Wheelchair Update

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March 2002

By Tom Johnston, PT

2002 brings major improvements for both manual and power wheelchairs.

In the past, a new year might signal the arrival of anodized wheelchair parts, changes in materials, or a few new colors. But this year, wheelchair options and accessories are not just focused on new color palettes. There are some major improvements for both manual and electric wheelchairs, including:

consistent fit,
company return policies,
shock-absorbing components,
electronics power delivery,
easier programming,
easier maintenance access,
legrest design improvements,
lever-adapted single-arm drive for manual chairs,
varied caster and tire selections,
angle-adjustable backrests,
horizontal folding frame members,
swing-away wheel locks, and
power-assisted manual wheelchair propulsion.

It’s All In The Fit
Currently, there is a particular emphasis on providing a consistent fit. Michael Schleppenbach, a rehabilitation equipment provider in Lincoln, Neb, says manufacturers are offering some of their adult-sized manual chairs with optional growth kits free of charge for one size change. This new option allows users who gain weight or atrophy significantly to modify and still use their chairs with the intended support and fit. This option has been available in the pediatric arena for quite some time, but is relatively new in the adult market.
Some accessory companies making cushions and backrests are extending their return policy to include parts damaged during customization for fitting by any member of the rehab team. Until recently, a cushion damaged by a therapist during modification could be replaced free of charge. However, if the supplier made the same mistake, the supplier would be responsible for the replacement cost. With a newly intensified focus on providing what is best for the client, replacements can be made as long as the damage was created while modifying the equipment. This does not apply if the damage occurred from normal wear and tear or under abusive circumstances.

New options are now available to address client responses to spastic conditions. Many new manual and power chairs can have dynamic accessory backrests and headrests installed that help absorb shock and diminish tonal increases.¹ These increases in tone or spasticity can be diminished by dampening vibration and accommodation of some aspects of spastic movement, thus diminishing the quick stretch that exacerbates complete motor unit recruitment of spastic muscle groups. Other options that provide this type of cushioning protection include integral frame suspension and proprietary or accessory caster suspension. This equipment is available in power and manual mobility options.

High-Tech Upgrades
Electronics for power mobility are also being improved. The inherent fishtailing of front-wheel-drive and mid-wheel-drive wheelchairs can be dampened to allow improved stability at faster speeds by using proprietary dampening electronic accessories to standard drive systems. Some systems allow for direction control in off-camber turns and when driving on hills. This allows for improved control when crossing thresholds or other obstacles in tight spaces. This option also greatly improves control of the chair while using other switch options that require latched drive use.²

Other electronic improvements include programming aspects. Some companies are offering modem links for improved field service of power chairs. They also provide computer programs that, through a personal computer, can allow all of the modes to be programmed at once with a visual graph reference of intermode differences. Using this new technology, providers or therapists can save their favorite settings as a file and download these settings to similar client chairs for later personal modification. User commands and menus have also been updated to improve understanding of programming options.

Some companies are also focusing more on maintenance issues and on building power chairs with improved accessibility to batteries and electronic components. This new focus is intended to decrease labor and improve turnaround time when exchanging or performing repairs to the drive systems. For example, some motors are now being made without brushes to minimize servicing. This also allows less internal friction and loss of energy.² Companies still vary, however, with respect to available options such as eliminating gear drives or improving gear drive meshing to achieve the same focus of reducing internal drive system friction and system noise. The intent of eliminating gears is to improve power delivery by decreasing resistance to motion, when the system is engaged and running, or out of gear and electronically shut down. A gear-driven system with improved meshing is intended to maintain excellent torque with minimal energy loss to internal system friction. Some new pediatric power chairs are manufactured with frames that break down for ease of maintenance and stowing in autos. Providing the option of breaking down a power chair into manageable pieces allows caregivers to transport pediatric chairs without owning a van with a ramp or lift.

Improved Accessories
Older legrests on both manual and power chairs typically had round tubular stock. Using round stock instead of square stock reduced weight without sacrificing strength. However, a major difficulty with this design surfaced when placing footrests that mount through the extension piece of the legrest with a lever on only one side of the tubing. The physics of this arrangement is that torque will be placed on the extension tubing that tends to twist it inside of the mounting tubing. New chairs always had even, perpendicular placement of the footrests; however, after wear and tear of a year or two, the footrests would tend to sag and require adjustment. In some cases, even after bolting clear through the tubes, the adjustment holes would get so worn out that it was impossible to maintain correct footrest placement.

