Aesthetic characteristics of the buttocks

The shape of the buttocks is determined by anatomical structures such as the underlying bone component, gluteus maximus muscle, adipose tissue, and skin. Their combination and interaction give individuals their characteristic buttock shape. According to ethnic ideals, some characteristics of the gluteal region should be preserved, recreated, or corrected in order to enable a harmonious result in relation to the rest of the body. They are described here and summarized in Box 23.1.

Gluteal augmentation with fat grafting

For gluteal augmentation, the majority of investigators believe that autologous fat can be considered the ideal filler as it is abundant, easily available, of low cost, and easily and repeatedly collected. The donor area is selected to contribute also to the final shape of the buttocks; thus, the alternative sites would be the supragluteal, paralumbar, subgluteal, and trochanteric regions (thigh bulges). In this way, while liposuction models the shape of the buttocks, lipotransfer improves their projection.

Fat may be obtained as a single process associated with regional or circumferential liposculpture, or combined with other procedures such as lipectomies. Table 23.1 describes the tumescent solution used for gluteal augmentation. Fat extraction is performed using 3–4 mm blunt-tipped cannulas to avoid the destruction of the adipocyte, with continuous negative aspiration at 0.5 atmospheres of pressure, collected in a sealed vial. For minor procedures 10, 20, or 60 mL syringes may be used.

Table 23.1 Tumescent solution used for gluteal augmentation

Correction of gluteal depressions with hyaluronic acid gels

Cosmetic body shaping is a new field that can be addressed by use of HA gels. One option is a recent large-particle product from the NASHA™ family (Q-Med AB, Uppsala, Sweden) called Macrolane™ VRF (Volume Restoration Factor). Macrolane VRF 30 is intended for deep subcutaneous or supraperiosteal deposition, and Macrolane VRF 20, a thinner gel, for more superficial subcutaneous injection; both are available in a 10 mL syringe. They may be used for correction of concave body deformities, trauma scars, asymmetries, and for shaping and / or augmentation of body areas such as calves, buttocks, chest, and breasts, with long-lasting results and minimally invasive procedures.

The advantages are the known safety record of the NASHA™ products, no requirement for a donor site, little downtime, reversibility, and the possibility of performing the procedure on an outpatient basis. The main disadvantage would be the cost when large amounts of the product are needed.

Macrolane for female breast augmentation was studied in an open trial conducted in 19 patients aged between 25 and 40 years. It was placed above the pectoralis major muscle and beneath the mammary gland. The mean injected volume was 211 mL per breast and patients were followed for 48 months using MRI, mammography, and ultrasound images. Treatment-related adverse events such as local pain, swelling, and redness were mild to moderate and persisted for up to 2 weeks. Two patients subsequently had their implant removed by aspiration: one due to capsular contraction and the other to inflammatory symptoms. In the majority of cases, satisfactory cosmetic results were observed for at least 18 months. MRI and mammography did not show any morphologic changes or microcalcification.

In another study evaluated after 1 year, out of 24 patients treated with a mean of 100 mL of Macrolane VRF 30 per breast, 69% had some improvement, with no inflammatory reactions. Capsular contracture was the most commonly reported adverse event.

Another study (by McCleave) raised important concerns regarding breast characteristics that may be related to possible complications after HA injections and concluded that long-term studies of Macrolane for breast augmentation are still lacking.

For other areas of the body the published papers are few in number. To evaluate efficacy, tolerance, and duration of effectiveness for correcting body irregularities from several causes (after liposuction, trauma, or surgery), another open pilot study was conducted in 56 patients. The mean volume of Macrolane injected was 20 mL, and investigators considered that, after 12 months, 57% of patients remained improved. No serious adverse events were reported and treatment-related side effects (e.g. injection-site pain, tenderness, and swelling) were mild and transitory.

Macrolane VRF 30 and 20 are currently approved in the European Union, Brazil, Mexico, Israel, Taiwan, Hong Kong, Indonesia, Philippines, and Russia.

Technical aspects

The areas to be treated are marked beforehand with the individual in a standing position. When the patient has been positioned, cleaned, and the incision sites covered with sterilized tissue, these are anesthetized using a 30 G needle. Since the passage of a blunt cannula through fat tissue is not a painful procedure, and in order not to distort the depressions, we use a minimal amount of anesthetic solution, as described in Table 23.2. Only the entry points are infiltrated and extra solution will be added solely to painful adherent locations. An average of two incision sites is planned per side, which are chosen in order to allow the cannula to reach the entire treatment area.

