Comparing Ultra Lightweight Wheelchair Frames

One of the first steps in selecting a wheelchair is to determine the type of wheelchair frame that is required. According to clinical practice guidelines, a fully configurable, ultra lightweight wheelchair is recommended for an individual who uses a manual wheelchair for independent mobility^{1, 2}. The ability to fully tailor a wheelchair for an individual will have an effect on positioning/postural support, ease of propulsion, and wheelchair stability and maneuverability. There are difference choices possible in ultra lightweight wheelchair frames – from those that fold with a cross-brace to those that are fully rigid. It is important to understand the similarities and differences in the wheelchair frames so that the initial choice of wheelchair frame type is optimal for individual clients.

Choices in Ultra Lightweight Wheelchair Frames

When choosing between folding and rigid, consider:

• Stability of individual's condition
  • anticipated change in client's size or function
• Level of postural support required
• Method of propulsion
  • bilateral upper extremities
  • hand-foot propulsion
  • foot propulsion
• Discrepancy of lower leg length or contractures of lower extremities
• Transfers
  • standing transfer
  • sliding board transfer
• Activity level of the individual
  • distance propelled daily and in what environments
• Transportation
  • ability to fold/lift the wheelchair
  • crash-worthiness for occupied transit

Folding Frame

• Cross-brace permits lateral (side-to-side) folding, for ease of transport or storage
• Lighter in weight than traditional, standard wheelchairs
• Appropriate for hand propulsion, hand-foot propulsion, or foot propulsion
• Appropriate for all transfers, including standing transfers
• Adjustable configurations
  • Choice of wheels, tires, handrims, wheel locks, casters, arm supports, lower leg support assembly (hangers and footplates), center of gravity
• Available in box frame, modular frame, and open frame models
• Better opportunity to suit active clients with higher positioning needs

Rigid Frame

• No cross-brace for lateral folding; however, back posts may fold down for ease of transport
• Lighter than folding wheelchairs due to material and design
• Appropriate for independent, active user who propels with the upper extremities
• Appropriate for side-to-side / sliding board transfers
• Adjustable configurations
  • Choice of wheels, tires, handrims, wheel locks, casters, arm supports, frame angles, frame insets, foot boards, center of gravity
• Available in closed/box frame and open frame models
• Available in adjustable and fixed/welded models
• Greater efficiency of propulsion compared to folding frame due to lighter weight, fewer moving parts, greater rigidity, which transfers the energy of propulsion into movement

Choices in Folding Wheelchair Frames

Modular Frame

• Side frame is made up of front frame, cross-brace, and rear frame
• Allows for choices in rear frame (square or rounded) and in front frame (hemi or fixed) to suit various needs
• Allows for change in frame components to accommodate change in size or function/condition
• Seat rail sits above cross-brace and wheelchair frame, providing dual rails for mounting positioning components if required

Box Frame

• Side frame is one piece
• Cross-brace is integrated into side frame to connect the two sides
• Allows for lower seat-to-floor height as seat rail is flush with wheelchair frame

Open Frame

• Cross-brace is more compact than traditional folding wheelchairs
• Choice of fixed front end for greater rigidity or swing-away lower leg assembly for ease of standing transfers
• Allows for greater efficiency of propulsion compared to modular or box frame folding wheelchairs due to lower weight, fewer moving parts, and rigidity in cross-brace & seat rail

Choices in Rigid Wheelchair Frames

Open Frame

• Tends to be lower in weight than closed frame, as there are fewer components in the frame
• Easier to transport, as lower section of frame is absent; can lift wheelchair across the body into a vehicle

Closed Frame

• Greater rigidity than open frame due to tube from camber well to caster housing
• Greater rigidity offers greater efficiency of propulsion
• Could be more challenging to transport into a vehicle due to shape of frame

Box Frame

• Tends to offer greater rigidity than open frame due to structural design of frame creating the shape of a box
• Tends to be heavier than open frame and closed frame wheelchairs
• Could be more challenging to transport into a vehicle due to shape of frame
• Allows for optional swing-out lower leg assembly due to box design

Rigid Frames: Adjustable or Fully Welded?

Rigid wheelchairs, whether open-, closed-, or box-framed, can come in adjustable or fully fixed/welded versions. Which one is right for an individual?

Adjustable Rigid Frame

• Allows for limited adjustments to be made after the purchase of the wheelchair
  • rear seat-to-floor height
  • center of gravity (CoG)
  • back post angle
• Appropriate for an individual whose condition may change after the purchase of the wheelchair to allow for changes to the wheelchair to accommodate current and ongoing needs
  • change in center of gravity on wheelchair to accommodate change in balance
  • change in back support angle to accommodate positioning/postural needs
• Greater efficiency of propulsion compared to folding wheelchairs due to lighter weight and greater rigidity than folding wheelchairs

Fixed/Fully Welded Rigid Frame

• Components are fixed in position, according to individualized specifications on order form
• Appropriate for an individual who is an experienced manual wheelchair user and team (therapist, supplier, client, etc.) knows exactly what is required for client for wheelchair setup; client's condition or function is not expected to change during length of wheelchair ownership
• Allows for improved efficiency of propulsion over adjustable rigid wheelchair. Increased rigidity from welded parts translates to movement when force is applied to the handrims

References

1. Rehabilitation Engineering and Assistive Technology Society of North America. (2012). RESNA Position on the Application of Ultralight Manual Wheelchairs.
2. Consortium for Spinal Cord Medicine. (2005). Preservation of Upper Limb Function Following Spinal Cord Injury: A Clinical Practice Guideline for Health-Care Professionals. Paralyzed Veterans of America.
3. Bjornson, A. (2019). An Overview of Ultralight Manual Wheelchair Frame Styles. Retrieved from https://www.sunrisemedical.com/education-in-motion/blog/october-2019/overview-ultralight-manual-wheelchair-frame-styles
4. Sherman, S. (2019). Understanding Choices in Rigid Wheelchairs. Retrieved from https://www.sunrisemedical.ca/education-in-motion/clinical-corner-archive/march-2019/understanding-choices-in-rigid-wheelchairs