The answer to the problem is different for all clients, but new options on the market include square tubing or at least one flat side to the tubing in legrests. An adapter is press fitted into the round mounting tubing so that the square extension tubing can be adjusted and stays in true alignment. The resulting fit does not eliminate torque, but does manage the torque better if properly maintained.³

In the past, clients who needed a manual chair but had the use of only one upper extremity for propulsion had the option of a chair with a connecting axle between the drive wheels and dual push rims on the side of the functional upper extremity. Controlling a one-arm-drive chair with dual push rims is quite difficult. Lever drive is now another option available to propel the chair with one upper extremity and/or one or two lower extremities. The lever can be lengthened to allow for optimal mechanical advantage for propulsion. In some models, the lever also steers one front wheel. This wheel is changed from a trailing caster to a wheel that is mounted straight in line with the caster housing to allow for steering via a connecting rod attached to the lever. This adaptation can be converted to allow the client to propel the wheelchair in neutral with the lower extremities and steer with the lever with the available upper extremity. Several companies now offer improved caster and tire options, which can be ordered with new chairs. There is a distinct positive correlation between use patterns and the degree of specific customization of a client’s system, so be active and precise in addressing specific client tire needs when justifying nonstandard accessories for a new or used system. Some companies will also do custom orders that are not listed on their order forms, therefore, when in doubt…ask the company.⁴

Many companies now offer angle- adjustable backrests. Some offer a simple hip angle adjustment and others offer a lumbar angle adjustment. The angle-adjustable backrest has been used on some models but now it is available in more models. If this option is ordered on the chair, an accessory backrest does not need to be used to create lumbar extension.

One troubling issue with folding frame manual chairs is that some energy is sacrificed to frame flex with every push effort. Rigid frame wheelchairs have eliminated or at least minimized frame flex to make manual propulsion more efficient. Offering a single footplate that reduces frame flex in folding manual chairs is one way to improve push efficiency. Another way to minimize frame flex is to use locks that increase the rigidity of the frame by securing the cross braces. Other manufacturers offer a horizontal, rather than a vertical, cross brace that maintains folding capability with minimized frame flex.

Ameliorations For Athletes
Many clients have scars on their thumbs that have been created by the lengthened push required for high-level skills performance and sports. This has typically been addressed by scissors wheel locks that fold under the chair and are out of the way. The problem with this approach is that scissors wheel locks are less handy to use than standard push-to-lock wheel locks because the user has to lean forward quite a bit to reach under the seat of his chair to apply the lock. More recently, we have an option on some manual chairs of fold-away, push-to-lock wheel locks. Using this option, the brake handle does not fold under the chair. The wheel-locking bar of the mechanism just swings out of the way under the frame when the wheel is unlocked. This creates improved clearance for a lengthened push stroke without placing the lock handle in a hard to reach position.⁵

Power assist for manually propelled chairs is also a new option available. Power assist may extend the range and/or terrain types over which one can propel. The concept is based on using manual efforts to initiate propulsion and to provide constant energy input. The size and weight of the system can be relatively minimal due to the fact that the batteries do not need to overcome the initial inertial resistance to rolling; instead they simply put variable energy into the equation to make up the difference between client effort and terrain demands. This is different from the common concept of powered mobility in that the user is constantly providing effort and the motors are only making up the difference of the terrain demands. By assisting the user’s efforts, barriers to endurance and limited strength can be minimized.⁶

All of these instances represent significant improvements that make it easier to provide individualized equipment to meet client needs. Clients should be able to get the ideal equipment for their needs through research, company contact, and supplier consultation.

References
1. Bergen A. Medtrade 2001—Day One. Available at: www.rehabcentral.com/art-adee.cfm?artID=9068. Accessed October 23, 2001.
2. Modelle B. Invacare 3G Arrow. Available at: www.wheelchairjunkie.com/3g.html. Accessed May 25, 2001.
3. Bergen A. Medtrade 2001—Day Four. Available at: www.rehabcentral.com/art-adee.cfm?artID=9071. Accessed November 8, 2001.
4. Smith M. Pumped Up—A WheelchairJunkie’s Guide to Sportschair Tires. Available at: www.wheelchairjunkie.com/sctires.html. Accessed February 7, 2001.
5. Bergen A. Medtrade 2001—Day Five. Available at: www.rehabcentral.com/art-adee.cfm?artID=9072. Accessed December 11, 2001.
6. Equipment Reviews, Power Add-ons. Available at: www.spinlife.com. Accessed January 7, 2002.

Tom Johnston, PT, is a staff physical therapist with a master of science degree in physical therapy who practices on the interdisciplinary spinal cord team at Madonna Rehabilitation Hospital in Lincoln, Neb.

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March 2002