Abstract
The anatomy of the nose of different ethnic groups has been widely researched in order to facilitate a better understanding of the individual nose as a foundation for improving surgical outcomes. There are six major global ethnic groups that have been anatomically described in the rhinoplasty literature: Caucasian, Asian, African, Mediterranean, Middle Eastern, and Latin American.1-5 Most research has been focused on Caucasians followed by the Asian, Mediterranean, and Middle Eastern groups.4-7 To our knowledge only one study has been conducted on the facial proportions of the Black people of Southern and East Africa and showed a significantly larger nasal height and width compared to North American Whites.1 The only anatomical research of the lower lateral cartilages (LLCs) available to the surgeon working with an African patient is to extrapolate data from studies already published.
The literature shows a single anatomical study on noses of Black individuals. This was done on 12 cadavers of African-American descent and the nose was classified into African, Afro-Caucasian, and Afro-Indian.8 The classic description of the ethnic African Black nose is that of an amorphous tip, thick skin, low and wide dorsum, wide base with excess flare and sill, acute nasolabial angle, and short columella.9,10 However in an anatomical and anthropometric study by Baker it was shown that this “typical African-American” nose is too simplistic,11 thus emphasizing the importance of understanding the ethnic nuances a rhinoplasty surgeon needs to master in order to optimize a patient’s surgical requests as an aesthetically pleasing result of rhinoplasty depends on thorough knowledge of nasal anatomy.12
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The LLCs impact significantly on the aesthetic appearance of the nose and the face as a whole. They are the dominant structures of the lower third of the nose as well as being major tip support structures.13-15 Knowledge and understanding of the LLCs is crucial in nasal surgery and in our understanding of nasal obstruction due to their intimate relationship with the external nasal valve.14-16
The three main features of LLCs that have been well documented include: dimensions (length, width, and thickness), distance from the inferior margin to the nasal rim, and morphological shape, all of which have an effect on the function and aesthetic appearance of the nose.4-8 The majority of studies of the LLCs have been done on noses of Caucasian origin, setting the norms to which other ethnic groups are compared.6,7 This is the first study to attempt to describe the LLCs of noses of Black South Africans.
Aim
The aim of this descriptive cadaveric study was to assess the normal anatomy of the LLCs in noses of Black South Africans. This was compared to data from studies on noses from Caucasian, Asian, Korean, and African-American populations.
METHODS
Study Design
This was a descriptive study of 90 LLCs from 45 cadavers of Black South Africans, without previous nasal surgery or nasal injury, fixed in formalin, which had been donated to the Department of Basic Medical Sciences at the University of the Free State. The dissection was carried out in the dissection hall of the Department of Basic Medical Sciences, University of the Free State between September 2013 and August 2014.
Ethical Approval
Permission to perform the study was obtained from the Head of the School of Medicine and the Dean of the Faculty of Health Sciences, University of the Free State. The study was approved by the Ethics Committee of the Faculty of Health Sciences of the University of the Free State (ECUFS № 133/2013).
Measurement
Results were summarized by means, standard deviations and ranges. Males and females were compared using the t test. Ninety-five percent confidence intervals were calculated for the means of this study so as to compare with means of published studies as many of the other studies did not report standard deviations.
RESULTS
Fourteen cadavers (31.1%) were female and 31 cadavers (68.9%) were male.
Table 1 shows the results of the length, width, and thickness of the three crura. Males and females differed significantly (P < .05) regarding lateral crus length and width, middle crus length and thickness, and medial crus width and thickness. The most common shape of the lateral crus of the LLC was smooth convex in in 36 (40%) of LLCs, followed by convex-concave in 20 (22.2%), concave-convex in 18 (20%), convex-concave-convex in 12 (13.3%), and irregular in 4 (4.5%).
DISCUSSION
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Our study was the first of its kind performed in Southern Africa and had a relatively large number of subjects. We found a significant difference (P < .05) between males and females in terms of the width and length of the lateral crus; the length and thickness of the middle crus; and the width and thickness of the medial crus (Table 1). In a study on Persian LLCs, there were no significant differences between males and females in terms of the length of the middle and lateral crura, but there was a statistically significant difference in terms of width.5 Although we wanted to compare our results with various ethnic groups, our main aim was to see if the only norms for the Black nose, as published more than 20 years ago, on a group of African-American noses,8 were comparable to what we found. Overall dimensions of the lateral crus of the LLCs of our study group, when compared to those of other studies, showed a statistically significant difference with the mean values of other studies falling outside the 95% confidence intervals our study’s mean values (Table 2). The LLCs in our study appeared to be both shorter and narrower than those of other ethnic groups.
The distance to the nasal rim from the caudal border of the lateral crus was also less than those found in other ethnic groups (Table 3). The mean at the anterior point was 3.1 mm, at the midpoint 4.5 mm, and at the posterior point 6.7 mm from the nasal rim. This is almost half as small in comparison to the study on African-American cadavers with dimensions of 6, 6, and 11 mm at the corresponding points. The close proximity of the lateral crus to the alar rim in our study would suggest the alar rim is better supported structurally by cartilage than previously thought.
