WHEELCHAIR BACK SYSTEM

Abstract: The invention describes a seat back system (20-30-10) for wheelchairs which provides for height adjustability of the back, adjust­ ment of the tilt of the back, a lumbar support (120, 130) which may be positioned to fit the specific height required by the wheel­ chair user independent of the height of the back, and provides for contoured, adjustable lateral support. The back system (20-30-10) may be readily attached to or detached from a wheelchair, in order to fold up the wheelchair for transportation or storage. The wheelchair back system (20-30-10) may be used on new wheelchairs and may be retrofitted on existing wheelchairs to replace existing back structures

Description: The present invention relates to a seat back system for wheelchairs which provides for height adjustability of the back, adjustment of the tilt of the back, a lumbar support which may be positioned to fit the specific height required by the wheel-chair user independent of the height of the back, and provides for contoured, adjustable lateral support. The back system may be readily attached to or detached from a wheelchair, in order to fold up the wheelchair for transportation or storage. The wheelchair back system may be used on new wheelchairs and may be retrofitted on existing wheelchairs to replace existing back structures. Background of the present invention Many of the problems faced by wheelchair users and particularly the paraplegics are kyphosis, scoliosis, instability, redness of the spine, and pain of the back, which conditions are aggravated by soft, curved "sling" upholstery conventionally used in wheelchairs. A modular wheelchair with an adjustable back is described in US-A-4 753 482. It contains modularly sized elements of a firm resilient and sculptable material, preferably made of a foam material and selected to fit the individual support needs of the user The present invention replaces the conventionally used wheelchair back upholstery with a comfortable, sturdy, adjustable, supportive, pressure relieving, easy-to-use back system designed to attack back problems. Kyphosis Kyphosis, probably the most common back deformity, is a rounding of the spine in a "humpback" posture and is often combined with a "slouching" posture, with the hips sliding away from the back of the wheelchair. This condition is most common among older patients, but is rapidly becoming a problem among young paraplegics and quadriplegics sitting against low "sport" backs that sag after a few months' use. The back system of the present invention is firm, to prevent sagging of the back, and it is contoured to conform to the natural curvature of the back and to provide lateral stability. Accordingly, a built-in-lumbar support allows the user to sit straighter, thus preventing rounding of the back and the resulting kyphosis. Scoliosis Scoliosis, an "S" curvature of the spine, is most frequently developed by females. It is often caused by a non-supportive sitting base that encourages pelvic obliquities (uneven hips) and aggravated by a wheelchair back that does not provide support from side to side. The back system of the present invention supports against side to side leaning and the development of scoliosis in three ways: 1. By restoring the lumbar curve of the user, it mechanically stabilizes the spine of the user to reduce the tendency to lean to one side; 2. By totally conforming to the back of the user, it naturally grips the user's back to provide natural lateral support; and 3. By allowing Velcro® attachment of contoured lateral supports, the user can take advantage of the most comfortable, unobtrusive lateral supports available today. Instability The tendency to fall from side to side or to fall forward is common among users with head injuries, multiple sclerosis, quadriplegics and other disabilities where there is an impairment of cognitive or nerve function. To prevent this tendency, these patients tend to slouch in their wheelchairs in order to lower their center of gravity and gain stability. This slouching may result in kyphosis, aggravated back pain, coccygeal pressure sores, and improper leg positions. The back system of the present invention is scientifically contoured to hug the back of the user, thus enabling the user to sit up straight. The contoured lateral supports provide the user with a stable back which allows the user to sit taller in the wheelchair, with less fear of falling. Redness of the Spine The spine is a series of bony protrusions that are subject to pressure, shearing and abrasion - and a resulting skin redness and breakdown. The most prevalent problems come with kyphosis and scoliosis, which can accentuate a bony prominence. Skin breakdown can also result from an extreme weight loss or a gibbus deformity (where the spine is fused after a break). The back system of the present invention reduces the outwardprotrusion of the spine, by sitting the user straighter. In addition, a fluid filled pad is inserted up and down the middle of the back, to solve pressure problems where they are most likely to occur - on the spine. Additionally, a 1/4-1/2 inch (0,63 - 1,27 cm) layer of reticulated open cell foam behind the cover increases comfort and reduces pressure on shoulder blades and other bony protrusions. Back Pain Back pain is undoubtedly the most common back complaint. It can be caused by any of the factors mentioned above. The most common cause, however, is a backward tilt of the pelvis, a loss of