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Cushion geometry: why are contours important?

Looking for more information on seating and positioning? Check out our digital page all about what to look for in seating and positioning products here. This is part 5 of our series on seating and positioning. See part 1, part 2part 3, and part 4.


When evaluating a cushion, it’s important to note whether it is linear or contoured. The geometry of the cushion can potentially impact transfers and freedom of movement. With contoured cushions, understanding what each contour is designed to do is key to meeting seating goals.

An example of using cushion contours to achieve a seating goal: What if my client has difficulty sitting upright over time?

Always consider the “why.” Often when someone gets into their wheelchair in the morning and looks great, then fatigues and starts slumping or needs to rest after a few hours, it’s because they have postural muscle weakness. We don’t think about this, but every day when we are sitting, postural muscles are working to keep us upright. When these postural muscles are compromised by injury or disease, they become fatigued more quickly.

The solution

One way to decrease the work required of the postural muscles is to provide a stable base of support in the cushion that is selected. This doesn’t mean that the cushion needs to be “hard”, it means that it should be supportive in the right areas. An offloading style cushion is often the most stable because of its inherent contours that provide the offloading.

How does it work?

Typically, the contours in the rear of the cushion load the trochanters which pushes the head of the femur into the acetabulum of the pelvis, which in turn stabilizes the pelvis. The best way to understand this is to feel it! Find a flat surface to sit on and place each hand, palms facing down, under the trochanters. Hold them there and rock side to side. While still rocking side to side, remove your hands and notice the difference in stability. By loading the trochanters, an offloading cushion provides pelvic stability that reduces the work needed from the postural muscles to sit upright over time.


Key attributes of wheelchair seat cushion


Share ButtonStacey Mullis

Stacey Mullis, OTR/ATP

Director of Clinical Marketing

Stacey serves as Director of Clinical Marketing for Permobil. A practicing OTR for over 20 years, she has experience in school-based pediatrics, inpatient rehabilitation, long term care, and home health. With her interest in wheelchair seating and positioning, Stacey engaged the challenges of providing appropriate seating in various clinical settings. She now uses this experience to develop programs and resources to educate clinicians on the principles of seating and wheeled mobility. She is passionate about equipping clinicians and through her previous role as Director of Clinical Education with Comfort Company and now with Permobil she has taught nationally and internationally to increase therapist capacity in this specialty area. Mullis graduated from Western University in London, Ontario, Canada with a BA Linguistics and BSc Occupational Therapy. She is a member of the NCOTA, CTF Executive Board, NRRTs, RESNA, and AOTA.

 

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