Innovations in wheelchair vibration dampening

Jordan Davies (BSc, IPEM), Rehabilitation Engineer at Wheelfreedom, brings us an extract from their CPD accredited course: Innovations in Wheeled Mobility and Seating.

When walking, a large percentage of the ground reaction force or vibration is lost or absorbed before it can be transmitted beyond the thighs. When using a wheelchair, being in a seated position to move can mean increased vibration through the legs and upper body, and often for a prolonged period of time.

RESNA describes wheelchair users as “particularly at risk from whole body vibration”. From a biomechanics perspective, it is ideal for vibration to be redirected at the earliest stage, or as distally as possible.

MEASURABLE BENEFITS

CONSEQUENCES OF OVER EXPOSURE TO VIBRATION

Increased exposure to whole body vibration has been shown to induce or exaggerate back pain, neck pain, fatigue, spasticity, and pressure injuries. The consequences of these for daily life as a wheelchair user are a serious issue.

VIBRATION DAMPENING SOLUTIONS

Reducing vibration transmission lowers pain and fatigue, whilst protecting skin and muscle tissue integrity

Reducing vibration transmission is not just about short-term benefits such as reducing pain and fatigue. Technology now allows us to record real time numerical data so we can observe the true impact of improved designs. There is real potential for measurable longterm benefit in protection of both skin and muscle integrity.

Previously the industry has looked to reduce the vibration that reaches a wheelchair user’s body with cushions or in the material of the chair, favouring titanium and carbon over aluminium frames. As healthcare equipment becomes more sophisticated, solutions have come to market that redirect vibration earlier in transmission which results in reduced end transmission to the wheelchair user. Ki Mobility released an active chair called the Ethos which has an interesting two-part frame that shows substantial reduction in vibration transmission to the occupant. The top part of the frame is in contact with the wheelchair user (backrest, seat, footplate) and the subframe houses the propulsion and caster wheels. The design of most active chairs links the casters to the footplates resulting in undesirable vibration transmission. Isolating the top frame means there is no transmission directly up through the feet and legs. This design also allows for the inclusion of shock absorbers at the connection between the top frame and subframe. Another noteworthy innovation in this area is the Loopwheel. Loopwheels chose to move away from the traditional central axle with spokes, instead crafting a trio of carbon loops with a moving hub that houses the axle pin. The elliptical carbon loops work in unison with the “floating” hub, allowing the wheels to act as springs and resulting in significantly reduced vibration transmission to the wheelchair user.

WHEELFREEDOM’S

JORDAN DAVIES (BSC IPEM), ACCREDITED CPD COURSE

REHABILITATION ENGINEER AT At Wheelfreedom, our accredited CPD course provides WHEELFREEDOM Occupational Therapists and other interested healthcare professionals a chance to learn about exciting new developments across the mobility and seating industry. It’s a great opportunity to get hands on with a diverse range of equipment whilst receiving expert and impartial advice from our specialist team. Unit 61, Barwell Business Park, Leatherhead Road Chessington, KT9 2NY tel: 0800 025 8005 email: enquiries@wheelfreedom.com web: www.wheelfreedom.com