Ultrasonic pain relief device -- boon or scam?

Factual Questions
1

My 86 year old mother has had painful chronic tendinitis that hasn’t responded to treatment from her doctor. My brother suggested we buy her this gizmo to help relieve the pain:

Sonic Relief Portable Pain Therapy System

My BS radar went to 11 when I first saw it, especially since it costs $249. I found one clinical study that appears to test ultrasonic pain relief, but I cannot parse the medicalese, or even if it is applicable to this particular device.

Does anyone have any links to clinical studies on this technology?

2

I’d be pretty leery of a cheap ultrasound device sold for home use, but I have had ultrasound treatments for neuromas in my feet. They did seem to have some effect on the sensations I was having.

Some links:

As I understood it, the machines used in a clinical setting do have the risk of causing damage to the tissues (by overheating them?) which is why they weren’t sold for home use. IANAD but I’d bet the unit you saw doesn’t have enough “oomph” to do all that much if it’s low-powered enough to be sold OTC.