The five morphological shapes into which the lateral crura were classified showed a far greater variety of all five shapes and not such a predominance of a particular shape as found in other studies (Table 4).4,5,8 Our study found that 60.2% of the lateral crura were either smooth convex or convex-concave. This is in contrast to the findings of the African-American study where 83.3% of their subjects were in one of these two categories.8 We did not observe any markedly concave lateral crura, which are usually expressed clinically as an alar depression.18
The LLCs contribute to the tip structures and airway resistance as they form part of the external nasal valve.14-16 Further studies could be done on the structural anatomy and its effect on airway resistance.
Clinical Significance
Each culture has a different perception of beauty and what aesthetic ideals are.3,19,20 While a culturally relevant beauty has to be strived for in general, in the individual patient the nose should also fit the face. Rhinoplasty surgeons should be aware of the anatomical and morphological differences in noses when they are performing procedures on patients from various cultures, especially cultures they are not familiar with.
During the dissections the unexpectedly long course of the medial footplates were seen repeatedly and were shown to be statistically significantly different in length and width compared to other groups. The clinical implications are that any incision on the columella for the open approach will likely have excellent wound support from the underlying cartilage and may safely be done closer to the upper lip (infero-posteriorly) than usual to aid in scar camouflage. When a V to Y incision is needed to lengthen the columella and aid tip projection without excessive pulling on the upper lip, this may be done with good support on the infero-posterior aspect of the columella.
While the skin thickness was not specifically measured, the dissections concurred with the clinical experience that skin thickness varies and in some cases the skin can be thin. Assessing skin thickness pre-operatively is essential for a good outcome and the surgical plan should be adjusted accordingly.
Osteotomies did not form part of the study but the authors advise caution as the nasal bones are generally very short in dorsal height and clinically it has been found that lateral and medial osteotomies may not lead to any gain in dorsal height.21
The dissection of the lateral alar rim should be done with caution in this patient group. The measurements showed the lateral aspect to be closer to the nostril than in other groups and care taken will avoid visible scarring or transecting of the LLCs.
The rhinoplasty surgeon would be well advised to take additional caution when operating on the nose of a black female patient due to the delicate nature of the LLCs, the possible thin skin and mucoperichondrium as well as the heightened cosmetic expectations. Additional structural support is likely necessary in both endonasal as well as open approaches to achieve good tip support. Alar rim resections will need to be decided on an individual level.
Limitations
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Ideally this study would have been done on fresh cadavers, but these were not available. Formalin preserved cadavers are readily accessible due to their use in dissections for medical students and the authors felt the possible impact of preservation on the outcome of the study had to be weighed against much smaller numbers if the study was carried out on fresh cadavers. Skin thickness was not measured as this was potentially significantly altered by preservation.
Noses that were obviously distorted by the preservation process were excluded. We did not find any congenitally abnormal cartilages, possibly due to the relative small sample size. Kosins et al22 showed an occurrence of less than 1% of congenitally abnormal alar cartilage.
While all cadavers were of adult patients, the exact age was not known in many cases. It was therefore not possible to determine if there were any differences in the LLCs by age.
The orientation of the LLCs plays an important role in tip projection and shape,13,17 but this was not measured in this study. We also did not assess the position of the lower lateral cartilages, which is normally parallel to the alar rim for at least half the length of the nostril.18
This study was performed on the lower lateral cartilages that form the upper nasal base. It would be useful to also study the lower nasal base, which consists of the columellar base, nostril sills, and alar lobules in Black South Africans as the interaction of these tissues influences compression and dilatation of the nostrils and external valves.23
It was not possible to perform hypothesis testing for the statistical analysis as the studies to which we compared our data did not report standard deviations. We therefore compared the means of published studies to the 95% confidence intervals of the means of this study.
CONCLUSION
There were statistically significant differences in terms of the dimensions of length, width, and thickness; distance to the nasal rim; and morphological shape of the LLCs in this study compared to previously published studies. The authors believe that this study points to the unique characteristics of the previously unrecognized Black Southern African nose. Further studies are required to confirm and further describe this new subtype of anthropological nose and possible subsets. Future studies should also focus on bony anatomy, airflow, soft tissue, and ligamentous tip support anatomy in this population. Anthropometric population studies are also needed. This study establishes benchmark norms for the LLCs in the Black Southern African nose that will help guide the rhinoplasty surgeon.
Disclosures
The authors declared no potential conflicts of interest with respect to the research, authorship, and publication of this article.
Funding
Karl Storz (Tuttlingen, Germany) provided Dr McIntosh with a 40% discount on the cost of instruments used for the dissections.
Acknowledgments
The authors would like to thank Mr Willie van der Heever for the illustrations.
REFERENCES
Author notes
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