Abstract

Objectives: Calcium hydroxylapatite is well-established as a biostimulatory agent for skin tightening and improving skin quality. While there are histologic studies detailing the tissue response to hyperdilute CaHA, objective imaging studies to characterize the effect of such treatment on the overlying skin are lacking. This study reports on observed changes in ultrasound appearance of the skin components following treatment with hyperdilute CaHA in the neck and correlation to clinical changes. Introduction: Calcium hydroxylapatite (CaHA) is a well-established biostimulatory filler, previously shown to stimulate collagen and elastin production. While there are histologic studies detailing the tissue response to hyperdilute CaHA, objective ultrasound imaging studies to characterize the effect of such treatment on the overlying skin are lacking. Changes in dermal and subdermal echogenicity and thickness have been previously found to correlate with aging and solar elastosis. We report on changes in these components after biostimulatory treatment with hyperdilute CaHA. Materials / method: A total of 4 patients were treated with 2 syringes of hyperdilute CaHA in the neck and submentum over 2 treatment sessions, spaced two months apart. Ultrasound imaging was done using an L4-20 MHz linear probe. Imaging timepoints include baseline as well as 2, 4, and 6 months. Change in thickness and echogenicity for the upper and lower dermis and subcutaneous fat was assessed, and effect of treatment on the subepidermal low-echogenic band (SLEB) monitored. These imaging assessments were carried out alongside clinical assessment of laxity, using the neck skin laxity improvement (NSL) scale. Results: Ultrasound imaging of the treated area following injection with CaHA permitted measurement of upper and lower dermis thickness, echogenicity, and assessment of SLEB prominence over time after treatment. Ultrasound findings and their relationship with clinical findings (NSL scale) are discussed. Conclusion: Hyperdilute CaHA is an important treatment option for managing skin laxity in the neck and submentum. These findings provide further mechanistic support for the positive clinical outcomes observed in real-world patients as well as the case series patients discussed herein.