Wheelchair Cushion Rigidizer
Varilite Wooden Cushion Rigidizers
Invacare Plastic Cushion Rigidizer
Future Mobility Aluminum Rigidizer
Why use a Rigidizer
Cushion rigidizers are designed to help wheelchair cushions maintain their shape while in use in a wheelchair with a sling seat. A sling seat is a panel made of fabric or leatherette material that is attached to the seat side rails of a wheelchair. They are most commonly found on folding wheelchairs but can also be found on some older power wheelchairs and some rigid manual wheelchairs.
Although sling seats have improved immensely over the years with many manufacturers moving to a very stiff and strong sailcloth seat material for their slings there is still the possibility that it may sag in the center causing discomfort for the user. This sagging is usually referred to as hammocking because the seat sling when stretched resembles a hammock shape.
When sitting in a wheelchair with a hammocking seat sling internal rotation of the lower extremities, sacral sitting, posterior pelvic tilt and pelvis obliquity are conditions that can occur. In extreme cases pressure sores could develop on the hips.
What is a Rigidizer
Rigidizers come in a variety of materials and styles but are all basically flat rigid panels that are slipped inside the cushion cover under the cushion. The original rigidizers were call apple boards and they were simply small sheets of plywood about 3/8" thick presumably made of apple wood. These boards were much stiffer than conventional plywood found in your local lumber store.
Depending on the manufacturer your rigidizer can be made of wood, aluminum or plastic and be either flat or contoured. The contoured models can be shaped to fill in the sag in the sling while providing a flat surface for the cushion while the flat boards are often supported mostly by the wheelchair seat side rails and simply bridge the sagging upholstery.
Depending on the therapist, the flat board type rigidizer may be ordered a little narrower than the seat side rails so it is supported by the sling instead of the side rails. By having the seat upholstery supporting the flat rigidizer the user's seat height will usually be a fraction lower than it would be if supported by the seat rails.
What Sizes are Rigidizers
Rigidizers come in many sizes from pediatric sizes up to sizes for use by larger than average adults. If a user needs a wheelchair with a seat width over 20" the rigidizer may not be as effective as it could be because the user's weight may force it to begin to flex. Most users of this size are normally prescribed wheelchairs with solid seat pans which do away with the need for a rigidizer.
One advantage of the wooden apple board type cushion rigidizer is that it can be cut down to size if the vendor doesn't have the correct size in stock or easily modified if necessary.
Other Use for Rigidizers
Rigidizers are intended to provide a solid seating surface across the width of a cushion but also provide rigidity along its length. Because of this they can also be used to cheat the seat depth of a wheelchair. In cases where, for whatever reason, the wheelchair seat depth is an inch or two too short to provide proper support for the user an over sized cushion can be used to extend the seat depth and the over hang will be supported by the rigidizer.