Seating and Mobility Considerations for Individuals Who Are Bariatric, Part 2: Ax and Seating

Canadian Clinical Blog by Sheilagh Sherman, BA, BHScOT, MHM, OT Reg. (Ont.) - Sunrise Medical

Hello all!

Last month, we started a discussion on seating and mobility considerations for individuals who are bariatric. I wrote about body shape and that it is a person’s unique shape and weight distribution that must be evaluated when assessing for seating and mobility. (If you missed last month’s article, click here for Part 1.) Let’s continue the discussion.

Assessing an individual who is bariatric for seating and mobility comes with unique challenges. (For a refresher on the hands on assessment and on seating goals and considerations, refer to two of my earlier articles here Hands on Assessment and Seating goals and considerations, respectively.) It can be difficult to control the pelvis when conducting a hands on assessment due to excess redundant tissue. In addition, palpating the bony landmarks of individuals who have excess adipose tissue can be difficult. To locate the ASIS or PSIS of the pelvis, look for skin folds or skin depressions.

If a measurement of the width of the ASIS is desired, this can be done in supine, coming from below an abdominal mass. Other measurements, however, should be completed with the individual sitting on a firm surface with the feet firmly supported. If measurements, apart from the distance between the ASIS are completed in supine, inaccurate measurements could result as the effects of gravity act on the adipose tissue. When measuring, it is helpful to use a caliper, if available, rather than a tape measure, to obtain accurate measurements. Care should be taken to measure the widest point when measuring the lower body, recognizing that this measurement may not be of the hips, depending upon the individual’s body shape and weight distribution. If the client presents with a gluteal shelf, additional measurements are required. 

A final consideration in the seating and mobility assessment is the person’s current weight to ensure that the weight capacities of the seating and mobility base will not be exceeded. In addition, having an understanding of the person’s weight history will help to identify if the person’s weight is stable or if there have been recent losses/gains. If a person’s weight is not stable, consider this effect on positioning and on the mobility base at the outset of the prescription. (For an article that refers to change in body size and manual wheelchair prescription, Click here.)

It is important to remember that individuals who are bariatric are at increased risk of pressure ulcers due to factors including immobility and poor vascularization of adipose tissue.1 Adipose tissue is not supportive and deep tissue injury can occur from immobility. The damage starts within the muscle, rather than the epidermis.2 Thus, damage can occur before it is observed on the skin level. People who are obese also are prone to profuse sweating,1 which can contribute to skin integrity issues through increased moisture on the skin over the bony prominences. In addition, the risk of pressure ulcers comes from increased risk of shearing if transfers and weight shifting are not completed well.

In determining appropriate generic product parameters of cushions for individuals who are bariatric, think about the material, cushion cover and product design and how these relate to skin protection and positioning. Fluid material in cushions provides better skin temperature control than other cushion materials by conducting heat away from the skin. Both fluids and air reduce shear forces by adjusting to body movements. (For a previous article on Skin Protection and Cushion Materials, Click here.)

In terms of cushion covers, a cover that has stretch in the material will have lower shear forces associated with it than a cover made with a stiffer, less giving material. A microclimatic cover enables heat and moisture dissipation through a layer of spacer fabric, facilitating a cool, dry environment on which to sit. (For a previous article on Skin Protection and Cushion Covers, Click here.)

In terms of product design, consider the contours of a cushion and the relative position of the person’s pelvis when sitting on the cushion. For example, if a cushion has a pelvic loading area well for a fluid insert, consider if the person’s pelvis will be positioned correctly over the pelvic loading area well, given increased adipose tissue. Someone who presents with increased adipose tissue posteriorly may require the pelvic loading area well to be customized and moved forward on the cushion in order to properly position the pelvis in the well to achieve the skin integrity benefits of the fluid or air insert. (A previous article on Skin Protection and Cushion Design can be found here.)

Understanding a person’s shape will also help in the selection of an appropriate back support. A back support should be selected based on the needs of the client, not the width of the wheelchair. For example, someone with wider hips and a narrower trunk should have a back support that provides sufficient posterior and lateral support. A narrower back support can be mounted on the back canes of a wider wheelchair through the selection of appropriate hardware (up to a difference of 2 inches). If a person has a gluteal shelf, a bi-angular back support can be used to provide support through the trunk and the pelvis. Alternatively, a gluteal shelf can be accommodated by mounting a firm back support above the level of the gluteal shelf to provide support through the trunk, while using a vanity or modesty flap on the back support to prevent the individual from feeling as though the back end is “hanging out”. (The gluteal shelf must be supported through the depth of the cushion.)

If someone experiences excessive perspiration, the open cell foam on a back support may degrade and become odourous. A possible solution to this is to customize a back support with an inner incontinent cover to protect the foam, while having a stretch outer cover over to protect the individual. The material of the inner incontinent cover should be a four-way stretch to continue to allow immersion of the bony prominences of the spine into the material structure of the back support.

For an individual with increased adipose tissue anteriorly, such as someone with an apple shape described in my previous posting, it can be difficult to sit at a 90 degree seat to back angle. Therefore, a more open seat to back angle will be needed to open the hip angle to accommodate the abdominal mass.

Understanding a person’s shape and risk of skin breakdown will help to guide the generic product parameters required for a cushion and back support for an individual. Next month, we will address set up of the mobility base.


  1. Rush, A. (2009). Bariatric care: Pressure ulcer prevention. Wounds UK. 4, 68-74.
  2. Corbyn, C. & Rush, A. (2010). Challenges of wound management in bariatric patients. Wounds UK. 6(4), 62-71.

As always, please provide your comments, questions, and suggestions regarding Clinical Corner. Please email me at I look forward to hearing from you!

Sheilagh Sherman BA, BHScOT, MHM, OT Reg. (Ont.) - Clinical Education Manager, Canada

Sheilagh Sherman, BA, BHScOT, MHM, OT Reg. (Ont.)

Sheilagh Sherman joined Sunrise Medical Canada in 2010 as a Clinical Educator. Prior to joining Sunrise, Sheilagh gained extensive clinical experience working in a variety of settings, including neurological rehabilitation, complex continuing care, and community rehabilitation. As the Clinical Education Manager, Sheilagh is a clinical resource for therapists across Canada involved in seating and mobility. She leads workshops, seminars, and webinars on the clinical aspects of seating and mobility. In addition, Sheilagh has presented at national and international conferences on seating and mobility.

Sheilagh also has an educational background that makes her well suited to the role of Clinical Education Manager. Sheilagh earned a Bachelor of Arts degree in Political Science from the University of Toronto in 1988, which enables her to understand healthcare policy and policy changes. Sheilagh graduated with a Bachelor of Health Sciences (Occupational Therapy) degree from McMaster University in 1994. In 2012, Sheilagh earned a Certificate in Adult Education/Staff Training from Seneca College. She applies adult learning principles to the workshops she leads. Finally, she also has a Master of Health Management (MHM) degree from McMaster University after graduating in 2015. Courses that Sheilagh completed during the MHM degree, such as Knowledge Translation, Evaluating Sources of Evidence, and Quality & Safety in Healthcare, assist Sheilagh in using an evidence-based approach in her work.

In her free time, Sheilagh enjoys running, in addition to practicing yoga.

Date: 2015-04-22

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