Pyramidal multiple‐theory (multi‐type, multi‐method and multi‐layer) for facial fat grafting

Age‐related changes to the face pertinent anatomy and important aspects of autologous fat grafting have been widely applied in facial rejuvenation. Various types of autologous fat products (Macrofat, Microfat, SEFF, nanofat, and SVF‐gel) with different properties and applicabilities have been introduced and available for surgeons.


| INTRODUC TI ON
Facial aging can be characterized by soft-tissue atrophy, redundant and ptotic skin, and craniofacial skeletal remodeling. Fat grafting has been used to treat facial deformities for over a century. In addition to cosmetic field of practice, the facial fat grafting has widely been adopted in a broad spectrum of cleft-related, craniofacial contourrelated, burn-related, and radiation-related indications. 1 Autologous fat grafting began to gain popularity and become widely accepted in the late 1990 s. This followed Coleman's description of his modified techniques for liposuction, lipofilling, and the long-term outcomes of facial fat grafting with lipoaspirates. 2 Theoretical and technical advances have contributed significantly to the increasing application of facial fat grafting over the last 20 years.
Fat tissue is composed of adipocyte, stromal vascular fraction (SVF) (including adipose-derived stem cells (ADSCs), pericytes, fibroblasts) and extracellular matrix (ECM). 3 In addition to the graft survival, fat grafting showed regenerative effect (improvements in terms of skin quality, scarring, and fine wrinkles) due to the ADSCs. [4][5][6][7] There has also been significant advances in the harvesting and processing of autologous fat, thus enhancing the applicability of facial fat grafting.
More specialized fat products, with variable particle sizes and different components, have been introduced, allowing their targeted application in different circumstances. For example, microfat and superficial enhanced fluid fat (SEFF) can be used for more superficial and delicate implantation, [8][9][10] due to their smaller particle sizes as compared with Coleman fat. Nanofat which destroyed all of mature adipocytes showed remarkable results with regard to regeneration. 11 The most recent reports described the development of SVF-gel, containing concentrated ECM and SVF and almost no oil; this gel showed remarkable capacity for regeneration with modest volumization capability. 12,13 However, to make the best of the variety of these fat products, and deal with the complexity of clinical problems, it is vital that we understand how to select appropriate fat produces for a combined application. In this article, we report our knowledge and experience of a pyramidal multiple-theory (multi-type, multi-method, and multilayer) for facial fat grafting. Multiple fat products were used, grafted with multiple methods, and into different tissue layers. These injections were based on the applicability and injectability of the fat products and were performed in a pyramid pattern with regard to the injection volume from deep to superficial layer.

| Strategy for facial fat grafting
There are three main purposes of facial fat grafting: volume restoration (filling to the deep layer, providing tissue support, and improving facial contours), fine contouring (filling to the superficial layer, providing limited volumization, and modest regeneration), and tissue repair (intradermal filling, predominantly used to fix aged, and damaged tissue). According to the previous reports of the applicability of various fat products, 14 here, we suggested our pyramidal multipletheory (PMT) fat grafting strategy. The fundamental aspect of this strategy was deep layer filling which provided restoration of volume along with a prominent supportive effect. This was especially important in cases involving volume loss by aging, or in cases requiring major contouring, such as in the forehead, temporal area, anterior malar region, chin, or nasal dorsum. Macrofat (Coleman fat) was our preferred fat product for these procedures. The middle aspect involved fine contouring; for instance, the contouring for the lip line, acne scar, cervical stripe, deep static wrinkles, or the unnatural transition where deep grafting was performed.
Such procedures did not require large volumetric filling and was mainly performed using microfat, SEFF, or SVF-gel. The first is based on the biology characteristics of fat derivatives. For shallow tissue filling, the volume filling effect of Microfat is better than SEFF, nanofat, SVF-gel, but the regeneration and repair ability is just the opposite. The second is based on the preparation, during liposuction just Macrofat, SVF-gel are usually chosen. Only Microfat, SEFF, and nanofat are more convenient. If there is a need for volume filling, SVF-gel is preferred to nanofat. Sharp needles could be used when injecting fat into the sub-dermal layer. The top layer was regeneration; this included the treatment of fine wrinkles, flecks caused by photo-aging, and dark circles caused by skin problems. These procedures were carried out with nanofat, or SVF-gel as an alternative, and involved sharp-needle intradermal fat grafting (SNIF). Based on this combination of multi-type, multi-method, and multi-layer grafting, we were efficiently able to restore the healthy tree-like structure of the facial soft tissue of patients with various conditions (Figure 1).

| Techniques
The preferred donor sites were the abdomen, inner thigh, and anterior thigh; these areas were clearly marked prior to treatment.
Fat was harvested after infiltration with a modified Klein solution (0.08% lidocaine and 1:1,000,000 adrenaline) through a 2-mm stab incision; the solution was allowed to infiltrate for 15 min prior to surgery commencing. For all liposuction procedures, we used a 20ml syringe to apply a low pressure manual suction. 15,16 Macrofat, Microfat, SEFF, Nanofat, and SVF-gel were prepared based on previous descriptions. 9,12,17 The procedures are showed briefly in Table 1 and Appendix S1(FigureA,B and Video C,D).

