Efficacy of Diluted Calcium Hydroxyapatite Filler for Neck Rejuvenation: A Pilot Study on Single-Session, Short-Term Outcomes

Background: Calcium hydroxyapatite (CaHA) fillers are widely used in esthetic medicine for skin rejuvenation; however, their efficacy and safety for neck rejuvenation remain underexplored.

Objective: To evaluate the clinical efficacy and safety of a diluted CaHA filler for improving skin barrier function, hydration, elasticity, and wrinkle severity in the neck.

Methods: This 4-week prospective, single-center pilot study involved 10 volunteers aged 19–70 years with a horizontal neck wrinkle severity (HNWS) score of 2 or higher. A total of 4.8 mL of CaHA filler (VoLassom) mixed with normal saline (1:2 ratio) was injected into the subdermal layer of the neck using a 28-gauge needle across 24 points (three horizontal lines and eight points per line). Clinical outcomes, including transepidermal water loss (TEWL), skin hydration, elasticity, and HNWS, were assessed at baseline and at 2 and 4 weeks after treatment.

Results: Nine participants completed the study. TEWL decreased significantly from 8.07 ± 1.53 g/m²/h at the baseline to 6.11 ± 2.17 g/m²/h at week four (p = 0.001), reflecting improved skin barrier function. Skin hydration increased from 57.72 ± 7.17 AU at the baseline to 64.78 ± 4.27 AU at week 4 (p = 0.01), and elasticity parameters (R2, R5, and R7) showed significant improvements (p < 0.05). The HNWS score decreased from 2.44 ± 0.53 at the baseline to 1.00 ± 0.00 at week 4. No significant adverse events were observed.

Conclusion: Diluted CaHA filler is a safe and effective option for neck rejuvenation, significantly improving skin barrier function, hydration, elasticity, and wrinkle severity within a short observational period.