon.
By looking at how these vibrational characteristics change during activity, the researchers can calculate tendon tension during movement. “We’ve found a way to measure the vibrational characteristics – in this case, the speed of a shear wave traveling along a tendon – and then we went further and determined how we can interpret this measurement to find the tensile stress within the tendon,” said Thelen.
So far, the researchers have tested the device on the patellar, hamstring, and Achilles tendons in volunteers, and observed differences in the tendons when the wearers changed their speed or step length. The technology could help clinicians to plan more effective treatments for injured patients or those with musculoskeletal disorders.
“We think the potential of this new technology is high, both from a basic science standpoint and for clinical applications,” said Thelen. “For example, tendon force measures could be used to guide treatments of individuals with gait disorders. It may also be useful to objectively assess when a repaired tendon is sufficiently healed to function normally and allow a person to return to activity.”
See an in-depth video about the project below.
Study in Nature Communications: Gauging force by tapping tendons…