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Skin and deep tissue mechanics and adaptive remodeling in pressure ulcer formation

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Different Geometry and Finite Element Views of Human ThighThe overarching goal of this project is to develop innovative models to describe and predict stress distribution within the soft tissues of the thigh and buttocks area that will aid in the design of novel solutions to prevent pressure ulcer formation in individuals with limited mobility. In my laboratory, we implemented a novel microstructurally inspired mechanical model of skin that takes into account collagen fibers organization; we then performed mechanical testing and histological analysis of rat skin to inform the model. We also collaborated with an international researcher, Prof. A. Ní Annaidh (University College Dublin, Ireland), who provided experimental data from human skin. A model that links the mechanical characteristics of skin with its microstructure will impact not only the study of pressure ulcers, but also areas such as plastic surgery, wound healing/formation, and radiotherapy side effects. Then, in collaboration with Prof. T. R. Bush, my group is currently working on the design of a wheelchair cushion that can minimize the stress concentrations in the thigh and buttock area, where pressure ulcers typically form. In my laboratory, we conducted a finite element study that, for the first time, quantifies the non-linear mechanical behavior of soft tissues in the thigh of healthy young individuals, in a large deformation regime. This model has the potential to inform the design of optimized interface surfaces (inspired by a beaded seat cover), to minimize deep tissue stresses and strains.

Collaborators: Prof. T. R. Bush (Mechanical Eng. Dept., MSU) and Prof. A. Ní Annaidh (Mechanical Eng. Dept., University College Dublin, Ireland).

Impact. Pressure ulcers negatively affect the lives of individuals mentally and physically, cause significant pain, have a high recurrence rate and can result in extended hospital stays for individuals with spinal cord injury. There is a critical need for better prevention methods; the current efforts to reduce the formation of pressure ulcers are ineffective. This study will have an immediate impact on spinal cord injury patients through the potential for pressure ulcer reduction, and will have broader impacts for the elderly, and patients who are bedridden or who have limited mobility (e.g., stroke).

Future Directions. The long-term goal of this project is to develop a mechano-chemo-biological model to describe the adaptive remodeling of skin. This model will allow us to better understand the process of wound formation and healing.

 

 

References

Scott J., Chen S., Roccabianca S., Bush T.R. (2020) The Effects of Body Position on the Material Properties of Soft Tissue in the Human Thigh. Biomechanics and Modeling in Mechanobiology, 110, 103964.

Chen S., Scott J., Bush T.R., Roccabianca S. (2020) Inverse finite element characterization of the human thigh soft tissue in the seated position. Biomechanics and Modeling in Mechanobiology,19(1), 305-316.

Chen S., Ní Annaidh A., Roccabianca S. (2020) A microstructurally inspired constitutive model for skin mechanics. Biomechanics and Modeling in Mechanobiology, 19(1), 275-289.

Sadler Z., Scott J., Drost J.P., Chen S., Roccabianca S., Bush T.R. (2018) Initial estimation of the in vivo material properties of the seated human buttocks and thighs. International Journal of Non-Linear Mechanics, 107, 77-85.

Presentations, proceedings, and papers

Broemer E., Chen S., Scott J., Bush T.R., Roccabianca S.* Effect of Seating Plane Inclination on Stress Concentration in Non-Linear Finite Element Model of Human Thigh. Summer Biomechanics, Bioengineering and Biotransport Conference (SB3C). June 17 - June 20, 2020. Virtual Conference

Broemer E.#, Chen S., Scott J., Bush T. R., Roccabianca S*. Optimizing non-linear mechanical behavior of soft tissues in finite element model of human thigh. Summer Biomechanics, Bioengineering and Biotransport Conference (SB3C). June 25-28, 2019. Seven Spring, PA. (Poster presentation)

Scott J.#, Chen S., Roccabianca S., Bush T.R.* Body position effects on thigh soft tissue properties. Summer Biomechanics, Bioengineering and Biotransport Conference (SB3C). June 25-28, 2019. Seven Spring, PA. (Poster presentation)

Chen S.#, Scott J., Bush T.R., Roccabianca S*. Non-linear finite element model of thigh soft tissue mechanical behavior informed by in vivo experimental data. 2018 Biomedical Engineering Society Annual Meeting. Oct 17-20, 2018. Atlanta, GA. (Podium presentation)

Chen S., Scott J., Bush T.R., Roccabianca S.#,* A subject specific model of the human thigh informed by in vivo experimental data. 8th World Congress of Biomechanics. July 8-12, 2018. Dublin, Ireland. (Poster presentation)

Chen S.#, Scott J., Bush T.R., Roccabianca S.* A subject specific model of the human thigh informed by in vivo experimental data, ICHITA-IT Forum conference. November 2-3, 2017. Kalamazoo, MI. (Podium presentation)

Chen S.#, Roccabianca S.* Determination of proper storage condition and constitutive model for rat back skin mechanical properties. Summer Biomechanics, Bioengineering and Biotransport Conference (SB3C). June 21–24, 2017. Tucson, AZ. (Poster presentation)

Chen S.#, Roccabianca S.* Effect of storage condition, orientation, location and gender on rat back skin mechanical properties. Midwest ASB Regional Meeting. February 23 - 24, 2017. Grand Rapids, MI. (Podium presentation)

Chen S.#, Ni Annaidh A., Roccabianca S.* Micro-structurally motivated constitutive model for human skin. Summer Biomechanics, Bioengineering and Biotransport Conference (SB3C). June 29 – July 2, 2016. National Harbor, MD. (Poster presentation)