Facial fat grafting — Microfat, nanofat and where fat must not go
What each processing method yields, the line separating lifting from volumising effect, the plane for each area, the two forbidden regions, and why a third to a half resorbs.
Content intended for healthcare professionals. It does not replace clinical assessment and is not written as patient information.
Key points
- Fat is not one product but four different products depending on processing, each with its own plane: macrofat, microfat, emulsified and nanofat.
- Nanofat contains no viable adipocytes: it delivers the stromal vascular fraction and its stem cells. It adds no volume; it improves skin quality.
- The ligament line separates two opposite effects: lateral to it you lift, medial to it you volumise. Confusing them causes almost every poor result.
- There are two zones where fat is not placed: the low cheek with the folds, which gives a simian look, and the anterior half of the jawline between marionette and prejowl, which masculinises and worsens the groove.
- Between a third and a half resorbs in the first 6 to 12 months, and that is not a failure: it is the biology of a free graft.
Where the indication comes from
The youthful face is an inverted triangle with its base above; the aged face is a triangle with an inferior base. That change of shape sums up what needs correcting: temporal hollowing, brow tail descent, tear troughs and bags, descent of the malar compartment with accentuation of the nasolabial fold and prejowl sulcus, lip atrophy, jowl formation with loss of the cervicomental angle and preauricular hollowing. Against that there are three tools not to be confused: the facelift repositions, commercial fillers add temporary volume, and fat grafting adds autologous volume with regenerative capacity. One nuance orders the indication: a vertical SMAS traction vector in the midface has been shown to restore that third’s volume by itself, without additional filler. In other words, not everything that looks like volume loss is volume loss.
The line that decides the effect
The same ligament line that in surgery marks where to release, in aesthetic medicine marks what effect the product will have. It runs from the temporal crest to the lateral canthus, follows the zygomatic ligament and reaches the mandibular one. Lateral to it, product lifts; medial to it, it volumises. Two prohibitions follow. First: do not inject medially, in the low cheek and the nasolabial and melolabial folds, because medial overcorrection produces the characteristic simian look. Second: do not inject between the marionette line and the prejowl sulcus, the anterior half of the jawline, because it masculinises the lower third and increases prejowl tissue, which is exactly what one wanted to correct.
The four products and what each is for
| Product | How it is obtained | What for |
|---|---|---|
| Macrofat | Cannulas with 2-3 mm holes | The traditional system. Large particle and risk of irregularities after injection |
| Microfat | Cannulas with 1 mm holes | Volume. It is the reference product for all deep planes |
| Emulsified, unfiltered | Microfat passed about 30 times between syringes through a connector, without a filter | Structured fat particles under 0.5 mm: more capillary contact, less resorption and no irregularities in superficial planes. 23 G needle, dermal plane, for coarse perioral and glabellar rhytids |
| Nanofat | Microfat emulsified and then filtered. Double emulsification, first with a 2.4 mm connector and then 1.2 mm, 40 passes each | A whitish fluid without viable adipocytes, containing the stromal vascular fraction and its mesenchymal stem cells. 27-30 G needle, dermal plane, for fine periocular and perioral rhytids and tear troughs |
Harvesting
- Donor sitesAbdominal flanks, lateral and inner thigh, and in some cases the buccal fat pad. A 5 mm incision with a number 11 blade, usually in the lower midline of the umbilical scar
- TumescentModified Klein solution: 400 ml saline, 1 adrenaline ampoule, 90 ml 1 % lidocaine and 10 ml 8.4 % bicarbonate. Wait 10 minutes
- AspirationBlunt-tipped cannula with a 20 ml syringe, in-and-out movements, pinching the fat deposit with the other hand for control. The aspiration cannula is larger than the injection one and has cutting holes
- The planeHypodermis, always. Never the dermal plane, because of the risk of permanent irregularities at the donor site
- YieldOf what is aspirated, only 30 % is adipocytes; the rest is blood, infiltrated fluid and other cells. In practical terms: 120 ml infiltrated yields about 80 ml aspirated and about 40 ml of usable microfat
Why bicarbonate, and why saline rather than Ringer’s
Two details of the formula have a reason. Bicarbonate alkalinises the anaesthetic from pH 5 to pH 7, more physiological, which translates into greater analgesic effect and considerably less pain on infiltration. There is a trade-off: on alkalinisation, local anaesthetics tend to precipitate; bupivacaine does so immediately — hence it is not combined — and lidocaine takes days, which makes it safe in this mixture. And saline rather than lactated Ringer’s: Ringer’s was used to reduce the anaesthetic’s metabolic acidosis, but it has shown more risk of metabolic alkalosis with hypokalaemia and intracellular oedema.
How to separate the fat
| Method | How | Assessment |
|---|---|---|
| Centrifugation | Tubes at 1,000 rpm for 2 minutes | Little used: it has been shown to damage adipocytes |
| Lipodialysis with a closed system | Fat is introduced through a port and washed with an equal volume of solution | Preferable: less adipocyte damage. About 50 % of the aspirate is recovered |
| Gravity and gauze | Syringes upright for 10 minutes to separate three layers — oil, fat and fluid — remove the lower one and decant the rest onto gauze to remove the oil | A good alternative if no closed system is available, and it needs no specific equipment |
A pressure detail that gets overlooked
Processed fat is transferred from 20 ml syringes to 1 ml syringes via a connector, and it is not a matter of convenience. The smaller the syringe, the lower the pressure exerted on injection, and pressure is precisely what ruptures adipocytes and what pushes product into a vessel. It is the same principle as with fillers: a small calibre forces slow delivery, and that protects. For the same reason infiltration is done on withdrawal, laying down threads, rather than depositing static boluses.
