INTRODUCTION
Facial aging is no longer considered purely gravitational
decent. Volume loss, a dynamic process with skin thinning
and collagen loss, fat redistribution, muscle atrophy
and bone remodeling, is a major component.1-3 While surgery
can address lax or sagging skin, or the need to tighten or resuspend
facial muscle, it does not address volume loss without
fat grafting, or treat the face as a whole.
Treatment options such as poly-L-lactic acid (PLLA, Sculptra®,
Sinclair Pharmaceuticals) that replace volume by considering
the entire face and its structural foundation provide a more holistic
approach, may forestall further deterioration, and avoid/
postpone need for surgery.1,2,4
The Dynamic Process of Facial Aging
Multiple changes in skin, subcutaneous fat, muscle and bone
contribute to facial aging.5-7 As facial aging primarily comprises
soft-tissue changes, bone atrophy and remodeling,2,8-10 evaluating
the whole face and structural tissue integrity is pivotal to
provide natural-looking results.
Bone
Craniofacial skeletal remodeling, with expansion and loss of
bone, is an important contributor to facial aging.4,11-25 By the age
of sixty, 25% of bone mass is lost,26 with increases in orbital aperture;
decreases in glabellar, pyriform, and maxillary angles.11
Mandibular angle changes may cause blunting or loss of lower facial border definition;4 pyriform aperture increases the appearance
of nose elongation and drooping nasal tip.16 Midfacial
bone loss may exacerbate the nasolabial fold by reorienting the
malar fat pad medially and inferiorly.22
Fat
Changes in fat contribute to facial aging.27,28 Fat pad compartments
are located in two layers: a superficial layer between the dermis
and fascia superficialis contributing to a healthy looking face, and
a deep layer around or under the muscles, contributing to a youthful
appearance.29 Age-related changes in volume and positioning
lead to changes in facial appearance.30,31 Fat redistribution causes
atrophy in certain areas (ie, periorbital, forehead, buccal, temporal,
and perioral areas) and hypertrophy in others.5 Fat pads become
more discernible as separate entities, as do many underlying
facial structures, such as submaxillary glands and bony protuberances.
32 The malar fat pad gradually slides forward and down to
bulge against the nasolabial crease, giving nasal fold prominence.
Fat redistribution and demarcation may disturb a smooth transition
from one anatomical region to another, giving an unbalanced
appearance. Sagging (jowl, submental area, and nasolabial fold)
becomes pronounced due to relative excess of skin and/or lack of
elastic recoil and fat accumulation.32
Muscles
It is unclear whether muscles age histologically, or change
physiologically in response to the aging process of underlying