Ethnic variation in lower face anthropometry on facial computed tomography scans for patients seeking facial feminization surgery

Abstract

BackgroundFacial feminization surgery (FFS) is the most common form of facial gender-affirming surgery. One of the current knowledge gaps is the understanding of racial group differences in baseline craniofacial norms for transgender and nonbinary patients. MethodsAll patients who sought consultation for FFS with a completed craniofacial computed tomographic (CT) scan at a single institution between the years of 2018 to 2023 were included. Patients with previous facial surgeries were excluded. Chart reviews were conducted for patient characteristics, including race, age, hormone therapy duration, and prior gender-affirming surgeries. Racial categorizations included White, Latinx, African American, or Asian. Patients with other or multiracial identity were excluded. Measurements of the lower face were derived from preoperative facial CT scans. Comparative analyses were performed on all measurements between racial groups. Results204 patients were included with an average age of 32.0±10.2 years and a median hormone duration of 2.0 years. Notable racial group differences were: 1. Zygomatic width was largest in Asian patients (13.5±0.6cm) compared to all other racial groups (p=0.03), 2. Nasolabial angle was smallest in African American patients (82.5±13.1 degrees, p<0.001), 3. Lower face height was largest in African American patients (6.9±0.7cm, p<0.001) and 4. Lateral mandibular flare was largest in African American patients (0.4±0.1cm) and smallest in Latinx patients (0.2±0.1cm, p<0.001). ConclusionsSpecific target areas of FFS should be carefully considered to account for possible baseline ethnic differences. Relative facial proportions may also be a more salient surgical planning tool for TGNB patients rather than absolute measurements alone.