Let’s Get It Clear: Customised seating
As an individual’s seating needs become more complex, the greater the need for that individual’s seating to be customised to meet their needs. What do new technologies such as 3D printing offer?
We are all individual, but the ‘80:20 rule’ suggests that 80 per cent of us will be suited by off-the-shelf equipment. However, there is a smaller percentage of individuals where their comfort, safety, health, positioning, and optimised functionality needs require adaptive seating customised to meet these more complex ends. How can we go about this best, and what are the options available to us from newer technologies?
Early and appropriate intervention should prevent complex skeletal deformities occurring, but in their absence gravity has exerted its effects on the shape of the body, and in many cases it’s too late to correct these deformities either through equipment or surgery. So how best to accommodate them? What is available ‘off the shelf’ and what needs to be bespoke?
Modular systems
At the simplest level there are off-the-shelf cushion solutions, such as the Varilite ProForm, where sections of the internal structures and foams can be cut away to accommodate different leg lengths, sensitive tissue areas, etc, or pieces of foam added to accommodate other anatomical discrepancies, all hidden beneath a stretch cover (Figure 1).
At the next level, there are seat cushion and back support offerings in the marketplace, such as some Jay, Spex, and other manufacturers’ offerings, which have off-the-shelf removable or adjustable components which can be rearranged between a solid backing and a flexible cover, to accommodate the individual’s body shape or tissue integrity needs. These components can also be adjusted over time as the individual’s needs change.
Moulded systems
Moulded seating is needed by people with more complex physical disabilities, chronic conditions, or asymmetrical body shapes which require significant postural support, pressure relief, and comfort that standard seating systems and products cannot provide, including those individuals with conditions like cerebral palsy, spina bifida, muscular dystrophy, or severe posture issues, with needs to help prevent pressure injuries, improve respiration, or manage spasms.
It’s for anyone who spends long hours seated and who needs tailored support for health, function, and independence, often involving detailed clinical assessment to create a custom fit.
A relatively easy and fast solution, providing a close match to the body’s shape can be achieved with the process of Foam-In-Place (FIP). FIP is a custom moulding process where liquid foam chemicals are mixed and poured into a bag or mould around a person’s body (often while they are in their wheelchair), creating an instant, perfectly contoured seat or back support for superior pressure relief, posture control, and comfort (Figure 2).
A more adjustable system uses polyurethane bags filled with small foam beads (Figure 3). The bag is formed around the individual, and then the air removed to maintain the impression of the person’s body. This system has the advantage that it can have the air let back in, and the shape adjusted as the person’s needs change.
More complex moulded seating is the next level, where an external orthosis in the form of a shell is created. A custom mould (impression) of the person’s body is taken using materials like FIP or beanbags, as described above, but these are used to provide the 3D shape from which a long-term mould can be produced.
Alternatively a 3D scan of the body can be used. This allows creation of a precise, unique seat shell that distributes pressure evenly, supports natural curves, and offers specific support where needed, improving overall function and comfort. The shells have been created from fibreglass, and more recently from polyethylene skins.
These were originally known as Derby moulds, having been developed at the Orthotics and Disability Research Centre in Derby and made available commercially by Specialised Orthotic Services, now part of Drive Medical (Figure 4).
These structures were found to be too rigid for many clients, and provided little scope for movement or growth. Carved foam has been a popular alternative where a 3D scan of the body provides the data from which a block of foam can be carved to fit the individual (Figure 5).
New materials
The hard shell and the carved foam solutions have limitations in that they are both bulky and relatively heavy. They are also difficult to clean or disinfect.
The advent of 3D spun elastomer materials has opened up a whole new choice of seating materials. They are lightweight. They are eminently breathable, providing enhanced microclimate management. They present better hygiene in that they do not absorb unwanted materials- rather, they are washable and can be disinfected at high temperatures. They are durable. They can provide beneficial energy return or energy dampening.
On the sustainability front, they have limited amounts of waste materials from the manufacturing process. Off the shelf you can get these benefits from spun elastomer cushions such as the Nest (Figure 6): the plastic used in these cushions can be chopped up and recycled, highlighting additional sustainability benefits.
The same elastomers can also be applied to custom-fitted cushions and seating. A scan of a body shape fed into a 3D printer can provide, a few hours later, a bespoke cushion (Figure 7) printed out for an individual to provide all the benefits outlined above.
The beauty of this system is that the programmer can select different densities and properties of the elastomer in different areas of the product, to accommodate specific requirements such as pressure-injury sensitive areas such as bony prominences.
These products are currently relatively expensive to acquire, and also still take quite some time to print, but as the costs of printers are falling quickly, and speeds are improving, this approach is likely to displace carved foam over time.
Adjustable customisation
While providing a good fit to the body shape at the time of assessment, these moulded/printed approaches have the disadvantage that the product takes time to produce, and the client has to wait for delivery. With time, the client’s needs may have changed or will change, and so the products have a limited life until they need to be replaced.
To meet these challenges, many years ago the Matrix seating system, followed by the Lynx systems were developed. These principles have evolved into the FreeForm seating system as the most recent manifestation (Figure 8).
These systems have been based on a modular adjustable network of linked connected components, each of which can be adjusted to fit the three-dimensional shape of the individual, and in most cases the complete system can be delivered on the day.
The open lattice provides for good breathability and therefore microclimate management. On the sustainability front, rather than being discarded when outgrown, the system can be adjusted over time to meet the client’s changing needs, and so can be updated and upgraded month by month, and year by year, as needed.
Covers
A critical element of any seating system will be the cover placed onto the system. With the more complex shapes, a good degree of stretch will be needed in the materials to avoid bridging or hammocking. The stretchiness can also offer reduction in shear stress benefits.
With the breathability of the elastomer products or of the FreeForm, it’s important that the cover will not negate these skin microclimate benefits. To this end, Symmetric Designs uses a Supracor Stimulite open honeycomb filling for their FreeForm covers.
In conclusion
Seating systems can be customised for individual specialist needs by a range of methods depending on the complexity of the needs. These adaptations can be achieved through minor adjustments to the inside materials of a cushion or the arrangement of discrete internal pads at the simpler level.
As requirements become more complex one-off customised moulded supports may provide the answer: current computer modelling and 3D printing can provide bespoke solutions which are lighter in weight, and provide better microclimate conditions than techniques and materials of old. Adjustable individual shell components can also provide a precise fit, with the benefit that the adjustments can be carried on over time as the person’s needs change.
Further items can be found at www.beshealthcare.net. If you are interested in receiving further information on the topic, please contact 
barend@beshealthcare.net.
Dr Barend ter Haar has been involved in seating and mobility for over 30 years, including lecturing internationally and developing international seating standards
