INTRODUCTION
The beauty of the nose is not defined exclusively by measurements but by proportion,
balance and harmony with the face1. Among the goals of rhinoplasty are the aesthetic proportions inserted in the context
of a functional nose, which improves respiratory quality and is naturally beautiful.
This complexity makes rhinoplasty one of the most challenging surgeries within plastic
surgery2,3.
Within facial balance, the nose has craniometric points, and these, when correlated,
are applied to anthropometry. The relationship of these points to each other determines
distances and angles that represent the proportion indices of the face. Among them,
the following stand out: glabella (G); radix (R); nasion(N); pronasale (PRN); rhinion (Rh); subnasale (SN); alare (AL); alar curvature point (AC); labrale superius (LS); and gnathion (GN)4.
From the craniometric points of the nose, the craniometric relationships are formed,
responsible for defining the nose’s length, width, inclination, and angles. The union
of the aforementioned craniometric points will also form the nasofrontal, nasolabial,
nasomental and nasofacial angles4,5.
The anatomical conformation of the nose directly influences the arrangement of nasal
angles, which is associated with aesthetic and functional characteristics. The face
will have proper proportions and symmetry when the points and craniometric relationships
are ideal. However, these proportions must be related to good nasal functionality,
and the main structures responsible for the function of the nose are the external
and internal nasal valves6.
The functional importance of nasal valves was evidenced when Constantian, in 1994,
found a 4.9-fold increase in airflow when nasal valve reconstruction was associated
with the treatment of septal deviation. However, septoplasty alone increased airflow
by only 1.1 times7.
Another relevant data from the author mentioned above was that the isolated reconstruction
of the external versus internal nasal valves resulted in an increase in nasal airflow
of 2.6 times versus 2.0 times, respectively. Thus, it became evident that the external
nasal valve is the most important structure for proper nasal functioning7.
OBJECTIVE
Define the ideal anatomical positioning of the lower lateral cartilages (LLC) associated
with optimizing the external nasal valve.
METHOD
The study was carried out through a narrative literature review in the following databases:
SciELO, LILACS and Medline. The descriptors used were: “nasal cartilages,”; “nasal
obstruction,” and “rhinoplasty,” being selected from 15 essential articles for the
understanding of the subject. The review was submitted to the Research Ethics Committee
of the Federal University of São Paulo/ Hospital São Paulo (UNIFESP/HSP) and approved
under protocol number 5890190419.
This review presents the contextualization between the inferior lateral cartilages
and the external nasal valve.
LITERATURE REVIEW
Aesthetics and nasal functionality are directly related to the positioning of the
LLC since these anatomical structures are the main structural element of the lateral
wall of the external nasal valve8.
The LLCs are formed by the medial, intermediate and lateral cruras, with the domus
as the point of greatest projection. The medial crura is the pillar on which the nasal
tip rests and is the primary component of the columella. The latter is responsible
for the visual correlation of the length of the nostril in the basal view9.
On the other hand, the lateral crura is the main component of the nasal alae, influencing
its shape, size and position9. Thus, some situations should always be an alert for diagnosing external valvular
nasal insufficiencies, such as boxy tip, bulbous tip, retraction of the nasal alae,
deep alar grooves and parenthesis deformity2,5,8,10,11. The malpositioning of the LLC is not only an aesthetic configuration but also reflects
on inadequate functionality of the external nasal valve2,8.
It was not until 1994 that the importance of nasal valves in respiratory function
was investigated in depth. Many surgeons believed that the air path was defined only
by the nasal septum and the inferior nasal turbinates before this date. Therefore,
if the patient had a deviated septum and/or inferior turbinate hypertrophy, this was
enough to justify nasal respiratory failure7,12.
Breathing involves pressure changes, and the nasal cavity needs to be stable to this
variation exerted by inspiration, whether forced or not. The importance of the external
nasal valve comes from the fact that it is the first place where airflow encounters
resistance10. That is, an external valve dysfunction results in air turbulence with impaired breathing12.
When the patient takes a deep inspiration, physiologically, there must be a dilation
of the external nasal valve so that the nasal airflow is laminar and can enter the
paranasal sinuses. The cause of the alar collapse or external valve insufficiency
during deep inspiration is a low-resistance, hypoplastic or malpositioning LLC10. Anatomical deformities of the lateral crura can also potentially contribute to valve
insufficiency6,13.
Constantian, in 1994, was responsible for a pioneering study, showing that when the
external nasal valve was reconstructed alone, nasal airflow increased by 2.6 times.
In comparison, with septoplasty alone, airflow increased only 1.1-fold. However, when
Constantian combined the correction of the external nasal valve, the internal nasal
valve and septoplasty, the respiratory flow improved 4.9 times, showing that the external
nasal valve alone is responsible for more than half of the nasal airflow7,12.
