Page 22 - Mobility Management, April 2018

ATP Series
Suspensions: Functional Comfort
is driving over objects or rough terrain.”
“In more technical terms, you could say that the suspension
aims to isolate the seating structure from vibrations that are generated by the driving surface and preserve users’ energy to accomplish daily tasks,” Bourque adds.
“I know ‘comfort’ is a dirty word when people talk about function or clinical bene t. However, in my experience even the most clinically bene cial technology or power mobility system will not be of much use if it is not comfortable, as it probably will not be used,” Peterson says. “People that are not comfortable will seek comfort. That may compromise position or lead them to use older technology.”
Minimizing exposure to vibrations
is important to promoting a power wheelchair user’s overall health, enhancing functional endurance and quality of life — Melissa Bourque, Permobil
A good suspension system is not all about comfort, however. It also provides several clinical bene ts.
Circle back to vibration reduction. Vibrations have many clinical implications for power chair users.
“If the person operating the wheelchair is being jostled around while driving the wheelchair, we will typically see an impact on their tone,” Doherty says. “Often, this impact is increased tone because the movements and shifting of the wheelchair can initiate a tonal response from the individual.”
Peterson agrees. Extensor tone and spasticity will then lead to poor positioning and head control, which increases risk for pressure injuries and reduces access to drive controls, he says.
With advancements in technology we can provide a suspension that climbs well and provides a smoother ride — Jay Doherty, Quantum Rehab
“Additionally, trunk control is compromised by consistent movement, rocking or larger ‘jolts’ that are unchecked by suspension,” Peterson says. “And these movements can also result in additional shear forces in vulnerable areas.”
In fact, “research has shown an increased risk of spinal damage associated with vibration forces transferred directly through the seating system to (the) user’s spine,” Bourque says. “Wheelchair users may also be more sensitive to vibration related to other factors, such as pain, increased tone and fatigue. Vibration forces can lead to a loss of position over the course of the day and contribute to shear forces along seated surfaces, which may increase risk for tissue breakdown.”
Doherty says that as the suspension system absorbs vibrations, it essentially stabilizes the seated position and increases the ability of the user to control the power chair.
This stability might feel a whole lot like comfort. After all, a user who doesn’t experience bumps can tolerate the seated position longer, Doherty says.
Cruising Along with Today’s Technology
Suspension has always been a part of power chair development,
How Suspension Differs for Front-, Mid-, and Rear-Wheel- Drive Power Chairs
Each manufacturer creates a suspension system that works a little differently, and those differences also vary across the drive chassis design. Jay Doherty, OTR, ATP/SMS, explains the differ- ence between Quantum Rehab’s suspension systems for front-, mid- and rear-wheel drive power chairs.
• The suspension system on a front-wheel drive power chair provides one of the most stable, smooth rides. “The suspen- sion on a front-wheel drive wheelchair maintains the front drive wheels’ and rear caster wheels’ contact with the ground,” Doherty says. “This power wheelchair has a more signi cant suspension system, which actually absorbs impact from terrain
and provides a smooth ride by absorbing the bumps that the person may drive over.”
• On the mid-wheel drive power chair, the suspension system incorporates a front caster wheel that can navigate a 3" obstacle. “While the caster wheel is raised, the suspension system pushes the drive wheel down to maintain contact with the ground so the wheelchair can continue to drive in the direction the individual desires,” Doherty says.
• On a rear-wheel drive, the power chair has a more rigid suspension system, Doherty says. “The suspension is more for climbing.” m
22 APRIL 2018 | MOBILITY MANAGEMENT MobilityMgmt.com