Chronic venous stasis ulcers, which typically occur at the ankle, are extremely difficult to treat and they have high recurrence rates after successful healing. A new patch that delivers ultrasound energy directly to the wound has been tested in a recent clinical trial and has shown to be quite effective in helping to heal venous ulcers.

Similar patches have been investigated in the past, but they operated at higher frequencies. Researchers at Drexel University, Philadelphia decided to investigate whether lower frequencies, in the 20 to 100 kilohertz (kHz) range, would be more effective. Turns out that the improvement was significant.  More details from the National Institutes of Health:

In an article to be published in the Journal of the Acoustical Society of America, the Drexel researchers report that patients who received low-frequency, low-intensity ultrasound treatment during their weekly check-up (in addition to standard compression therapy), showed a net reduction in wound size after just four weeks. In contrast, patients who didn’t receive ultrasound treatment had an average increase in wound size during the same time period.

In order to determine the optimal ultrasound frequency as well as treatment duration, the researchers treated patients with either 15 minutes of 20 kHz ultrasound, 45 minutes of 20 kHz ultrasound, 15 minutes of 100 kHz ultrasound, or 15 minutes of a sham (placebo) ultrasound. The group receiving 15 minutes of 20 kHz ultrasound showed the greatest improvement, with all five patients experiencing complete healing by the fourth treatment.

The team’s clinical findings were corroborated by their in vitro studies in which mouse fibroblasts —cells that play an active role in wound healing—experienced on average a 32 percent increase in cell metabolism and a 40 percent increase in cell proliferation compared with control cells 24 hours after receiving 20 kHz ultrasound for 15 minutes.

NIH: Ultrasound Patch Heals Venous Ulcers in Human Trial