As wheelchair codes evolve and multiply, so will the complexity of reimbursement. A thorough understanding of wheelchair features, options, and accessories—as well as their application—will become necessary for your business to survive.

For example, the other day a sales rep came into my office and said, “I’ve got some great deals on K3s and K4s.”

“What’s a K3?” I asked, and he thought I was kidding. “Look, I’m a rehab guy,” I continued, “I need to know what features your chairs have first. We figure out how we are going to bill for it after we figure out what the client needs.”

There are hundreds of models of wheelchairs on the market today. Ten years ago, the lightweight and ultralight wheelchairs we see today barely existed. As the products have become refined, there are many more available features designed to improve function and independence for the end user. Consequently, as choices have multiplied, so has the difficulty of finding the best piece of equipment for the end user and their needs. As more and more wheelchair and seating codes are developed, understanding the differences in chairs, their features, and their application will be essential to obtain proper reimbursement.

Frame material is one of the factors that determine the cost, weight, and performance of a wheelchair. Steel is probably the most used frame material and steel comes in five varieties:

1) Cold rolled or low tensile steel. Tubing made from this type of steel is inexpensive. Due to its lower strength, thicker tubes must be drawn for the tubing to be rigid enough to serve its purpose. Wheelchairs made of this material are typically inexpensive and heavy.

2) Stainless steel saw a big upswing in the mid to late 1980s because of its light weight when compared to low tensile steel. It does not rust and is less expensive than higher strength alloy steel. Experience, however, showed that unless perfect welding techniques were used, welds could crystallize over time and fail. Today, this material is typically used in less expensive, imported wheelchairs (stainless steel is inexpensive abroad).

3) Alloy steel (cromoly steel) has high strength, enabling it to be drawn into thin walled tubes, which reduce weight. Due to its higher cost, you will not find it on inexpensive wheelchairs. Many prescription- or custom-fitted wheelchairs use this material.

4) Aluminum is lighter than steel, but to achieve the rigidity necessary for use in wheelchairs, aluminum tubing must be drawn into thicker walled tubes than high-quality alloy steel tubing. In addition, because aluminum is also relatively soft, it must be reinforced at points of wear and stress, which increases weight. Even though these factors reduce the weight advantage of aluminum over steel, aluminum has good vibration absorption qualities and does not rust, making it a popular choice for some standard lightweight wheelchairs and most custom and custom ultralight wheelchairs.

5) Titanium possesses extremely high strength at a low weight. It is also a difficult material to work with and is more brittle. It is typically used in high-end custom lightweight wheelchairs where cost is less of a factor. Titanium has good vibration absorption qualities and can reduce fatigue in the end user over the course of the day—improving sitting tolerance.

Frame Construction
The advantages of rigid-frame wheelchairs come in the form of improved efficiency for the user. Rigid frames require fewer components (and material) and thus weigh less. In addition, because the frame is in essence a welded box, it has inherently less flex. The user’s energy goes directly to propelling the frame as opposed to propelling and flexing the frame as is experienced in a cross-folding frame. Rigid frames are more durable because they have fewer moving parts.

However, some rigid designs do not accommodate growth or frame size changes. In an active user, whose weight has stabilized and is no longer growing, this poses no problem. There are several rigid designs that do provide for growth and frame size change. Consider them when a rigid frame is desirable and the need to change the frame’s size is anticipated.

One perceived disadvantage is that rigid wheelchair frames do not fold like cross-folding wheelchair frames. Typically, the backrest folds flush with the wheelchair seat. This may make the frame more difficult to transport in the trunk of a car or behind the seat of a smaller car. Some rigid wheelchair frames have a smaller profile, which enables them to be stored more compactly. Quick-release wheel axles are standard equipment on these chairs.

Cross Folding
An advantage of cross-folding wheelchairs is a more modular design than rigid frames and an easier accommodation to width and depth changes. This can be required when the user grows or sustains a substantial weight gain or loss. Folding chairs are often perceived as easier to transport and also offer some shock-absorbing qualities due to the flex in the cross braces.

Cross-folding frames are less efficient due to the flex that normally occurs in the frame during propulsion. Because of the additional components that are used in cross-folding chairs, they are heavier and less durable than rigid frames. The most common place of frame failure is at the cross brace, because it is the point that endures the most stress. An extremely active user may break several cross braces in the life span of their chair.

Wheelchair Features
Wheelchair features affect both performance and cost. It is important to not only select the features that are necessary, but also to recognize what features may be unnecessary. The wheelchair should be configured so that the features incorporated will improve rolling efficiency and function.

Seat Width
Standard seat width is 18 inches and narrow is 16 inches. The most typical error regarding seat width is that it is too wide. If the seat is too wide, the wheels may be too far away to efficiently propel the chair. The excessive shoulder abduction that may be required could lead to shoulder problems. Excessive seat width may also promote scoliosis.

Most custom chairs have seat widths available in one-inch increments. Pediatric sizes go as low as eight inches. For adults, the range is 14 to 20 inches, but heavy-duty chairs may be 22 or 24 inches. Even wider sizes are available on specially reinforced frames. There are several companies that produce wheelchairs for the obese or bariatric population.

