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Science Matters: The Effects of Cushion Setup and Posture on Tissue Deformation

Program ID : IC73.2019
Webinar Length of Time: 1.0 Hour

Link to view the lecture presentation:




Alexander Siefert, PhD
Wölfel Engineering GmbH & Co.kg, Germany

Alexander Siefert is working at Wölfel since 2003 at leads currently the seating department as an engineering director. He made his PHD at the TU Darmstadt about the topic: "Numerical modelling of mechanical properties of the human tissue and its implementation in a whole body model". He published several papers in the field of human body modelling and made a lot of presentation on international conferences about seating, human modelling and pressure sores.

Bart Van Der Heyden, PT
Private PT Practice: De Kine SuperSeating, Belgium

Bart Van der Heyden is an independent physical therapist specializing in wheelchair seating & mobility as well as wound care with 25 years of experience and over 20 years of experience mentoring service providers. Bart is licensed and has practiced as a physical therapist across Europe and the United States. Based in Belgium, he travels the world for lectures, educational events, and hands on sessions to varied audiences on seating and mobility issues, the provision of wheelchair equipment for children and adults with moderate to severe physical challenges, and wound related problems. Bart maintains his skills and experience by continuing to work in his private practice. He is also a clinical consultant on clinical applications, design, and functionality of medical devices for several wheelchair manufacturers and has conducted clinical studies for these companies as well. His expertise lies in client and service provider training and education, spasticity management, pediatrics, wound care and evidence based clinical decision making.

Presented at the 35th International Seating Symposium, Pittsburgh, PA USA

Note: Faculty for this activity have been required to disclose all relationships with any proprietary entity producing health care goods or services, with the exemption of nonprofit or government organizations and non-healthcare related companies.

  • No conflicts have been disclosed.


The selection of cushions is often based on clinical experience in combination with user feedback about experienced comfort when sitting for a limited time. There exists a great variety in type, the setup of the cushion and how its fits to the final user. In general, all types of cushion can be distinguished by material (foam, gel, air cells and hybrids), dimension (size and thickness), contour, interface and stiffness. In the presented study the influences of general parameters such as dimension, friction and stiffness are investigated for a simple foam setup. In addition, the influence of posture and anthropometrics is analyzed. In order to reduce time and cost, the analysis was carried out with using Finite Element Analysis. Therefore 3D human body models are applied, which is more or less a standard in the automotive sector to evaluate and optimize car seats. FEA provides reproducible data about result values as immersion and pressure distribution. Further, FEA is used in other industries to analyze the internal behavior of body structures. The computed internal tissue strains can be used to visualize and analyze the Volumetric Strain Distribution (VSD), a quantitative value for the risk evaluation of pressure ulcers. Finally, each parameter and its influence on relevant assessment values will be analyzed and presented. Based on these general conclusions, we can improve our understanding of the mechanical interaction between the human body and the wheelchair cushion.

Learning Objectives

Upon viewing this webinar, participants will be able to:


CEU Registration and Cost

0.100 Continuing Education Units (CEUs) will be awarded to individuals for viewing 1.0 hours of instruction.
The cost for the webinar is $59.00

Instructions to Obtain CEUs

go to the RSTCE web site at: www.rstce.org

    1. Enter username and password or create new profile
    2. Select Webinars
    3. Select the webinar:IC73.2019 - Science Matters: The Effects of Cushion Setup and Posture on Tissue Deformation
    4. Complete your registration

A payment confirmation will be sent via e-mail.
(Allow 10 minutes for the database to process payment and send a confirmation e-mail).

After viewing the webinar

    1. log back into database and Select Post Tests and Evaluation for:
      IC73.2019 - Science Matters: The Effects of Cushion Setup and Posture on Tissue Deformation
    2. Select and complete Post Tests and Evaluations

You will receive your CEU Certificate via e-mailed as a PDF file (Please allow 10 minutes for the database to process your certificate and send it to your e-mail)

The University of Pittsburgh, School of Health and Rehabilitation Sciences awards Continuing Education Units to individuals who enroll in certain educational activities. The CEU is designated to give recognition to individuals who continue their education in order to keep up-to-date in their profession. (One CEU is equivalent to 10 hours of participation in an organized continuing education activity). Each person should claim only those hours of credit that he or she actually spent in the educational activity.
The University of Pittsburgh is certifying the educational contact hours of this program and by doing so is in no way endorsing any specific content, company, or product. The information presented in this program may represent only a sample of appropriate interventions.

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Updated | 06.27.2019