Efficacy and Safety of Poly-L-Lactic Acid Microspheres for Temporal Hollowing Correction: A Multicenter, Randomized, No-Treatment–Controlled, Evaluator-Blinded Trial

Background Temporal hollowing may reflect constitutional craniofacial morphology, acquired soft-tissue loss, or age-related change. High-quality evidence specifically validating poly-L-lactic acid (PLLA) for temporal augmentation remains sparse. This study evaluated the efficacy, safety, and durability of PLLA microspheres for temporal hollowing correction. Methods In a multicenter, randomized, evaluator-blinded trial, 162 adults with mild-to-severe bilateral temporal hollowing (Allergan Temple Hollowing Scale [ATHS] grades 2–4) were randomized (2:1) to PLLA microspheres (up to 3 sessions) or no treatment. The primary endpoint was the blinded-evaluator-assessed ATHS responder rate at Month 6. Secondary endpoints, interpreted as exploratory, included ATHS responder rates at Months 1, 3, 9, and 12, 3D volumetric changes, Global Aesthetic Improvement Scale (GAIS), and subject satisfaction/pain assessments. Results The Full Analysis Set included 161 subjects. At Month 6, the ATHS responder rate was 80.2% (PLLA) versus 1.8% (Control) (difference: 78.4%; 95% CI 68.1%–85.9%; P < 0.001). Early efficacy was observed (Month 1: 65.3%; Month 3: 76.5%). By Month 6, 95.8% of treated subjects self-reported aesthetic improvement. 3D imaging showed a mean volume increase of 0.66 mL in PLLA subjects versus small negative mean changes of 0.37–0.44 mL in controls. Responder rates were 91.7% at Month 9 and 89.5% at Month 12. Device-related adverse events occurred in 8.5%, with no device-related serious AEs. Conclusions PLLA microspheres provided significant, progressive, and durable correction of temporal hollowing compared with no treatment, with a favorable safety profile. Level of Evidence V This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .