It speeds up healing
All day long our bones undergo a process called remodeling, which keep the bones healthy by fixing small breaks, all the time.
Remodeling, bone healing, is slower when there's no stress
on the bone when it is immobilized: when you can't walk on it, or when it's in a cast
and you can't move it. Ultrasound acts like stress on a bone and tricks the bone into growing.