Anatomical Basis for "Superficial Flow Volumetry" and "Deep Support Volumetry".

Sir:

The following comments pertain to “Biophysical characteristics of hyaluronic acid soft-tissue fillers and their relevance to aesthetic applications” by Sundaram and Cassuto[1] and “Cohesive polydensified matrix hyaluronic acid for fine lines” by Sundaram and Fagien.[2]

According to the authors’ conceptualization, definition of “superficial flow volumetry” is “soft, spreading filler that integrates homogeneously into tissue, can be injected superficially to fill fine lines, and can be flowed in an intradermal or superficial subdermal sheet.” The concept of “deep support volumetry” is “firmer, less spreading fillers that remain more defined in the tissue, can be implanted deeply at the subcutaneous and preperiosteal levels.”[1] Sundaram stated that superficial and deep volumetry can provide tissue support by means of 3-dimensional vectoring in the viewpoint of rheology; however, she did not provide the anatomical basis.

To support the “superficial flow volumetry” and “deep support volumetry,” a few articles of the anatomical basis were available.

According to Macchi, in the full-thickness samples of the parotid, zygomatic, nasolabial fold and buccal regions, 2 different fibroadipose connective layers were bound to the laminar connective tissue layer (superficial musculoaponeurotic system, SMAS). The superficial fibroadipose layer, vertically oriented fibrous septa, connected the dermis with the superficial aspect of the SMAS. Deep fibroadipose connective layer, obliquely oriented fibrous septa, connected the deep aspect of the SMAS to the parotid-masseteric fascia.[3] She emphasized that in the parotid region, the mean thicknesses of the superficial and deep fibroadipose connective tissues varied according to the regions (1.63 and 0.8 mm, respectively, at parotid area; 0 and 2.9 mm, respectively, at nasolabial fold).

Nakajima, who investigated subcutaneous adipofascial tissue over the entire body, had a similar opinion. The subcutaneous adipofascial tissue was made up of 2 adipofascial layers. The superficial layer (protective adipofascial system) is formed by the solid structure because it protects against external forces. The deep layer (lubricant adipofascial system) is a mobile structure, which lubricates musculoskeletal movement.[4]

In my recent research, in the cheek, horizontal fibrous connective tissues, which were connected with the zygomaticus major, were seen as a continuous membrane (membranous layer of superficial fascia, MSF). MSF divided the superficial fascia into the superficial fatty layer and the deep fatty layer. The thickness of the superficial fascia depended upon the thickness of the superficial fatty layer because the thickness of the MSF was very similar, irrespective of the 3 levels.[5]

The above 3 articles mentioned that the subcutaneous layer of the face is not homogenous “subcutaneous tissue.” In injection of the fillers, the layered structures and its histological nature should be considered, and also the characteristics of fillers.

ACKNOWLEDGMENT

The authors are grateful to Nooraini Mydin, MA, journalist, for English editing.