Injection plane by area
| Area | Plane | Caution |
|---|---|---|
| Temple | Between the two leaves of the deep temporal fascia or intramuscular, beneath it. A pop is felt on entry and the cannula stops showing through | Avoid the subcutaneous plane: irregularities and risk of temporal vessel embolism |
| Upper eyelid | The retro-orbicularis plane without perforating the septum, preperiosteal, placing the fat beneath the supraorbital rim | Never perforate the orbital septum |
| Malar | All planes over the malar eminence, including supraperiosteal | Avoid the low cheek and the folds: this is the simian-look zone |
| Tear trough | Suborbicularis, in the SOOF: passing through orbicularis is felt | High risk of irregularity and persistent oedema. Small volume and undercorrect |
| Mandibular angle and border | Supraperiosteal only | Avoid the anterior half of the mandible, between prejowl sulcus and marionette line |
| Chin | Supraperiosteal for volume and projection | Stay in the midline so as not to deviate it |
| Lip | Submucosal, in three stages: first the upper vermilion near the white roll, then the wet line, then the roll | The upper lip has three tubercles and the lower two: with nanofat they are hard to respect |
| Perioral | Subdermal with a blanching technique, followed by CO₂ laser | Beware overcorrection: it shows immediately here |
The five entry points
- Lateral to the lateral canthus: gives access to the tear valley and malar bone, and optionally the upper eyelid and brow tail.
- Over the malar bone, at the crossing of the ala-tragus line with the lateral canthus-commissure line: gives access to the tear trough.
- Lateral to the oral commissure: gives access to the nasolabial fold, malar bone and optionally lips and melolabial fold.
- Mandibular angle: gives access to the jawline and preauricular area.
- Hairline at the zygomatic arch: gives access to the temporal area.
Before or after the facelift
There is a solid argument for doing the fat grafting first, and it is worth knowing: with the planes still intact, infiltration respects the anatomical spaces better and swelling is less, so product can be placed more precisely. There is also a practical consequence that breaks a rule: the zone between melolabial fold and marionette line is off-limits for hyaluronic acid because it accentuates the prejowl, but with fat and before a facelift it does allow volume gain along the jawline, because the subsequent traction redistributes what was placed. It is a specific exception, not a general licence.
Why it resorbs, and how much
Expected resorption is a third to a half of the material in the first 6 to 12 months, and it has an orderly biological explanation. After infiltration, the graft organises into three zones according to distance from the recipient bed’s vessels: in the superficial zone both adipocytes and stem cells survive; in the intermediate zone adipocytes die but stem cells regenerate them; and in the deep zone both die. All the practice follows: fine, well-distributed threads maximise contact surface with the bed, which is why emulsified particles under half a millimetre resorb less. And one consequence to bear in mind in irradiated oncological patients: with a poorly vascularised bed overall resorption is greater, so it is preferable to inject less and repeat at six months.
Aftercare and what to warn about
- Donor site: compressive dressing for 48 hours, then a girdle or elastic stocking for one week day and night and another at night only.
- Recipient site: antibiotic and anti-inflammatory, and local cold for the first 48 hours.
- Always warn about swelling, bruising and irregularities: all three are expected and all three alarm if not announced.
- And warn about the result at six months, not the immediate one: what is seen at the end includes oedema and a portion of volume that will not stay.
References
- 1.Coleman SR. Structural fat grafting: more than a permanent filler. Plast Reconstr Surg. 2006;118(3 Suppl):108S-120S.
- 2.Tonnard P, Verpaele A, Peeters G, Hamdi M, Cornelissen M, Declercq H. Nanofat grafting: basic research and clinical applications. Plast Reconstr Surg. 2013;132(4):1017-1026.
- 3.Eto H, Kato H, Suga H, et al. The fate of adipocytes after nonvascularized fat grafting: evidence of early death and replacement of adipocytes. Plast Reconstr Surg. 2012;129(5):1081-1092.
- 4.Suga H, Eto H, Aoi N, et al. Adipose tissue remodeling under ischemia: death of adipocytes and activation of stem/progenitor cells. Plast Reconstr Surg. 2010;126(6):1911-1923.
- 5.Rohrich RJ, Pessa JE. The fat compartments of the face: anatomy and clinical implications for cosmetic surgery. Plast Reconstr Surg. 2007;119(7):2219-2227.
- 6.Jacono AA, Malone MH, Talei B. Three-dimensional analysis of long-term midface volume change after vertical vector deep-plane rhytidectomy. Aesthet Surg J. 2015;35(5):491-503.
- 7.Klein JA. Tumescent technique chronicles: local anesthesia, liposuction, and beyond. Dermatol Surg. 1995;21(5):449-457.
Related specialty: Facial Aesthetic Surgery