Anatomical and radiological evaluation of modiolus anguli oris in facial anatomy

Abstract

Aim: Modiolus is a dense, mobile fibromuscular structure lateral to the mouth corner. It is of great importance in aesthetic and reconstructive surgery. The aim of this study was to enlighten the structural changes in modiolus with demographic variables such as age and gender in living individuals.Methods: This retrospective cohort study was conducted on MR images of healthy individuals. Age and sex-related changes in modiolus level and volume were retrospectively analyzed in 64 patients [37M; 27F; mean age 48.2(16.3)] who underwent head and neck magnetic resonance imaging. ROC analysis was performed to determine the cut off values for age of modiolus. Correlation analysis (Pearson and point biserial correlation) was used to determine whether there was a significant correlation between age and volume. Significance of the differences between the volumes of right and left modiolus of the same individual were evaluated by dependent t tests.Results: The mean volume of the modiolus was calculated as 0.51(0.26) mm3. The volumes of right and left modioli decreased by aging. Ninety-one percent of the patients with modioli located inferior to horizontal line were over 49 years old. Right and left modioli relocated inferior to horizontal line with age. Modiolus volume was prominently less in women and the downward displacement of modiolus in women was 3.3 times higher than in men. Gender and age had significant effects on modiolus level. The right and left modiolus volumes were similar (P=0.975).Conclusion: Surgeon’s knowledge on modiolus and its relations will provide benefit, not only for the procedures such as face lifting and botulinum toxin injection, but also for the surgeries of facial paralysis and trauma patients.