the natural lumbar curve, and the resulting strain placed on the spine and on connecting muscles. The back system of the present invention reduces back pain by pushing the pelvis into a forward tilt, thus restoring the natural lumbar curve and reducing the stress on the user's back. The back system of the present invention also provides a universal mounting system which will accommodate wheelchairs having differing widths, wherein the vertical posts are spaced at different distances, it will accommodate posts of different diameter, and it will accommodate posts which have a different tilt or curvature. This allows the back system of the present invention to be retrofitted on existing wheelchairs, as well as installed as original equipment on new wheelchairs. Moreover, the mounting system which forms a part of the present invention allows ready removal of the back system in order to collapse the chair for transportation or storage and provides for easy reinstallation to produce a stable wheelchair back. The attachment system is also easy enough to use that a quadriplegic with limited hand function can still install it. BRIEF DESCRIPTION OF THE PRESENT INVENTION The present invention provides a wheelchair back system which provides a high degree of support and adjustability in order to accomplish various therapeutically significant functions, while at the same time providing a wheelchair back system which has a streamlined appearance and is generally aesthetically pleasing. Specifically, the wheelchair back system of the present invention provides a back which may be raised and lowered to accommodate the stabilization needs of the patient; it may be tilted forward or to the rear to accommodate the needs of the wheelchair user; it includes an adjustable height lumbar support; a unique spinal protection device; and adjustable side bolsters to provide back support and stability as may be needed by a wheelchair user. Further, the back support system of the present invention provides for ready adjustment of these features and, at the same time, provides for easy disengagement of the back system when it is desired to fold up the wheelchair for transportation or storage. Still further, the present invention provides a wheelchair back system with a cover which may be readily removed for laundering. The wheelchair back system of the present invention may be retrofitted on existing wheelchairs, as well as fitted as original equipment on wheelchairs. DESCRIPTION OF THE DRAWINGS In order that the invention may be more readily understood including the various embodiments of the invention, references are made to the accompanying drawings in which: FIGURE 1 is an isometric front view of the wheelchair back system, affixed to a wheelchair, with the cover in place thereon: FIGURE 2 is an isometric, exploded front view of the wheelchair back system showing the cushion separated from the hard plastic shell positioned on the vertical wheelchair posts; FIGURE 3 is an isometric rear view of the wheelchair back system showing the attachment of the hard plastic shell to the vertical wheelchair posts; FIGURE 4 is a cross-sectional top view of the wheelchair back system, taken at section 4-4 of FIGURE 1; FIGURE 5 is a cross-sectional side view of the wheelchair back system, taken at section 5-5 of FIGURE 4, FIGURE 6 is a fragmentary cross-sectional side view of the wheelchair back system, taken at section 6-6 of FIGURE 1; and FIGURE 7 is a fragmentary cross-sectional top view of the wheelchair back system, taken at section 7-7 of FIGURE 6. DETAILED DESCRIPTION OF THE PRESENT INVENTION The wheelchair back system of the present invention generally comprises plastic shell 20 and mounting system 30 which is used to affix plastic shell 20 to vertical posts 60 of a wheelchair. Mounting system 30 attaches plastic shell 20 to vertical posts 60 and provides for vertical adjustment of the plastic shell 20 with respect to posts 60. Cushion 70 is removably attached to plastic shell 20 and serves to cushion the back of the wheelchair user. Vertical channel 80 in cushion 70 provides space for pad 90 which is filled with a flowable fluid and thus provides for protection of the spine, particularly in the thoraic region, for wheelchair users. Lumbar support 120 is affixed to cushion 70, preferably astride channel 80 and under flowable fluid filled pad 90. Lumbar support 120 is vertically adjusted along channel 80 of cushion 70. Bolsters 130, which are removably attached to cushion 70, provide additional lateral support to the wheelchair user, if necessary. Cover 140 is adapted to cover cushion 70 along with bolsters 130 and the lumbar support 120, etc., and extend around the edges of cushion 70, and lock between cushion 70 and plastic shell 20 when cushion 70 is mounted to plastic shell 20. Cover 140 thus provides the wheelchair back system with a streamlined, aesthetically desirable appearance. PLASTIC SHELL Plastic shell 20 is a hard, relatively rigid, relatively inflexible matrix which extends between the wheelchair posts 60 and provides mechanical support for the back system. It may be produced by formed ABS plastic about 150-200 mils (0,375 - 0,5 cm) thick. In wheelchair back systems designed for adult use, plastic shell 20 should be about 17 inches (43 cm) from top to bottom. The overall width should be sufficient to extend from the outside edge of one vertical wheelchair post 60 to the outside edge of the opposite vertical wheelchair post 60. Plastic