Title:
Leg and knee support devices for squatting and kneeling
Kind Code:
A1


Abstract:
One or more devices designed to decrease stress to the knee for use in activities requiring longstanding or repetitive squatting and/or kneeling positions. The devices include at least one cushion that increases the distance between the buttock and the calf during squatting, and may optionally include other cushions for the knee and ankle area. The devices may optionally comprise at least one weight-supporting layer and at least one pressure distribution layer.



Inventors:
Michalow, Alexander (Bourbonnais, IL, US)
Application Number:
09/761258
Publication Date:
07/18/2002
Filing Date:
01/16/2001
Assignee:
MICHALOW ALEXANDER
Primary Class:
International Classes:
A41D13/06; (IPC1-7): A47G9/00
View Patent Images:
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Primary Examiner:
CONLEY, FREDRICK C
Attorney, Agent or Firm:
Faegre Drinker Biddle & Reath LLP (Chicago) (CHICAGO, IL, US)
Claims:

What is claimed is:



1. A device for relieving stress to the knee comprising at least one compressible cushion having one or more convcavely shaped sides generally conforming to a body part to be cushioned, wherein the cushion is removably attached to the body.

2. The device of claim 1 wherein at least one cushion comprises a chamber filled with one of the group selected from a fluid, a gas, a bead or a solid.

3. The device of claim 2 wherein the chamber is surrounded by compressible foam.

4. The device of claim 1, wherein at least one cushion comprises: a weight-supporting layer; a pressure distribution layer having at least one generally concave surface; and an attachment means for removably affixing the device to the body.

5. The device of claim 4 wherein the weight-supporting layer comprises at least one encapsulated filled chamber, and the pressure distribution layer surrounds the chamber.

6. The device of claim 5, wherein the chamber contains material of a greater density than the pressure distribution layer.

7. The device of claim 4, wherein the weight-supporting layer comprises at least one fluid, foam, bead, solid or gas filled chamber and the chamber is surrounded by a layer of compressible cellular material.

8. The device of claim 1, wherein the device is shaped to be positioned between a buttock and a calf and an ankle, wherein the device increases the distance between the buttock and calf during squatting.

9. The device of claim 1, wherein the device comprises two juxtaposed cushions that are shaped to be concave on the side opposing the body and generally planar on the side opposing the opposite cushion.

10. The device of claim 1, wherein the cushions are irremovably attached using straps.

11. The device of claim 4 wherein the cushions are irremovably attached using straps.

12. The device of claim 1, wherein the device includes one cushion adapted for attachment to the buttock, and a second cushion adapted for attachment to the lower calf and heel.

13. The device of claim 12, wherein the device further includes a third cushion adapted for attachment to the ankle and shin.

14. The device of claim 13, wherein the third cushion extends to cover the knee.

15. The device of claim 13, wherein the device includes a fourth cushion adapted to be attached opposite the knee.

16. The device of claim 1 wherein the attachment means is a garment to which the cushion or cushions are attached.

17. The device of claim 4 wherein the attachment means is a garment to which the cushion or cushions are attached.

18. A device for relieving stress to the knee comprising at least one compressible cushion having one or more convexly shaped sides generally conforming to a body part to be cushioned, wherein the cushion comprises a weight-supporting layer and a pressure distribution layer, and wherein the weight-supporting layer may further comprise at least one fluid or solid or bead or gas filled cell and the pressure distribution layer comprises a cellular foam material and wherein the cushion(s) are removably attached to the body.

19. A method for decreasing stress to the knee during squatting on a surface, comprising the step of inserting at least one cushion with at least one concave side between the buttock and calf that separates the buttock from the calf during squatting by a distance of from 2 inches up to 12 inches, wherein at least one concave side faces the buttock.

20. The method of claim 19 wherein the method includes the additional step of inserting at least one cushion with at least one concave side between an ankle and the surface, wherein the concave side faces the ankle.

