The potential role of stereolithography in the study of facial aging.

The potential role of high-resolution stereolithography for the study of facial aging was evaluated. Stereolithography has been used extensively in the engineering sciences to create model replicas prior to full production. More recently, stereolithography has found a role in the preoperative planning of complex dentofacial anomalies. Previous work has suggested that continued differential growth of the maxilla may occur throughout life. To further evaluate this finding, computed tomography scans were collected from younger (mean, 20.2 years) and older (mean, 58.8 years) individuals (N = 20). Both men and women were included. An exact replica of the facial skeleton was made for each subject by the process of laser polymerization. The angles of the maxillary wall and piriform aperture, defined by specific points, were measured relative to sella-nasion. Height, width, and depth changes were also evaluated. Findings show that angular changes occurred with age. The mean angle of the maxilla relative to sella-nasion decreased from 69 degrees to 56.8 degrees with age (P =.015). The mean angle of the piriform likewise decreased from 65.1 degrees to 55.7 degrees (P =.019). This angular change with age suggests that differential growth may continue throughout life. This work highlights the potential role of 3-dimensional modeling for future research in the field of facial aging. Curve and contour analysis are 2 additional areas in which stereolithography may yield valuable insights into the mechanisms of facial growth.

Biological arches and changes to the curvilinear form of the aging maxilla.

The facial skeleton can be conceptualized as a series of arches aligned along a vertical axis, with regional differences in shape. Previous work suggested that the maxilla undergoes differential growth with time. Because these arch forms resemble geometric forms, it may be possible to measure changes to their shape with the aging process. A contour analysis of the aging maxilla was undertaken. Computed tomographic data were assembled retrospectively. Only men were studied, and they were divided into two groups: young (aged 18 to 24 years; n = 6) and old (aged 40 to 66 years; n = 6). The computed tomography data were reconstructed into three-dimensional images and underwent standardization for comparison purposes. An axial view of the maxilla along the Frankfort horizontal was used for analysis. To quantify changes between curves, measurements were made of the vertical distance from eight equidistant points along each curve perimeter to a standardized baseline. Average arch forms for young and old men were then generated for comparison purposes. Each of the eight points along the older maxillary arch form existed further from the baseline than the younger arch form. This difference reached statistical significance at three of the eight points measured along the two curves. The greatest difference occurred at point 8 (p = .0006), which was at the medial maxilla near the nasomaxillary junction. The results of the study suggest that the actual contour of the maxilla undergoes changes as a result of the aging process. Mathematically defined idealized skeletal contours could help guide reconstructive surgery and aesthetic augmentation of the facial skeleton in the future. In addition, certain soft tissues of the face and torso seem to share a common shape (an alpha contour). This shape may also exhibit idealized forms open to quantitative analysis. The skeletal arch form and alpha contour most likely exhibit sexual dimorphism and will require further investigation. The ubiquity of the arch form in nature and possible implications for growth and development of the human facial skeleton are also discussed.

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.

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.

Changes in ocular globe-to-orbital rim position with age: implications for aesthetic blepharoplasty of the lower eyelids.

Changes in the relationship of the anterior globe to the orbital rim, orbital fat, and cheek mass are examined in the present study. Two groups of individuals (N = 28) were studied, young versus old, using three-dimensional computer tomography. A computer-derived soft tissue reformat of the data allowed the anterior-posterior changes to be evaluated at the midpupillary plane. Analysis of the data brings to light two important changes which occur with aging. First, the orbital rim moves posteriorly relative to the anterior cornea with age (p = 0.0007). This is important because overresection of orbital fat during lower blepharoplasty accentuates the proptotic appearance of the eye which occurs naturally with age due to orbital remodeling. A second finding is that there is a tendency for the cheek mass to move posteriorly with age relative to the anterior cornea (p = 0.0038). The negative vector, a warning sign for lower blepharoplasty, becomes more common with advancing age. It is suggested that the presence of a negative vector is a sign of generalized maxillary hypoplasia. Certain individuals with a negative vector can be further identified preoperatively by the clinical triad of scleral show, prominent medial fat, and a prominent nasojugal crease. These individuals likewise exhibit maxillary hypoplasia and may be more prone to complications after blepharoplasty. Lastly, a summated model of skeletal remodeling is presented. The significant points are as follows: (1) contrary to previous work, the craniofacial skeleton remodels throughout adulthood, (2) changes in the skeletal architecture impart their effects on the overlying soft tissues, and (3) facial aging is a summation of both hard and soft tissue changes which occur throughout life.