shell 20 preferably has a slight convex curvature to generally conform to the backward bend used by most wheelchair posts. The lateral edges of plastic shell 20 preferably comprise U-shaped channels 22, which extend from the top to the bottom of plastic shell 20. Channels 22 are made up of inner leg 24 and outer leg 26. The space between inner leg 24 and outer leg 26 should be wide enough to wrap around vertical posts 60 of different diameters and having different spacings. Accordingly, it is preferred that channels 22 be about 2 inches (5 cm) wide. Outer leg 26 of channel 22 preferably extends approximately to the rear of vertical posts 60 and provides side to side support for the back system. Outer leg 26 is also aesthetically designed to serve as a cover for vertical posts 60. Outer leg 26 may be shortened if desired for aesthetic purposes. If plastic shell 20 has a slight convex curvature, channel 22 is also convex, but it is preferred that channel 22 have flat portions 28 at its upper and lower end in order to provide for a two point contact of the channel 22 against vertical post 60. Preferably, the flat portion 28 of channel 22 will cooperate with spacers 50 in adjusting the tilt of the back system, as is described below. It is contemplated that the inner legs 24 of channels 22 will abut the vertical posts 60 in those wheelchairs which are designated 17 inch (43 cm) wheelchairs. Similarly, it is contemplated that the outer legs 26 of channels 22 will abut the outer side of vertical posts 60 in 18 inch (46 cm) wheelchairs. It is contemplated that for wheelchairs having posts with nonstandard spacing, spacers may be employed to securely position vertical posts 60 with respect to legs 24 and 26. It is contemplated that additional sizes will be introduced for 12 - 13 inches (30 - 33 cm) wide, 14 - 15 inches (33 - 38 cm) and 19 - 20 inches (48 - 51 cm) wide wheelchairs. THE MOUNTING SYSTEM Mounting system 30 is a "soft system" (i.e., it is essentially free of hardware components) and comprises straps 32 affixed to outer legs 26 and adapted to extend to the rear of vertical post 60 and extend along the back of plastic shell 20, over pad 34. Preferably, pad 34 is a rectangle of VELCRO affixed to the back of plastic shell 20, as shown in FIGURE 3. Extension 36 of strap 32 is also fitted with a VELCRO surface on its forward side, where it is adapted to gauge or mate with pad 34, thus securing strap 32 around post 60. Preferably, strap 32 is about 4 inches (10 cm) wide. Extension 36 of strap 32 may include handle means 38 which facilitates disengaging extension 36 from pad 34. Strap 32 may be affixed to outer leg 26 by a variety of means which will be known to those skilled in the art. Bracket 40 is affixed to vertical post 60 and is vertically adjustable thereon. Preferably, bracket 40 includes a vertical slot 42 through which screw 44 affixes bracket 40 to vertical post 60. Vertical adjustment of bracket 40 may be achieved by loosening the screw 44, and sliding the bracket 40 upwardly or downwardly, as the screw 44 slides in slot 42 and tightening the screw when the desired elevation is achieved. Bracket 40 also includes lower shelf 46 and upper shelf 48 which straddle strap extension 36 and lock strap extension 36 in the desired elevation, thus causing the back to remain at the elevation selected through the adjustment of screw 44 in slot 42 of bracket 40. Most wheelchair vertical posts 60 are arcuate in shape, as is shown in FIGURE 5. Consequently, plastic shell 20, which may be essentially planar, contacts the vertical posts 60 at the top and the bottom. Thus the tilt (forward and backward) of the seat back system is to some extent a function of the particular curvature of vertical posts 60. The present invention contemplates the use of spacers 50 which are disposed in channel 22, at the top and bottom of channel 22, against flat portions 28, between plastic shell 20 and vertical posts 60. Conveniently, spacers 60 may be adhesively attached to plastic shell 20. In order to obtain tilt adjustment, spacers 50 are either removed or stacked upon one another to create the desired adjustment. THE CUSHION Cushion 70 is preferably fabricated from a self-skinned polyurethane foam, although other materials may be used. Cushion 70 preferably extends into the well defined by plastic shell 20 between channels 22 and extends laterally beyond vertical posts 60. The height of cushion 70 should be approximately the same as the height of plastic shell 20. Thus a cushion of about 18 x 18 x 1 inches (46 x 46 x 2,5 cm) is contemplated. Cushion 70 is preferably removably affixed to plastic shell 20 by a plurality of VELCRO closures. In the preferred embodiment, as shown by FIGURE 2, side VELCRO strips 50 and top VELCRO strips 52 are affixed to plastic shell 20. Corresponding side VELCRO strips 72 and top VELCRO strips 74 are adhesively affixed to the back of cushion 70 and are adapted to engage side VELCRO strips 52 and top VELCRO strips 54 to removably affix cushion 70 to plastic shell 20. THE CHANNEL Channel 80 is vertically disposed along the center of cushion 70 and extends generally from the top of cushion 70 to the bottom, as shown in FIGURE 2. Preferably, channel 80 is about 4 inches (10 cm) wide and about 1/2 inch (1,25 cm) deep, although the dimensions are not particularly critical. Similarly, the channel may be shorter, i.e. have a smaller height (measured from top to bottom) than the channel illustrated in FIGURE 2. Pad 