Description:

BACKGROUND OF THE INVENTION

[0001] Problems at the knee and ankle joints are well known to anyone involved in the treatment of the knee or performance of activities that require a prolonged or repetitive squatting and/or kneeling position. Examples of such activities include carpet and tile installation, mechanical auto work, home cleaning, carpentry, gardening, baseball catching, meditation, etc. Many medical problems experienced from prolonged or frequent squatting or kneeling concern the patella (kneecap) and the patellar tendon. Secondary are effects on the lateral and medial menisci (a pair of structures in the knee that separate the femur from the tibia and function as shock absorbers for the knee). A third problem is the development of bursitis, a painful inflammation of the bursa, the structure between the patella and skin. Finally, squatting and kneeling maneuvers can also harm the ankle and Achilles tendon. The effects of squatting and kneeling on these structures are described below.

[0002] Squatting, kneeling and shifting position while squatting and kneeling is performed largely through contraction of the quadriceps muscle. This contraction can be harmful to the knee, particularly the patella and related structures, as explained below.

[0003] The patella acts as a type of pulley for the quadriceps/patellar tendon mechanism, which gives the quadriceps muscle a mechanical advantage in extending the leg. Thus, forces generated by the quadriceps muscle (which extends the lower leg) are transmitted through the patella. More specifically, these forces act on the contact points, which are the cartilage surfaces of the patella, and on the adjacent femoral cartilage. When the knee is in a position of flexion beyond 45°, the quadriceps muscle becomes less effective in extending the leg from a squatting position and also simply performing leg extension movements. To compensate for this loss of effectiveness during quadriceps extension, the contact point of the femur and the tibia rolls back on the tibia, which lengthens the leverage, or contact, point from the patella, as explained further below. The extension leverage gained with “rollback,” however, does not completely compensate for the mechanical disadvantage of the hyperflexed knee position. Thus, a larger contraction force is required to extend the leg from a hyperflexed position than when it is at 45 degrees of flexion. However, during quadriceps contraction, a compression force is created on the patella by the tension on the patellar mechanism. The quadriceps generally contract during shifting and squatting, or rising from a squatting or kneeling position. The compression forces generated by such contraction are transmitted to the patellar cartilage, which result in wear and tear of the patella and related structures such as ligaments and tendons.

[0004] Also, when the knee is hyperflexed (as in a completely squatted position), the direction of the force generated by the quadriceps during contraction is nearly perpendicular to the patellar cartilage contact. However, when the knee flexion is less, the quadriceps forces are more tangential to the patellar contact points, which causes less pressure on the patella. Thus, because a larger quadriceps contraction is required to quit a hyperflexed position, and the line of force to the patella is more direct (i.e., perpendicular), relatively large forces and thus pressure are transmitted to the patellar and adjacent femoral cartilage surfaces at their contact points when the quadriceps muscle contracts while the knee is in the hyperflexed position. These high forces stress the cartilage, which can lead to its breakdown. Prolonged or repetitive hyperflexion as in squatting can, thus, result in increased wear to the patellar cartilage, which often leads to inflammation and pain. Ultimately, this can lead to patellar arthritis, among other conditions.

[0005] While prior art often indicates that passive maintenance of a squatting position causes knee problems, the more serious and frequent problems in the patella are generally caused by the active contraction of the quadriceps muscles while one is entering or quitting a squatting or kneeling position, or by shifting alignment while in a passively squatted position.

[0006] When in a squatted position with the quadriceps muscles relaxed, the primary areas in the lower extremities that absorb body weight are the contact points of the calf and hamstrings muscles. Some weight is also borne by the posterior tibio-femoral contact area. For a non-arthritic knee, when one is squatting, the first discomfort often occurs in the calf and hamstring muscles due to the significant amount of compression they endure At the onset, pain can arise from simple mechanical strain. Next, this compression leads to a disruption of the muscle's blood supply, leading to localized hypoxia (low oxygen) which itself is a painful condition. The pain that arises in these muscles causes the individual to change position to relieve this pressure and discomfort. This change in position requires active contraction of the quadriceps muscle.

[0007] In addition to patellar wear, there are a number of other medical conditions that can result from quadriceps contraction. One of these, tendonitis, is the result of transmission of forces that are generated by the contraction of the quadriceps muscle across the patellar tendon. These forces, along with direct pressure to the patella when one is kneeling and squatting simultaneously, can lead to wear in the tendon. The inflammation and pain resulting from this wear and tear is tendonitis.

