Title: Aging of the Mid-face Bony Elements: A Three Dimensional CT Study
Authors: Robert B. Shaw, Jr. BS, David M. Kahn MD
In order to effectively rejuvenate the aging face, it is necessary to understand the dynamic aging process. Much is known in regards to how the face loses volume as the soft-tissue structures age. Epidermal thinning and the decrease in collagen cause skin to lose its elasticity. Loss of fat, coupled with gravity and muscle pull, leads to wrinkling and the formation of dynamic lines. These factors contribute to the formation of jowls, crow’s feet and the drooping appearance of aged facial skin. The aging process also affects the facial bones. There are various studies, from the analysis of male skulls, suggesting maxillary clockwise rotation and the enlargement of the bony orbit with changes to its curvilinear form with age.1,2 Changes in face width and mid-face height have also been demonstrated with increasing age.3 In this multi-part study we will demonstrate how specific bony aspects of the face change with age in both men and women and what affects that may have on the application of facial cosmetic surgery.
Method: Facial bone computed tomography (CT) scans were obtained from 60 Caucasian patients, (30 female, 30 male). There were ten male and ten female patients in each of three age categories: young (25-44 years), middle (45-64 years), and old (65+ years), (Table 1). Each CT scan underwent 3D reconstruction with volume rendering and the following measurements were obtained: glabellar angle (maximal prominence of glabella to nasofrontal suture), pyriform angle (nasal bone to lateral inferior pyriform aperture), and the maxillary angle (superior to inferior maxilla at the articulation of the inferior maxillary wing and alveolar arch). Each angle was taken in reference to the sella-nasion line. The area of the nasal aperture was also measured on each 3D model. Analysis of variance and Student’s t-test were used to identify any trends between age groups, with results considered significant at a p-value less than .05.
Results: The glabellar angle in our female population had a statistically significant decrease from the young to middle age group (p=.007), while our male population had a significant decrease from the middle to oldest age group (p=.046).
The maxillary angle in our female population showed a significant decrease from the young to middle age group (p=.0023), and from the middle to oldest age group (p=.0475). The maxillary angle in our male population also had a significant decrease from the young to middle age group (p=.0171), and from the middle to oldest age group (p=.0092). For both genders, the maxillary angle was greatest in the young age group.
The pyriform angle did not show significant change between age groups for either gender.
There was a significant increase in nasal area from the young to middle age group for our male population (p=.0346) and female population (p=.0373). For both genders, the nasal aperture area was greatest in the oldest age group.
Discussion: The decrease in glabellar angle found in this study suggests that the supra-orbital bar and nasion recede with age. This bony change may result in the appearance of brow ptosis and lateral orbital hooding noticed in the older population. The eyebrows appear to droop below the receded orbital rim and the upper eyelid skin appears deflated. The maxillary angle decrease may be responsible for the malar fat pad sliding down and forward, causing it to push up against the nasolabial crease and thus making it more prominent. The increase in the nasal area makes it evident that the bone recedes around the pyriform aperture, without a change in the pyriform angle. This may result in the appearance of nose elongation and drooping noticed with aging. These results suggest that the bony elements of the mid face change dramatically with age and coupled with soft-tissue changes lead to the appearance of the aged face. Thus, we feel the most effective approach towards facial rejuvenation should be two-fold: restoring volume to compensate for the loss of bony volume, and lifting and reducing the aged and less elastic soft tissue envelope. A balanced approach to facial rejuvenation between volume augmentation and soft tissue envelope repositioning and reduction will hopefully avoid the distortions of either approach alone.
Table 1. Average Age by Gender in each Age Category
Young Middle Old
Male Female Male Female Male Female
Mean(Years) 33.8 30.4 57.7 54.5 75.4 75
Std. Dev. 7.6 5.3 4.8 4.5 6.6 7.6
Table 2. Mean Angular and Area Measurements by Gender in each Age Category
Age Category
Young Middle Old
Measurement (SD)
Glabellar Angle Male 73.3(3.6) 71.8(3.7)68.6(3.0)b
Glabellar Angle Female77.1(2.9) 73.4(2.6)a71.4(5.5)
Maxillary Angle Male62.3(3.3) 58.4(3.3)a53.2(4.6)b
Maxillary Angle Female64.4(5.0) 57.7(3.4)a53.6(5.0)b
Pyriform Angle Male60.1(3.1) 59.1(3.8)60.3(3.4)
Pyriform Angle Female60.5(4.4) 56.7(4.6)56.9(4.0)
Nasal Area(mm2) Male 610.4(44.4) 664.4(60.1)a 669.8(44.5)
Nasal Area(mm2) Female 497.9(47.7) 550.1(55.8)a 556.3(51.5)
Legend: a: statistically significant decrease from young to middle age group
b: statistically significant decrease from middle to old age group
Figure 1.
Example CT scan of a female subject in the young age group compared to a female subject in the old age group. Mean angular measurements are applied to each image.
References:
1. Pessa, J.E., and Chen, Y. Curve Analysis of the Aging Orbital Aperture. Plastic and Reconstructive Surgery 109:751-755, 2002.
2. Pessa, J.E. An Algorithm of Facial Aging: Verification of lambros’s Theory by Three-Dimensional Stereolithography, with Reference to the Pathogenesis of Midfacial Aging, Scleral Show, and the Lateral Suborbital Trough Deformity. Plastic and Reconstructive Surgery 106:479-487, 2000.
3. Bartlett, S.P., Grossman, R., Whitaker, L. Age-Related Changes of the Craniofacial Skeleton: An Anthropometric and Histologic Analysis. Plastic and Reconstructive Surgery 90:592-599, 1992.