Split-Face Comparison of Two Hyaluronic Acid Fillers: Intersection of Rheology and Tissue Behavior in Midface Rejuvenation

Hyaluronic acid (HA) fillers are one of the most popular aesthetic treatments for midface volumization, achieving optimal aesthetic improvements. Given the variety of HA filler products available, it is important for injectors to understand how their rheological properties can influence behavior in tissues. To evaluate and compare (1) product integration and dynamic support and (2) lifting capacity of 2 rheologically different HA fillers (HA Contour [HACON] and HA Voluma [HAJVOL]) through ultrasound and clinical photography. Randomized, split-face study (n = 11) comparing 2 midface HA fillers over a 12-month period with initial injection along the zygomatic arch at Day 0 and optional touch-up at Month 1. Eligible patients were aged 22 to 65 years with midface volume loss and contour deficiency. Assessments included ultrasound (neutral and smiling), clinical photography with 3D volume change (lifting capacity) analyses, and adverse event reporting. Volume change was assessed at 2 regions: midface and infraorbital hollow (IOH). With similar average total injection volumes, both fillers had comparable lifting capacity in the midface (HACON: ≥2.07 mL and HAJVOL: ≥2.08 mL; P > .05) and IOH (HACON: ≥0.45 mL and HAJVOL: ≥0.57 mL; P > .05) areas for up to 12 months. Ultrasound showed that HACON integrated into the tissue, stretching and elongating during a smiling expression, whereas HAJVOL did not integrate as much, with aggregates consistent in size and shape during both neutral and smiling expressions through 12 months. No adverse events were reported during the study. HACON demonstrated a similar duration of lifting capacity (volumization) as HAJVOL but had more distributed product integration and flexibility to support dynamic expressions through 12 months.