Table 23.2 Anesthetic solution used for Macrolane injections

0.9% Unpreserved saline solution	180 mL
2% Lidocaine	10 mL
epinephrine concentration	1 mg/mL
Epinephrine	0.4 mL
8.4% Sodium bicarbonate	10 mL

Incisions are made using an 18 G needle, and an 18 G,70 mm long blunt disposable cannula is used for injection. Initially, it is employed with a back-and-forth movement to release the skin from its attachments to deep planes. Where these attachments are fibrous and strong, undermining them may be painful and the specific site may need to receive additional anesthetic solution.

Pearl 2

Macrolane VRF 30 is usually chosen where the overlying skin thickness is greater than 1 cm.

One single defect can be addressed by using different entry sites. Before injection, the cannula is filled with the product, until a droplet is visible at the tip.

Pearl 3

The gel is injected deep into the subcutaneous layer in multiple passes, injecting small amounts with each pass. Large volumes in isolated pockets are not recommended.

Palpation of the area with the non-dominant hand helps to evaluate whether the desired result is being achieved.

Macrolane VRF 20 is injected more superficially in the subcutaneous layer to allow a smooth finishing of the correction. With both products, injection ends before the cannula reaches the skin surface. Overcorrection is not recommended.

After treatment, the area may be massaged to even out possible irregularities. The borders of each skin incision site are everted and closed directly with adhesive (micropore) tape. After that, the whole treated area is covered with micropore tape. Patients are advised to wear a mild compressive garment, to avoid excessive physical activity, and also to be careful with their sitting position for 1–2 weeks, to prevent dislocation of the gel from the treated sites.

Some swelling and tenderness are expected after the procedure. If a local induration is detected, it may be addressed by massage, non-steroidal anti-inflammatory drugs, topical corticosteroid creams and, if infection is suspected, antibiotics. The product may be also aspirated through an 18-gauge needle or, if complete removal is desired, hyaluronidase may be used.

After 1 month, if the final aesthetic correction proves suboptimal, touch-up injections may be planned. Figures 23.1 and 23.2 illustrate two treated cases.

Figure 23.1 (A) A 40-year-old female with multiple depressions on the buttocks. (B) The areas to be treated are marked with the patient in an upright position. (C) Partial but good result after 25 mL of Macrolane VRF (10 of VRF 30 and 15 mL of VRF 20; total amount: 25 mL). Touch-up correction may be planned after a month period.

Figure 23.2 (A) A 32-year-old thin female showing some concavities on both buttocks sides and also two depressed and darkened skin areas under the ischial tuberosities. (B) The depressed areas are marked with the patient in an upright position. (C) Results after 15 days: the ischial depressions and concavities were filled with one syringe (10 mL) of Macrolane VRF 30 plus half syringe (5 mL) of Macrolane VRF 20. The buttocks looks lifted and with uniform surface contour.

As patients continue to opt for non-surgical procedures that offer predictable results, the possibility of using HA for body enhancement offers the cosmetic surgeon a new tool. Whereas NASHA™ gels are associated with a solid safety record as facial fillers, Macrolane VRF has several advantages that promise to extend its indication in the near future: it needs only local anesthesia in an office-based environment, and there is no need for hospitalization, minimal trauma, minimal pain management, and a short recovery time. The product is non-permanent but long lasting and, if necessary, it is easily removable by aspiration or hyaluronidase administration.

Conclusion

There is an expanding search for techniques and products to enhance body shape and contours. Whenever possible, patients prefer minimally invasive procedures. Autologous fat transfer or HA injections can offer the advantages of rapid, predictable, and durable correction through reproducible implantation techniques. In distinction from implanted fat, the use of HA gel for correction of body defects is relatively recent, however, and questions of its durability over time and association with other energy-based techniques are still to be answered.

Recently, Altman and co-workers proved that human adipose tissue-derived stem cells successfully integrate within non-animal stabilized HA and this may allow the development of a novel, injectable, cell-enhanced, soft tissue augmentation strategy. Further longer term studies will allow a better understanding of this novel method and its potential for use in soft tissue augmentation and reconstruction.

Case Study 1

Figure 23.3 shows a 38-year-old woman who underwent liposuction and fat grafting in different layers of the buttocks: intramuscular, and between the deep fat tissue. Fat graft was mixed with growth factors. She also received superficial fat injections in banana folds. Part A shows the preoperative condition. B is postoperative, 4 months after the procedure.

Figure 23.3 Liposuction and grafting of fat mixed with growth factors in different layers of the buttocks: intramuscular, and between the deep fat tissue, in a 38-year-old woman. She also received superficial fat injections in banana folds. (A) Preoperative condition; (B) 4 months after the procedure.