That is an excellent question. In my experience, I have found thermage to be the best treatment for the crepiness and laxity under the belly button. I can provide you with a basic science answer as a comparison.
First thermage is FDA approved for skin tightening, if you look at the FDA clearance on Velashape, it is indicated for dermal heating, not skin tightening. Thermage is also a stronger machine, working at the highest Mg Hz on the market for a RF device. Being that thermage is monopolar it is able to work deeper into the skin to effect change, thereby penetrating at least 4.2 mm into the skin, while velashape at its max is 1.5mm. Since the Dermis, which is the main collagen structure of your skin is deeper than 1.5 mm it makes more sense to utilize the machine that treats the dermis.
Hope that helps!
