The importance of seating and good postural support in the prevention of pressure ulcers

Pressure ulcers remain a significant problem within health and social care organisations and cost the NHS £3.8 million every day1.  Whilst many patients are at risk of pressure ulcer development, it is often the elderly, malnourished and those with acute illness who are at increased risk of pressure related tissue injury due to their inability to reposition themselves2,3.  

Over the years there has been a significant focus on providing the correct therapeutic support surfaces (mattresses and cushions) to patients at an elevated risk of pressure ulcers. Successful pressure ulcer prevention in at risk individuals, or reductions in pressure ulcer incidence within organisations are often synonymous with the provision of pressure redistributing mattresses and cushions to those at greatest risk. These specialist support surfaces undoubtedly play an essential role in pressure ulcer prevention and management, however they are, in part, dependent on the underlying bedframe or seat to deliver optimal pressure area care for patients.

Although effective pressure area care for ‘at risk’ patients is rightly recognised as a 24-hour requirement, the focus for many of us is the patient’s bedframe and mattress with less emphasis being placed on the needs of the seated patient.

When considering that patients can often sit out in chairs for long periods during their day, it is important to recognise that if not managed correctly, this prolonged sitting can present further complications in terms of pressure ulcer prevention and management in at risk individuals, and whilst the provision of a suitable pressure redistributing cushion is likely to be considered, in some instances little thought is given to the chair that the cushion will be placed upon and where the person will sit all day4.  

Many of the chairs used within health and social care organisations were never designed to be used for lengthy periods of time by patients at risk of pressure ulceration. They will often have little or no inherent pressure redistribution properties built into them and limited, if any, capacity for adjustment to support patient’s individual postural needs. 

With 75% of a seated patient’s body weight passing through just 8% of their surface area5 where underlying structures include the ischial tuberosities, buttocks, sacrum and the back of the upper thighs6, the posture and positioning of the seated patient is a critical component of pressure ulcer prevention and management. 

Body posture and positioning has a direct relationship to the load applied to tissues at specific anatomical locations of the patient when seated and must therefore be carefully considered when devising pressure ulcer prevention strategies7 and any associated interventions, such as pressure redistributing cushions, which accompany them. A holistic assessment should be performed encompassing both intrinsic (muscle weakness, spinal deformities, core strength) and extrinsic factors (seat height, seat depth, adjustable arm rests, foot plates, trunk support etc), thereby ensuring that patients’ seated posture and positioning are optimised.

Sitting vulnerable patients out of bed, on inadequate or inappropriate chairs, could potentially contribute to pressure damage by increasing pressure and/or shear on the patient’s tissues and this may reduce or negate the potential benefit offered by specialist pressure redistributing mattresses or cushions4. Setting patients up with the correct seated posture can help to reduce shear strain on internal tissues whilst simultaneously distributing the load across the different contact points of the seated patient i.e. the feet, forearms, lower back etc, thereby reducing the pressure on the tissues overlying the ischial tuberosities, sacrum etc.

It is therefore important to not only assess for and implement the correct therapeutic support surfaces but to also assess and implement the correct seating solution for your patient.  Seating should complement the support surfaces and allow the patient to sit out comfortably with good posture to prevent and/ or reduce the risk of pressure related tissue injury. The closer contact a patient has with the chair, the greater the surface area over which pressure can be distributed thereby reducing the risk of pressure ulcer development4. Therefore getting the correct chair for your patient is imperative and should form an essential element of any pressure ulcer prevention and management care bundle.

