摘要

Objectives: To offer rational bases to inform surgical or cosmetic strategies aiming to counteract aging by acting on selected biophysical mechanisms. Introduction: Aging causes gradual facial changes like dark spots, wrinkles, and jowls. Despite jowl reduction being a common plastic surgery reason, quantitative links between age-based tissue biomechanics and facial sagging are poorly understood. Our study addressed this by conducting an observational clinical study on women with varying facial sagging. We then calibrated a 3D biomechanical face model using in vivo measurements of cheek tissues. This model simulates and quantifies jowl formation and gravimetric descent under different age-based remodeling, skin growth, and anchoring loss scenarios. Materials / method: Cheek deformability was quantified in 36 women (18-71 y) using a suction-based protocol. A 3D statistical model was used to quantify real-life face aging as no data were available on the same subjects during their life span. These data provided a ground-truth for jowl formation. A biomechanical face model, detailing skin, hypodermis and deeper tissues was developed. The effects of the age-based tension relaxation (induced by skin growth), the skin and hypodermis remodeling (extracted from suction experiments) and the anchoring loss were simulated and quantified. Results: Simulation of gravity application on models with experimentally-informed constitutive parameters for skin and hypodermis shows that anchoring loss can explain only 21% of the expected peak sagging in the jowl. This value increases to 44% when further accounting for age-based remodeling of skin and hypodermis. Lastly, allowing for skin tension relaxation by including skin growth accounts for nearly 70% of the ground truth sagging in the jowl. Conclusion: Our work rationalizes the contribution of several tissue layers and aging-based mechanisms to the development of a sagged appearance. It proposes potential causal links between tissue biomechanical changes and macroscopic hallmarks of facial aging,