Product Profile: Tilt-in-Space Technology
- By Benjamin H. Grumbles, Brent Campbell
- Jul 01, 2003
For many years, tilt-in-space wheelchairs have provided people with the ability to dynamically change their position in space in order to enhance sitting posture and function and to protect skin integrity. This clinical benefit is important to anyone who is unable to independently shift his or her seated position or cannot maintain an upright sitting position against gravity for long periods of time. Like recliners, tilt-in-space chairs reorient the body in order to redistribute the user's body weight away from vulnerable bony areas, thus reducing the risk of skin breakdown. The tilted position also reduces the effort required to maintain an upright posture, thus helping to prevent the compensatory postures resulting from fatigue and the potential respiratory, digestive, communication and functional complications that can occur as a result of these postures. Unlike recliners, tilt-in-space chairs provide this change in position while maintaining the user's optimal posture, joint angles and muscle lengths. Tilting in space also eliminates the shearing forces on the skin that occur during recline and return.
The first tilt-in-space chairs that were designed included a single pivot tilt system in which the upper seat frame rotated back at a single point in relationship to the bottom frame. Although the single pivot system provided all the clinical benefits of a positional change, it involved a significant horizontal shift of the user's center of gravity (COG) when the chair was tilted back. This posterior shift of the user's COG can result in several potential problems. First, it necessitates the use of a long base frame in order to maintain rearward stability of the chair. A longer base frame results in decreased maneuverability and potentially limited accessibility. Secondly, in order to improve the stability while in the tilted position, the chairs are often designed so that the COG is positioned toward the front casters when in the upright position. This causes front loading of the casters which results in further decreased maneuverability, as well as the potential for forward tipping of the chair when it is loaded. Thirdly, because the user's COG moves away from the pivot point of the chair during the tilt cycle, the caregiver must essentially lift or lower the user's weight when tilting and un-tilting the chair. This necessitates the use of mechanical assists, such as gas cylinders or springs, in order to reduce the amount of effort required by the caregiver.
Finally, for some clients the disturbance created by the horizontal shift in COG could be a trigger for flexor or extensor spasticity or other tonal responses. Additionally, for clients with cognitive or anxiety issues, this disturbance might cause agitation or a protective extension response. Later designs that followed the single pivot design, including the multi pivot point systems and the pivot and slide systems, helped to reduce this horizontal movement of the COG and allowed a shorter frame length, but neither system was completely successful in resolving the issues of the single pivot tilt.
The new Quickie Intelligent Rotation In Space (IRIS) is a rotational design that dramatically reduces or eliminates any horizontal center of gravity movement. This innovative system features a rocker that allows the seat frame to rotate on the base frame, while maintaining a user's COG in the same spot and keeping the COG aligned with the chair's center of rotation.
The tilted position also reduces the effort required to maintain an upright posture, thus helping to prevent the compensatory postures resulting from fatigue and the potential respiratory, digestive, communication and functional complications that can occur as a result of these postures. |
This alignment is maintained when the chair is either tilted or brought to upright. Because the user's COG remains constant, with virtually no horizontal shift, the IRIS can use the shortest base frame on the market without compromise to stability. Since there is no need to position the COG toward the front of the chair to maintain stability, there is no front loading of the casters and no compromise to maneuverability or safety. Because the user's COG and the chair's center of rotation remain aligned, the caregiver is not lifting or lowering the user's weight when tilting and un-tilting. With the Quickie IRIS, these movements are smooth and effortless, with no need for mechanical assists. For the user, a constant COG means elimination of the triggers or disturbances that could result in spasticity, agitation or protective reactions. With these benefits, the Quickie IRIS can provide unsurpassed maneuverability, accessibility, safety and function.
Since the key feature of the Quickie IRIS is the alignment and consistency of the user's COG, it is critical that the system provides a way to adapt to any changes in COG position. The location of each user's static COG is dependent on his or her body type and the size, type or location of the specific seating system being used. If these variables change for a particular user, the COG must be realigned with the center of rotation of the chair in order to achieve maximum benefits from the tilt system. To accommodate these variations, the Quickie IRIS uses adjustable back posts and adjustable front seat tubes (with hanger brackets) that can be moved forward or backward on the frame. This provides the ability to adjust the position of the user's COG in relationship to the center of rotation of the chair, while still maintaining the correct available seat depth.
For example, if a thicker solid back is attached to the front of the backposts, the user's COG is now positioned in front of the center of rotation and is no longer in alignment. Moving both the backposts and the front seat tubes rearward will move the COG rearward and realign it with the center of rotation, without changing the available seat depth. Similarly, adjustments to accommodate changes in the user's seat depth can be made without compromise to the COG/center of rotation alignment. For example, to accommodate growth, a longer seat depth can be created by adjusting the back posts rearward and the front seat tubes forward, thus maintaining the COG position. Twelve backpost positions (in one half inch increments) on the seat frame and three front seat tube lengths, each with 4 feet of horizontal adjustment, provide combinations that result in seat depths from 15 inches to 22 inches.
Another key feature of the Quickie IRIS is the inherent stability that allows the use of the shortest frame on the market and optimal positioning of the upper seat frame over the base frame. If this relationship is compromised, usually due to changes in seat depth, the whole rocker system and upper seat frame can be adjusted forward or backward on the base frame to accommodate these changes and reposition the upper seat frame for maximum stability and maneuverability . For example, if the seat depth is increased to accommodate a user with very long legs, the seat frame will extend further over the base frame, potentially increasing the load on the front caster and decreasing front stability. With the Quickie IRIS, the upper seat frame can be repositioned rearward on the base frame to redistribute the weight of the upper seat frame and user. Four hole positions provide a total of 3 feet of horizontal adjustment.
The Quickie IRIS includes a number of adjustments and options to make it the most versatile and user-friendly chair on the market. Axle plate adjustments provide seat to floor heights from 14 and a half inches to 20 inches in half inch increments. A seat to floor height of 12 and a half inches can be achieved with a drop seat. The seat width can be adjusted from 14 inches to 22 inches in half inch increments with no additional parts. The range of tilt can be set at 5 degrees anterior to 50 degrees posterior, 0 degrees to 55 degrees posterior or 5 degrees posterior-60 degrees posterior. Adjustable back posts provide seat to back angles of-10 degrees to 30 degrees in 5 degree increments. The backposts also feature a patent pending placeholder that allows adjustment of horizontal position and angle without hardware removal. Other options include a reclining back, a contracture footrest, adjustable height stroller handles, a four-hole caster fork, a one-arm drive, transit option brackets, vent and vent battery tray, an adjustable-depth drop seat pan, a tilt indicator and a heavy duty (350 lb) weight limit package.
The Quickie IRIS combines a unique rotational design with innovative features and adjustments. While still providing all the clinical benefits of tilt, this system eliminates some of the inherent problems with the previous designs of single pivot, multi pivot and pivot and slide systems. For the user this translates into a system that features maximum stability, accessibility and safety with minimal disturbance or disruption. For the caregiver, this system provides maximum maneuverability and ease of use, with the most user-friendly, efficient and functional adjustments of any other system. The Quickie IRIS has taken the evolution of the tilt (rotation) in space chairs to a new level.
This article originally appeared in the July 2003 issue of HME Business.