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Video 12.1 Mandible angle augmentation. This video demonstrates the placement of a
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porous polyethylene mandible angle implant immobilized with titanium screws.
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Chapter 13
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Rejuvenation of the aging face and skeleton with implants
In his article “Anatomy and pathophysiology of facial aging”, Zimbler states, “Facial aesthetics begin with the marriage of hard and soft tissue integration; however, it is the changing balance of these elements that is the hallmark of the aging process A youthful face therefore represents a point in time when a particular set of skeletal proportions are ideal for their soft tissue envelope.”
SOFT TISSUE AGING
Soft tissue ptosis secondary to gravity has long been considered the major mechanism responsible for facial aging. There is no doubt that gravity and ptosis are the main factors leading to facial aging.2 Lambros and others have concluded that changes in volume of cheek fat, both loss and gain, rather than ptosis account for an aged appearance. ever, show that there are also many changes to the craniofacial skeleton as patients age that contribute to the aging process.
The aging face typically shows the following changes: descent of the brow, changes in contour of the upper eyelid, medialization of the lateral canthus, lower eyelid descent, deflated infraorbital skin envelope, increased visibility of the lid–cheek junction and nasojugal crease, increased prominence and depth of the nasolabial fold, and increased prominence of the labiomandibular crease. These signs of aging have been related to changes in skin and soft tissue.
In addressing soft tissue ptosis and volume changes, many facelifting tech­niques involve the removal of excess skin and also fat grafting and sculptur­ing. The main purpose of this chapter is to address the skeletal changes in the face that contribute to aging. Other chapters discuss the techniques available to address and reconstruct the facial skeleton for a more youthful appearance as a sole procedure or in addition to other techniques. 
3,4
Numerous anatomical studies, how-
1
FACIAL SKELETON AGING
In addition to soft tissue changes, it has been demonstrated that there is remod­eling of the craniofacial skeleton with age, the orbit.
which is the process of skeletal remodeling due to mechanical forces of soft tis­sue on bone.
factors and processes are the prior, proximate, extrinsic, and primary cause of all adaptive, secondary responses of skeletal tissues and organs.”10 This
8,9
These will be discussed separately in the remainder of this chapter.
One of the theories behind the skeletal changes is mechanotransduction,
10
The functional matrix hypothesis states that “epigenetic, extra skeletal
5–7
for example, bony remodeling in
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Chapter 13 Rejuvenation of the aging face and skeleton with implants
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is, in essence, a restatement of Wolff’s Law, which is the observation that a long bone changes its external shape and internal architecture in response to stresses acting on it. A recent revision of the functional matrix hypothesis stresses the importance of mechanotransduction, which is defined as the pro­cess of intercellular transaction of mechanical information into osteoblastic changes.
10
Several studies have shown craniofacial changes as a result of facial muscle and nerve ablation. Sinsel et al. in a laboratory study on rabbits demonstrated misdirection of bony growth and changes in bony shape after ablating the buc­cal branches of the facial nerve and the muscles innervated by these branches.11 Matic et al. also demonstrated a decrease in bone volume of the mandible and zygoma in rabbits after paralyzing the masseter muscle unilaterally with botu­linum toxin.
12
A study conducted on patients with Moebius syndrome by Instrum et al. exemplifies the relationship between musculature and bony changes. In this neuromuscular syndrome, patients suffer congenital facial paralysis that is usu­ally bilateral and involves cranial nerves VI and VIII. In some patients, cranial nerve V is also involved, causing paralysis of the muscles of mastication. Skel­etal changes are evident on cephalograms of patients with Moebius syndrome and research has shown that these changes are more apparent in the cephalo­grams of patients with cranial nerve V involvement. These patients were found to exhibit an “extreme pattern of vertical growth, clockwise rotation of the man­dible, and an anterior open bite.”
13
Craniofacial skeletal changes, including significant lengthening of the face and an anterior flare of the upper incisors, has been found to occur in patients with spinal muscular atrophy and myotonic dystrophy, both syndromes that cause weakening of the muscles of mastication.
14
The above studies indicate that muscle functionality is important to the development of the bones on which they insert. When comparing the cranio­facial skeletal changes that occur in aging with the changes that occur with neuromuscular syndromes, it becomes apparent that the two are quite similar. Therefore, we can conclude that normal facial muscle strength is important in maintaining a youthful craniofacial skeleton. 