[0008] A secondary problem associated with the hyperflexed position of the knee and related quadriceps contraction is stress on the menisci. The menisci are a pair of structures that are wedged between the two weight bearing surfaces of the femur and tibia. When the knee is in a hyperflexed position, rollback of the contact, or pressure, point of the force occurs between the tibial and femoral articulum surfaces, shifting the contact point of force farther back on the tibia. This causes increased force at the back of the knee joint and, thereby, on the menisci. If one of the menisci is “pinched” between the opposing surfaces and there is sudden change in position, such as arising or twisting, this may cause a tear of a meniscus, which often requires surgery to correct.

[0009] Another condition that occurs at the patella is bursitis, a painful swelling of the bursa. This condition occurs with prolonged kneeling, or with kneeling on hard surfaces. Although squatting by itself doesn't cause this condition, kneeling and squatting occur simultaneously in many circumstances.

[0010] Yet another area of discomfort caused during squatting and kneeling relates to the Achilles tendon and ankle area. If the ankle is kept in a prolonged dorsiflexed (extended or upward) position, as in squatting, there is increased strain on the ankle structures and Achilles tendon. The individual will shift position to alter the stresses on these structures. This shifting of position results in quadriceps contraction, which can cause the problems described above.

[0011] In order to reduce stresses to the above areas, some type of support/cushioning device is generally thought to be effective. The idea of decreasing stress to the knee while in the squatted position using cushioning is known. However, most prior art devices for relieving stress suffer from a number of drawbacks generally related to materials and positioning, as described below.

[0012] Any cushioning support device requires adequate strength for the support of body weight. A number of different materials are used for cushioning in prior art devices, most commonly foam rubber, or gas, gel or fluid filled bladders. Foam rubber materials, most often flat cushions, suffer from the drawback of imperfectly conforming to the shape of the cushioned object, thus failing to utilize the entire surface area over which the supporting force is applied. In addition, a foam cushion has “memory,” which is a tendency to return to its original shape Both of these behaviors often result in large contact pressures, the largest pressures being transmitted to the most prominent areas of bone, which are those directly contacted by the foam. Lastly, most cellular foam materials lack sufficient density to adequately support the necessary weight. Gas, gel or fluid-filled “bladders” depend on a mechanism called “hammocking” in order to suspend the cushioned object. While generally having adequate weight-supporting capacity, hammocking devices can cause high peak pressures to develop at protruding body parts such as the contact point between the calf and hamstring muscles, and can result in ineffective or minimally effective support to the cushioned area. In addition, bladder-type devices are subject to bursting.

[0013] Common prior art stress-relieving devices generally include seat or chair apparatuses, kneeling/sitting combined support structures such as cushioned knee troughs or cushions with an attached “chair” to unload the knees, and wedged cushions or pillows placed between the thigh and lower leg. Such chair-type and combined structures suffer from the drawbacks of generally not being portable and impractical for many settings such as construction or gardening, and thus are limited in their use. In addition, they generally utilize foam or fluid-filled bladders, which may have the weight-supporting drawbacks discussed above.

[0014] Wedged devices, generally cushioning placed between the thigh and leg are more practical in settings requiring portability. There are, however, some limitations to such devices—in general, they have a limited ability to separate the thigh and leg sufficient to provide significant relief of stress on the patella. Second, the cushioning surfaces, being generally convex foam cushions or filled bladders, often provide less than adequate support and dispersion of stress as they are not adequately shaped to conform to the body part being cushioned. Also, most prior art wedged devices are bulky, and are difficult to use if frequent shifting of position is performed.

