Quantification of Cephalometric Changes in Gonial Angle Morphology Following Facial Feminization Surgery

Facial feminization surgery (FFS) is a type of gender-affirming surgery aimed at bringing masculine facial features more in line with typically feminine characteristics. Specifically, mandibular contouring can create a softer jawline and help create a more round, feminine face. As the popularity of FFS continues to increase, improving surgical techniques and patient satisfaction is imperative. However, no quantitative measurement system currently exists to measure these changes. In this study, the authors describe the use of a novel segmentation technique using computerized tomography imaging to quantify the bony changes that occur during gonial angle reduction. Further, authors utilize this technique to describe changes in a cohort of 13 patients, and how these changes correlate with patient satisfaction. The authors found that gonial angle volume and surface area significantly decreased, as well as the intergonial:interzygomatic ratio, with a smaller ratio associated with more feminine features. In addition, patient satisfaction significantly increased post-operatively both specifically regarding jawline appearance ( P = 0.0014) and regarding overall social and psychological function ( P = 0.0021 and P = 0.0032, respectively), as captured by the FACE-Q and World Health Organization Quality of Life (WHOQOL) surveys. Patients with greater changes in surface area reported greater improvements in WHOQOL psychological scores ( P = 0.0086), and patients with greater changes in the intergonial:interzygomatic ratio reported greater improvements in WHOQOL social scores ( P = 0.0299). Overall, our novel technique captures significant changes in gonial angle shape and can be applied to a wide range of future studies to improve the quality and accessibility of FFS.