Concepts of Midface Soft Tissue and Skeletal Aging

Traditional concepts of periorbital and midface aging and rejuvenation focus on the soft tissues. Recently, senescent changes in the supporting facial skeleton been investigated. Findings in these studies revealed retrusion of the midface skeleton and support the concept of alloplastic augmentation of the midface skeleton as part of the algorithm for periorbital and midface rejuvenation and enhancement.

Senescent changes to the soft tissues are apparent and therefore have been the focus of periorbital and midface rejuvenative surgery. The traditional belief of how facial appearance changes with age centered on the development of a lax skin envelope that becomes ptotic under the influence of gravity. Recent studies have challenged this concept and introduced a number of components and mechanisms (some contradictory) as contributing to periorbital and midface aging.  Lambros has demonstrated through closely matched images taken of an individual over time that descent probably does not play as large a role in the aging process as previously thought. Coleman advocates the role of fat atrophy in contributing to the volume loss and sagging of the soft tissue envelope. In contrast, Gosain in an MRI study of the cheek fat pad concluded the changes in the midface were related to a combination of hypertrophy and ptosis.  More recently, Le Louarn  postulated that the facial muscles are the predominant factor in the aging process. In his paper he concludes that the repeated motion of the facial musclulature results in a redistribution of the facial fat over time creating the aged face. These conflicting hypotheses and data suggest that changes that occur to the facial soft tissues with time and manifest as the aging face may be a mix of addition, subtraction and redistribution.

Controversy also exists as to how the facial skeleton changes with aging. Some early investigators thought that the craniofacial skeleton grew until skeletal maturity and then became stable.  Other early investigators believed that the facial bones continued to remodel throughout life. Bartlett, in his analysis of skulls from the Smithsonian, concluded that the skeleton expanded with age. But in their subjective analysis of facial form they noted a general coarsening of bony protuberances at the site of facial musculature origin form the bone and a general softening in the areas of bone with no muscle attachment. It was also noted that facial height decreased as a result of tooth loss and the subsequent loss of alveolar bone

Pessa and colleagues furthered the concept that the facial skeleton continues to change throughout life. The collective studies of Pessa have demonstrated that changes occur with age along the inferior orbital rim. The rim moves relatively posterior to the anterior cornea as well as undergoing progressive curve distortion particularly in the infero-lateral aspect. Pessa’s studies in the midface also confirm that the craniofacial skeleton continues to undergo differential changes with age. Shaw and Kahn’s work reinforces Pessa’s findings that the midface skeletal structures retrude with age relative to the upper face.

Levine’s analysis of Behrents Atlas of Growth in the Aging Craniofacial Skeleton, indicated to him that facial bone growth continues throughout adulthood. He concluded that it is soft tissue descent and volume loss that leads to the associated changes of aging. Furthermore, he believes that the negative vector eyelid or polar bear appearance seen in some individuals is the result of a horizontal maxillofacial deficiency present throughout life that is unmasked by the soft tissue changes of aging. Levine contends that Pessa’s, as well as Shaw and Kahn’s, cohort comparison studies using statistical analyses of three dimensional images are unsound because  they are not longitudinal, that is, they do not study any one individual over time. Pessa counters that Levine’s longitudinal analysis of cephalometric tracings is unsound because it is based on angular measurements which can be interpreted in different ways depending on the point of reference.

In my analysis, both the soft tissues and the skeleton contribute to midface contour and both components are impacted by the aging process. Hence, both soft tissue and skeletal augmentation can be appropriate to restore midface convexity. However, these modalities are not equivalent in their impact on the appearance of the midface.  Free fat grafting and the injection of various fillers is intuitive for the restoration of soft tissue volume loss due to senile atrophy.  It has a limited role in simulating the effect of an increase in skeletal projection.  Whereas augmenting the facial skeleton results in an increase in the projection of the skeleton, augmenting the soft tissue volume results in an inflation of the soft tissue envelope and blunting of the contours of the skeleton.  Over augmentation of either component brings home the point. If overly large implants were placed on the skeleton, the appearance would be too defined and ultimately, skeletal.  If too much fat were placed in the soft tissue envelope, an increasingly spherical and otherwise undefined shape would result.