Background: Hyaluronic acid (HA) fillers have become the most popular tool for wrinkle treatment and volumization, although HA is generally absorbed within 6-12 months and requires repeated treatments to maintain the effects.
Methods: HA was injected onto the bone for volumization with a small 30-gauge needle to examine the long-lasting effects. Of the 63 Japanese patients with 97 treated sites followed up more than 12 months, 51 had HA injections for cosmetic purposes and 12 were treated for reconstructive volumization of facial deformity such as localized scleroderma and postsurgical bony deformity. Treated sites included the forehead, temple, nasal root, mentum, tear trough, and infraorbital sulcus.
Results: After long-term follow-up (12-93 months, mean = 21.6), persistent volumizing effects were observed in most patients. In fact, 86.6% of the treated sites showed >50% volume retention and 49.5% showed >75% retention. Magnetic resonance imaging analyses revealed that the injected space was well maintained, capsulated, and filled with heterogeneous content. Magnetic resonance imaging quantitative T2 maps indicated that much of the injected HA was replaced with other materials. Together with clinical inspection, these findings suggest that onlay injection of HA on the bone induced formation of capsule, fibrosis, and/or calcification/ossification, which contributed to persistent volumization.
Conclusions: Semipermanent volumizing effects can be achieved by HA injection if the target area has an underlying bony floor. Periosteal stem cells may be activated by HA injection and may contribute to persistent volumizing effects. This treatment may be a much less invasive alternative to fat or bone grafting.