Still, for the same author, it was possible to classify the positioning of the LLC
in the preoperative period as adequate or inadequate, based on a straight line drawn
between the lateral crura of these cartilages to the patient’s pupil 2,7,14.
When this line projects medially to the pupil, the angle formed between the lateral
crura of the LLC and the margin of the nasal alae is greater than 45°, which is considered
inadequate. This is because the nasal tip and alae of the nose lack adequate cartilaginous
support to maintain the stability of the external nasal valve during inspiration.
On the other hand, the positioning of the LLC is considered adequate when the line
drawn between the dome and the insertion site of the inferior lateral cartilage in
the piriform aperture coincides with the pupil or is lateral to it 2,7,14 (Figure 1).
Figure 1 - Classification of the angle formed between the lateral crura of the inferior lateral
cartilage and the margin of the nasal alae.
Figure 1 - Subtitle:Green: angle less than or equal to 45º (adequate); Red: angle greater than
45º (inadequate).
Figure 1 - Classification of the angle formed between the lateral crura of the inferior lateral
cartilage and the margin of the nasal alae.
Figure 1 - Subtitle:Green: angle less than or equal to 45º (adequate); Red: angle greater than
45º (inadequate).
Toriumi & Asher, in their studies, classified the positioning of the LLCs intraoperatively,
taking as a reference the angle formed between the lateral crura of this cartilage
and the median sagittal plane and used an instrument called a finger goniometer5 for this measurement.
They classified it as inadequate when the angle is equal to or less than 30°, a situation
in which the lateral wall of the external nasal valve does not have adequate stability,
predisposing to insufficiency of this valve. On the other hand, they considered the
angle adequate when it was equal to or greater than 45° 5,13 (Figure 2).
Figure 2 - Classification of the angle formed between the lateral crura of the inferior lateral
cartilage and the median sagittal plane.
Figure 2 - Subtitle:Green: angle greater than 45º (adequate); Red: angle less than or equal to
30º (inadequate).
Figure 2 - Classification of the angle formed between the lateral crura of the inferior lateral
cartilage and the median sagittal plane.
Figure 2 - Subtitle:Green: angle greater than 45º (adequate); Red: angle less than or equal to
30º (inadequate).
In 2020, Silva improved the Toriumi classification and exposed the concept of the
angle of divergence, which is formed between the lateral cruras of the LLC, as a classification
parameter for the intraoperative LLC positioning15.
It is important to point out that, in this classification, the author above used the
bilateral sum of the angle of the Toriumi classification; that is, the positioning
of the LLC was defined as inadequate when the angle of divergence was less than 60°
and adequate when the value was equal to or greater than 90° 15 (Figures 3 and 4).
Figure 3 - Divergence angle less than 60º.
Figure 3 - Divergence angle less than 60º.
Figure 4 - Divergence angle greater than or equal to 90º.
Figure 4 - Divergence angle greater than or equal to 90º.
The rhinogoniometer was developed in 2018 to measure the angle of divergence. This
device has a patent registration with the National Industrial Property Industry (INPI)
under the process number BR 10 2018 073213 7. It is an innovative surgical instrument
created specifically for this purpose, allowing the measurement of intraoperative
angles with precision, including the divergence angle15 (Figure 5).
Figure 5 - Rhinogoniometer.
Figure 5 - Rhinogoniometer.
The positioning of the LLC is very important because when they are malpositioned,
having a divergence angle below 60°, Silva agrees with Toriumi5,13 in carrying out the transposition of these cartilages using the lateral crural strut
graft11. Situation in which, if the divergence angle is measured by computerized analysis,
the difference between this and the rhinogoniometer is only 0.79°, which does not
interfere with the surgeon’s conduct and provides practicality and safety in such
a delicate surgical maneuver15.
CONCLUSION
The external nasal valve was associated with better functioning when the lower lateral
cartilages are well-positioned and may have three measurements depending on the anatomical
references used:
- The angle formed between the lateral edge of the LLC and the alar margin is close
to 45° or less;
- The angle formed between the LLC and the midsagittal plane is close to 45°;
- The divergence angle formed between the LLC is close to 90°.
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1. Universidade Federal de São Paulo, São Paulo, SP, Brazil
2. Universidade Estadual de Ponta Grossa, Ponta Grossa, PR, Brazil
Corresponding author: Eduardo Nascimento Silva Avenida Doutor Francisco Búrzio, 991, Ponta Grossa, PR, Brazil, Zip Code: 84010-200,
E-mail: dr_eduardosilva@yahoo.com.br
Article received: July 18, 2020.
Article accepted: March 06, 2022.
Conflicts of interest: none.