The effect of skeletal remodeling on the nasal profile: considerations for rhinoplasty in the older patient.

The effect of continued differential growth of the adult male craniofacial skeleton on the nasal profile is examined in the present study. Two groups of individuals (N = 20) were compared, young (ages 16-23) and old (49-64). A three-dimensional CT scan was created for each individual in a standardized view. The change in position of four skeletal reference points with soft tissue correlates was analyzed. Changes were evaluated in both the vertical and the horizontal dimensions relative to the sella-nasion and to a perpendicular from the sella-nasion. Results show that the area of the maxilla at the pyriform remodels posteriorly with age (p = 0. 017), while the position of the other three points does not change in a significant fashion. This suggests that differential growth continues to occur in the aging craniofacial skeleton. Differential growth is further documented by calculating the percentage change in the position of any of the four points: the pyriform changed 80.2% from young to old, while the other points changed only from -9.3 to +22.1%. The craniofacial skeleton is the scaffold for the overlying soft tissues. Because the pyriform aperture represents the skeletal platform for the nasal pyramid, pyriform remodeling in a posterior direction retrudes the nasal profile with age. In addition, loss of pyriform height may distort the normal relationship of the alar base to the columella. These changes require assessment for the optimal result from aesthetic rhinoplasty.

A technique for three-dimensional cephalometric analysis as an aid in evaluating changes in the craniofacial skeleton.

A technique is presented for creating a standardized view for use in three-dimensional cephalometry. Three-dimensional cephalometric analysis has become a valuable tool in the assessment of skeletal remodeling, contour changes, and changes in proportion that occur with aging. Computer-assisted tomographic data can be used in either coronal or axial sections; the present study was performed with axially acquired data that was processed in several steps to achieve a standardized position of the facial skeleton for further evaluation. This technique may be a useful adjunct to standard cephalometrics to evaluate the craniofacial skeleton.

Concertina effect and facial aging: nonlinear aspects of youthfulness and skeletal remodeling, and why, perhaps, infants have jowls.

The effect of aging on the orbitomaxillary region is evaluated in the present study. The observation was made that infants look like aged individuals in terms of the midface soft-tissue contours of the midface. Because preliminary work has shown that the facial skeleton remodels throughout life, this observation led to the hypothesis that infants and older individuals appear similar because they have comparable skeletal dimensions, specifically in the orbitomaxillary region. The design is a retrospective analysis of three-dimensional computed tomographic scan data. Three groups of male subjects were studied: infant, ages 1 to 12 months (n = 5); youthful, ages 15 to 24 years (n = 13); and old, ages 53 to 76 years (n = 12). Orbital and zygomaticomaxillary vertical dimensions were measured in both medial and lateral planes between fixed anatomical landmarks. Results were compared by using analysis of variance, Student-Newman-Keuls, and Student's t tests. The findings show that skeletal remodeling is such that the ratio of the maxillary height to orbital height is greatest during youth; during infancy and old age, there is a short maxilla relative to a larger orbit. This finding is significant in the medial plane from orbital rim to pyriform aperture (p < 0.05). Furthermore, there is an actual decrease in vertical maxillary height in this medial plane (p < 0.01) from youth until old age, which occurs secondary to normal skeletal remodeling in the dentate individual. The combined effect of downward expansion of the orbital shelf and the upward migration of the pyriform effectively decreases the space available to support the overlying soft tissues of the midface. An accordion-like or "concertina" effect may lead to compression or restriction of the facial soft tissues over a relatively deficient bony platform. These results highlight the importance of skeletal remodeling in determining the soft-tissue contours of the aging face. The process of skeletal remodeling may also allow for a tentative definition of facial youthfulness. Infants are born with a short maxilla relative to a large orbit, and the maxillary wall is angled posteriorly. This ratio and angle change from infancy until youth, when there is a balance between the bony skeletal support and the overlying soft-tissue envelope, i.e., the skin, facial muscles, and adipose tissue. It is when skeletal remodeling continues past this point that a disharmony occurs. Because the ratio of maxilla/orbit, and the angle of the maxillary wall, in the older person reverts toward that of an infant, the attainment of youth occurs partly in a nonlinear or multimodal manner. This work is part of an emerging concept of facial aging, which we would term an integrated model of facial aging. This model allows facial aging to be viewed as a biological "system," in which there are primary and secondary factors that interact in the process of facial aging. Additional research such as this continues to suggest the importance of bony remodeling in facial aging.

