Traumatic injury resulting in nasal deformity poses unique challenges to the surgeon. Optimal management requires careful preoperative analysis and thoughtful surgical planning. The goals of rhinoplasty are to correct both cosmetic and functional problems that may not have otherwise been an issue prior to the injury. Although it is overly simplistic to group all individuals from one ethnicity as having one type of nose, the rhinoplasty surgeon must understand the common variations of nasal anatomy seen in various races of individuals. This article discusses ethnic anatomic differences in the non-Caucasian nose in the context of posttraumatic nasal deformity. The various rhinoplasty techniques and strategies to address these issues are reviewed.
Traumatic injury resulting in nasal deformity poses unique challenges to the surgeon. The goals of rhinoplasty are to correct both cosmetic and functional problems that may not have otherwise been an issue prior to the injury. As for all rhinoplasty patients, preoperative evaluation of posttraumatic nasal deformity requires attention to the observed deformities of the nose as well as the baseline anatomy. This baseline anatomy varies significantly from individual to individual, often owing to characteristic ethnic features. Although it is overly simplistic to group all individuals from one ethnicity as having one type of nose, the rhinoplasty surgeon must understand the common variations of nasal anatomy seen in various races of individuals. In addition, certain anatomic features may affect the pattern of injury or deformity following nasal trauma. The ethnic anatomic differences in the non-Caucasian nose in the context of posttraumatic nasal deformity are discussed in this article. The various rhinoplasty techniques and strategies to address these issues are reviewed.
Nasal anatomy
A comprehensive review of nasal anatomy is beyond the scope of this subject. In this section, the pertinent anatomy relevant to patterns of nasal trauma is discussed. In particular, the structural anatomy of the nasal bones and nasal septum has bearing on the patterns of injury following trauma. This section reviews this general anatomy. The following section outlines variations of anatomy based on variable ethnic features.
The skeletal framework of the nose is often divided into 3 sections: the upper third consists of the osseous vault; the middle third consists of the upper cartilaginous vault; and the lower third consists of the lower cartilaginous vault. The nasal septum provides support in all 3 sections and divides the nasal cavity in half. The septum has 2 distinct portions, a cartilaginous portion anteriorly and a bony portion posteriorly.
The nasal septum is a sagittal midline structure that divides the nose into 2 cavities, and provides structural support to the osseous and cartilaginous vaults. The septum is divided into 2 components. The cephalic-posterior osseous septum consists of the perpendicular plate of the ethmoid and the vomer. The caudal-anterior cartilaginous septum consists of the quadrangular cartilage. The dorsal aspect of the osseous septum is formed by the perpendicular plate of the ethmoid. The thickness of the perpendicular plate of the ethmoid varies considerably. This plate attaches superiorly to the frontal bone, anteriorly the nasal spine, and posteriorly the cribriform plate. The septum articulates with the inward projection of the nasal bones in the midline anterosuperiorly, and it borders the quadrangular cartilage anteroinferiorly. Posteroinferiorly it borders the vomer. The vomer is shaped like the keel of a boat. The vomer articulates with the perpendicular plate of the ethmoid superiorly. Along its inferior aspect, the vomer attaches to the midline nasal crest of the palatine bone posteriorly and the maxilla anteriorly. Anterior to its articulation with the vomer, the maxillary crest forms a groove into which the quadrangular cartilage sits.
The cartilaginous septum comprises the quadrangular cartilage. The inferior aspect of the septum rests within a groove in the nasal spine and maxillary crest. The ventral surface of the quadrangular cartilage is typically thickened in comparison to the remainder of the structure. The dorsal aspect of the quadrangular cartilage forms the external contour of the nasal bridge. The dorsum of the central third of the nose is formed by the upper lateral cartilages’ articulation with the cephalic aspect of the quadrangular cartilage. The least rigid portion of the cartilage is the most caudal, which extends anterior to the nasal spine. The membranous septum is the soft tissue continuation of the cartilaginous septum. The membranous septum consists of a central layer of subcutaneous areolar tissue between the vestibular skin on each side, thereby bridging the caudal edge of the cartilaginous septum to the medial crura of the lower lateral cartilages and columella. Within the membranous septum are the ligamentous attachments of the medial crura to the caudal septum. The membranous septum is mobile, and displaces easily with manipulation of the columella due to the lack of cartilage.
