Dynamic seating is a term which covers a variety of seating applications. This article highlights why one or more dynamic aspects should be consisted of in the evaluation and prescription of a seating system.
So what can we do to absorb the energy from these motions to protect the wheelchair, while providing, or attending to, dynamic motions which increase the residents health and performance?
Wheelchairs undergo sources of a varying range of dynamic forces on their parts. A number of these can result in failure or harm to these parts. These forces might develop from everyday usage, as the wheelchair passes over barriers and abnormalities in the surface on which they are utilized.
Along with this, lots of wheelchair users are constantly moving in their seats, frequently involuntarily– for instance due to the nature of their disorder creating athetoid motions– and often to eliminate pain or discomfort. Other users use movement to increase their performance, but these also offer extra structural stresses on wheelchair elements.
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Figure 1. Frog Leg caster suspension system
It is therefore vital for the safety of the occupant that only belts and harnesses which pass the ISO 16840-3 tests are used on a chair. Other elements at threat are the more stiff products on a chair, such as back supports, foot supports, head rests and so on which are impacted by the motions of the occupant within the wheelchair, and from the forces included with running over rough terrain.
For other components of the chair, various manufacturers have come up with a variety of spring-loaded systems which soak up the energy from extension convulsions and other greater forces on the components.
What can be done to soak up these forces and minimize damage to parts? Frog Legs Inc4 in the US have actually established a suspension system for front casters which soak up the energy come across by the casters– these also lower the vibration through the chair, which is a major element causing tiredness of the resident. 80 per cent of the vibration experienced by the user comes from the casters, and Frog Legs minimize this by 76 percent– both the chair and the occupant benefit.
There is a new standard3 that is being published extremely soon that recommends tests for the resilience of casters, the death of which must provide greater guarantee to prescribers and users of wheelchairs.
The mechanical components most at threat of failure on a wheelchair are the casters. Mhatre et al2 have actually released a report that revealed that 40 percent of casters failed within a year, which none in their study lasted more than 2.5 years. They likewise revealed that, where there was prepared preventative maintenance and replacement, the incidence of failure dropped considerably.
There are various parts that come under tension during daily use of a wheelchair. These include the belts and harnesses which help position the occupant in the chair. The strength of these items carrying out under one-off forces, and under repeated forces, are checked for within the tests in ISO 16840-31.
Passive dynamic assistance
Such gadgets can likewise improve proprioceptive input from the receptors located in our joints, as well as supply physiotherapeutic gain from muscles working against the spring forces.
Keep in mind, nevertheless, that some chest utilizes referred to as butterfly harnesses have actually been known to ride up as they are extended and relaxed, and there are records of people who have actually been choked to death as a result– this can be prevented by directing the stretch in your area around the shoulders, and not through the entire harness.
A vibrant anterior shoulder harness enables the occupant to move forward (therefore increasing their performance), but the elasticity assists bring the private back to their original position, especially when getting fatigued.
A dynamic component can likewise be of favorable support to the wheelchair resident. The spring packed devices, as explained above, can be used to soak up energies, but on the other hand the springs can work to help the resident to adjust their position.
In addition, it is critical that a pelvic positioning belt is in place and changed properly.
Figure 2. Dynamic anterior chest harness with targeted elasticity.
Active dynamic assistance
Research studies have actually shown that dynamic seating systems in the classroom cause improved attention. Some dementia customers become less upset with an applied rocking movement, while sub-aroused customers ended up being more alert after rocking, and gained from associated reduced anxiety and anxiety.
Dynamic aspects of a seating system increase sensory input, and this can be applied clinically to increase alertness, decrease agitation, decrease tiredness, and boost vestibular input, inter alia. Movement promotes the vestibular device in the center ear, which can be either calming or arousing depending upon the customer.
In this short article I have actually skimmed the subject( s) of vibrant seating, and there are lots of elements of importance and significance to any, and all, wheelchair users.
A further application under the purlieu of vibrant seating is where sensors in the seating system find modifications with time, and set off a change in the seating system to accommodate the change. One such case might be where prolonged pressure under the bony parts of the pelvis might be offering a threat of tissue damage in the buttocks.
Figure 3. The AERGO PS vibrant seating system.
For more extensive info, the fairly recent RESNA position paper on aspects of vibrant seating6 is free to download and is a very important read.
Another pertinent instance is where a person with muscle weak point is beginning to plunge as an outcome of fatigue. An example of equipment that can compensate for this is the Aergo seating system5, where inflatable thoracic lateral, lumbar, and seat cushion pads adapt to adjust the customers posture to accommodate the changes.
1. BS ISO 16840-3 Wheelchair seating– Part 3: Determination of fixed, impact and recurring load strengths for postural support devices.
2. Mhatre, A et al Community-based wheelchair caster failures call for enhancements in quality and increased frequency of preventative maintenance, Spinal Cord 2021
3. ISO FDIS 7176-32 Wheelchairs– Part 32: Standard practice for wheelchair castor resilience screening.
6. Lange, ML et al, RESNA position on the application of vibrant seating 2020
Dr Barend ter Haar has been involved in seating and movement for over 30 years, consisting of lecturing worldwide and developing global seating standards.
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Click to read more from the Lets get it clear series from Dr Barend ter Haar
Wheelchairs are subject to sources of a varying range of dynamic forces on their elements. There are various components that come under stress throughout daily usage of a wheelchair. The mechanical components most at risk of failure on a wheelchair are the casters.
Dynamic seating is a term which covers a range of seating applications. This post highlights why one or more vibrant aspects should be consisted of in the evaluation and prescription of a seating system.
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