"It's got a wee strap and that goes round where the break was," he explained.
"I put some gel on the probe and then I just put the probe inside the strap and then just basically leave it for 20 minutes. There's no sensation at all, it's completely painless."
Mr Denham's injury was so severe that there was a chance it would never heal and might eventually have to be amputated.
After ultrasound treatment, he was back on his feet within months.