The inner layer of the septum consists of either perichondrium or periostium, covered by an outer layer of mucosa. The vascular and nervous supply to the septum is contained within the 2 septal lining layers. In a traumatic septal hematoma, separation of the mucoperichondrium from the underlying cartilage may occur, which in turn may lead to ischemic necrosis of the affected septum and result in a perforation or a saddle nose deformity. This situation arises due to the fact that the perichondrial and periostial layers bear the majority of the biomechanical strength of the septal lining and bone.
Septal deviations off the mid-sagittal plane often have both functional and cosmetic implications, especially in the setting of nasal trauma. Deviations along the floor of the nasal airway may cause considerable airway obstruction. Combinations of cartilaginous and osseous deformities often contribute to the obstruction. Portions of the septum may be jagged and angulated in the setting of nasal trauma. Surgical treatment may require removing or repositioning these deviated skeletal elements. If deviations of the perpendicular plate of the ethmoid and vomer are not adequately corrected, persistent posterior airway obstruction after septal surgery may result.
Deviations of the caudal and dorsal edge of the septum also have cosmetic and functional implications. Along the rhinion to the anterior nasal spine, septal deviations may manifest as visible external deformities. A crooked nose deformity at the upper cartilaginous vault, the nasal tip, the columella, or the columellar base may be due to a deviation of the mid-dorsal septum, anterior septal angle, mid-caudal septum, or posterior septal angle, respectively. These irregularities may originate from a traumatic event, and thus correction of a severely crooked nose may require surgical intervention.
Together with the bony septum, the osseous vault is a pyramidal structure that provides the principal structural support for the nose. The distance from nasion to rhinion defines the cephalic-caudal length of the osseous vault. This vault consists of the frontal process of the maxilla and the paired nasal bones. The osseous vault articulates cephalically with the frontal bone at the nasofrontal suture line. The nasal bones superiorly derive midline support from the perpendicular plate of the ethmoid. At the keystone area, the caudal edge of the nasal septum is joined by a connective tissue to the upper cartilaginous vault. Each nasal bone can be described as an elongated quadrangle, with its lateral long edge articulating with the frontal process of the maxilla and its medial long edge articulating in the midline with the contralateral nasal bone. The bones cephalically are narrow and thin at the nasofrontal suture line, and wider and thinner along its free caudal edge. Most traumatic nasal fractures occur in the caudal, more projecting portion of the nasal bones where they are the thinnest.
In brief, the upper cartilaginous vault consists of the paired, shieldlike upper lateral cartilages that are fused in the midline to the dorsal edge of the cartilaginous septum. The nasal bones provide the majority of reinforcement to the upper lateral cartilages at their cephalic margin, the keystone area. The key elements in the lower cartilaginous vault are the paired lower lateral (or alar) cartilages. With the septum, the lower lateral cartilages provide support to the nasal tip.
Ethnic anatomic differences
Ethnic variations that have been described to influence nasal morphology are categorized into 3 general forms: leptorrhine, platyrrhine, and mesorrhine.
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The leptorrhine (“tall and thin”) nose is associated with Caucasian or Indo-European descent. This type of nose has served as the basis of aesthetic ideal in Western culture. The leptorrhine nose has become the reference point for comparison when studying noses of different ethnicities, because it is the most extensively studied type of nose in modern nasal analysis.
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The platyrrhine (“broad and flat”) nose is associated with African descent. Its characteristics include very thick skin, a low radix, a bulbous and lower projected tip, a short dorsum, and flared nostrils.
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The mesorrhine (“intermediate”) nose has features of both the leptorrhine nose and the platyrrhine nose. The “typical” Asian or Latino nose is commonly regarded as mesorrhine, which is characterized by a low radix, rounded and less projected tip, variable anterior dorsal projection, and rounded nostrils. There is, however, considerable variation in this group.
