An Axisymmetric Computational Model of Skin Expansion and Growth

Socci, Laura; Pennati, Giancarlo; Gervaso, Francesca; Vena, Pasquale

doi:10.1007/s10237-006-0047-9

Cited by 37 publications

(33 citation statements)

References 37 publications

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“…69 Our group and others have previously proposed a theoretical and computational model for skin expansion based on the theory of finite growth and finite element analysis. 15,50,61 To demonstrate its clinic potential, we have now established a novel experimental protocol towards a detailed kinematic characterization of skin deformation, prestrain, and growth in a chronic porcine model that closely resembles the clinical scenario. 10 We believe that our results constitute a major step towards validating skin expansion models.…”

Section: Discussionmentioning

confidence: 99%

The Incompatibility of Living Systems: Characterizing Growth-Induced Incompatibilities in Expanded Skin

et al. 2015

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Skin expansion is a common surgical technique to correct large cutaneous defects. Selecting a successful expansion protocol is solely based on the experience and personal preference of the operating surgeon. Skin expansion could be improved by predictive computational simulations. Towards this goal, we model skin expansion using the continuum framework of finite growth. This approach crucially relies on the concept of incompatible configurations. However, aside from the classical opening angle experiment, our current understanding of growth-induced incompatibilities remains rather vague. Here we visualize and characterize incompatibilities in living systems using skin expansion in a porcine model: We implanted and inflated two expanders, crescent, and spherical, and filled them to 225 cc throughout a period of 21 days. To quantify the residual strains developed during this period, we excised the expanded skin patches and subdivided them into smaller pieces. Skin growth averaged 1.17 times the original area for the spherical and 1.10 for the crescent expander, and displayed significant regional variations. When subdivided into smaller pieces, the grown skin patches retracted heterogeneously and confirmed the existence of incompatibilities. Understanding skin growth through mechanical stretch will allow surgeons to improve— and ultimately personalize—preoperative treatment planning in plastic and reconstructive surgery.

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Section: Discussionmentioning

confidence: 99%

The Incompatibility of Living Systems: Characterizing Growth-Induced Incompatibilities in Expanded Skin

et al. 2015

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“…Recent studies have used computational models to predict skin growth in response to mechanical loading [10, 50]. Experimental data to calibrate these models exist [6], yet, at a very low spatial and temporal resolution.…”

Section: Discussionmentioning

confidence: 99%

Characterization of living skin using multi-view stereo and isogeometric analysis

et al. 2014

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Skin is our interface with the outside world. In its natural environment, it displays unique mechanical characteristics such as prestretch and growth. While there is a general agreement on the physiological importance of these features, they remain poorly characterized, mainly because they are difficult to access with standard laboratory techniques. Here we present a new, inexpensive technique to characterize living skin using multi-view stereo and isogeometric analysis. Based on easy-to-create hand-held camera images, we quantify prestretch, deformation, and growth in a controlled porcine model of chronic skin expansion. Over a period of five weeks, we gradually inflate an implanted tissue expander, take weekly photographs of the experimental scene, reconstruct the geometry from a tattooed surface grid, and create parametric representations of the skin surface. After five weeks of expansion, our method reveals an average area prestretch of 1.44, an average area stretch of 1.87, and an average area growth of 2.25. Area prestretch is maximal in the ventral region with 2.37, area stretch and area growth are maximal above the center of the expander with 4.05 and 4.81. Our study has immediate impact on understanding living skin to optimize treatment planning and decision making in plastic and reconstructive surgery. Beyond these direct implications, our experimental design has broad applications in clinical research and basic sciences: It serves as a simple, robust, low cost, easy-to-use tool to reconstruct living membranes, which are difficult to characterize in a conventional laboratory setup.

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“…However, despite a few exceptions [41], most of these attempts remain restricted to an axisymmetric response. Unfortunately, the same is true for the only computational model for skin growth proposed to date [59], which is unsuitable to model arbitrary tissue expander geometries. It is of axisymmetric nature and can therefore only be applied to model skin growth using a circular tissue expander.…”

Section: Motivationmentioning

confidence: 99%

Growing skin: A computational model for skin expansion in reconstructive surgery

Tepole

Ploch

Wong

et al. 2011

Journal of the Mechanics and Physics of Solids

115

106

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The goal of this manuscript is to establish a novel computational model for stretch-induced skin growth during tissue expansion. Tissue expansion is a common surgical procedure to grow extra skin for reconstructing birth defects, burn injuries, or cancerous breasts. To model skin growth within the framework of nonlinear continuum mechanics, we adopt the multiplicative decomposition of the deformation gradient into an elastic and a growth part. Within this concept, we characterize growth as an irreversible, stretch-driven, transversely isotropic process parameterized in terms of a single scalar-valued growth multiplier, the in-plane area growth. To discretize its evolution in time, we apply an unconditionally stable, implicit Euler backward scheme. To discretize it in space, we utilize the finite element method. For maximum algorithmic efficiency and optimal convergence, we suggest an inner Newton iteration to locally update the growth multiplier at each integration point. This iteration is embedded within an outer Newton iteration to globally update the deformation at each finite element node. To demonstrate the characteristic features of skin growth, we simulate the process of gradual tissue expander inflation. To visualize growth-induced residual stresses, we simulate a subsequent tissue expander deflation. In particular, we compare the spatio-temporal evolution of area growth, elastic strains, and residual stresses for four commonly available tissue expander geometries. We believe that predictive computational modeling can open new avenues in reconstructive surgery to rationalize and standardize clinical process parameters such as expander geometry, expander size, expander placement, and inflation timing.

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An Axisymmetric Computational Model of Skin Expansion and Growth

Cited by 37 publications

References 37 publications

The Incompatibility of Living Systems: Characterizing Growth-Induced Incompatibilities in Expanded Skin

The Incompatibility of Living Systems: Characterizing Growth-Induced Incompatibilities in Expanded Skin

Characterization of living skin using multi-view stereo and isogeometric analysis

Growing skin: A computational model for skin expansion in reconstructive surgery

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