Derek. The use of various 'modalities' over active growth plates (like ultrasound, laser, shortwave etc) has been listed for many years as a contraindication - though the direct evidence for such a listing is thin to say the least. There is the potential for an adverse effect rather than a known adverse effect (we are in the middle of looking at this topic right now as it happens). In theory, if you apply sufficient energy and it actually reaches the growth plate while it is in its active phase, it might be possible to change growth plate behaviour. Most of the experimental work in this area is (understandably) done on animal models (nobody is going to let us do the experiments on children eh?) and the doses that they are delivering to these very young animals in order to have an adverse effect are very high. I would suggest that there is no need to worry on this one. I would not go out of my way to hit the active growth plate with any external energy - but that is precautionary rather than because of a known adverse effect at therapy level doses in humans. Any help?????