Static and dynamic high-resolution ultrasound analysis of tissue distribution of poly-L-lactic acid particles during subdermal application in two different presentations.

Abstract

All the changes the skin goes through, peaking at flaccidity, occur in the dermis and hypodermis, leading to loss of support and a lower capacity to totally accommodate displacements or any loss of subjacent volume, bringing about the onset of furrows and sagging. Improvements in facial sagging may be obtained with the administrations of substances like poly-L-lactic acid (PLLA), which triggers a tissue response through a controlled inflammatory reaction. Compare the tissue distribution of the particles of PLLA of both products available in Brazil (Sculptra® and Rennova Elleva®) during and immediately after their subdermal administrations, with 22G cannulas, through high-resolution ultrasound imaging. A total of four patients aged between 18 and 64years had the inner part of the upper arms divided into eight quadrants and treated with 16ml of each product, reconstituted to correspond to 9.5mg/ml. The sites where PLLA was injected were analyzed through the high-resolution ultrasound during (dynamic imaging) and immediately after the procedures (static imaging). During Sculptra® injection, high-resolution ultrasound revealed that its distribution did not follow the trajectory of the cannula homogeneously. It was characterized by a more hyperechogenic central portion and an anechogenic peripheral portion, forming discrete posterior acoustic shadowing at times. Regarding Rennova ELLEVA® injection, the high-resolution ultrasound analysis showed a homogeneous distribution of the product across the subcutaneous tissue following the trajectory of the cannula without formation of significant interface with the surrounding tissue, maintaining the sonographic aspect of thinly granulated hyperechogenic deposits, with strong posterior acoustic shadowing during and immediately after its administration. Static and dynamic high-resolution ultrasound imaging show a more homogenous distribution of PLLA particles with the use of Rennova ELLEVA® when compared with Sculptra®, which may induce the formation of capsules and a subsequent more dispersed fibroplasia, with larger area of action and a possible better therapeutic result. The interest of this article lies in its originality, highlighting the differences in the tissue distribution of two different brands of PLLA particles, which can impact the clinical response to the two products - which we are researching and seems to interfere with the increase in dermal thickness.