Tierney (2022) identified four key principles of pressure management in seating and suggests that every seating assessment should address each of these four elements 4:

Four Principles of pressure management in seatingDescription
Loading The BodyWhen you increase an individual’s surface area in contact with their chair, you reduce the pressure exerted through any point.
It is imperative the chair is measured and adjusted to the size and shape of the patient and adjusted to load their body properly. 
For example, when loaded properly, the feet take 19% 8 of the body’s weight in seating. If there is no footplate on your chair, or the feet are incorrectly loaded, then however much of this 19% of the body weight which is not supported by the feet will be redistributed through the body and will potentially end up going through the buttocks and thighs instead, therefore increasing the pressure (and therefore risk) to this area.
Providing Postural SupportIt has been shown that better posture has a direct link to improved pressure management. 
For example, a person with a scoliosis and leaning to the left over their chair will have greater weight going through one side of their pelvis. Due to this unbalanced weight distribution, they will have an increased risk of skin breakdown under that side of their body. 
Proper support on the left side will help to stabilise the patient in a midline posture and equalise the distribution of pressure through the body, rather than it being focused on a smaller area. 
To this end, the correct use of lateral and head supports will ensure improved posture, balanced loading and therefore reduced risk of pressure related tissue injury.
Effective RepositioningGuidelines recommend seated individuals are repositioned every two hours. This is to increase blood flow and the amount of oxygen reaching the skin and subcutaneous tissues. 
Repositioning can be accomplished by a change in the seated position, lifting the body off the weight-bearing area, or by standing. This can take a lot of energy, work and time, and in some cases, this leads to a patient not getting adequate or regular weight shifts. 
Research shows that 45° tilt “maximises the potential for significant blood flow increases and pressure reduction” by allowing the patient to completely off-load their pelvis and allow re-oxygenation of the tissue9
With caregiver or user-operated 45° tilt in a chair, it is much easier to reposition the patient periodically and thus facilitate effective weight shifts. If 45° of tilt is not appropriate or suitable for a patient based on an assessment, 30° of tilt will also give a degree of repositioning.
The CushionThere are ranges of cushions on the market to provide different levels of support, postural alignment and for pressure management. 
In seating, it is important to be able to select different cushions to meet the individual needs of that person.
(Four Principles of Pressure Management in Seating4)

Incorporating the four principles outlined above as part of a comprehensive seating assessment will ensure the patient is not only comfortable when seated throughout the day, but will also ensure their pressure area care needs are fully met by having a chair that is appropriate to need, complimenting the therapeutic mattress support surfaces to maximise the pressure ulcer prevention potential. 

For more information contact our OSKA pressure care experts.


  1. NHS Improvement (2018) Pressure Ulcers: revised definition and measurement. Summary and Recommendations. NHS Improvement, London. 2018.  Available online: NSTPP-summary-recommendations.pdf ( Accessed 9 June 2022
  2. Fisher, A. R., Wells, G., & Harrison, M. B. (2004). Factors Associated with Pressure Ulcers in Adults in Acute Care Hospitals. Holistic Nursing Practice, 18(5), 242-253.
  3. Lindgren, M., Unosson, M., Fredrikson, M., & Ek, A. (2004). Immobility – a major risk factor for development of pressure ulcers among adult hospitalized patients: A prospective study. Scandinavian Journal of Caring Sciences, 18(1), 57-64.
  4. Tierney, M.  (2022) The Clinicians Seating Handbook: A Reference Guide for Clinical Seating provision, 8thEdition.  Limavady, Seating matters.
  5. Trumble, H.C. (1930) The skin tolerances for pressure and pressure sores. Medical Journal of Australia, 2, pp. 724–726.
  6. Stockton, L., Kryzstof, F., Gebhardt, B., Clark, M. (2009) Seating and pressure ulcers: Clinical Practice Guideline. Journal of Tissue Viability, 18 (4) pp. 98-108.
  7. Sprigle, S., Sonenblum, S. (2011) Assessing evidence supporting redistribution of pressure for pressure ulcer prevention: A review. Journal of Rehabilitation Research & Development (JRRD), 48, (3) pp. 203-214.
  8. Staas, W.E., Cioschi, H.M. (1991). Pressure sores: a multifaceted approach to prevention and treatment.  Western Journal of Medicine, 154, pp. 539-544.
  9. Hibbs, P. (1998) The past politics of pressure sores.
    Journal of Tissue Viability 8(4) pp. 14–5