[0015] Devices that are wedged between the mid thigh and leg may result in less than optimal patellar stress relieving properties, because they often increase the leverage effect that they are supposed to relieve. If the surface of the device is flat and wedged between the calf and hamstring contact areas, it may cause a separation stress on the components of the knee. The shifting that occurs in an effort to relive this stress causes quadriceps contraction, and accordingly, may result in increased patellar wear. In addition, such devices often have a flat or convex surface, leaving them with suboptimal cushioning capabilities in that the stress forces are not distributed over the entire surface of the cushion, causing increased contact pressure between the calf and hamstrings muscles. This increased pressure will lead to increased shifting in position and thus quadriceps contraction to relieve. Thus, such devices may result in a counterproductive increase in patellar pressure, rather than the desired decrease in stress to the patella. In addition, such wedge devices generally don't increase the buttock to heel distance, and thus do not provide the necessary relief of tension.

[0016] Although numerous devices for cushioning the knee are readily available, they generally include cushioning only for the patella, which will not serve to relieve the stress on the tibia during squatting. Lastly, most support devices suffer from the drawback of not providing ankle and heel support, for relieving stress during kneeling or when squatting or quitting a squatting or kneeling position.

[0017] From the above analysis it can be summarized that a device(s) intended to reduce stress at the knee joint from prolonged squatting and kneeling, needs to have an optimal mechanical stress-relieving function. This would include a device that: (1) supports bodyweight directly under the buttocks and upper thigh, placed so as to minimize weight bearing stress from the area near the knee joint up to the mid-thigh/mid calf contact points, (2) separates the thigh and leg in order to decrease the amount of knee hyperflexion, (3) supports the distal leg and ankle thereby reducing strain at the ankle and Achilles tendon, and (4) appropriately cushions the knee and proximal tibia to relieve contact stresses with the ground.

BRIEF DESCRIPTION OF THE INVENTION

[0018] It is an object of this invention to provide an improved cushioning device for use while kneeling and squatting that supports the knee and ankle.

[0019] It is also an object of this invention to relieve mechanical stress on the knee during squatting and kneeling by providing a support wherein distance is placed between the buttock and calf sufficient to lower patellar stress.

[0020] It is further an object of this invention to relieve discomfort on the ankle and Achilles tendon while one is in the squatting position by providing a support that minimizes flexion of the foot and ankle during squatting and kneeling.

[0021] It is a further object of this invention to provide a device for relieving stress on the prepatellar bursa of the knee during simultaneously squatting and kneeling.

[0022] It is also an object of this invention to provide a device for relieving pressure between the calf and hamstring muscles while squatting.

[0023] It is yet another object of this invention to provide a support device with improved cushioning ability over prior art devices.

[0024] It is a further object of this invention to provide a multi-layered support device for use in squatting and kneeling with improved weight-supporting ability over some prior art devices.

[0025] It is yet another object of the invention to provide a device for relieving stress to the knee that can be used where frequent shifting of position is performed.

[0026] Thus, the invention includes one or more devices designed to decrease stress to the knee for use in activities requiring longstanding or repetitive squatting and/or kneeling positions. The devices include at least one cushion that increases the distance between the buttock and the calf during squatting, and may optionally include other cushions for the knee and ankle area. The devices may optionally comprise at least one weight-supporting layer and at least one pressure distribution layer.

[0027] These and other objects and advantages of the present invention will become apparent from the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG. 1 is an illustration depicting the anatomy of the leg during squatting.

[0029] FIG. 2 illustrates the distribution of forces within the knee during squatting and kneeling.

[0030] FIG. 3 illustrates various embodiments of the invention.

[0031] FIG. 4 depicts a cross-sectional view of various embodiments of the multi-layered device of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0032] One way that patellar problems can be lessened is by the use of a device that decreases contact pressures at the calf and hamstrings muscles, thereby decreasing the fidgeting factor. Second, if the flexion angle can be made less acute, this would also decrease the force on the patellar cartilage. One way that this can be easily accomplished is by the use of a device that increases the buttock to heel distance so that pressure between the calf and hamstring muscles is lessened. Since the angle of force then becomes more tangential (rather than perpendicular to the patella) as the angle of flexion increases, the overall pressure to the patellar cartilage will be lower.

[0033] Stress to the menisci would be relieved if the amount of body weight that is transferred to the back of the knee with rollback were decreased. This could be accomplished by a device, which supports body weight on the opposite end of the thigh. A support under the buttock, which also separates the thigh from the lower leg would accomplish this goal.

