Consensus Recommendations for the Reconstitution and Aesthetic Use of Poly-D,L-Lactic Acid Microspheres – Comment on the Facial Injection Techniques [Response to Letter]

Dear editor

We sincerely appreciate the thoughtful comments and valuable insights provided by Dr Jui-Yu Lin and Dr Chuan-Yuan Lin regarding our article, “Consensus Recommendations for the Reconstitution and Aesthetic Use of Poly-D,L-Lactic Acid Microspheres.” Their expertise significantly enriches the ongoing discourse on optimizing the aesthetic application of poly-D,L-lactic acid (PDLLA).

Supraperiosteal Injections

Drs Jui-Yu Lin and Chuan-Yuan Lin’s recommendation to use boluses of the thickest suspension of PDLLA (D1.5–D3) and sharp needles for supraperiosteal injections is highly valued. However, our consensus¹ prioritized patient safety and consistent reconstitution to minimize complications and optimize outcomes. Thicker suspensions, while providing greater projection due to their increased elastic modulus (G′),² pose a higher risk of nodule formation, particularly in the supraperiosteal layer where particle dispersion is limited. Additionally, the added viscosity may produce unnatural results in dynamic areas or when larger volumes are required.³ We also considered that excessive or irregularly placed collagen-stimulating fillers, such as PDLLA, are not easily corrected compared to hyaluronic acid, which serves as an alternative for bone projection.

As the dilution reduces pressure on the plunger, it reduces the risk of needle clogging, eases filler delivery for the injector, facilitates it’s even spread, minimizes unevenness, decreases the risk of papules and nodules, provides better coverage, and creates a better overall result.² By adopting the D9–D10 suspension, we aim to balance effective collagen stimulation with a uniform tissue response, minimizing the risk of palpable irregularities or visible lumps. While tailored reconstitution volumes may offer situational advantages, our recommendations emphasized consistent reconstitution to maximize safety and reproducibility across diverse clinical scenarios.

Regarding the choice of tools, our consensus acknowledges the utility of sharp needles but favored recommending blunt cannulas for most PDLLA injections due to their superior safety profile and precision. Blunt cannulas reduce the likelihood of intravascular injection and enable a less traumatic navigation through tissue planes.³ Studies highlight their precision in maintaining filler placement and minimizing displacement or vertical migration compared to needles.⁴ Additionally, evidence suggests that supraperiosteal boluses injected with sharp needles may increase the risk of nodule formation when large amounts of poly-lactic acid-based fillers are used in a single location.⁵ Thus, while sharp needles may be cautiously used in specific contexts, we respectfully recommend that blunt cannulas remain the preferred option for most applications.

Using Codes

We commend Dr Lin’s development of the AestheCode system, which provides a structured framework to enhance the safety and efficacy of PDLLA injections. This approach is particularly valuable for standardizing techniques and achieving predictable outcomes, especially for less experienced practitioners. However, our consensus deliberately avoided rigid codes, favoring a flexible, patient-centered approach. While predefined codes are undoubtedly useful, we humbly believe that empowering clinicians to make nuanced, case-specific decisions supports personalized treatments, optimizing both safety and outcomes. This difference in philosophy highlights the diversity of approaches within aesthetic medicine, with both methods aiming for optimal patient results.

We are grateful that our recommendations have sparked meaningful dialogue on this critical aspect of cosmetic dermatology.