In the previous article – Screening for Wheelchair Seating and Positioning Needs – we identified individuals that could benefit from a change in their wheelchair seating system. There are several choices for a replacement wheelchair:

  • Change to a facility owned unit
  • Private pay option
  • Request for a specialized wheelchair seating system through the Department of Social and Health Services

Before you order a new chair, you need to determine why the current seating system is not working for the individual.
Most facility owned wheelchairs are a sling seat-back style of wheelchair. This type of wheelchair is not designed for long-term, extended use as it typically does not provide adequate support. If the wheelchair is an older style both the seat and backrest material stretch over time. The seat, even with a cushion, assumes a scoop appearance, like sitting in a hammock all day. This does not provide adequate pelvic support and can increase pressure to the lateral pelvis and thighs.
If the backrest is stretched out you will notice that it increases the pelvic-trunk angle greater than 90º which places more pressure to the coccyx and ischial tuberosities as the individual assumes a sacral (posterior pelvic tilt) sitting posture. This area is prone to shearing and potential skin breakdown. Adding an anti-sling pad, or an anti-sling type of cushion, can provide the necessary support. A solid seat base with a curved or personal backrest system is the ideal solution as it provides the best overall support.
Back to the Basics: How to Measure for a Wheelchair
Seat Width: Measure the width of the patient’s hips and add 2”
Potential problems:

excessive width – results in added difficulties in reaching over the armrests to self-propel the wheelchair using the UE’s, does not provide adequate support of the torso and pelvis and which may result in a right/left lateral lean

too narrow – results in increased pressure to the lateral hips/thighs and is an area of increased pressure and potential for decreased skin integrity. Too narrow of a wheelchair is also impacted and accentuated if the person wears bulky clothing.

Seat Depth: Measure from the posterior buttock to the popliteal fossa and subtract 2-3” (if they self-propel primarily with BLE’s you want to allow sufficient LE excursion, then subtract the 3”)
Potential problems:

too short seat depth – failure to support the thigh adequately, may impact LE circulation due to increased pressure from the front edge of the seat into the posterior thigh

too deep seat depth – may compromise posterior knee circulation due to pressure of the leading edge of the seat against the popliteal fossa, may increase instance of sacral sit postures (posterior pelvic tilt) with resulting increased pressure to the coccyx and ischial tuberosities with potential for skin breakdown

Backrest Height: The backrest height will vary depending on the amount of support the patient needs and torso length. Measure from the seat platform to the lower angle of the scapula, mid-scapula, top of the shoulder depending on the amount of support desired. Seat cushion depth must be added to the patient measurement. Custom backrests can be requested with lateral supports for those individuals who are unable to maintain an upright posture in the wheelchair.
Potential problems:

too low backrest top level of the backrest lies distal to the lower angle of the scapula.  Insufficient support to the upper trunk causing increased pressure and potential for skin breakdown to dorsal spinous processes. Lack of upper torso support increases tendency for sacral sit postures.

too high backrest may prevent the patient from limit UE excursion needed for self-propelling, may increase forward flexed postures, may alter head/neck position.

Seat Height: Minimum clearance between the floor and footplate is 2”
Potential problems:

too high seat-floor w/o footrests – increases sacral sit postures as patient attempts to assume a foot flat position on the floor. This is also the problem with leg rests that are too long.

Too low seat-floor w/o footrests – places knees higher than hips and increases pressure to coccyx and ischial tuberosities. Makes self-propelling the wheelchair difficult due to limited LE excursion thereby limiting their mobility and independence. This is also the problem with too short of footrests (want to attend to this with patient’s s/p THA)

Armrests: Measure the patient from the seat platform to just under the elbow held at 90º with shoulder in neutral position. Armrests can be locked or adjustable, fixed or removable depending on the age of the wheelchair.
Potential problems:

too low armrests – cause excessive shoulder depression. Patient posture in the wheelchair as they attempt to rest UE’s on armrest will be a forward flexed posture.

too high armrests – will cause excessive shoulder elevation. May notice that the patient will remove UE’s from the armrest and place UE’s to their side. If they have diminished trunk stability then the UE becomes pinned between the armrest and trunk causing excessive and prolonged pressure to the UE and potential skin breakdown.

This is a lot of information, and certainly there are variations and other issues to address, but these topics are just some of the basics. These are also your justifications in your documentation. Look at the patient in their current wheelchair and ask yourself the cause and effect of how they are seated.  You know your anatomy. If there is pressure to an area, what structures lie underneath?  Nerves, arteries?  And, if you have to, sit in a wheelchair and assume the position you are seeing to identify pressure areas. Can you imagine sitting in that posture, without moving, for an hour? 2 hours or more?  You have your justification.

Keri Poffel is a Physical Therapist and Master Clinician with Infinity Rehab. She earned her Master’s in Physical Therapy from Eastern Washington University. She joined the Infinity Rehab family soon after graduation and has practiced at Avamere Olympic Rehab of Sequim since December 2003. Keri became a board certified Geriatric Clinical Specialist in 2008 and earned her Clinical Instructor accreditation from the American Physical Therapy Association in 2009.

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