Pyriform augmentation as an ancillary procedure in facial rejuvenation surgery.

A patient is presented in whom augmentation of the pyriform aperture of the maxilla was performed with porous hydroxyapatite in concert with a face and brow lift. Basic research has recently shown that remodeling of the facial skeleton continues throughout life and that this remodeling process leads to changes in the position of several key areas. The pyriform aperture was identified as one region that remodels in a posterior direction, leading to retrusion of the alar base in the older individual. This skeletal retrusion occurs in a very site-specific fashion, and its effects are reflected on the overlying soft tissues of the face. With aging, remodeling of the pyriform aperture posteriorly causes the alar base to appear recessed and decreases the nasolabial angle, changes that are noted on the profile of the older individual. Augmentation of the pyriform aperture can be achieved through a buccal sulcus incision and, when used in conjunction with standard facial rejuvenation procedures, can improve the overall result in facial cosmetic surgery.

Variability of the midfacial muscles: analysis of 50 hemifacial cadaver dissections.

The region of the midface represents a challenging area to both reconstructive and aesthetic surgeons. An anatomic study was performed that attempted to identify patterns and variations of the muscular anatomy. The goals of this study were twofold: to identify patterns and variability of the midfacial muscles that might impact on reconstructive efforts and to attempt to correlate this anatomy with features of the overlying soft tissues, specifically the nasolabial crease. Fifty hemifacial cadaver dissections were performed. The information collected was assembled into a large data base, and statistical significance was analyzed using Fisher's exact probability test. Results demonstrated that, although a great degree of variability exists with respect to the midfacial muscles, seven distinct patterns of these muscles did emerge. The most common pattern was the presence of a levator alae nasi, levator labii superioris, and zygomaticus major, which occurred in 44 percent of specimens. Specimens that possessed a risorius, zygomaticus minor, or both, were relatively uncommon. The consistent presence of the levators suggests adding a superior vector to recreate a smile in facial reanimation surgery. Two important anatomic variations were noted. A bifid zygomaticus major was found to be present in 34 percent of individuals. Because the inferior bundle had a dermocutaneous insertion, this anomaly may represent the anatomic correlate of a cheek "dimple." A second anomaly noted was the lateral cheek crease, which appeared to be associated with a cutaneous attachment from the underlying platysma muscle. However, no correlation could be found for facial muscle pattern and the overlying nasolabial crease structure. This lack of correlation may indicate that the facial muscles alone do not dictate the structure of the nasolabial crease and that other dynamic factors are involved in determining this feature of the aging face.

Double or bifid zygomaticus major muscle: anatomy, incidence, and clinical correlation.

The anatomy of the double or bifid zygomaticus major muscle is investigated in a series of 50 hemifacial cadaver dissections. The double zygomaticus major muscle represents an anatomical variation of this muscle of facial expression. This bifid muscle originates as a single structure from the zygomatic bone. As it travels anteriorly, it then divides at the sub-zygomatic hollow into superior and inferior muscle bundles. The superior bundle inserts at the usual position above the comer of the mouth. The inferior bundle inserts into the modiolus below the corner of the mouth. The incidence of the double zygomaticus major muscle was 34% in the present study, as it was found to be present in 17 of 50 cadaver dissections. This study shows that variation in the individual morphology of the mimetic muscles can be a common finding. Clinically, the double or bifid zygomaticus major muscle may explain the formation of cheek "dimples." The inferior bundle was observed in several specimens to have a dermal attachment along its mid-portion, which tethers the overlying skin. When an individual with this anatomy smiles, traction on the skin may create a dimple due to this dermal tethering effect.

