Introduction

In the early 1980s, when soft tissue augmentation began its meteoric rise to become one of the most important procedures in cosmetic dermatology, bovine collagen was the only product available, and treatment focused solely on filling lines and furrows that marked the onset and progression of the aging face. Intradermal injections were performed superficially in the epidermal–dermal junction, whereas more stabilized preparations were recommended for ‘deeper’ injections into the dermis. After piercing the surface of the skin, the needle was positioned parallel to the skin; examples of horizontal injections include the multiple puncture or linear threading technique, either singularly or in a fan-like manner.

Further developments in soft tissue augmentation – among them the recognition of the importance of volume loss – have led to a better understanding of what is needed to rejuvenate and restore the individual potential beauty of an aged or ‘mature’ human face. As new materials have become available and greater anatomical knowledge is gained, clinicians now have a better opportunity to restore volume lost through the aging process using innovative, vertical injection techniques that aim to provide optimal structural support.

Anatomical considerations

Initial treatment approaches for volume restoration did not focus on the existing facial anatomy. As a result, dynamic muscular activity led to pronounced compression of all soft tissues, negatively affecting the superficial appearance of the surface of the skin resulting in a possible overcorrection. With the transition to more vertical injection techniques, augmentation results have become more predictable. However, it has become increasingly obvious that precise knowledge and understanding of the subcutaneous facial anatomy are prerequisites for successful volume restoration in facial rejuvenation.

The facial skin and subcutaneous tissue (referred to as the soft tissue ‘flap’) comprise a dense, superficial formation of connective tissue that makes up the dermis and epidermis, a honeycomb web-like subdermal structure of connective tissue embedded in fat lobules, and muscle, which traverses the soft tissue flap (Fig. 25.1). Anatomical studies show that the immediate subdermal layer contains a large connective tissue network made up of small fat lobules with many septa, whereas the deeper subdermal layer features large fat lobules with only a few septa. Dynamic musculature presents in sometimes overlapping, multiple layers, and may even form entire complexes – as in the brow area where the frontalis, corrugator, and orbicularis muscles merge into one complex with the ability to move medially, proximally, and distally (F. Anderhuber, personal communication).

Figure 25.1 Facial skin and subcutaneous tissue.

The analysis of the anatomical composition of the connective tissue is of greatest interest in volume augmentation. The soft tissue flap is attached to the underlying bony structure via connective tissue bands called retinacula or real retaining ligaments (Fig. 25.2), which show no or very limited elasticity. So-called false retaining ligaments – the most important of which include the nasolabial fold, the zygomatic ligament, and the maxillar–buccal ligament (Fig. 25.3) – add to the character of the flap surface. Although false retaining ligaments have no bony attachment, they act in a fence-like manner, compressing dynamic muscular activity and influencing the appearance, shape, and correction of the skin surface.

Figure 25.2 Real retaining ligaments.

Figure 25.3 False retaining ligaments.

A brief description of the soft tissue anatomy of the human face is not complete without a discussion of the fat compartments, which are located around and below the eye, in the cheek, and in the perioral region (Fig. 25.4). The suborbicularis oculi fat (SOOF) and retro-orbicularis oculi fat (ROOF) pads are the dominant features of the periorbital region. As the most proximal entity in the mid-facial region with the least coverage of musculature structures, the SOOF pad plays a key role in the process of facial aging and has a direct impact on the clinical presence of the medial and lateral infraorbital hollow. Another important, shape relevant structure in the submalar area is induced by an indented groove from the medial orbital hollow to the lateral lower midface caused by the zygomatic ligament.

Figure 25.4 Fat compartments of the face. SOOF, suborbicularis oculi fat.

Biological characteristics of filler materials

Autologous fat or other biodegradable materials, such as hyaluronic acid (HA), calcium hydroxylapatite (CaHA), or poly-l-lactic acid (PLLA), are the most frequently used agents in volume replacement soft tissue augmentation today. All agents differ with respect to interaction with the recipient site and therapeutic effect in the tissue. In this respect, the main characteristics of interest include overall duration of effect, neocollagenesis, and water retention.