Let’s get it clear: What makes a good a positioning belt? 1. The anatomy of a belt

Let’s get it clear: What makes a good a positioning belt? 1. The anatomy of a belt

In previous concerns of THIIS in the Lets Get it Clear series, we have covered What makes a great cushion? over six parts. Similarly essential elements of numerous seating systems are the postural support gadgets (PSDs) supplied with the seating to match the cushion and back assistance aspects. This is the very first in a series covering PSDs, where we look at the style of different components of a placing belt to ensure optimal results for the user.

Postural assistance gadgets (PSDs) are medical gadgets designed to manage body language, either blocking, reducing, or guiding movements of specific body sections to attain wanted results, while consisting of safety within the seating system. Normal results include increased sitting stability, preserved or corrected posture, increased reach, boosted propulsion of a mobility gadget, or upkeep of a desired seated position for safety functions (including prevention of falls from the chair). In many cases, the function of a PSD can be a combination of one or all of these aspects.

Lets start with a pointer that placing belts are not to be confused with safety belts, as utilized in lorries, which are made offered as restraints. Placing belts are meant to help position the specific to help them in postural control and normal everyday functions; whereas car restraints exist to limit the body from flying out of the seat in a traffic accident. The applications, and therefore the styles, are really various for the 2 different types of belt, and should not be confused with each other.

Pelvic positioning belts

Before other PSDs (e.g. ankle or shoulder supports) can be issued, the individual will need a pelvic positioning belt, and we will for that reason be concentrating on these in this post. Position and control of the hips is important to postural alignment and control, and theres possibly a lot of motion to manage.

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A pelvic positioning belt is employed to bring as much control as possible to the hips, to the advantage of numerous other parts of the body, and for practical activity.

Postural reflexes drive people to aim to preserve their centre of gravity within this base of support. Due to the connection of L5 to the top of the pelvis, any change in pelvic position in turn affects the shape of the spinal column.

The positioning of the pelvis is therefore likewise vital for the alignment of the spinal column. Some of these asymmetries are inescapable (or fixed), and from time to time some are preferable. The essential component is to manage them appropriately, which is why the selection and positioning of flexible PSDs is so crucial (see BS 86251).

The most affordable vertebra in the spine, L5, is attached to the top of the hips. The hips has scope to rotate in 3 dimensions: posteriorly and anteriorly as viewed from the side; obliquely to the left or right when seen from the front; and rotationally when viewed from above. All these movements get translated into the spine via the L5 vertebra.

The position of the hips likewise greatly alters the distribution of interface pressure in between the resident and any assistance surface areas, especially the seat cushion and back support. This is an important factor to consider for the prevention of pressure injuries.

The anatomy of a flexible placing belt

Padding positioning


Where the belt is placed throughout the occupants thighs, to increase pressure redistribution the pad requires to wrap around the thighs to the most lateral points of the thighs– see Figure 2. When choosing the belt to be released, this range must then be utilized to provide the dimension of the versatile PSD pad length (B in Fig. 1) when the belt remains in location and tightened up.

Pressure distribution

The design must not permit any curling of the padded assistance such that the forces would no longer follow the shapes of the residents body. Where edging is used to the pad to stop tearing of the pad, the edging material needs to not provide a danger to the tissue integrity of the occupant– from wrinkling or other contortions, or from localized pressure points.

Figure 1. The parts of a pelvic positioning belt

The webbing products require to be strong enough to be able to hold up against the forces applied to them by the chairs resident, adjustable for a great fit, and non-slip so that they remain in place. BS 86251 requires that the belts be evaluated to ISO 16840-32, which covers recurring and static load tests. Amongst the pass/fail requirements is one that specifies that the belt needs to not slip more than 10 mm under the recurring load test.

In choosing a suitable belt, the belt length needs to be enough time to be able to thread through completion fittings at the belt mounting points. The webbing width i.e. versatile PSD width: A in Fig. 1) can come in different sizes: up to 25 mm ± 3 mm is Small; 26 mm to 38 mm ± 3 mm is Medium; and 39 mm to 50 mm ± 3 mm is Large (from BS 86251).

The newly published revision of ISO 16840-103 covers the flammability testing of PSDs, and gives particular assistance as to the procedure for checking the resistance to ignition of harnesses and belts.

Pressure distribution or redistribution, e.g. by padding, surface shapes, or elastic fabrics, should be offered where the belt interacts with the occupants body, in order to safeguard the resident from harm from the webbing materials (e.g. where it might can be found in contact with bony prominences or where significant force is used over soft tissues).

A description of the parts of the belt are explained in Figure 1.

Figure 2. Body measurement needed to size a placing belts pad length

The essential parts of a flexible placing belt are the webbing, the padding under the webbing, the buckle (or other closure), and the means to repair the belt to the seating system. Closures and mounting systems are covered in more information in later articles in this series.

Material selection by the maker is seriously important. The pressure distribution components ought to be developed to follow the shapes of the occupants body, and to dissipate equally the forces of the support on the residents body.

Additional safety

Do no damage

Dr Barend ter Haar has been involved in seating and movement for over 30 years, including lecturing internationally and establishing worldwide seating requirements.

Behind the philosophy of recommending devices that does no harm, knowing the requirements for evaluating the safety of the recommended items, the qualities of the products used, and the products usage to relieve or prevent harm is an important part of expert devices arrangement. Knowing what to search for, and indeed difficult limitations on the availability of devices for prescription, is necessary for the wellness of your customers. Using the assistance within the most recent requirements guarantees that you can be positive in your decisions.

BS 8625:2019 Selection, placement and fixation of versatile postural assistance gadgets in seating. Specification
ISO 16840-3 Wheelchair seating– Part 3: Determination of static, effect, and recurring load strengths for postural support devices
ISO 16840-10:2021 Wheelchair Seating– Part 10: Resistance to ignition of postural assistance gadgets– Requirements and test techniques

Additional products can be discovered at www.beshealthcare.net. Please contact barend@beshealthcare.net if you are interested in getting more details on the topic.


Click to read more from the Lets get it clear series from Dr Barend ter Haar

BS 86251 requires that the belts be tested to ISO 16840-32, which covers fixed and repetitive load tests. Among the pass/fail requirements is one that specifies that the belt should not slip more than 10 mm under the repetitive load test.

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The applications, and therefore the styles, are really various for the 2 different types of belt, and need to not be confused with each other.

Similarly crucial components of many seating systems are the postural support devices (PSDs) offered with the seating to complement the cushion and back support elements. This is the first in a series covering PSDs, where we look at the design of different elements of a positioning belt to guarantee ideal results for the user.