Seat Depth
Standard seat depth is typically 16 inches. To accommodate longer leg lengths and proper pressure distribution, an appropriate seat depth is required. Most custom chairs have seat depths available in one-inch increments. Pediatric sizes go as low as eight inches and adult sizes range from 14 to 20 inches. Proper seat depth is also necessary for appropriate foot position.

Working our way up the chair, standard back height is typically 16 inches. Many custom chairs have adjustable back heights, typically 14 to 18 inches. Back height is normally determined by the patient’s injury level and type, level of function, and ability to propel. A patient with a lower-level spinal cord injury (SCI) may prefer a low back height, because it does not restrict arm and scapular range of motion while propelling the chair. A person with a higher-level SCI or neuromuscular condition may need a higher back height for stability and function. Back height also affects the type of seating components that can be mounted to the chair.

A change in back angle (differs from reclining back) may be made to accommodate hip range of motion limitations, thoracic kyphosis, stability considerations, and sometimes head control. Back angle adjustment normally requires the use of tools.

The frame seat to floor height measurement is typically available in the standard adult height of 19 inches. A hemi-height frame is normally two inches lower. A tall adult frame is two inches taller. Frame sizes accommodate different patient heights: tall people would need a taller frame because the floor-to-seat height would be inadequate to properly support their leg lengths.

A low (hemi) size would be necessary for shorter users and hemiplegics using a foot for straight-line propulsion. Wheel and caster sizes, in addition to position, affect floor-to-seat height. Lightweight performance wheelchairs normally have no “standard” floor-to-seat height. Floor-to-seat height is determined by the frame height, caster, and fork—as well as the position and size of the rear wheel.

Tilt-in-Space
In the tilt-in-space or orientation, seat and back are tilted without changing hip angle. Tilt may be limited to facilitate head control but is usually not limited to any significant degree (except safety) as a means to relieve pressure and/or decrease tone without shear or postural displacement (sagittal plane shift). Most tilt chairs tilt from 0° to 45°, and up to 60°. Research has shown pressure relief does not occur until tilt reaches 45°.

Another consideration is frame recline, which provides passive range of motion, pressure relief, and positional changes. Frame recline may be used to improve sitting time and tolerance, and help in daily living chores. To accomplish this, the back angle of the chair is opened up in a variety of ways. The recline provides some limited pressure relief but is significantly inferior to tilt for this purpose.

Adjustable Wheel Positions
Standard wheelchairs have fixed wheel positions typically located in the center of the rear of the wheelchair frame at the posterior aspect of the seat. Often referred to as center-of-gravity adjustment, moving the wheel rearward increases the chair’s stability (desirable for an amputee) but makes the chair more difficult to propel. Moving the wheel forward reduces the stability of the chair but dramatically reduces the energy required to propel the chair while increasing maneuverability, reducing turning radius, and allowing for “popping” front casters over obstacles. Moving the wheel up or down changes the seat angle as well as floor-to-seat height. This is necessary to establish the most efficient height for transfers in and out of the chair or into the car. It also allows adjustment for proper hand position on the wheel for more efficient propulsion. Center-of-gravity adjustment is one of the most significant adjustments you can make to a wheelchair to improve propulsion efficiency.

Adjustable Casters
Standard wheelchairs have fixed casters. When changing wheel sizes, caster sizes, floor-to-seat height, and seat angle, it is necessary to adjust the caster housing to 90° (perpendicular) to the floor. Incorrect front caster adjustment may cause “flutter” and/or may not allow the wheelchair to track in a straight line. This may not only be unsafe, but can cause the wheelchair user to expend additional energy on corrective movements to keep the wheelchair tracking in a straight line.

Standard casters are typically eight inches in diameter. Smaller casters have lower rolling resistance and less flotation. A three-inch caster wheel offers excellent rollability but may not smoothly negotiate small cracks on the pavement. A five-inch or six-inch caster will better accommodate cracks and debris, has better tight turning, and allows for steeper front frame angles with reduced interference of the feet—and is a better all-around choice. Eight-inch casters may interfere with rear wheels and are not normally good for chairs with adjustable rear wheel positions. Their flotation is not appreciably better than five- or six-inch casters.

Active users (with good cognition) are better candidates for smaller casters. Because smaller casters do not negotiate debris as well as their larger counterparts, the user must anticipate the need to lighten the front end of the chair to avoid debris. Most active users find the increased rollability more than offsets the flotation problems.

Wheel Type and Size
Mag (injection-molded plastic) wheels require lower maintenance but have higher rolling resistance due to their heavier weight (a heavier wheel requires more effort to put it into motion due to higher inertial mass). Rollability overall is poorer, and the wheel does not absorb shock as well. A mag wheel is more rigid but is actually weaker than a spoked wheel. An active user can destroy a mag wheel in a short period of time.

Spoked wheels offer better rollability due to lighter weight and improved shock absorption. Spoked wheels flex more and absorb shock better. This flex, however, loosens spokes and increases maintenance. When spokes loosen, the rim loses its roundness and must be corrected.

Sydney Gubin, ATP/S, CRTS, is president of Home Health Supply Inc doing business as The Seating Center, Palm Springs, Calif. He has been a registrant of NRRTS since 1995 and has served two terms on its board of directors as well as 7 years on its ethics committee. He is a member of the RESNA professional standards board and the Medicare Region D DAC Rehab A Team. Gubin can be reached via email: sgubin@dc.rr.com.