[0034] Another area of discomfort relates to the Achilles tendon and ankle area. An individual generally shifts position to alter the stresses on these structures, causing muscle contraction and the resultant patellar problems described above. However, if the stress is reduced at the Achilles tendon and ankle area, the individual will shift positions less often, leading to fewer problems with the knee.

[0035] In addition, the incidence of bursitis could be lessened by using a device that supports both the patella and the proximal tibia during squatting, since weight is borne by both of these structures.

[0036] The invention described herein accomplishes each of these goals.

[0037] The device of the invention is an improved cushion that is designed to decrease stress on the knee during squatting and kneeling, as shown in FIG. 1. The leg 1 is comprised of a thigh 2, a knee 3, a calf 4, and ankle 5 and a foot 6. The thigh 2 includes a quadriceps muscle 7, a hamstring muscle 8, and a femur bone 24. The knee in relevant part comprises a patella, or kneecap 9, a patellar bursa (“bursa”) 10, a patellar tendon 11 and a pair of ligaments, each 12. In addition, the knee 13 includes a tibia articulation surface 14, and a femur articulation surface 15. The calf 4 in relevant part comprises a tibia bone 16 and a calf muscle 17. Opposite the calf is a shin, 18.

[0038] Referring now to FIG. 2, the action of squatting and kneeling is performed in large part by a contraction of the quadriceps muscle 7. The direction of force during this contraction is from the knee 3 to the torso, as shown by the arrow. In addition, the articulation surfaces of the femur and tibia (14 and 15 respectively) are compressed together, causing tibio-femoral compression at the posterior 13 of the knee, with the direction of force shown by the arrows. Moreover, this movement causes direct compressive force on the patella 9, in the direction shown by the arrow, and distraction force, or tension, primarily on the patellar tendon 11.

[0039] During passive squatting, the quadriceps 7 is relaxed, and the primary force absorbing regions are the contact points of the calf 4 and the hamstrings 8, as shown by the arrows in FIG. 2. When one shifts position while squatting to relieve discomfort at these contact points due to mechanical strain or localized hypoxia, the quadriceps muscle 7 is actively contracted, resulting in a distribution of force as described in the above paragraph, including large forces on the patella 9 and the patellar tendon 11. The forces described above are those that the present invention seeks to mitigate.

[0040] The device of the invention, several embodiments of which are shown in FIGS. 3a and 3c-k, seeks to reduce damage to the knee by reducing the need to shift position while squatting or kneeling, and seeks to provide improved support for the knee during squatting. FIGS. 3a, c, f, h and j comprise a shaped upper cushion 18 and a shaped lower cushion 19. These cushions contain a front surface 25 that is formed in a concave shape approximates the curvature of the body part they are disposed adjacent to. For instance, in the device designed to be attached to the calf 4 and buttock 20 as illustrated in FIG. 3a, first and second cushions 18 and 19 respectively, are shaped to correspond to the buttock 20 and calf 4, respectively, with a planar contact surface 22 between the cushions themselves. As depicted in FIG. 3a, the cushions are situated between the buttock 20, and the lower calf 21 and ankle 5. The purpose of positioning the cushions thusly is to increase the distance “d” between the buttock 20 and calf 21 to at least two inches up to approximately 12 inches, thus reducing the direct force on the patella 9 by changing the direction of the force, as shown in FIG. 3b. With use of the device of the invention, during contraction of the quadriceps 7, the force on the patella 9 is no longer direct and perpendicular (as illustrated in FIG. 2), but is largely tangential or indirect to the patella 9, as indicated by the arrows in FIG. 3b. Moreover, increasing the distance between the buttock 20 and calf 21 (FIG. 3a) has the added benefit of reducing the compressive force on the articulation surfaces of the femur and tibia (15 and 14, respectively) by reducing the weight and thus contact pressure at the hamstring/calf contact points. Lastly, separating forces on the knee are mitigated by use of such a device.