THE AGING ORBITAL SKELETON
The notion of orbital aging has been the focus of several strands of research. Pessa analyzed the changes to the orbital rims in 30 male skulls in three age categories at the Smithsonian Institute. It was found that there was no change in orbit width or height with increasing age. However, there was curve distor­tion of the superomedial upper orbit and inferolateral orbit, which led Pessa to believe that the orbital rims receded in only these regions, without an overall change in orbit height or length.
In a more comprehensive study by Kahn and Shaw, 60 white patients (30 female, 30 male), underwent facial bone computed tomography (CT) scans to demonstrate how specific bony aspects of the orbit change with age. The study population included 10 male and 10 female patients from each of the three age categories: young (25–44 years), middle (45–64 years), and old (65+ years). CT scans underwent three-dimensional reconstruction with volume rendering.9
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The results, illustrated in Fig. 13.1, concluded that, with age, bony changes and soft tissue consequences occur. These include the following:
8
Young Female Old Female
Youth Age
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• A significant increase in orbital aperture width and area.
• A significant increase in height of the superior orbital rim medially, sug­gesting that the superior orbital rim recedes with age in this region. The superomedial rim reshaping may cause exposure of the medial upper lid fat, a change currently attributed to weakening of the orbital septum.
• The glabellar angle becoming more acute leads to the perceived descent of the medial brow and the formation of glabella skin creases.
• The inferiolateral rim remodeling and increase in orbital aperture width may contribute to the formation of crow’s feet and lower lid lag.
• The mediolateral rim remodeling found in the male study population may contribute to the formation of the nasojugal groove and lower lid lag.
• The changes seen in the upper half of the orbit may result in the soft tissues rolling into the orbital aperture and thus, the appearance of brow descent and lateral orbital hooding.
• In the lower half of the orbit, the tissues may roll over the recessed bony ledge leading to lag of the lower lid, appearance of descent of the lid–cheek junction, and a deepening of the nasojugal groove as dispro­portionate tissue piles up against the orbicularis origin along the medial rim.
This study expanded on previous literature, as it accounted for bony change trends in males and females separately. It also provided a more accurate three­dimensional representation, with the CT scans measured at 1.25-mm slice widths, as opposed to 3-mm CT slices in previous studies. It therefore provides convincing evidence that bony elements of the orbit undergo dramatic changes with age and, along with soft tissue changes, lead to the appearance of the aged eye and orbit.
The more extensive aging of the inferior orbital rim in male subjects than in female subjects in this study correlates with the findings of Van den Bosch in 1999.15 His study of 320 male and female subjects, aged between 10 and 89 years, found that after the age of 35, both genders experienced lower lid droop, but the extent of this droop was twice as much in the male subjects. These two studies draw a correlation between the recession of bone and soft tissue droop­ing in the lower lid lag.
The aging orbital skeleton
Fig. 13.1 Upper panel: Illustrations showing the typical appearance of orbital tissues in youth (left) and old age (right). Lower panel: Three-dimensional CT scans showing typical contours of the orbital skeleton in a young female (left) and old female (right). These illustrations and images correlate the aging changes that take place in periorbital appearance with changes to the underlying skeleton as described in detail in the body of this chapter.
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Chapter 13 Rejuvenation of the aging face and skeleton with implants
Youthful Orbits Aged Orbits Rejuvenated Orbits
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A B C
Fig. 13.2 Alloplastic augmentation of the infraorbital rim can restore youthful contour in an aged skeleton. (A) Youthful orbit. (B) Aged orbit. (C) Implant augmenting aged orbit to simulate contour of youthful orbit.
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A B
Fig. 13.3 Clinical example of a 45-year-old man who underwent infraorbital rim skeletal augmentation together with subperiosteal midface elevation to rejuvenate the aged orbit. Note postoperative elevation of lower lid and cheek, lengthening and narrowing of palpebral ssure, as well as lateralization of lateral canthus. (A) Preoperative appearance. (B) Postoperative appearance at 1 year after surgery.
Alloplastic augmentation of the infraorbital rim can restore youthful contour in an aged skeleton as demonstrated in Fig. 13.2. Together with midface eleva­tion, the stigmata of skeletal and soft tissue periorbital aging demonstrated in
Fig. 13.1 can be ameliorated with implant elevation and subperiosteal midface
soft tissue elevation (Fig. 13.3). 
