The effect of combined of hyaluronic acid dermal filler and microfocused ultrasound treatment: A clinicopathological study.

[OBJECTIVES] Microfocused ultrasound (MFU) and hyaluronic acid (HA) filler injection are increasingly popular aesthetic procedures. HA filler injection is generally recommended after MFU if combined treatment is required in a single visit. However, data regarding the safe and optimal time of MFU treatment after HA injection is still limited. The purpose of this study was to evaluate the degree of HA loss when performing MFU treatment after dermal filler injection.

[METHODS] Fourteen subjects were recruited in this pilot study. HA was injected intradermally on four 2 × 2 cm areas at the abdomen (0.25 ml/site). Site A was served as control whereas site B, C, D were treated with MFU using 1.5 mm transducer at 60 min, Day 14, and Day 28 after the injection, respectively. All experimental sites were biopsied using a 3-mm punch biopsy to evaluate the histopathological profile at baseline and Day 56. Grading of the quantity of retained HA was evaluated by a blinded experienced dermatopathologist.

[RESULTS] All 14 subjects completed the study. One subject has been excluded due to the poor quality of histopathologic slides. Seven subjects (53.9%) at site B and 6 subjects (46.2%) at site C had HA loss at Day 56 compared with baseline. The mean HA grading at baseline and Day 56 was 3.7 vs. 2.8 (p < 0.001) at site B and 3.7 vs. 3.0 (p = 0.001) at site C, respectively. There was no statistical difference between the mean HA grading at baseline and Day 56 at site D (3.7 vs. 3.3, p = 0.073). No inflammation or granuloma was observed on Day 56 of the study.

[CONCLUSIONS] MFU treatment after HA injection appears to be safe. However, some degree of HA loss was observed if MFU treatment was done within 2 weeks after HA injection.