A Comparison of the Efficacy and Safety Between Hyaluronic Acid and Polylactic Acid Filler Injection in Penile Augmentation: A Multicenter, Patient/Evaluator-Blinded, Randomized Trial

ABSTRACT Background Studies about the clinical utility of fillers on penile augmentation (PA) are lacking. Furthermore, no randomized study has compared the utilities of fillers. Aim To compare the efficacy and safety between hyaluronic acid (HA) and polylactic acid (PLA) filler injection for PA. Methods This prospective, randomized patient/evaluator-blind, comparative multicenter study consisted of an initial 2-week baseline period and 48-week patient/evaluator-blind post-injection period. 72 patients with small penis syndrome were enrolled from 3 institutions between March–July 2016. Patients were divided into 2 groups: the HA group, comprising 36 patients injected with HA, and the PLA group, comprising 36 patients injected with PLA. Main Outcome Measures Penile girth and satisfaction were assessed at baseline and at 4, 12, 24, and 48 weeks after injection. Results Penile girth increases adequately lasted ≤48 weeks in both groups (16.95 ± 10.53 and 13.49 ± 9.98 mm of mean increase in the HA and PLA groups, respectively; P < .001). The mean penile girth increase in the HA group was significantly greater than that in the PLA group at 4 weeks (P < .001). Subsequently, it gradually decreased and was no longer significantly different at 48 weeks (P = .075). Satisfaction levels increased after injection and were maintained ≤48 weeks. No significant differences were observed in the overall satisfaction level between the groups (P > .05). Filler injection–related adverse events were mild and transient and occurred in 1 and 3 patients in the HA and PLA groups, respectively. Clinical Implications This study provides an overview of the efficacy and safety of HA and PLA fillers, which are the most commonly used soft tissue fillers for PA. Strength and Limitations This study, to our knowledge, is the first to compare the efficacy and safety between different filler injections for human PA. However, it was impossible to perform a researcher-blinded trial because of the unique properties of fillers, and 31 patients (43.1%) were dropped during the study period. Conclusions Both HA and PLA filler injections for PA led to a significant augmentative effect without serious adverse events and had clinically comparable efficacy and safety.