Understanding the Deep Fat Pads

By Dr Raquel Amado / 19 Oct 2022

Dr Raquel Amado details the anatomical structure of the deep fat pads in the mid-face

When addressing rejuvenation volume replacement, the mid-face is an important area to focus on. Despite it being an area of the face which is frequently discussed and educated on, I still find when delivering training to new or even more experienced practitioners alike, there remains a lot of confusion.

The mid-face is composed of five layers. The order of the layers is skin, subcutaneous fat, superficial musculoaponeurotic layer (SMAS), deep fat and spaces and the deep fascia/ periosteum.1 However, for the purpose of this article, I will be exploring the anatomy of the deep fat pads in the mid-face.

As the deep fat compartments have been shown to be relatively stable during ageing (they are not displaced inferiorly onto the bone), deep soft filler implantation in these compartments and in contact with the bone will provide support for the overlying structures and increase anterior projection.2

Deep fat pads

There are five deep fat compartments: lateral sub-orbicularis oculi fat (LSOOF), medial sub-orbicularis oculi fat (MSOOF), deep lateral cheek (DLCF), deep medial cheek (DMCF) and deep nasolabial fat. These fat pads adhere to the bone and provide support to the overlying soft tissue. The SMAS and superficial fat have an important role on the facial topography.2 In his cadaveric studies, plastic surgeon Dr Fabio Ingallina found that the MSOOF is a triangular fat compartment extending from the lateral canthal line onto the maxillary bone. It is separated from the lateral SOOF by a vertical septum, and from the inferior eyelid’s pre-septal space by the orbicularis retaining ligament (ORL). Inferiorly, the MSOOF also connects with the medial zygomatic cutaneous ligament (ZCL).2

The LSOOF lies laterally to the vertical septum and covers the prominence of the zygomatic bone. The lateral ZCL and the DLCF pad constitute its inferior border.2 The DMCF lies underneath the superficial medial cheek fat and the SMAS. It is triangular-shaped and directly overlies the maxillary bone.2

As we age, we see atrophy of these compartments, however they will still maintain their position, therefore we will witness a decrease in the cheek volume but not a descent of the upper cheeks. Subsequently, injecting soft filler deep into these fat compartments will give the projection required to rejuvenate the area.3,4

Anatomy

Without understanding and respecting the ageing face, we cannot predict our outcome and the safety of the procedure.

An article by Cotofana et al. explains how soft-tissue filler injections can result in different skin surface effects depending on the targeted facial fat compartment.5 It revealed that the SOOF compartment had the highest correlation coefficient and the highest surface-volume coefficient.

In practical terms, this means that by using the lowest volume of soft filler, the most correction can be achieved. Therefore, practitioners have the anatomical knowledge to prioritise where they are going to place the filler to bring their patients the best aesthetic outcome.

Surmising from this study, we understand that the first deep fat pad that we should target to get the best outcome on a mid-face rejuvenation is the SOOF.5 However, we also need to consider that should the patient present with infraorbital hypertrophy, malar mounds, festoons or any kind of lymphatic compromise in this area, caution needs to be taken in order to not exacerbate and potentially compromise this area further.

We also need to consider where in the SOOF we are going to place our soft filler. The SOOF is divided into two compartments (superior and inferior) by the malar septum.1 If we inject the soft filler into the superior SOOF compartment, the injected filler could possibly compromise the lymphatics by blocking them and inhibiting drainage. The other consideration that must be factored in is that due to the hydrophilic qualities of the HA filler, the lymphatic drainage system in this area could become overwhelmed, resulting in inactive lymph drainage and oedema. If this happens, then practitioners should avoiding treating the patient.

Anatomy of the deep fat pads on the face. Image courtesy of Dr Marcus Mehta.

Vasculature

Each patient’s anatomy is slightly different in position and therefore there are no safe zones. Treating each patient as an individual and having a deeper knowledge of the anatomy is key. When treating the deep fat pad compartments, the main vasculatures that we need to be aware of are the infraorbital foramen (IFO), facial artery and facial vein. Dentists will be aware that the IFO location correlates with the second premolar on a vertical axis, however if this tooth is missing or if you are not a dentist, this is probably not the easiest way of finding your IFO.6 According to a study, we know that the average distance between the IFO and the infraorbital rim is 10mm and 26mm from IFO to the lateral orbital rim.6

The facial artery supplies the lower anterior part of the cheek and there are a staggering 50 different variations of the facial artery.7 A study from Hong et al. demonstrates this rather articulately. So, when it comes to injection vasculature it’s more favourable to rely on depth rather than distribution. In the mid-face we know if the facial artery is present, it runs superficially in layer two.7

The facial vein is often located underneath the zygomaticus major and minor muscle, along the mid-cheek groove. This divides into the deep medial and lateral cheek fat pad, therefore we shouldn’t inject directly into the groove.8 As the harmonious veins accompany the arteries, we can conclude that the facial artery is likely to be in this area too.2,9

Injection techniques

When it comes to injection techniques, this will depend on the injector’s experience and preference. You can find multiple techniques to treat this area. Therefore, the technique used will be dependent on the practitioner’s experience, patient presentation and the product selection.

Cannulas and needles

Cannulas tend to be more comfortable for the patient and have less risk of complications, as they are less likely to penetrate the arterial wall.10 However, they are more technique sensitive due to being longer and more flexible than needles.11

Needles offer more precision than cannulas as they are sharper; however, they can be more traumatic to the tissues and carry a higher risk of vascular compromise.10 My preferred way to inject the deep fat pads is by using a needle as opposed to a cannula because of the challenge of the accuracy in the SOOF, which is due to the presence of the malar septum, as explained above. Despite this, some practitioners may prefer to use cannulas in their technique.

Products

When selecting products for this area, I focus on cohesive and viscoelastic products. Products I recommend are Neauvia Intense LV, Teosyal RHA 4 or Ultra Deep, but there are many other suitable reputable brands available. In my experience, these products are going to offer the projection required to lift the three layers above, but also allow patients to look natural in both static and dynamic movement as well as resist deformation.

Tips for success

It’s important to take into consideration the gender and ethnicity of your patients. When we know that female patients wish to achieve more anterior projection than males, and therefore care must be taken not to over feminise a masculine face.9 Consideration also needs to be taken in relation to a patient’s ethnicity and their features. For example, Asian faces are naturally flatter.12 This is why the consultation is important to determine what patients are after and manage their expectations.

It is vital to discuss all these considerations during the consultation and explain to the patient how the treatment will affect the outcome. You must respect heritage features and consult carefully, being sure to listen to what patients are seeking to achieve. Conversely, there are instances where patients are seeking treatments to enhance features and create a ‘westernised appearance’. The resounding message here is that consultation is the key before any treatment plan is carried out.

Age is also an important factor. Replacing volume in the deep fat compartments and on bone is where I begin my mid-face rejuvenation. You will generally find that in younger patients, replacing the deep fat compartments is often enough to create a good clinical outcome. However, in cases of severe volume deficit, usually in older patients or patients that have had significant weight loss, additional treatment would be recommended. Often, a multi-layered technique is used to address the superficial fat pads to optimise the clinical outcome, however this is outside the remit of this article.

Increase your knowledge

In summary, having an in-depth knowledge and understanding around the anatomy will make your treatments safer and more predictable. There are constantly new updates and studies being performed in this area. To be a progressive practitioner it’s crucial that we are aware of new findings. Registering with academic resources, undertaking cadaveric courses or attending aesthetic conferences such as ACE and CCR are all ways you can do this.

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