Loose skin on lower back. Which procedure is better for skin tightening: Renuvion vs Morpheus8?

a picture would have been very helpful here. The answer depends on whether or not there is some residual pockets of fat in the loose skin. If there are pinchable pockets of fat in the loose skin, i would recommend coolsculpting for the removal of the residual fat, followed by morpheus starting at one month after the coolsculpting for skin tightening after fat removal

Morpheus 8 is a non-invasive skin and soft tissue tightening treatment that is consistently amazing in our patients. We use the Morpheus to exact fractional induced RF into the skin or tissue in order to tighten collagen and stimulate contraction of the tissue. For acne scars, it is quite useful to build collagen in patients who have atrophic scars but is not very productive for ice-pick scars which require TCA Cross. For tissue tightening, Morpheus is ideal for the face and neck and we often combine it with CO2 laser or Ultherapy to further enhance results. Chemical peels and skin resurfacing should be done at least 5 to 7 days after, but can be performed earlier, depending on treatment severity. Avoid exfoliating skin treatments before Morpheus and expect a period of 2-4 weeks for skin contraction to set in.

Best,
Dr. Karamanoukian
Realself100 Surgeon

Depends exactly where on your back and how loose to determine the best plan, so you should be seen in person to discuss your goals, but Renuvion and morpheus are not comparing apples to apples. Renuvion is a device that requires a stab incision and tigthens from under the skin. Morpheus is radiofrequency microneedling. The better comparison would be Bodytite (which is Inmode's device that is more like renuvion in how it functions) to renuvion. My preference is bodytite and morpheus together in most situations.
You should know, the FDA has issued a warning on the use of the Renuvion device for aesthetic skin tightening, which you can read if you google "fda renuvion"