The Beverly Hills Rhinoplasty Surgery Blog published a worthwhile critique of a 2007 report — published in the Archives of Dermatology — that claimed that the injection of crosslinked hyaluronic acid fillers, such as  Restylane and Juvederm, stimulated new collagen production. A new study looked at the injection of Radiesse and found no increase in collagen production.

Peyman Solieman, MD, and Jason Litner, MD, FRCSC, write:

We decided to review both papers to see if we could find the source of the discrepancy, and we think we may have. It seems that those who cite the original Restylane paper may not have noticed that, in the study, volunteers had an entire syringe of Restylane injected in one small area identified on the forearm. One to three separate sites were injected this way and then samples were taken that showed increased collagen production. Why is this important?

Simply put, this study does not make a lot of sense for at least 2 reasons. First, and most important, no one injects an entire syringe of Restylane into one designated area. It is generally used in the face to fill in wrinkles distributed over some distance. Since the doctors propose that mechanical stretch is the reason they think new collagen production is induced, we now can discern that it would take a whole lot of Restylane to be injected into any one area of the face to allow for collagen production. Not only would this likely be cost prohibitive, but it would also counter normal aesthetics. Second, the study used the forearm of participants to examine the effects, and we know that skin from different areas of the body respond differently to injection of these fillers.

Read it all.