The subcutaneous fat of the face is partitioned into discrete anatomic compartments. Facial aging is, in part, characterized by how these compartments change with age. The concept of separate compartments of fat suggests that the face does not age as a confluent or composite mass. Shearing between adjacent compartments may be an additional factor in the etiology of soft-tissue malposition. Knowledge of this anatomy will lead to better understanding and greater precision in the preoperative analysis and surgical treatment of the aging face.

Loss of volume of deep medial cheek fat leads to pseudoptosis and is an additional determinant of the nasolabial fold. Augmentation of deep medial fat has four effects: it increases anterior projection (not addressed by lateral redraping alone); it diminishes the nasolabial fold; the V-deformity is corrected; and a youthful cheek with natural boundaries is recreated. The term "malar fat" is probably a misnomer: this region is composed of both distinct superficial and deep fat compartments. Submentalis and sub-orbicularis oris fat play a role is the formation of the labiomental hollow and aging lip respectively. Understanding the anatomy of this area lends greater precision to our ability to rejuvenate the aging face.

An algorithm of facial aging is presented that serves as the conceptual basis for understanding aesthetic surgical principles and techniques. This model begins with the verification of Lambros's theory of skeletal remodeling. It was suggested that bony changes of the midface may be summarized as a clockwise rotation of the midface relative to the cranial base. Three-dimensional stereolithography/rapid prototyping was used to test this hypothesis. A precisely duplicated facial skeleton was created for young and old men (n = 12) by laser polymerization. Angular measurements confirmed that the angle of the pyriform and maxilla decreased with age (p = 0.004 and 0.005, respectively); there was a trend for the angle of the glabella (frontonasal angle) and orbits to do the same. These results validate Lambros's theory, which serves as a basis to further comprehend the pathogenesis of midfacial aging and the formation of ectropion and scleral show. The algorithm of facial aging is extrapolated from these data, from previous research, and from clinical observation. This model encompasses three main concepts or tenets, and it may serve as a clinical tool for the diagnosis and treatment of facial aging.

Summary:The etiology of age-related facial changes has many layers. Multiple theories have been presented over the past 50–100 years with an evolution of understanding regarding facial changes related to skin, soft tissue, muscle, and bone. This special topic will provide an overview of the current literature and evidence and theories of facial changes of the skeleton, soft tissues, and skin over time.