Anatomy of the Gluteal Subcutaneous Tissue in Different Skin Conditions and Its Impact on Hyaluronic Acid Injections

Plastic Surgeon Dubai-based shared on an ISAPS article the importance of the anatomical knowledge and how this information is key in achieving safe and optimal results.

The use of hyaluronic acid for buttocks augmentation is a growing trend as it is a good alternative to provide immediate and predictable results. Furthermore, it is a viable option for thinner patients or those who do not want to go through surgery and prefer a less invasive method. 

Anatomical knowledge is a key factor to achieve optimal and safe results. Likewise, the ability to adapt the technique is important to the patient’s needs and skin condition. During my last four-year clinical practice in the UAE, I have injected more than 1,500 syringes into many types of skin, from young to old patients, with excellent and durable (1–2 years) results and no severe complications. 

Anatomy of Buttocks Fat Layers

The subcutaneous fat layer of the buttocks is composed of superficial (SAT) and deep (DAT) adipose tissues that are separated by a membranous layer of connective tissue called Fascia Superficialis.

In SAT, the adipocytes are organized by fat lobules in close contact, while in DAT the fat lobes consist of lobules more spaced by interstitial tissue with a major predisposition toward displacement. Between the fat layers, we find retention ligaments in the transition areas between the gluteus maximus and gluteus medius muscles and the lateral part of the trochanter, as well as perpendicularly oriented fibrous septa, anchoring the dermis to the superficial fascia, and responsible for skin elasticity.

The DAT instead is a less elastic tissue with oblique fibrous septa connecting the superficial and the deep fascia above the muscle. Although the ideal candidate for the procedure would have healthy skin, this is not common. In general, we usually treat patients with unhealthy skin: fibrous cellulite or laxity with loose tissue that may present stretch marks following childbirth or a rapid change in BMI, respectively.

Injection Approaches

Similar to implants, fillers are heavier than fat and need a supporting base. There is no general strategy or volume because the patient’s skin must be considered when it comes to HA injection. In the case of water retention such as cellulite, adipocytes and lobules are larger, thus reducing the interstitial space.

In this situation, my strategy is to inject into the DAT layer allowing the fibrous septa to relax from below and reduce the superficial depressions of the skin while giving volume. In contrast, loose tissue presents a reduction in collagen and connective tissues with more interstitial space in both the SAT and DAT layers. This implies the need for a greater filler volume, but with an elevated risk of ptosis due to the poor elasticity of the tissue that cannot support its weight.

In mild laxity treatable cases, I prefer a multilayer approach, injecting preferentially in the upper third of the buttocks and avoiding boluses that concentrate the filler’s weight. We should consider that pronounced laxity is an exclusion criterion. 

For unhealthy skin cases, it is better to have a stepwise strategy in two or more sessions every 2–3 weeks to achieve the desired result. During this period, in my experience with the HYAcorp MLF2 product, the filler has perfectly integrated into the adipose tissue and has a minimal risk of migration. 

Even when dealing with patients with healthy skin, I use a multilayer approach, starting by injecting the SAT to take advantage of its elasticity. This allows a greater expansion with less product due to the compactness of the lobules which prevents its dispersion.

The filler finds support in the superficial fascia that pushes it upwards conferring projection. Once maximum tension is reached in the superficial layer, injecting the deeper layer helps create a support structure at the base that further improves the result.

Treatment of Hip Dips in the trochanteric area is different. At the base we find the gluteal fascia which continues laterally with the tensor fascia latae and caudally with the iliotibial band and a single, thinner layer of fat.The choice of the access point is crucial. To reach the lateral depression I prefer to enter from the lower trochanteric area, that way it is easier to avoid injecting the filler into the tendon with a high risk of migration into the groin area. 

In this direction, the cannula encounters the fibrotic tissue perpendicularly, breaking it and generating breaches between the fibers that allow support for greater volume and therefore greater skin expansion. This way, we can obtain better and safer results even with deep stretch marks.