| Patients
From June 2020 to Jan 2022, 58 patients (54 females; 4 males) underwent PMT facial fat grafting. Each patient was fully informed and provided written consent. Patient age ranged from 24 to 56 years (mean: 35.6 years). Follow-up time ranged from 6 months to 24 months (mean: 10 months). Six patients underwent a second treatment; these were performed 3 to 6 months after the first surgery. Photographs were taken before and after each treatment, and at each follow-up visit. Each patient completed the subject satisfaction assessment (ASA) scale at the 6 month follow-up appointment to rate their change in appearance (−1 for worse to 3 for best improvement) and their satisfaction (−3 for very dissatisfied to 3 for very satisfied). The surgeon also completed the Global Aesthetic Improvement Scale (GAIS) to rate the F I G U R E 1 Illustration of pyramidal facial fat grafting. Specific fat products with various particle sizes and components are grafted into different layer of the facial soft tissue. Thus we can restore the natural tree-like structure of the facial soft tissue.  15 The clinical experience of a surgeon and patient-based requests were included in outcome analysis.

SMAS
ASA and GAIS are considered the key outcome measurement of facial aesthetic procedures. Clinical images are in Figure S2 in Appendix S1.

| Case 2
A 29-year-old female patient with forehead/cheek depression and tear troughs with dark circles, presented for treatment ( Figure 4). In each side of the forehead, 5 ml of macrofat was injected into the DMFFC; 2 mlof microfat was injected into the MTFC. Into each temple, we injected 8 ml of macrofat into the UTC (3 ml) and the LTC (5 ml); 2 ml of microfat was injected into the LOFC (0.5 ml) and LTFC (1.5 ml). In each cheek, 3 ml of macrofat was injected into the DMCFC (1 ml) and BF (2 ml); 1 ml of microfat was also injected into the LTFC in order to smoothen the transition. For each tear trough, 1.5 ml of macrofat was injected into the medial SOOF, 0.5 ml of microfat was injected into the NFC and MCFC, and 0.3 ml of nanofat was injected intradermally. Photographs of pre-operation and 6 months post-operation are showed in Figure 4.

| Case 3
A 34-year-old female patient with temporal/malar depression, tear troughs, and nasolabial folds, presented to our clinic for treatment.
In each side of the temple, 11 ml of macrofat was injected into the UTC (4 ml) and the LTC (7 ml); 2 ml of SEFF was injected into the LOFC (0.5 ml) and LTFC (1.5 ml). In each side of the malar region, Over the last 20 years, the development and popularity of facial fat grafting have increased rapidly. 16 Apart from the regenerative effect of fat grafting that being increasingly studied, more and more specific fat products have been introduced. Autologous fat should be considered as more than a simple filler. 22 Different harvesting and processing techniques, result in the difference in particle size, components, and applicability of fat products, thus allowing the targeted application of these techniques for different cosmetic and reconstructive scenarios. Collectively, these developments and advances have led to facial fat grafting becoming well suited for the 3 main purposes of cosmetic injections: volume restoration, fine contouring, and tissue repair.
The volume restoration is a fundamental aspect of fat grafting.
As we know, aging decreases the volume of the deep layer structures of the face (both bone and deep fat compartments). This volume loss and the consequential retaining ligament laxity and tissue displacement can be treated by restoring the volume and supportive structures. Marcofat is considered the most suitable fat product for this purpose. It has relatively larger particle size, with an intact fat lobule structure, and an abundance of ECM. Therefore, it provides better volumization and strong supportive effect. 5 Major contouring of the face to correct local hollowing has similar requirements, including but not limited to the forehead, temple, malar region, and cheek.
Fine contouring is another critical aspect of facial fat grafting. For finer and more superficial contouring in tear troughs, lip lines, acne scars, cervical stripes, and deep static wrinkles, fat grafts with intact fat lobules can cause inaccuracies of injection volume and irregularities. Therefore, fat grafts with smaller particle sizes are required, without intact fat lobules, such as microfat and SEFF. 8-10 Nanofat can be higher or lower in cell counts and populations, which can have markedly different outcomes in clinical practice. Nanofat is simply a term, as is SEFFI, to describe another smaller graft. Furthermore, these fat grafts are also suitable for the irregularities and unnatural transitions that occur following deep layer grafting.
Tissue repair is also nonnegligible in facial fat grafting. For the intradermal injection here, grafts that show prominent volumization effects would be inadequate. Nanofat, in contrast, is well suitable for this purpose. It destroys all viable adipocytes and shows strong regenerative effect. 7,11 SVF-gel, contains concentrated SVF and ECM and very little oil, is an alternative for the regeneration purpose. 12,13 The aging process affect each layer of the facial tissue differently. For each individual patient, it is very common that problems originated from more than one layer of tissue are presented and

| CON CLUS IONS
The targeted, combined, and multilayered facial fat grafting strategy can take advantage of the range of different fat products. Thus, we can achieve optimal overall improvement.

CO N FLI C T O F I NTE R E S T
The authors have no conflict of interest to declare in relation to the content of this article.

E TH I C A L A PPROVA L
Research involving human participants,all patients approved to fat filling and image published.

DATA AVA I L A B I L I T Y S TAT E M E N T
The data that support the findings of this study are available from the corresponding author upon reasonable request.