THE AGING MIDFACIAL SKELETON
The midfacial skeleton, consisting of the inferior orbital rim, the maxilla (including the pyriform aperture), and the zygoma, are also subject to the process of facial aging and bony changes. Literature by Pessa, and others of the midface as the aging process unfolds (Fig. 13.4). These changes can be
10,11,20,21
has shown a number of changes that occur to the bones
16,17
defined as:
• retrusion of the lower maxilla, resulting in the development of nasolabial
folds18;
• retrusion of the orbital rim and anterior cheek mass in relation to the cor-
neal surface17 (Fig. 13.5). The above bony changes may result in the appearance of a midface concavity, which gives the appearance of being tired due to the presence of long lower eyelids, loss of cheek prominence, rounding of the lateral canthal angle, and increased vertical height of the palpebral fissure.
22
Shaw,
18,19
The aging midfacial skeleton
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A
B
angles. (A) Young female skeleton. (B) Aged female skeleton. From Shaw and Kahn,18 with permission.
Fig. 13.5 Artist’s depiction of the changes on the
Aging faceYouthful face
midface and periorbita that occur with aging as described by Pessa etal.17 He showed that in the youthful face, the cheek fat lies anterior to the cornea and the orbital fat lies slightly anterior to the orbital rim (A). With aging, the cheek mass tends to lie posterior to the anterior surface of the cornea, the orbital fat moves slightly anterior, and the infraorbital rim has a signicant movement posteriorly (B). Hence, retrusion of the infraorbital rim with aging makes the eyes appear more
Orbital fat
Infraorbital rim
Cheek mass
A
Cornea Cornea
B
Orbital fat
Cheek fat
prominent by changing globe–rim relations, and it signicantly impacts the appearance of the lower lid bags, particularly in those who tend toward maxillary hypoplasia.
It is believed that the decrease in bony projection that occurs with aging speeds the effect of gravity on the descent of an unsupported soft tissue enve­lope.22 An alternate hypothesis is put forward by Levine, who suggests that soft tissue descent is the “engine” driving the aging process, with bone relocation and reshaping determined by the pull of surrounding tissues.20 Regardless of the pathophysiologic mechanism, skeletal augmentation provides an effective method to restore facial convexity and to rebuild a platform that supports the soft tissues of the face.
23
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Chapter 13 Rejuvenation of the aging face and skeleton with implants
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The potential for implants to restore youthful midface contours is illustrated
in Fig. 13.6 and demonstrated clinically in Fig. 13.7. 
A B
C D E
Fig. 13.6 The potential for implants to restore youthful midface contours is illustrated. (A) Young skeleton. (B) Aged skeleton. Illustrations
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demonstrating the potential of implants to restore a youthful (more projecting and convex) midface skeletal contour. (C) Infraorbital rim implant, (D) malar implant, and (E) pyriform aperture implant.
The aging lower facial skeleton
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A B
Fig. 13.7 An example of the projecting and rejuvenating eect of pyriform aperture augmentation on the lower midface: (A) preoperative and (B) postoperative appearance.
THE AGING LOWER FACIAL SKELETON
The mandible is the foundation of the lower face. Normal mandibular propor­tions, including ramus height and length of the mandibular body, provide excel­lent support for the soft tissue repositioning that occurs with aging. However, patients with a short ramus, rounded mandibular angle, and decreased man­dibular projection are less skeletally equipped to gracefully support middle and lower face soft tissue repositioning with age.
What exactly happens to the mandible as it ages? Which proportions are affected by the aging process? In a study by Shaw et al.,21 facial bone CT scans were obtained from 120 white subjects, of which 60 were female and 60 were male. The population was further organized into three different age groups (20–40 years, 41–64 years, 65+ years), with 20 females and 20 males in each age category. The patients were mea­sured for: bigonial width, ramus breadth, ramus height, mandibular body height, mandibular body length, and mandibular angle. Fig. 13.8 demonstrates the mor­phology of a young and aged female mandible. The results revealed the following:
• Mandibular width did not significantly change with increasing age, which
implies that skeletal width of the lower face does not impact the aged ap­pearance of the lower face.
• Mandibular angle increased with age and became more blunted, which
results in less jawline definition and a softer, more oval appearance of the lower face.
