Abstract
BACKGROUND: The long-term efficacy and safety of hyaluronic acid fillers injected into the neck have yet to be analyzed in a prospective trial in the United States. OBJECTIVE: Analyze the long-term efficacy and safety of a hyaluronic acid filler for static horizontal neck rhytids. MATERIALS AND METHODS: Twenty-six subjects were enrolled in the study. Six subjects were randomized to receive saline and 20 subjects were randomized to receive HA RR. All subjects were randomized to use a cannula on 1 side and needle on the other with optional retreatment on day 30 and optional crossover treatment with different assignment on day 60. The subjects were graded using the Transverse Neck Line Scale, Canfield photography, and the Global Aesthetic Improvement Scale on day 360. RESULTS: A significant improvement from baseline on day 360 was achieved on the Transverse Neck Line Scale according to the blind evaluator, subjects, and investigator without any delayed-onset or prolonged side effects. There was no significant difference in the average improvement from the short-term analysis on day 60 to the long-term analysis on day 360. CONCLUSION: HA RR achieved significant long-term improvement in static horizontal neck rhytids without any long-term side effects.