Many of the functional and aesthetic ethnic differences in the nose is due to variations in the size and development of the nasal septum. Septal projection may be highly variable. Because the septum is attached to the cartilages that determine nasal shape (lower lateral and upper lateral cartilages), its overgrowth may lead to excessive projection of these structures. For example, the tension nose deformity is the situation whereby the septum pulls the cartilaginous elements of the nose under tension. These types of noses are characterized by a high cartilaginous dorsum, a low hanging columella that is created by a prominent caudal septal border, and a tip-defining point that is determined by a projecting anterior septal angle.
In a recent study, Asian noses were compared with Caucasian noses. Overall, Asian noses were found to have less projection, in general, at all levels compared with Caucasian noses. The average Caucasian male nasal tip projection was 3.2 cm, whereas the average Asian male projection was significantly less than 2.5 cm ( P <.001). The average Caucasian female nasal tip projection was 2.8 cm, whereas the average Asian female projection was 2.4 cm ( P = .010). Similar significant findings were found of nasion projection between the Caucasian and Asian noses. Decreased nasal projection may protect Asian individuals from a greater degree of nasal trauma relative to Caucasian individuals. When comparing the width of the bony vault, Caucasian female noses on average were significantly narrower compared with their Asian counterparts. In regard of variations in nasal bone length, differences in length may also be partially influenced by ethnicity. With the notion that the Asian nose, in general, is broader in appearance compared with the Caucasian nose, the Asian nose also tends to have a shorter nasal length relative to the Caucasian nose, as evident by a larger width-length ratio. Furthermore, variations in the width and medial-lateral position of the nasal bones may be hereditary or acquired. Hereditary variations are more likely to manifest as a symmetric but unusually narrow or wide osseous vault; acquired traumatic injuries typically manifest in gross asymmetries. These observations reflect the generally accepted notions that the Asian nose is broader and shorter along the dorsum, the nasal tip is less projected, and the radix is low lying (ie, mesorrhine nose).
Another aspect of the nasal anatomy that varies between ethnic groups is the thickness of the nasal skin-soft tissue envelope (SSTE). Individuals of African decent tend to have very thick, inelastic SSTE overlying the nasal skeleton, whereas individuals of Asian decent tend to have SSTE of intermediate thickness. In general, the SSTE of Caucasian individuals tends to be thinner. Thus, it is reasonable to consider that in the context of nasal trauma, skin thickness may influence the external appearance of the nose by camouflaging the apparent defects of the nasal skeleton. Furthermore, the thickness of the SSTE may influence the type of maneuvers that are feasible during operative repair of posttraumatic nasal deformities.
With regard to nasal trauma, it is the authors’ opinion that the leptorrhine nose, with its greater projection along the osseous vault and dorsum, renders it more susceptible to significant distortion following nasal trauma. The flatter profile of the mesorrhine and platyrrhine nose provides relative protection against impact to the nose. In addition, when fractures to the bones of the nose do occur, it may be more apparent in the leptorrhine nose due to the greater prominence of the osseous vault and septum. The lower pyramidal geometry and thicker skin envelope of the non-Caucasian nose tends to mask whatever skeletal distortion may occur ( Fig. 1 ).
Even with these 3 descriptions of ethnically based nasal morphology, caution is warranted if one were to overly generalize rhinoplasty for the non-Caucasian nose. To classify a non-Caucasian nose as an “ethnic” nose to which “ethnic rhinoplasty” principles apply may be overly simplistic. Significant variations may exist between 2 noses from the same ethnic background as well as 2 noses from 2 different ethnic backgrounds. For example, Latinos with Caribbean ancestry are more likely to have platyrrhine noses, whereas those of Central and South American descent have more leptorrhine noses. It would be inappropriate to uniformly apply ethnic group characteristics to an individual patient based one’s ethnic or racial background. However, possessing an awareness of the global differences between ethnic nasal morphologies will allow a rhinoplasty surgeon to be more sensitive to the needs of all patients. Ethnic anatomic nasal variations are important to understand to properly assess the nasal defects and plan the appropriate surgical management strategy for posttraumatic nasal deformities.