• Mandibular height and mandibular length (projection) significantly de-
creased with age. Interestingly, the mandible projection decreases before there is a decrease in mandible length. These changes may cause the ap­pearance of a receding chin, and the overall loss of mandibular volume
21
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Chapter 13 Rejuvenation of the aging face and skeleton with implants
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A B
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Fig. 13.8 Morphologic changes that occur with age in the mandible. (A) Young skeleton. (B) Aged skeleton.
may weaken the support of the buccal fat pad, allowing it to descend and cause the appearance of jowls. Loss of mandibular volume also affects the aging process of the neck by contributing to the increased laxity of the platysma and soft tissues of the neck.
• The male study subjects had greater values for ramus height and mandibu­lar body length as compared to the female subjects.
• The only measurement that was larger for female subjects compared to male subjects was the mandibular angle. This explains why males tend to exhibit stronger, more prominent jawlines than females, as the male man­dibular angle is more acute.
The mandible changes dramatically with age, and the bony aging process is primarily that of contraction and morphologic change. Effective rejuvenation of the mandibular area should thereby account for both soft tissue treatments and bony loss compensation. This approach is demonstrated in Fig. 13.9 where a 53-year-old woman underwent chin and mandible augmentation together with rhytidectomy.
A limitation in the above-referenced human studies is that they are cohort studies, not longitudinal, meaning they involved different groups of patients at different age intervals, rather than observing the same patients over time. In 2017, the first longitudinal study of human facial skeletal aging was published by Paskhover et al.24 It documents patterns of change in the facial skeleton of 14 patients who underwent CT scans at least 8 years apart, with the initial CT measurements documented between 40–55 years. The study revealed that, with aging, the maxillary and piriform angles significantly decrease, as do the glabellar and maxillary angles, whereas the piriform width significantly increases. The study also notes some differences in these patterns between sexes.24 
PEARL
Facial skeletal convexity and projection identify facial youth.
References
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Fig. 13.9 The rejuvenative eect of combined skeletal augmentation and soft tissue manipulation. (A) Preoperative appearance of a 53-year-old woman. (B) Postoperative appearance 1 year after rhytidectomy combined with chin and mandible angle augmentation. (C) Illustration of implant augmentation.
A
C
B
DELAYING SKELETAL SENESCENCE
Shaw et al.25 have suggested that skeletal bone mineral density of the face changes with age similar to the axial skeleton. Their pilot study attempts to pinpoint the time when these skeletal changes occur, which can allow objective testing of specific treatments aimed at slowing or reversing these bony aging changes. Pharmaceuticals and mechanical devices may delay, treat, or even prevent these facial skeletal changes from occurring, opening up a whole new paradigm in facial aging prevention.24 In the meantime, the aging process can be masked and rejuvenated using facial implants in combination with soft tis­sue manipulations.
REFERENCES
1. Zimbler MS, Kokoska MS, Thomas JR. Anatomy and pathophysiology of facial aging. Facial Plast Surg Clin North Am 2001;9(2):179–87, vii.
2. Tonnard PL, Verpaele A, Gaia S. Optimising results from minimal access cranial suspension lifting (MACS-lift). Aesthetic Plast Surg 2005;29(4):213–20; discussion 221.
3. Lambros V. Observations on periorbital and midface aging. Plast Reconstr Surg
4. Coleman SR. Facial recontouring with lipostructure. Clin Plast Surg 1997;24(2):347–67.
5. Israel H. Recent knowledge concerning craniofacial aging. Angle Orthod 1973;43(2):176–84.
6. Behrents RG. Growth in the aging craniofacial skeleton. Monograph 17. Craniofacial Growth Series. Ann Arbor: Center for Human Growth and Development, University of Michigan;
1985.
7. Bartlett SP, Grossman R, Whitaker LA. Age-related changes of the craniofacial skeleton: an anthropometric and histologic analysis. Plast Reconstr Surg 1992;90(4):592–600.
8. Pessa JE, Chen Y. Curve analysis of the aging orbital aperture. Plast Reconstr Surg 2002;109(2):751–5; discussion 756–760.
9. Kahn DM, Shaw RB. Aging of the bony orbit: a three-dimensional computed tomography study. Aesthetic Surg J 2008;28(3):258–64.
10. Moss ML. The functional matrix hypothesis revisited. 1. The role of mechanotransduction. Am J Orthod Dentofac Orthop 1997;112(1):8–11.
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