90, which is filled with a flowable fluid, is positioned in channel 80 and preferably occupies substantially the entire volume of channel 80. VELCRO strips, not shown, are affixed to pad 90 and corresponding positions in channel 80, in order to secure pad 90 in channel 80. Pad 90 generally comprises an envelope 92 constructed of a front layer 94 and a back layer 96 of flexible material such as polyethylene or polyurethane. Layers 94 and 96 are heat sealed about the periphery 98, in order to form a container to hold flowable fluid 100. Pad 90 has at least one transverse lateral segment 102 formed by heat sealing front layer 94 to back layer 96 which divides pad 90 into a plurality of horizontally divided chambers. The transverse segment 102 prevents the flowable fluid 100 from flowing downwardly and thus maintains the flowable fluid throughout the entire height of pad 90. Preferably, a tube which is approximately 125 % of the length of channel 80 may be filled with a required amount of flowable fluid, flattened and sealed at each end. The tube thus makes up both the front layer 94 and back layer 96 of pad 90. The tube is then heat sealed transversely at appropriate spacings to form transverse segments 102. The transversely sealed tube is then inserted in the channel and the extra 25 % of material is draped over the transverse segments 102 as shown in FIGURE 6, thus providing for flowable material between the transverse segments and the wheelchair user. Alternatively, front layer 94 is puffed out during manufacture, so that the front layer 94 contains more material (more square centimeters of material) than back layer 96. The use of added material in the front layer 94 allows the front layer 94 to lap over transverse segment 102 as shown in FIGURE 6, and thus allow the flowable fluid to come to rest over the transverse segment 102 and provide a cushioning material between the transverse segment 102 and the patient's back. THE FLOWABLE FILLING MATERIAL The flowable fluid may be selected from a number of different fluid types. Gases, such as air may be used, but liquids such as water are preferable because the weight of the water provides more stability. However, it is preferred to employ as the fluid a highly viscous liquid, i.e. plastic or viscous thixotropic material, which flows gradually when pressure is applied to it, but which maintains its shape and position in the absence of pressure (hereinafter sometimes referred to as "plastic"). One such viscous fluid is commercially available under the trade name FLO-LITE, the registered trademark of Alden Laboratories. Suitable flowable materials are described and claimed in the U.S. Patent Numbers listed below, which are incorporated by reference herein: 3,237,319 3,402,411 3,635,849 3,798,799 4,038,762 4,083,127 4,108,928 4,144,658 4,229,546 4,243,754 4,255,202. Additionally, the flowable fitting material described in Applicant's patent application Serial No. 017,711 filed February 24, 1987, now U.S. Patent No. 4,728,551, may be used as the flowable material in the practice of the present invention. LUMBAR SUPPORT Lumbar support 120 is designed to fit in channel 80, but be moved vertically to the position which most comfortably supports the lumbar region of the wheelchair user. Lumbar support 120 may be produced from a solid piece of foam material, such as self-skinned polyurethane or polyethylene. Alternatively, the lumbar support may be a pad of the style used for pad 90, that is, filled with a flowable, viscous, thixotropic material. Lumbar support 120 is affixed in the channel 80 through Velcro strips (not shown) attached to the rear side of lumbar support 120 where they engage Velcro strips which extend vertically up and down the length of channel 80. This allows the lumbar support to be positioned at the correct elevation, independent of the height at which the wheelchair back is set. Lumbar support 120 is designed to fit under pad 90 and thus thrust pad 90 forwardly in the region of the lumbar support as shown in FIGURE 4 - see 120A. THE BOLSTERS Bolsters 130 are designed to be removably affixed to the sides of cushion 70 where they provide lateral support for the wheelchair occupant. Preferably, horizontal Velcro strips 132 are adhered to the rear side of bolsters 130 where they engage vertical Velcro strips 134 attached to the sides of cushion 70. This allows for vertical and horizontal adjustment of the bolster position with respect to cushion 70. Alternatively, bolsters of the type disclosed in U.S. Patent 3,542,421 may be used. THE COVER Cover 140 is designed to fit over cushion 70 and over bolsters 130 to provide the wheelchair back system with a streamlined, aesthetically pleasing appearance, as shown in FIGURE 1. As shown by FIGURE 4, the cover extends around to the rear of cushion 70. Preferably, elastic means 142 is positioned at the edge of cover 140 in order to urge the cover edges to surround cushion 70. When cushion 70 is affixed to back 20, the edges of the cover 140 are held between cushion 70 and plastic shell 20. Elastic means 142 facilitates the positioning of the cover on cushion 70 before cushion 70 is affixed to the plastic shell 20. Preferably, the cover is lined with a reticulated, open-cell foam, in 1/4 to 1/2 inch (0,63 - 1,27 cm) thickness, to encourage air circulation and provide extra comfort. Preferably, cover 140 has tucks of extra material sewn into the top and/or bottom to allow expansion of the cover when using bolsters 130.

