The Quadrangular Cartilage in Rhinoplasty: A surgically focused CT dimensional analysis of Black African and Caucasian populations.

The apparent lack of quadrangular cartilage in Black African noses is commonly observed both from a radiological and clinical point of view. To the best of our knowledge only a few research papers has been conducted on the facial proportions and structural anatomy of black people of Southern and Eastern Africa. The aim of this retrospective comparative study is a radiological assessment of the total amount of septal quadrangular cartilage by measuring its area in sagittal CT views, in two selected Black South African (SA) and Caucasian (CA) samples and the comparison with the literature in our hands. Statistical analysis was conducted, Categorical variables are showed as frequencies and percentages, while continuous variables as means and standard deviations (SD). Normal distribution of variables was verified using the Shapiro-Wilk test or by means of skewness and kurtosis values. Differences among unpaired groups were evaluated using the independent Student's t test for normally distributed data (complemented by the Cohen's d to show the effect size with the following cut-off: d=0.2, "small" effect size; d=0.5, "medium" effect size; d=0.8, "large" effect size) and Mann-Whitney U test in case of no normal distribution. Statistical significance was defined as p < 0.05 setting the α-error probability at 5%. This study shows that on average there is a 30% more cartilage available in caucasian compared to Black African noses and confirms the apparent lack of quadrangular cartilage and in Black African noses which is commonly observed in surgery. The need for an adequate amount of autologous septal cartilage makes cartilage availability a major concern before surgery and being able to pre-operative accurately measure the amount of septal cartilage that is available to be harvested for other grafts in the surgery is essential.