by Michelle Agostini, PT, DPT, and Eileen Yorke, OT, ATP, SMS
Seating systems have been undergoing changes constantly to adapt to the needs of the client base. Advances in design, electronics, and materials are among the many notable leaps forward that have improved quality of life for daily wheelchair users. The current trends and new designs on the market have much to offer the user experience, but they can be a bit overwhelming. This article breaks down this array of important developments to help therapists zero in on optimum solutions for their clients.
Manual Seating Systems
Manual wheelchairs are manufactured from various materials. Titanium and aluminum are two commonly used metals. Titanium is the lighter material, which dampens vibration forces transferred through the wheelchair. However, it is much more expensive than aluminum, which is also expected to be more durable. Material choice is dictated by end user functional needs.
Manual wheelchairs come in multiple designs to address various needs. These different designs have benefits and drawbacks. Rigid frame manual wheelchairs offer increased energy conservation due to the lack of cross bridge, therefore less joints. Without the cross bridge, more effort from each propulsion stroke is transferred to the wheels and in turn more forward force is elicited, rather than lost through multiple brackets and hinges. The limitation of rigid manual wheelchairs is the inability to fold. There are different designs for rigid frame manual wheelchairs: mono-tube or dual tube. A dual tube rigid frame wheelchair offers increased stability with better ability to disseminate forces transferred through the caster wheels during propulsion. A dual tube rigid frame also weighs less than the mono-tube frame. When loading dual tube wheelchairs, users have difficulty passing the wheelchair over his/her lap due to the cumbersome lower bar. Sometimes a mono-tube frame is warranted to maintain independence with car transfers. It is also significant to note that while comparing weights of manual wheelchairs, it is important to trial all types with proper configurations. Once a wheelchair is configured to meet the user, there is limited perceived difference.
Folding manual wheelchairs offer the convenience of folding to just a few inches wide, allowing easier storage within the home. Transportation of the wheelchair, specifically in smaller vehicles, is less complicated with folding frames. Folding manual wheelchairs fold in two ways: frame-in-frame and frame-on-frame, with reasoning behind engineering of both. The frame-in-frame folding allows for a lower seat-to-floor height, which is important for users who propel with their feet. The frame-in-frame model also provides more rigidity to the design. Folding frames with curved cross braces allow for smaller folding widths, important for users with limited storage space.
Newer folding frames on the market allow for 20 degrees of backward tilt. This combines the benefits of an ultra-lightweight folding frame, including a lighter wheelchair, with the resting and pressure-relieving properties of traditional tilt-in-space wheelchairs.
Manual tilt-in-space wheelchairs are a great option for many wheelchair users. They offer the ability to tilt backward up to 55 degrees. The backward tilt allows for adequate pressure relief and limits skin breakdown. A comfortable resting position for the user minimizes transfers in and out of bed throughout the day. Manual tilt-in-space wheelchairs allow for a small degree of tilt forward, which is beneficial for stand pivot transfers. This decreases the amount of physical assistance a client would need to perform these transfers. It can also allow a user to place his/her feet on the floor, enabling foot propulsion for short distances. Many modifications available on tilt-in-space manual wheelchairs facilitate ease with propulsion and steering for caregivers. Adjustable stroller handles and various back cane heights accommodate a caregiver’s height, allowing for proper mechanics, therefore reducing risk of injury.
Power assist systems have become more user-friendly and customizable with advancements in technology. Although these products have been out for many years, the ability to program and further individualize the electronics to meet clients’ needs has significantly developed. A power assist system is commonly added to ultra lightweight wheelchairs. With this aid, energy demand of the client’s wrists, arms, and shoulders is reduced, in turn reducing risk of repetitive strain injuries. This enables users to continue using a manual wheelchair for a longer time before transitioning to powered mobility. Power assist systems can either be push-rim or motion activated. The push rim activation designs are integrated into the wheels. These wheels enhance the user’s force production during each propulsion stroke. Power assist wheels are programmable for indoor/outdoor modes as well as modifiable to meet the user’s specific needs, such as differences in upper extremity strength. Power assist systems can be added or removed easily from the ultra-lightweight frame. Some systems can be activated by a sensor on the wrist. A simple tap can accelerate, cruise, or turn off the system. Other removable systems are joystick controlled. The drawback to the power system driven by joystick is there is no suspension system, which can create a turbulent ride.
In today’s world, no one leaves home without a cell phone. In response, power wheelchairs now have the ability to integrate Bluetooth, Infra-Red, and Wi-Fi technology into the electronics; providing clients more access to their environment. Clients with motor control challenges can operate a power wheelchair via alternative drive options, using a variety of access points. While alternative drive systems (such as head array, mini-joystick, or sip-n-puff) have been utilized by clients with tetraplegia for many years, systems are now more refined in the ability to adjust various aspects of sensitivity, reducing clients’ energy demands. Light touch pressure switches can be mounted almost everywhere for access such as at the knee support, shoulder, foot, and single finger controls are options for clients with limited movement. Wireless integration has been a big push over the past few years. Clients can now access tablets, phones, and computers through the joystick via wireless access. This enables clients to access their environment using either voice activation or through the joystick. Power wheelchairs can now have a USB port integrated into the joystick, allowing users to charge the electronic devices on which they depend.
Suspension systems for powered mobility have been evolving, with manufactures providing enhanced performance on various terrains as well as during curb negotiation. With improved suspension systems, the end user experiences a smoother ride. This is important to maintain skin integrity, manage tone, and limit unwanted shifting of the user within the seating system.
Power wheelchair systems are now integrating seat elevate into their power seat functions, allowing clients to travel 8 to 12 inches upward. This provides accessibility for reaching into cabinets, over countertops, and work surfaces with less physical assist. Advancements in these systems allow clients to propel at a speed comparable with walking while in full elevation. This is essential for clients to be visible in the community by pedestrians and motorists, as well as meet eye gaze of peers during social interactions. Use of the power adjustable seat height facilitates transfers from the wheelchair and decreases overhead/shoulder reaching. This in turn reduces the client’s risk for neck and shoulder pain and injury. Power wheelchair standers have advanced in the way a client can achieve a standing position by allowing the user to program his/her desired upright position and transition directly. The overall time and energy required for a client to go from a sitting to standing position is now more proficient.
A challenge for many clients is wheelchair failure. Many manufacturers are able to monitor wheelchair electronics, drive times, distances, and other details remotely. Remote monitoring is beneficial as it limits the need for users to attend clinic and vendors to make home visits. Vendors provide prompt responses to the clients, getting them up and running more efficiently. This is a game changer for most wheelchair users.
So what’s next for power wheelchairs? Eye tracking technology is being developed and introduced to the power wheelchair world. A tablet can be mounted directly to a power wheelchair base and positioned in front of the client. This technology allows the client to control the entire computer using eye movements. This technology is evolving and not formally ready for wheelchair client use but will be in the near future. As technology evolves, we hope to see advances in extended battery life for increased mobility ranges, further advancement in wheelchair suspension systems, improvements in the motor and drive design, as well as continued integration of smartphone and environmental-friendly technology. RM
Michelle Agostini, PT, DPT, is a senior physical therapist at Kessler Institute for Rehabilitation. She has experience in spinal cord injury, stroke, amputee, and brain injury, specializing in seating for those populations.
Eileen Yorke, OT, ATP, SMS, is an advanced clinical specialist at Kessler Institute for Rehabilitation. She specializes in the area of wheelchair seating and positioning and has earned her Assistive Technology Professional (ATP) and Seating and Mobility Specialist (SMS) certifications. For more information, contact [email protected].