Ethnic anatomic differences
Ethnic variations that have been described to influence nasal morphology are categorized into 3 general forms: leptorrhine, platyrrhine, and mesorrhine.
- ■
The leptorrhine (“tall and thin”) nose is associated with Caucasian or Indo-European descent. This type of nose has served as the basis of aesthetic ideal in Western culture. The leptorrhine nose has become the reference point for comparison when studying noses of different ethnicities, because it is the most extensively studied type of nose in modern nasal analysis.
- ■
The platyrrhine (“broad and flat”) nose is associated with African descent. Its characteristics include very thick skin, a low radix, a bulbous and lower projected tip, a short dorsum, and flared nostrils.
- ■
The mesorrhine (“intermediate”) nose has features of both the leptorrhine nose and the platyrrhine nose. The “typical” Asian or Latino nose is commonly regarded as mesorrhine, which is characterized by a low radix, rounded and less projected tip, variable anterior dorsal projection, and rounded nostrils. There is, however, considerable variation in this group.
Many of the functional and aesthetic ethnic differences in the nose is due to variations in the size and development of the nasal septum. Septal projection may be highly variable. Because the septum is attached to the cartilages that determine nasal shape (lower lateral and upper lateral cartilages), its overgrowth may lead to excessive projection of these structures. For example, the tension nose deformity is the situation whereby the septum pulls the cartilaginous elements of the nose under tension. These types of noses are characterized by a high cartilaginous dorsum, a low hanging columella that is created by a prominent caudal septal border, and a tip-defining point that is determined by a projecting anterior septal angle.
In a recent study, Asian noses were compared with Caucasian noses. Overall, Asian noses were found to have less projection, in general, at all levels compared with Caucasian noses. The average Caucasian male nasal tip projection was 3.2 cm, whereas the average Asian male projection was significantly less than 2.5 cm ( P <.001). The average Caucasian female nasal tip projection was 2.8 cm, whereas the average Asian female projection was 2.4 cm ( P = .010). Similar significant findings were found of nasion projection between the Caucasian and Asian noses. Decreased nasal projection may protect Asian individuals from a greater degree of nasal trauma relative to Caucasian individuals. When comparing the width of the bony vault, Caucasian female noses on average were significantly narrower compared with their Asian counterparts. In regard of variations in nasal bone length, differences in length may also be partially influenced by ethnicity. With the notion that the Asian nose, in general, is broader in appearance compared with the Caucasian nose, the Asian nose also tends to have a shorter nasal length relative to the Caucasian nose, as evident by a larger width-length ratio. Furthermore, variations in the width and medial-lateral position of the nasal bones may be hereditary or acquired. Hereditary variations are more likely to manifest as a symmetric but unusually narrow or wide osseous vault; acquired traumatic injuries typically manifest in gross asymmetries. These observations reflect the generally accepted notions that the Asian nose is broader and shorter along the dorsum, the nasal tip is less projected, and the radix is low lying (ie, mesorrhine nose).
Another aspect of the nasal anatomy that varies between ethnic groups is the thickness of the nasal skin-soft tissue envelope (SSTE). Individuals of African decent tend to have very thick, inelastic SSTE overlying the nasal skeleton, whereas individuals of Asian decent tend to have SSTE of intermediate thickness. In general, the SSTE of Caucasian individuals tends to be thinner. Thus, it is reasonable to consider that in the context of nasal trauma, skin thickness may influence the external appearance of the nose by camouflaging the apparent defects of the nasal skeleton. Furthermore, the thickness of the SSTE may influence the type of maneuvers that are feasible during operative repair of posttraumatic nasal deformities.
With regard to nasal trauma, it is the authors’ opinion that the leptorrhine nose, with its greater projection along the osseous vault and dorsum, renders it more susceptible to significant distortion following nasal trauma. The flatter profile of the mesorrhine and platyrrhine nose provides relative protection against impact to the nose. In addition, when fractures to the bones of the nose do occur, it may be more apparent in the leptorrhine nose due to the greater prominence of the osseous vault and septum. The lower pyramidal geometry and thicker skin envelope of the non-Caucasian nose tends to mask whatever skeletal distortion may occur ( Fig. 1 ).
