Mr Deniz Kanliada provides an introduction to using hyaluronic acid-based dermal filler products for buttock augmentation
Buttock augmentation is one of the most popular aesthetic treatment trends of the last decade.1 The Brazilian Butt Lift (BBL) is a common procedure for augmentation and aims to shape the buttocks by obtaining fat from other areas of the body through liposuction and reinjecting it into the lower back and loins.1
However, it has become a controversial treatment due to significant complication rates with the highest reported death rate of all cosmetic surgery procedures.2,3
For patients seeking an alternative to the BBL, dermal fillers can be a suitable treatment to consider. The poly-L-lactic acid dermal filler Sculptra gained approval from the US Food and Drug Administration for use in human immunodeficiency virus-related facial lipoatrophy in 2004, leading to its use in buttock augmentation.4,5 However, the search for alternative methods has recently led to hyaluronic acid (HA) products also being used, and products that are specifically designed for buttock enhancement have emerged.
As with any injectable treatment, knowing the anatomical area inside and out will help to ensure successful results and minimise the risk of complications. The gluteal region is the transitional area between the trunk and the lower extremity. It is composed of two rounded prominences or buttocks located posterior to the hips formed by subcutaneous fat and the gluteal muscles.6 This region extends in the vertical axis from the iliac crests superiorly to the infragluteal folds inferiorly.
The width of the gluteal region includes the area between the depression of the greater trochanter of each lateral thigh at the iliotibial tract and is separated in the middle by the gluteal cleft.6 While the gluteal region is anatomically part of the trunk, it is functionally part of the lower extremity. Important external landmarks include the iliac crest, posterior-superior iliac spine (PSIS), sacrum, coccyx, and ischial tuberosity. The gluteus maximus, which is the largest and most superficial of the gluteal muscles, is the muscle most responsible for the shape of the buttocks.
The gluteus maximus originates from the posterior surface of the ilium, sacrum, and coccyx and extends across the buttock at a 45-degree angle. This muscle forms most of the bulk of the buttock. It inserts into the iliotibial tract and gluteal tuberosity of the femur. The gluteus maximus is a powerful muscle that extends the hip joint and is used for forced extension in activities such as running, climbing, and rising from a seated position.6 It is not important posturally, is relaxed standing and is used minimally in walking. It is innervated by the inferior gluteal nerve.6
The gluteus medius lies between the gluteus maximus and the gluteus minimus. It is a fan-shaped muscle whose muscle fibres are oriented vertically, arising from the ilium and inserting into the greater trochanter. This muscle can only be palpated in the superolateral portion of each buttock. Its action is abduction of the hip and lateral rotation of the thigh. It is innervated by the superior gluteal nerve.6 The smallest of the gluteal muscles is the gluteus minimus, situated beneath the gluteus medius muscle. It originates from the ilium and inserts into the greater trochanter and works in concert with the gluteus medius to prevent adduction of the thigh and to stabilise the hip. It is innervated by the superior gluteal nerve.6 The piriformis muscle is an important anatomical landmark dividing the gluteal region into a superior and inferior part. The superior gluteal artery and nerves emerge superiorly to the piriformis, while the inferior gluteal artery and nerve emerge into the gluteal region inferiorly to the piriformis.6
The sciatic nerve is the longest and widest nerve in the body. It arises from the lumbar and sacral plexus L4 to S3 and exits the pelvis through the greater sciatic foramen, inferior to the piriformis muscle, although variations in its exit have been described.7 It then travels beneath the gluteus maximus down the posterior thigh. It does not innervate the gluteal muscles.6
The gluteal arteries arise from the internal iliac artery. The superior gluteal artery is the largest branch of the internal iliac artery and exits the pelvis above the border of the piriformis muscle. It accompanies the superior gluteal nerve beneath the gluteus maximus and divides into branches that supply that gluteal musculature. The inferior gluteal artery exits beneath the piriformis and accompanies the inferior gluteal nerve beneath the gluteus maximus to supply the gluteus maximus, piriformis, and thigh. The gluteal veins accompany the gluteal arteries and drain into the internal iliac vein.6
In a study of 150 male subjects and 148 female subjects, analysis revealed a significant difference in gluteal region fat thickness between male and female subjects. The average gluteal fat thickness for female subjects was 33.2mm, while the average for male subjects was 23.1mm.8
In my experience, there are several different buttock shapes that patients are likely to present with (Figure 1). The square and ‘V’ shape is more masculine, and the rounder and heart shape are more feminine.9 From my experience, the heart shape is more desired amongst slimmer patients and the round shape is more desirable amongst larger-sized patients. Men prefer more projection than an hourglass figure, so heart shape or round shape needs to be adjusted according to the body type and goals. I find that these trends are similar across different ethnicities.
When considering a patient for buttock enhancement using HA fillers, it is important to identify any contraindications.10 These are the same as dermal filler placement in other areas and include:
I find that the most ideal patients are young individuals with or trochanteric depressions – colloquially known as hip dips, these are the inward depression along the side of the body, just below the hip bone – who do not have excess fat and cellulite around the butt area.
