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Fat grafting
Fat grafting
Some consider autologous fat the optimal filler, since it is relatively abundant, highly biocompatible, able to provide natural-appearing volumetric correction, and potentially permanent, although rates of graft survival are variable.39 The concept of fat transfer is not new. However, older en bloc techniques required excision of a solid section of tissue with subsequent implantation in larger segments, a process that left not only a new donor-site defect but also possible graft-site incisional scars. The advent and popularity of liposuction in the 1980s made lipotransfer more feasible. Aspirated fat could be reinjected through small-bore cannulas or needles with minimal scarring.40,41
Deficits at the nasolabial folds, cheeks, marionette lines, lips, infraorbital region, as well as atrophic scars (i.e., those from acne) and areas of stable, subcutaneous, facial atrophy (i.e., from linear morphea or ParryโRomberg syndrome) may all be improved with autologous fat transfer. Correction of HIV-related lipoatrophy and rejuvenation of the dorsal hands are other documented indications. Lipotransfer is unable to treat fine lines or small, superficial scars that require dermal placement of filler.42โ44
There are multiple modalities for harvesting, processing, and injecting fat.45,46 No studies to date have established an optimal donor site, and any region of excess adipose may be reasonable. Common sites are readily accessible, insensitive to weight loss via diet and exercise, and associated with low morbidity: periumbilical, lumbar back, trochanteric buttocks and/or medial thigh, and medial knee or arm.47 Common harvesting practices involve pre-medicating patients with anxiolytic and/or narcotic drugs as needed, infiltrating the subcutaneous space at the donor site with tumescent anesthesia, consisting of saline admixed with small amounts of lidocaine with epinephrine, and making small incisions. A traditional aspiration cannula or 14-gauge single-holed microcannula attached to a hypodermic Luer-Lokยฎ syringe can be used to harvest the fat. Graft survival is directly related to graft trauma, and care must be taken to maintain suction at less than 1 atmosphere (i.e., by using small syringes). Increased suction vaporizes and breaks adipocytes.39 Gravity layers out the supernatant fat, so it can be washed of oils, blood/serum, and anesthetic fluid. Kuran et al. reported good success with open system purification,48 but this technique may increase the risk of infection. Centrifuge separation is also an option; however, resultant trauma may decrease graft survival.49,50 Extracted adipose can be frozen at โ30ยฐC (slow freezing, slow thawing process) and stored for as long as 12 to 18 months.51 There are also several ways to place the fat grafts. Fat is deposited with a large-bore 16- or 18-gauge
needle or cannula parallel to the target rhytides. Alternative methods include pearl fat grafting or microautologous fat transplantation (MAFT).40,48
Postinjection massage helps mold and distribute the grafts evenly. Unlike Sculptra, patients should not continue this massaging at home, and should avoid dynamic facial animation, since the motion may encourage graft migration. Systemic antibiotics and aspirin/NSAID-free pain management regimens are other frequent postoperative practices. Patients should be counseled about edema that may last for weeks.
Determining the degree and longevity of graft survival has proven difficult and unpredictable.45,46,52 Outcomes depend on technique and experience, with new methods showing up to 50% long-term success.39 In general, repeated, small volume injections every 3 months are better than large volume augmentation. If the graft is too big, then passive diffusion from the recipient bed may not sufficiently maintain its metabolic demand and revascularization is insufficient. Overcorrection anticipates some graft loss but increases the rate of failure and even necrosis. Graft migration occurs with overfilling as wellโmoving to areas with less tension or better blood supply.
Although there have been many developments in the field of lipotransfer, questions persist. Patients should thoroughly understand the strengths and limitations, in particular the need for two procedures (harvesting and implantation) and multiple sessions, as well as likely downtime.34,53