Relative maxillary retrusion as a natural consequence of aging: combining skeletal and soft-tissue changes into an integrated model of midfacial aging.

The contribution of maxillary retrusion to the formation of the nasolabial fold is evaluated in the present study. Clinical observation of patients from the craniofacial unit with concomitant maxillary retrusion revealed prominent signs of midfacial aging: specifically these individuals displayed a prominent nasolabial fold at an early age. This observation led to the hypothesis that relative maxillary retrusion occurs as a normal feature of the aging process. Retrusion of the lower facial skeleton below the soft tissue of the nasolabial fold causes the nasolabial fold to appear more prominent. To test this hypothesis, computed tomographic data were assembled retrospectively and included both males and females, young and old. The age range of the males (n = 14) was 18 to 24 years (young) and 43 to 57 years (old); the age range of the females (n = 14) was 15 to 30 years (young) and 43 to 57 years (old). All individuals had complete upper dentition and had no bony facial injury. Computed tomographic data were reconstructed into three-dimensional images, and a technique was developed to create a standardized lateral view which eliminated rotational variance. Analysis of anterior-posterior changes showed that there is a tendency for the lower maxillary skeleton at pyriform to become retrusive with age relative to the upper face in individuals with complete dentition. Findings were very significant for both males and females (p = 0.0001 and p = 0.002, respectively). In both groups, a slight increase in vertical maxillary dimension was noted, consistent with previous studies. It is suggested that relative maxillary retrusion is a factor in the development of the nasolabial fold. The skeletal features of normal midfacial aging can be combined with the soft-tissue features such as ptosis and atrophy into an integrated model of midfacial aging. A model such as this has significance regarding both the timing and choice of procedure used to restore the aging midface.

Anatomy of a "black eye": a newly described fascial system of the lower eyelid.

The anatomy of a black eye is examined in a series of cadaver dissections in which a previously unreported fascial system of the lower eyelid is identified. This fascia originates at the orbital rim, and is in continuity with the orbital septum and with the periosteum of the orbital floor and anterior maxillary wall. This fascia contributes to the thickened area along the orbital rim called the arcus marginale. At the level of the orbicularis oculi muscle, this fascia was noted microscopically to fuse with a fibrous septa of the superficial cheek fat. This creates one long continuous membrane from the orbital rim above to the cheek skin below. Dye injection techniques show that this membrane is impermeable and traps injected dye in the same place where a black eye forms. After periorbital injury, extravasated hemoglobin pigment is confined to the area above the cutaneous insertion of this membrane. This fascial system has been named the septum malaris: malar describes its origin along the orbital rim of the cheek, and septum further describes the partitioning nature of this ultra-thin membrane.

Reconstruction of the extremity with the dorsal thoracic fascia free flap.

The dorsal thoracic fascia is the anatomic layer that contains the blood supply to the scapular and parascapular fasciocutaneous flaps. The cutaneous vascular territory of the circumflex scapular artery and its parascapular branches is well known. During the past 8 years, the authors have employed the dorsal thoracic fascia free flap for extremity reconstruction in 17 patients (upper extremity, n = 9; lower extremity, n = 8). The indications for using this free flap included primary coverage after trauma (n = 10), resurfacing of "unstable" scar (n = 3), coverage of plantar foot ulceration (n = 3), and coverage of an exposed lower extremity distal arterial bypass graft (n = 1). The large anatomic boundaries of this flap, the consistent vascular anatomy, and the thin yet durable quality of the tissue make this flap an excellent choice for the reconstruction of upper and lower extremity defects.

The anatomy of the labiomandibular fold.

The anatomy of the labiomandibular fold was evaluated in a series of 12 fresh hemifacial cadaver dissections. The techniques of methylene blue dye injection, histologic evaluation, and gross dissection all confirm that the labiomandibular fold has distinct anatomic boundaries. The superior boundary is formed by the cutaneous insertion of the depressor anguli oris muscle at the labiomandibular crease. The inferior boundary is determined by the mandibular ligament, which has been previously described. The cutaneous insertion of the depressor muscle and the mandibular ligament act as relative points of fixation. The dynamic forces of both aging and facial animation act about these two points to create the typical appearance of the labiomandibular fold. This anatomy is consistent with that seen in other areas of the face such as the nasolabial and nasojugal folds, where the dermal insertion of muscle and/or fascia defines an anatomically distinct region. Clinically, this anatomy may suggest that a subcutaneous plane of dissection during the face lift procedure may allow manipulation and reduction of the fat that was noted lateral to the dermal insertion of the depressor anguli muscle. Subcutaneous dissection also avoids lateral pull on the platysma muscle, which may tend to accentuate and distort the labiomandibular crease due to its intimate association with the overlying depressor muscle.

