A new anatomical study highlights critical technical problems to guarantee the safe performance of the increasingly popular “Brazilian facelift” – a procedure using the patient’s fat to increase and improve the appearance of the buttocks. The study appears in the May issue of Plastic and Reconstructive Surgery® , the official medical journal of the American Society of Plastic Surgeons (ASPS).
“ The study confirms that the gluteal fat transplant is safe, only if the injections remain in the subcutaneous tissue “, said Daniel Del Vecchio , MD, plastic surgeon in Boston who developed the protocol and is a leading world expert in this field. Video commentary by co-author Rod J. Rohrich, MD, of the Dallas Plastic Surgery Institute, emphasizes the need to avoid injecting fat into the gluteal muscle itself to prevent serious complications.
New evidence on the injection technique
Fat grafting has become a popular buttock improvement technique in patients who want a fuller appearance and smoother, without using implants. In this procedure, the fat obtained by liposuction of a part of the body (such as the abdomen) is treated and injected to improve the gluteal region. According to ASPS statistics, more than 24,000 buttock increases with fat transplant were performed in 2018, an increase of 19% compared to the previous year.
However, the serious complications resulting from this procedure are causing increasing concern. An article from 2015 on plastic and reconstructive surgery reported a series of 22 deaths in patients undergoing an injection of gluteal fat in Colombia and Mexico. The deaths were caused by pulmonary embolism: fatty deposits blocking the arteries of the lungs.
In 2018, the ASPS partnered with other companies specializing in plastic surgery to issue an urgent warning regarding the “alarming” number of deaths linked to the increase in gluteal fat. A notice to plastic surgeons described the steps to follow to ensure that fat is only injected under the skin, never into the muscle.
To form the basis of evidence for this recommendation, Drs. Del Vecchio and Rohrich and their colleagues conducted a study on corpses to assess patterns of fat spread in the gluteal region after an injection. Four approaches were evaluated, simulating injection techniques that can be used by plastic surgeons performing gluteal fat grafting.
In three of the four injection techniques, the spread of simulated fat was mainly limited to the subcutaneous area, immediately under the skin. Even when small perforations were made in the aponeurosis – the layer of connective tissue separating the muscle from the subcutaneous space – the simulated fat had not spread to the muscle itself at all.
Even with multiple perforations and high injection pressures, the muscle fascia prevented simulated fat from passing through the muscle. Researchers discuss the “subcutaneous migration” process that prevents the injected fat from spreading into or under the gluteal muscle, if injected into the subcutaneous “safe zone”.
The results were different in the fourth scenario, where several punctures were performed in the gluteal muscle. In this situation, large amounts of indirect fat were found under the muscle, demonstrating that there was “deep intramuscular migration”. Once fat has migrated into the submuscular space, damage to the veins in this area could allow fat cells to enter the circulation, with a potential risk for pulmonary embolism. 
The experimental study provides important evidence in support of previous recommendations aimed at ensuring the safety of the Brazilian facelift. The researchers conclude: “ These convincing results are deep enough to suggest a new standard of care: no sub-fascial or intramuscular injection should be given and all injections should be made exclusively in the subcutaneous tissue.
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