Claims: A wheelchair back system adapted to be mounted on vertical posts (60) of a wheelchair, said back system comprising: a plastic shell (20), a mounting system (30) and a cushion (70); said mounting system (30) comprising a pair of vertical channels (22) attached to said plastic shell (20), said channels (22) having an upper end and a lower end, said channels (22) adapted to partially encircle the vertical posts (60) of the wheelchair and contact said posts (60) at said upper end and said lower end; brackets (40) affixable to the vertical posts (60) of the wheelchair; straps (32) affixed to said channels (22) adapted to engage said brackets (40) to hold said shell (20) adjacent to said wheelchair posts (60) and to vertically position said back on said wheelchair posts (60); and said cushion (70) removably affixed to the front side of said plastic shell (20). A wheelchair back system as described in claim 1, wherein said cushion (70) includes a vertical channel (80) adapted to receive a pad (90), said pad (90) comprising a plurality of horizontally divided chambers, said chambers being filled with a flowable fluid (100). A wheelchair back system as described in claim 2, wherein said chambers are filled with a viscous liquid material which flows under pressure, but which maintains its shape and position in the absence of applied pressure. A wheelchair back sytem as described in claim 1, wherein said cushion (70) includes a vertically movable lumbar support (120) pad removably affixed to said cushion, said lumbar support (120) adapted to be affixed to said cushion (70) at a selected hight, independent of the height of said back. A wheelchair back system as described in claim 1, wherein said cushion (70) includes bolsters (130) which are removably affixed to the front lateral portions of said cushion (70), said bolsters (130) being affixed to said cushion at a selected position and adapted to provide lateral support to a person sitting in the wheelchair. A wheelchair back system as described in claim 2, wherein said cushion (70) comprises a cover (140) which surrounds said cushion (70) and which extends to the rear of said cushion (70), whereby said cover (140) extension is located between said plastic shell (20) and said cushion (70) when said cushion (70) is attached to said plastic shell (20). A wheelchair back system as described in claim 1, wherein said straps (32) are essentially free of hardware. A wheelchair back system as described in claim 4, wherein said lumbar support (120) is removably attached to said back system, said lumbar support (120) being adjustable as to height, independent of the height of said back. A wheelchair back system as described in claim 5, wherein said back system includes a curved and contoured cushion (70) which is generally concavedly curved, wherein the lateral portions of said cushion (70) are forward of the central portion, said system further comprising bolsters (130) which are adjustable as to hight, said bolsters (130) having a convex surface which is complimentary to the concave surface of said contoured cushion (70), attachment means adapted to affix said bolster (130) to said cushion (70) in the area of said convex surface independent of the height of said back. A wheelchair back system as described in claim 2, wherein said back system includes a vertical central channel (80) in said back, said channel (80) being filled with a pad (90) having a plurality of chambers divided horizontally by transverse segments (102), said chambers being filled with the flowable fluid (100) which is a viscous liquid which flows under pressure, but which maintains its shape and position in the absence of applied pressure. A wheelchair back system as described in claim 10, wherein said chambers filled with the flowable fluid (100) overlap the respective transverse segments (102) lying underneath. A wheelchair back system as described in claim 1, wherein said channels (22) comprise flat portions at said upper and lower ends adapted to contact said posts (60), wherein the angle of the seat back is adjusted by placement of spacers (50) between said flat portions and said wheelchair posts (60), and wherein said cushion (70) is being positioned on the front side of said shell (20). A wheelchair back system as described in claim 12, wherein said channels (22) are curved, to approximate the curvature of said wheelchair posts (60) between said upper and lower flat portions.

Inventors: JAY, ERIC C., NORDQUIST, MICHAEL H.
Applicants: JAY MEDICAL, LTD.
Application year: 1989
Main classification: A61G5
IPC codes: A47C7, A61G5