The malar septum: the anatomic basis of malar mounds and malar edema.

The anatomy of malar mounds and malar edema is evaluated in a series of 18 fresh cadaver dissections. Dye injection, histologic evaluation, and gross anatomic dissection are used to identify a previously unrecognized fascial structure of the lower eyelid and cheek. The malar septum originates from orbital rim periosteum superiorly and inserts into cheek skin 2.5 to 3 cm inferior to the lateral canthus. This fascial structure acts as a relatively impermeable barrier that allows tissue edema and hemoglobin pigment to accumulate above its cutaneous insertion. The malar septum, which acts as both a functional and a structural barrier, defines the lower boundary of several clinical entities: malar mounds, malar edema, malar festoons, and periorbital ecchymosis. The permeability characteristics of the malar septum suggest that, at least in some persons, malar mounds may be accentuated by chronic lower eyelid edema, and these characteristics may imply a time course in the progressive development from malar edema to malar mounds and, ultimately, to malar festoons. The anatomy of the malar septum is clinically relevant because it defines the four anatomic compartments of the malar mound that should be considered during surgery: the superior compartment of suborbicularis oculi fat, orbicularis oculi muscle, and superficial cheek fat and cheek skin superior to the cutaneous insertion of the malar septum.

The role of facial muscle resection in reconstruction of the paralyzed face.

The technique of resecting the levator labii superioris alaeque nasi muscle can help improve nasal symmetry and is a useful ancillary procedure in reconstruction of the paralyzed face. In 3 patients with facial paralysis, this technique markedly changed the nasal deviation seen at rest and also affected the nasolabial angle and medial nasolabial fold. A patient report is presented.

Improving the acute nasolabial angle and medial nasolabial fold by levator alae muscle resection.

An acute nasolabial angle and a prominent nasolabial fold are two features that are often associated in the aging face. A new technique is presented that simultaneously addresses both of these features. Levator alae (levator labii superioris alaeque nasi) muscle resection, performed through a subciliary incision, improves the acute nasolabial angle without concomitant rhinoplasty. At the same time, levator alae muscle resection softens the medial nasolabial fold. Partial levator labii superioris muscle resection has occasionally been added to further weaken the middle nasolabial fold. Fresh cadaver dissections were performed to define the anatomy and to plan the surgical approach. This report describes a series of 10 patients who underwent this procedure, with improvement of the acute nasolabial angle and softening of the medial nasolabial fold.

Independent effect of various facial mimetic muscles on the nasolabial fold.

The independent effect of the contraction of various facial mimetic muscles on the nasolabial fold was defined through study of cadaver dissections. The four major lip elevator muscles were identified and the effect of traction of these muscles on the nasolabial fold was studied. This study identified the levator alae muscle (levator labii superioris alaeque nasi) as the primary facial muscle responsible for creating the medial nasolabial fold. The levator labii superioris muscle was found to define the middle nasolabial fold. These two facial muscles may be significant in the etiology of the prominent nasolabial fold that occurs with aging.

The repair of nail deformities with the nonvascularized nail bed graft: indications and results.

Twenty-four cases of nonvascularized nail bed grafting to correct nail deformities were reviewed. The highest success rate in improving the appearance of the deformed nail, 86%, was achieved when the split-thickness nail bed graft of sterile matrix was used to correct a nail deformity caused by a sterile matrix injury; the same procedure used to correct a nail deformity caused by a germinal matrix injury had a 0% success rate. Donor site morbidity occurred in 25% of split-thickness nail bed grafts and 100% of full-thickness nail bed grafts. The split-thickness nail bed graft of sterile matrix, if used in properly selected patients, will consistently improve the appearance of the deformed nail.