Simulation of Skin Stretching around the Forehead Wrinkles in Rhytidectomy
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Simulation of Skin Stretching around the Forehead Wrinkles in Rhytidectomy Ping Zhou1 · Shuo Huang1 · Qiang Chen1 · Siyuan He1 · Guochao Cai1 Received: 14 January 2019 / Revised: 9 August 2020 / Accepted: 1 October 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Skin stretching around the forehead wrinkles is an important method in rhytidectomy. Proper parameters are required to evaluate the surgical effect. In this paper, a simulation method was proposed to obtain the parameters. Three-dimensional point cloud data with a resolution of 50 μm were employed. First, a smooth supporting contour under the wrinkled forehead was generated via b-spline interpolation and extrapolation to constrain the deformation of the wrinkled zone. Then, based on the vector formed intrinsic finite element (VFIFE) algorithm, the simulation was implemented in Matlab for the deformation of wrinkled forehead skin in the stretching process. Finally, the stress distribution and the residual wrinkles of forehead skin were employed to evaluate the surgical effect. Although the residual wrinkles are similar when forehead wrinkles are finitely stretched, their stress distribution changes greatly. This indicates that the stress distribution in the skin is effective to evaluate the surgical effect, and the forehead wrinkles are easily to be overstretched, which may lead to potential skin injuries. The simulation method can predict stress distribution and residual wrinkles after forehead wrinkle stretching surgery, which can be potentially used to control the surgical process and further reduce risks of skin injury. Keywords Skin aging · Rhytidectomy · Finite element analysis · Numerical analysis · Stress distribution List of Symbols Zsup Three-dimensional rigid supporting contour Zc The forehead wrinkles ε The surface with wrinkles Zf (x,y) the fitting surface Cj The control points * Ping Zhou [email protected] 1
School of Biological Sciences & Medical Engineering, Southeast University, 210096 Nanjing, People’s Republic of China
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Sensing and Imaging
(2020) 21:50
Nj,p The fitting polynomial nx The numbers of nodes along the x axis ny The numbers of nodes along the y axis p The order of the fitting polynomial C The control point matrix B The approximate value of the second partial derivatives Λ The weight of the sum of the second partial derivatives Zi-1 The result of the (i-1)th iteration Zd A surface that do not contain wrinkles P An arbitrary particle of the forehead wrinkle mp The mass of the particle t Time Δt Time step FP,t The tensile force vector applied on particle P at time t 𝐢𝐧𝐭 𝐟𝐏,𝐭 The internal force 𝐞𝐱𝐭 𝐟𝐏,𝐭 The external force E The elastic modulus of skin i 𝐟𝐏,𝐭 The internal force exerted by the ith surrounding structure unit at time t Ui,0 The initial length vectors of the ith tensile structure unit at time t ΔUi,t The elongation vectors of the ith tensile structure unit at time t Am The area of wrinkles whose depth is great
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