The choice between cannulas and needles for dermal filler injection has direct implications for safety, efficacy, and patient experience. This narrative review synthesizes evidence from randomized controlled trials, observational studies, cadaveric/anatomical work, and expert consensus to compare complication profiles and practical use-cases. Across multiple studies, cannulas—by virtue of their blunt tips and gliding technique—are associated with lower rates of bruising and a reduced signal for vascular occlusion in high-risk, vessel-dense regions, while also improving patient comfort and downtime. However, cannulas are not inherently risk-free: arterial wall penetration and ischemic events remain possible with improper plane selection, excessive injection pressure, or inadequate anatomical control. Needles retain advantages for precise, focal periosteal or ligamentous support and for select micro-bolus indications. Publication bias and heterogeneous endpoints likely underestimate true complication rates for both devices. Guided by anatomy and procedural goals, a tailored approach is recommended: preferential cannula use for broad, low-pressure distribution in vessel-dense areas; needle use for targeted structural points with strict low-volume, low-pressure technique. Ultrasound guidance further enhances plane confirmation and vascular avoidance. We conclude that device selection should be individualized to region, indication, and operator skill, coupled with slow injection, minimal aliquots, and ongoing training to optimize patient safety and outcomes.

Eyelid sagging is a frequent concern among aging patients, yet achieving noticeable improvement with noninvasive methods remains challenging. This prospective cohort study evaluated the efficacy and safety of high-intensity focused ultrasound (HIFU) for improving upper and lower eyelid sagging. Thirty-four Korean women (aged 31–67 years) with mild to moderate eyelid laxity underwent a single session of HIFU (ULTRAFORMER MPT) using a 2.0-mm, 4-MHz probe, delivering 120 shots to the periocular region. Outcomes were assessed at 12 weeks via a four-point scale rated by blinded clinicians and patients. Eyelid length was measured using standardized photography. Mean eyelid length decreased by 0.94 ± 0.34 mm (p < 0.0001). Clinical improvement was reported by 76 % of patients and recognized by clinicians in 59 % of cases. The mean scores for overall improvement, eyelid tightening, and crow’s feet reduction were 2.25 ± 0.3, 2.10 ± 0.4, and 1.95 ± 0.3, respectively. Mild pain and erythema were the only reported side effects, resolving within 3–4 days. HIFU is a safe and effective noninvasive option for improving both upper and lower eyelid sagging, with high patient satisfaction and minimal adverse effects.

Injectable biostimulatory agents such as poly-L-lactic acid (PLLA), polycaprolactone (PCL), and calcium hydroxyapatite (CaHA) have emerged as key tools in regenerative aesthetics due to their ability to stimulate adipogenesis and adipocyte metabolic activity, enhance collagen production, and improve dermal quality. This review aimed to provide an updated synthesis of the role of these agents in adipocyte stimulation, focusing on their mechanisms of action, clinical efficacy, and therapeutic applications. A comprehensive search of the MEDLINE, PubMed, and Ovid databases was conducted for studies published from 2018 onward, including in vitro and in vivo experiments, randomized controlled trials, and observational studies, which were evaluated according to the Oxford Centre for Evidence-Based Medicine hierarchy. The findings demonstrated that PCL promotes adipose-derived stem cell differentiation and extracellular matrix remodeling, while PLLA exhibits dual effects on collagen synthesis and adipocyte stimulation, with clinical trials such as the SPLASH study confirming significant improvements in dermal thickness and adipogenesis. CaHA provided immediate volumizing benefits with long-term tissue regeneration, and innovative approaches including combination therapies and novel injection protocols expanded clinical applications. Overall, PLLA, PCL, and CaHA represent effective and versatile biostimulatory agents that support natural and durable outcomes in aesthetic practice. Nevertheless, the absence of large-scale trials and standardized protocols highlights the need for further research to optimize safety, efficacy, and long-term treatment strategies.

Background: Subzygomatic arch depression (lateral sunken cheek) is a frequent midface contour concern associated with age‑related soft‑tissue redistribution and retaining ligament laxity. It can be difficult to correct with conventional hyaluronic acid (HA) filler because taut ligamentous boundaries may limit smooth volumization and predispose to contour irregularity or an “overfilled” appearance. Objectives: To describe a cannula‑based superficial fat injection technique using a highly diluted poly‑ D,L ‑lactic acid (PDLLA) hybrid injectable (Juvelook Volume; VAIM, Seoul, Korea) for subzygomatic arch depression and to report clinical outcomes from a consecutive case series. Methods: Adults with lateral sunken cheeks underwent 3 treatment sessions at 3‑week intervals. PDLLA hybrid injectable was reconstituted with 8 mL normal saline and injected 4 mL per side per session into the superficial fat layer using a 25‑gauge, 50‑mm cannula. A single entry point just inferior to the zygomatic ligament proper was used for 3‑vector fanning with retrograde linear threading. Outcomes were assessed at 3 months after the final session using investigator‑rated Global Aesthetic Improvement Scale (GAIS) and patient satisfaction. Safety events were recorded. Results: Twenty‑four patients completed the protocol. At 3 months, GAIS was rated very much improved in 7 (29.2%), much improved in 11 (45.8%), improved in 5 (20.8%), and no change in 1 (4.2%). Median GAIS score was 2 (much improved) and differed significantly from the no‑change score (Wilcoxon test versus 4; P <0.001). Twenty‑one patients (87.5%) were satisfied or very satisfied. Transient ecchymosis occurred in 3 patients (12.5%) and resolved within 10 days; no nodules, infections, granulomas, or vascular events were observed. Conclusions: A superficial fat, cannula‑based, highly diluted PDLLA hybrid protocol may provide predictable improvement of subzygomatic arch depression with low downtime. The approach leverages gradual biostimulation rather than immediate bolus volume and may be useful in areas constrained by retaining ligaments. Controlled comparative studies with objective volumetric endpoints are warranted.