There are many patients who have had buttock implants or fat transfer who want to improve their shape or believe they need more volume. Fillers can be a good option to correct irregularities or increase the projection and the size even more; however, there is currently a lack of research in treating patients who have previously had fat transfer or implants with HA fillers in this area. Practitioners must therefore proceed with caution because there will likely be scarring and fibrotic attachments in the area which will make the injections harder. It will also be more difficult to spread the product equally and there is risk that the blood supply may be further decreased because of high volume of fillers compressing the blood vessels against the implants. If practitioners are to go ahead with treatment, I recommend that products should be injected slowly and carefully.
Poly-L-lactic acid injections are often used by practitioners to augment the buttocks and the literature suggests they are an effective treatment for patients seeking non-invasive gluteal enhancement with minimal downtime, improving gluteal firmness, shape, proportion, and projection.5
However, if the main goal of the treatment is volume replacement, enhancement or contouring, then HA injections are preferred.11 Because of their biochemical nature, HA fillers are viscoelastic and absorb water and expand further for better volume replacement.12
There is only one HA-based filler on the market indicated for restoring loss of volume and contouring body surfaces such as the buttocks, which is the product I choose for my patients. Like other biphasic hyaluronic acid-based products, the reabsorption rate is around 18-24 months. The lifestyle of the patient, such as their occupation if they sit more or wear tight clothing, as well as exercise, can affect the lasting time of this product.13
Body fillers are best indicated for enhancement of the upper and middle thirds of the buttocks and the lateral trochanteric depressions. I recommend not to inject into the lower part of the buttock because it will make the area heavier and cause a saggy appearance. As mentioned, all important arteries, veins and nerves run beneath the gluteus maximus muscle, so all injections need to be made above to avoid complications.14 The deepest points and borders of injection should be marked while the patient is standing. Gluteal skin and fat thickness are important to consider when planning the treatment because it indicates the correct cannula length and injection depth for each patient.
Buttock injections are done with blunt cannulas and usually an 18-19 gauge 100mm cannula is recommended by the product manufacturers. 14 gauge and 16 gauge cannulas are not indicated because of leakage risk and a high quantity of product injected in a single layer can create lumps.
After cleaning the area with alcohol or another antiseptic solution, I choose to inject anaesthetic (2% lidocaine 5ml mixed with 10ml isotonic solution). I will inject 0.3ml of 1% lidocaine using a 30 gauge needle for the cannula entry points. For a blunt cannula of 19-20 gauge, I will usually create the entry points using an 18 gauge sharp needle. Note that a large volume of local anaesthetic may alter the shape of the defects to be corrected, which may alter your results.
Injections into the buttocks will start from lateral to medial and from deeper layers, with larger boluses, to superficial layers, with smaller boluses. As mentioned, it’s vital that filler is placed above the muscles. To be able to enhance the volume smoothly and equally, 3D multilayer injections (subdermal, into the fat, under the fat layer) are needed. My technique usually involves inserting multiple macro droplets of around 3mls each and I find this gets the best results.
After volume restoration, to be able to create nice contouring for the waist and legs, more superficial injections can be used; the fanning technique is my recommendation.
The fanning technique may also be needed while injecting the depressions in the lower portion of the buttock or sides closer to the skin. Injection should continue until all the marked areas have been treated.
The amount of product required for this procedure is vast compared to other areas. For example, for hip dip corrections, 50-70mls each side is usually needed and if patients need both hip dip correction and buttocks lift, then around 100-120mls each side is needed. I do not recommend that practitioners inject more than 300mls in the first session and multiple sessions may be required.
Following the treatment, I advise patients to avoid hot showers, green teas, ibuprofen, or multivitamins for three days. The gym should also be avoided for a week and butt exercises should be avoided for six weeks.
If the patient desires more volume in the area, I would look to retreat in three to four weeks because this is when expansion of the product should be expected.
Complications of buttock fillers are similar to other filler treatments like pain, bruising, swelling, redness, allergic reactions, itching and a feeling of pressure.7 In my experience, pain in the buttocks or back is expected to occur in the first two to three days. Due to swelling in the area, sitting, walking, or running will also be painful during this period, but this can be decreased by taking paracetamol.
Because of toilet and bathroom use, antibiotics should be considered for three to five days if high volumes have been injected (200-300mls) or if the patient has had fat transfer or butt implants before.
There is a lack of evidence and research into the risk of vascular compromise in the buttocks. The vessels are large in the buttock and it is not a complication I have ever seen. As with other dermal filler treatment areas, practitioners should be well-versed and trained in recognising complications and management protocols.
Buttock augmentation, enhancement, lifting and contouring is getting more popular and popular every day. Patients are requesting quick, safe, and effective treatment to increase volume in the buttocks or to create a rounder and more lifted look. When considering butt lift and enhancement options, it’s important to note that fat transfer is easier than surgery and results last many years, but general anaesthesia is needed and complications can be life threatening.15,16
HA-based filler is a good alternative to surgery and fat transfer in my experience, as it has similar results, good longevity of up to 18-24 months and the treatment can be done in the clinic under local anaesthesia. Complications are less common and life-threatening complications are extremely rare. Like all other advanced treatments, buttock enhancement and body contouring using dermal filler requires a high amount of experience, advanced training and skills, and must be done by an experienced specialist.
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