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Invacare Matrx: Using A High Resilient Foam

Invacare Matrx
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Invacare Matrx products use a High Resilient foam that is constructed using a premium, open cell, flexible polyurethane foam structure. It also includes additives that do things like reduce the flammability of the cushion, stabilize the foam’s cell structure, and regulate the density.

Foams are made up of tiny cells known as “struts” and “windows.” Windows are created when air pockets burst during the foam manufacturing process. That leaves an open space inside the foam. The outer wall of the pocket is known as the strut, and it defines the structure of each individual cell. Struts give foam its spring-back action while windows allow gasses and liquids to move freely, helping air to circulate throughout the foam.

Density Versus Firmness

Density is the weight of material in a given volume. Lower foam density means there are less struts and material to withstand loading forces. Density is a good indicator of foam durability because a high density cushion will have more struts, therefore making it able to last longer. Just like any other load bearing material, repeated loading and unloading on the foam will eventually break it down.

Strut fatigue is the term for a reduction in the foam’s height, recovery, or firmness. Because high-density foams have more load bearing material to share the work, they exhibit better resistance to fatigue. High-density foams last a long time without becoming permanently compressed. That’s why Invacare Matrx cushions and backs are manufactured only with high-density foams.

Foam firmness is how much force is required to sink into the foam. To measure this, an indenter plate is used to see how much weight it takes to compress the foam to 25% of its original thickness. This test is part of the International Organization for Standardization tests that characterize the properties of wheelchair cushions. It is called the Indentation Force Deflection.

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The amount of foam firmness that is desireable varies. Different seat and back cushion designs will have different thicknesses, layering, shapes, and application.

Compression modulus is also known as the support factor. This term describes the relationship between the top support surface firmness and the core support firmness in a piece of foam. Cushions should feel soft, initially, as you sink into them and are enveloped. But the core support should be firm enough to keep bony prominences from bottoming out and reaching hard surfaces.

The Difference Between Slab Foam and Moulded Foam

Slab foam is foam that has been cut down to size from a foam block. It is often used in back supports or applications where a single layer of foam may provide adequate support and immersion. If more load is going to be applied, thicker foam can be used, or multiple layers of softer and firmer foam can be combined.


Moulded foams are made through chemical reaction. A certain volume of chemical is injected into a mould at a set temperature. The reaction then creates a foam structure inside the mould. When removed, the foam is rolled through a machine to release any trapped carbon dioxide. The end result is a foam cushion.

Moulded foams are more expensive to create, but they can be made with greater precision. Sometimes precise shapes are needed, such as for an anatomically formed pelvic well. This is where moulded foam will provide better support and fit. And moulded foam is easier to clean than cut foam since it retains a top finish that can be wiped off.

Matrx Seating Philosophy

Invacare believes the use of foam as a core support medium has these advantages:

  • Performance- it provides excellent pressure re-distributing properties
  • Stability- It offers a stable foundation to control pelvic movement.
  • Maintenance Free- There’s no need to adjust it.
  • Lightweight- It reduces weight in mobility systems.
  • Comfort- It facilitates sitting for longer periods of time.
  • Suspension- It provides shock absorption.
  • Durability- It maintains support properties.

Two Cushion Options: The Matrx Libra and Matrx Vi

If you are looking for seating options made from Matrx range, then Invacare has two top-of-the-line seat cushions that have different things to offer.

The Matrx Libra

The Matrx Libra is a seat cushion that offers superior comfort with the highest level of protection and positioning. The Libra has a unique design that includes a foam base that is anatomically contoured to optimise pelvic support and positioning. The durable high resilient foam is made with Ultra-Fresh anti-microbial and odour protection. And the fluid sac is a dual layer with sealed compartments that gives maximum protection around areas of bony prominence.

The functional benefits of the Libra are pre-ischial support, which prevents sliding to
reduce shear. The trochanteric shelf promotes a level pelvis for lateral stability. The extended cushion radius helps prevent posterior pelvic tilt. A waterfall front edge accommodates tight hamstrings and foot propulsion. And an ab/adductor contour gives you a comfortable midline leg position.

The Libra is also reliable and lightweight. Its self-equalising fluid is non-temperature sensitive, so there is no kneading or maintenance required. For complex seating needs, there is a range of easy to use positioning accessories available. And being lightweight makes this cushion suitable for an active lifestyle.

The Matrx Vi

The Invacare Matrx Vi Cushion is designed to provide skin protection and positioning for individuals at high or very high risk of skin breakdown. The unique three part foam construction targets skin protection to where it is needed most and features improved stability, support ,and comfort. The main features of the Matrx Vi are the rear cushion radius, waterfall cut front edge, and its anatomical design.

The rear cushion radius of the Vi stabilizes the pelvis to prevent sliding. A curved extension of the foam base increases pressure redistribution by maximizing the surface area, while minimizing the gap between the seat and the backrest

Having a waterfall front edge means that there is a diagonal cut along the front edge of the cushion. This offers maximum support along the entire length of the thighs plus accommodation for shortened hamstrings. A decreased knee angle also aids in foot propulsion and standing transfersAnd the Vi is anatomically moulded. The design of the seat well is based on anthropometric measurements of the adult pelvis and provides targeted immersion for the IT’s and stabilization of the pelvis from all directions. The trochanteric shelf offers lateral stability and support for the femurs while the pre-ischial contour stabilizes the pelvis anteriorly to prevent sliding and reduce the risk for shear. The contoured foam base conforms and envelops, which aids in positioning the hips and thighs both medially and laterally for enhanced postural stability.


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