According to this study, ultrasound can be used to stimulate the growth of bones in vitro. This is really cool and has some implications.
Physical therapy may be able to help a wider range of injuries in the future (such as fractures and the like) with ultrasound accelerated healing. However, too much ultrasound can be damaging.
More research needs to be performed on this because a new era of medicine lies beyond this door.
At the same time, stuff like this concerns me about how ultrasound could affect the ossification of fetal bones and otherwise affect fetal development.