Transportation of people seated in wheelchairs:

Jason Williams

PMG2024 Training | Conference | Exhibition

Monday 15 July to Wednesday 17 July 2024 in Telford. Our annual event provides an educational programme, industry exhibition and networking opportunities for professionals working in the field of posture and wheeled mobility.

Clinical science innovation: is your performance affected by stability?


Belinda Ball

Clinical Scientist

15 March 2018

Whilst preparing to write this article, I reflected on my role within postural management, and how I would most like to use my skills and knowledge in moving forwards with my career. Following my clinical scientist training in Salisbury, and with a year’s experience working full-time in specialist seating and postural management in Oxford, attending PMG Conference 2017 in Cardiff was a great chance to discover more about the academic and commercial projects emerging in the field.

I believe one of the reasons for hosting conferences is to encourage collaboration and sharing across many disciplines, and the strong sense of community and working towards similar goals was evident from the conversations and interactions I had over the three days of this conference. Most importantly for me, it was an opportunity to learn more about what fellow clinical scientists are achieving in the field. 

This report highlights one particular session which was presented by two clinical scientists, John Colvin and Simon Fielden, and rehabilitation engineer Mike Heelis. Is your performance affected by stability? was a brilliant session showcasing the innovation and service development they have instigated in their respective departments. They presented on the various ways that stability is measured for wheelchair users, and on the development of a load cell-based stability platform which users can roll on and roll off. I have had experience of using only a variable ramp to assess stability in clinic, a process which requires a variety of safety considerations, both for the client and clinician, and which some clients find daunting. Therefore, hearing about this alternative method, which has been developed with the client in mind, was a brilliant thing to learn and take away from the conference. 

The presenters were transparent that they are still trying to work out the significance, if any, of the data collected. How would the readouts affect the adjustment and set-up of the chair? Would it change the overall selection? And what does 'better' really mean in terms of stability? There are so many factors to be taken into consideration when helping clients with the selection of a wheelchair which will work best for them, and we are normally presented with only a snapshot of their life and function during their time in clinic. It is not practical to find out about all the different road surfaces, gradients and cambers which they come across when in their wheelchair, or map the pattern of their driving to understand the dynamic stability when accelerating and braking. As with most of the decisions made in clinic, it is a balance of risk versus benefit, whether that is postural or functional benefit, and having the confidence of reasoning to make that decision.

The two presentations included in the session were complementary, with Simon and Mike talking about how to improve confidence of reasoning in clinical decision making. They discussed the three main scenarios of powered, attendant and self-propelled wheelchairs, and the important guidelines and measurement tools which could be used to assess stability alongside performance. Using these tools, your confidence level can gradually build to the point at which you are happy to commit to a decision, and feel sure it is backed up by clear reasoning.

An exciting project, WheelSense, is being trialled in three large hospitals in the UK (Stefanov et al, 2015). The system uses several force platforms which sense the weight distribution of the wheelchair, the contact points of the wheels, and the distance between them. This provides information about the centre of gravity and where it is acting within the wheelchair, and calculates the wheelchair stability parameters (Stefanov et al, 2014). All of this is presented with a user interface for the clinician to decide whether the system could be optimised for the client, and provides direct comparisons of different configurations.

I feel a system like this provides several advantages over a variable ramp test. When interfacing custom seating to a wheelchair, adding accessories (e.g. bespoke footplates, armrests and medical equipment), and accounting for anatomical differences, several variables have been introduced, thus straying away from the manufacturer's specification. The opportunity for live feedback of wheelchair stability data, in a comfortable and safe environment for the client, would provide clinicians with increased confidence in the system, and may enable more directed advice being offered on the use and manoeuvrability of the wheelchair. Still in the trial phase, more evaluation and iterations of the design are necessary to make it accessible for all clinics. Currently the cost and overall weight of the system appear to be its primary limiting factors.

The session prompted many ideas and good discussion. It also highlighted some relevant and informative online literature which may be useful for services to adapt or offer to clients. The British Healthcare Trades Association (BHTA) has produced guidelines on stability for wheelchair users (BHTA, 2016) and the Medicines and Healthcare Products Regulatory Agency (MHRA) device bulletin provides a useful refresher for visualising aspects of the wheelchair set-up and usage which could adversely affect stability (MHRA, 2004).

Being awarded a bursary to attend PMG Conference 2017 at this stage of my career has been incredibly helpful. During my time training and working in two hospitals I had already created important ties with many different healthcare professionals; incorporating these relationships with the potential of the PMG community will prove invaluable in my career going forward. Having the time and space to explore commercial options within the industry, whilst matching them to clinical practice, is a great way to accelerate professional development, to help kick-start changes within clinicians' own practice, and encourages collaboration to develop services.

Photograph is of John Colvin from WestMARC presenting in the session on stability, at PMG Conference 2017


BHTA, British Healthcare Trades Association (2016). Get wise to making sure your wheelchair remains stable [Online] Available at (Accessed 20 February 2018)

MHRA, Medicines and Healthcare Products Regulatory Agency (2004). Device Bulletin: Guidance on the stability of wheelchairs. DB2004(02)

Stefanov, D. et al (2004). A novel system for wheelchair stability assessment design and initial results. In Medical Measurements and Applications (MeMeA), 2014 IEEE International Symposium on (pp. 1-4). IEEE.

Stefanov, D. et al (2005). The development and testing of a system for wheelchair stability measurement. Medical Engineering and Physics, 37(11), pp.1061-1069.

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