A review of the presentation given by Matthew Eveleigh, Clinical Educator, UK Sunrise Medical at PMG Conference 2018.

In his presentation, Matthew talked us through the essential features of an ultralight wheelchair, and how to achieve optimal adjustment for the user, in line with latest research and clinical guidelines, to:

• Maximise efficiency and ease of propulsion
• Reduce incidence of repetitive strain injuries (RSI)
• Maximise user function
• Improve postural stability
• Increase comfort in wheelchair

Matthew highlighted the importance of achieving optimal set up, not only to enhance client function and independence, but also to reduce the risk of upper extremity (UE) injury. He cited that, as many wheelchairs now weigh less than 9kg, the number of people using ultralight wheelchairs is increasing annually, yet the incidence of UE pain reported among users remains high (Paralysed Veterans of America Association (PVA) 2005) with between 25-80% suffering wrist, elbow and shoulder injuries (Cooper et al 2001).

These injuries have been attributed to a number of factors including:

• Increased activity level and an “ageing” population
• Increased time spent in wheelchair
• Prolonged manual propulsion which can lead to pain and repetitive strain injury (RSI)

Matthew discussed the increasing concerns regarding RSI, caused by frequent repeated motions which result in injuries to tendons, muscles, ligaments and nerves. He stated that active users make contact with wheelchair rims between 2000-3000 times/day (Koontz et al 2006), which equates to approximately 75,000 times per month or almost a million times per year!

He also referred to large clinical studies around carpel tunnel syndrome (CTS), reported by over 50% of wheelchair users surveyed, and showed that the incidence of CTS is directly proportional to the duration of wheelchair use.  Matthew quoted from the Rehabilitation Engingeering and Assistive Technology Society of North America (RESNA) position paper on ultralight manual wheelchairs (2012) which states A person cannot conform to the chair, but the chair must conform to the individual.  This is  a guiding principle when selecting and optimising provision of an ultralight wheelchair.

He highlighted some of the guidelines and opinions by the RESNA paper (2012), Spinal Cord Injury Rehabilitation Evidence (SCIRE 2014),  Paralysed Veterans of America Association (PVA 2005), and Koontz AM et al (2006) which all consider the provision and set up of ultralight wheelchairs and draw conclusions based on the latest evidence on:

• wheelchair features
• propulsion technique
• wheel position
• weight
• equipment selection, for example wheels, tyres

Matthew drew our attention to the RESNA position paper (2012) which focuses on the key elements that significantly affect posture, wheelchair stability, manoeuvrability and ease of propulsion including:
• seat height, width, depth and angle
• back support height
• leg/foot support
• horizontal and vertical position of rear axle
• rear wheel camber
• wheel and castor size and type
 
He then looked at the PVA Clinical Practice Guideline (CPG 2005) regarding optimising weight, rear wheel position and propulsion techniques, and broke these components down in more detail:
 
Weight
The CPG advises providing manual wheelchair users with spinal cord injury high strength, fully customisable manual wheelchairs made of the lightest possible material.

He discussed the importance of selecting the lightest materials available when choosing a chair because ultralight chairs:
•require less force to propel, reducing rolling resistance and the forces transmitted to the UE
•reduce frequency of propulsion
•are usually more adjustable, allowing for optimisation of propulsion mechanics
•are made of quality materials for greater performance and durability.

He touched on the advantages and disadvantages of different materials and compared aluminium, the most commonly used material in ultralight wheelchairs; titanium, which is vibration dampening, but tends to have more flex in the frames; and carbon fibre, which is very light but fragile, so is more suited to lower weight limits.

Matthew also discussed the cost effectiveness of prescribing an ultralight versus a lightweight chair. He revealed surprising statistics that show an ultralight chair costs half the amount to operate, yet lasts 5 times longer than a lightweight chair (~16kg). It also costs less than a third to operate and lasts 13 times longer than a standard manual chair (RESNA 2012).
 
In addition to wheelchair weight, Matthew noted that the wheelchair users’ weight management is important in order to reduce excessive push forces (SCIRE 2014). 

Rear wheel position.
Another major factor that Matthew expanded on was the importance of optimally adjusting the position of the wheel axles so that 70%-80% of the client’s weight is over the rear wheel and the remaining 20%-30% is over the front castors.  He advised for optimum wheel access, the tip of middle finger should reach centre of the wheel hub and emphasised that by moving the horizontal position of the rear wheel as far forward as possible, it will:

• decrease weight on casters
• decrease power required
• decrease for UEs
• decrease overall length/turning radius
• improve neutral shoulder position
• increase ­efficiency of stroke
  
  Matthew also discussed other aspects of set up, including accurately setting the vertical height of the rear wheels to optimise wheel access and reduce propulsion effort; the postural benefits of using tilt -  both dump and squeeze; and the impact of camber and castor size on turning efficiency and stability.

Propulsion technique
Finally Matthew explored different propulsion techniques. He cited that 4 styles of propulsion have now been identified (Shimada et al. (1998); Boninger et al. (2002):

• Arc
• Single loop over
• Double loop over
• Semi-circular
  
  He stated that a semi-circular stroke has been deemed best practice as the lower stroke frequency and increased time spent in push phase requires less force and results in less median nerve injury.
  
  Conclusion
  I found the presentation very informative, covering as it did many of the key considerations to be addressed when configuring an ultralight chair.
  I believe the presentation to be valuable for practitioners, carers and clients as a helpful guide to fitting a chair for optimal usage, in line with current best practice.

References

Koontz AM et al. (2006) Investigation of the Performance of an Ergonomic Handrim as a Pain-Relieving Intervention for Manual Wheelchair Users. Assistive Technology

PVA Consortium For Spinal Cord Medicine (2005). Preservation of Upper Limb Function following Spinal Cord Injury. A Clinical Practice Guideline for Health-Care Professionals.  Paralysed Veterans Association of America. https://www.pva.org/publications/clinical-practice-guidelines
RESNA (2012) RESNA Position on the Application of Ultralight Manual Wheelchairs
https://www.resna.org/Portals/0/Documents/Position%20Papers/UltraLightweightManualWheelchairs.pdf 
SCIRE (2014) Spinal Cord Injury Rehabilitation Evidence Wheeled Mobility and Seating Equipment
https://scireproject.com/evidence/rehabilitation-evidence/wheeled-mobility-and-seating-equipment