The STIIM UP Protocol: Exploratory Evaluation of the Potential of Combined Calcium Hydroxyapatite, Hyaluronic Acid, and Botulinum Toxin A in Neck Rejuvenation.

Background/Objectives: Cervical integument aging is a complex, multifactorial process characterized by thinning dermis, loss of elasticity, and platysmal band prominence. Multimodal treatments targeting these distinct anatomical layers simultaneously remain limited. This study aimed to evaluate the clinical efficacy, safety, and rejuvenation potential of the STIIM UP Protocol, a single-session treatment combining calcium hydroxyapatite (CaHA), hyaluronic acid (HA), and botulinum toxin type A (BoNT-A) for neck rejuvenation. Methods: This prospective, open-label, exploratory clinical study enrolled 13 healthy women (n = 13) presenting with cervical laxity. The STIIM UP suspension was delivered bilaterally into the subdermal plane of the anterior neck region using a retro-injection fanning technique with a 22G cannula at Day 0 (D0). Evaluated outcomes included the IBSA Neck Grading Scale, Global Aesthetic Improvement Scale (GAIS), FACE-Q module scores, and high-frequency ultrasound (USG) tissue thickness measurements at baseline and Day 120 (D120). Safety was monitored throughout. Results: The median consensus IBSA scores decreased significantly from 4.0 at baseline to 2.0 at both D30 and D120 (p-value < 0.01), indicating a rapid and sustained reduction in laxity. At D120, the GAIS responder rate reached 100% according to independent evaluators and 90.9% based on patient self-assessments. Quantitative USG confirmed statistically significant bilateral tissue thickening across the epidermis, dermis, and subcutaneous strata (p-value < 0.05). Progressive, clinically meaningful improvements were captured via the FACE-Q scales. No local or systemic adverse events were observed. Conclusions: The STIIM UP Protocol is a safe and effective multilayer intervention that successfully achieves comprehensive neck rejuvenation, bridging immediate clinical enhancement with sustained, tissue-proven structural remodeling.