[0041] Many of the devices of the invention further include support for the ankle region 5, as illustrated in FIGS. 3h-j. The ankle cushioning 23 is sufficiently thick so that the ankle 5 and foot 6 are prevented from fall flexion up or down. Support at the ankle 5 results in less ankle discomfort, which results in less shifting and less active quadriceps contraction, and thus less stress on the patella. Such support may extend over the shin 18, and include the knee 3, as shown in FIGS. 3i and 3j.

[0042] The cushions of the invention comprise a generally polyhedron shape, having a front 25, a back 26, and first and second side surfaces 27 and 28 respectively), as shown in FIGS. 3f and 4. The front 25 is adapted to contact the body part to be cushioned, and the back 26 is adapted to be disposed adjacent to the back surface of the opposing cushion or adjacent to a front surface that faces an opposing body part. If the back 26 is adapted to be adjacent to another cushion, the back has an approx. planar surface for optimal maximum contact with the opposing surface, as illustrated in FIGS. 3a, c, f, g, h and j. Front surfaces 25 are generally concavely curved to provide maximum contact area with the wearer (providing cushioning and pressure distribution), and the back surfaces 26 are configured to maximize contact with the opposing surface (be it a body part or an opposing cushion) so as to provide the greatest surface area for the distribution of weight supporting forces. Thus, where a curved surface is desired, the cushions of the invention utilize curved, concave surfaces rather than the flat or convex surfaces of much of the prior art.

[0043] The dimensions of the curve should approximate the curvature of the part to be cushioned, for instance, the front of the knee cushions should approximate the general shape and curvature of the leg at the knee (as illustrated in FIGS. 3h-j), and the front of the buttock/calf cushions should approximate the general shape and curvature of the buttock and calf (as illustrated in FIG. 3 generally). In addition, if a single cushion will be used between two body parts, the opposing surface of the cushions should be shaped to the opposing surface. For instance, the cushions designed to fit between a buttock and a calf, the cushion should have a degree of curvature and shape approximating a buttock on one front, and a shape and contour designed to fit the opposing calf on the other front, i.e., it should be shaped in the saggittal plane as viewed from the side, and have a longer back than front to better mimic the angle of the calf and thigh that is assumed in the squatting position. In these instances, the back is disposed between the two fronts. Where the back 26 opposes another cushion back 26 (as in the double cushion embodiments illustrated in FIG. 3), the back surfaces should be planar.

[0044] Contoured cushions are preferred over flat or convex surfaces because forces are distributed to the cushion over the largest area possible, resulting in lower peak contact pressures, thereby more comfort and less fidgeting. This results in the lowest possible contact pressures, which result in the most comfort for the longest periods of time, hence the least number of changes in position and less quadriceps contraction. In preferred embodiments, the devices of the invention will be variously sized to accommodate various body types and sizes.

[0045] As illustrated in FIG. 3, the cushions may be detachably attached to the wearer by means of straps 24, although other releasable attachment means may be used, including but not limited to velcro, hooks, pockets in garments, and any other suitable means now known or hereafter developed. In addition, attachment to garments such as a pair of pants or work overalls, is also depicted and within the scope of the invention, as shown in FIG. 3k. This attachment may be either permanent (for instance sewn or glued attachment) or the cushions may be removable, such as but not limited to cushions inserted into pockets.

[0046] The devices may utilize a single cushion, as shown in FIGS. 3d and e, or multiple cushions, as shown in FIGS. 3c, g, h, i and j. FIG. 3c is a multiple-cushion device, including support covering the posterior ankle region 33. FIG. 3d illustrates a single-cushion device, also providing support for the posterior ankle region 33. The single cushion may be attached to either the torso/thighs as illustrated in FIG. 3d, or, alternatively, to the leg, as illustrated in FIG. 3e. FIGS. 3i and j illustrate the use of the cushions of the invention during kneeling, for instance, an ankle cushion 23 in conjunction with the buttocks/calf cushion or cushions (18 and 19 respectively) of the invention. FIGS. 3h-j depict variations of the device, wherein the ankle/knee support extends continuously from the anterior ankle 34 to the knee 3. FIG. 3k illustrates various embodiments of the invention wherein one or more of the cushions of the invention are attached to a garment. This embodiment is useful when the wearer will be moving frequently, or alternating between squatting and kneeling. In such an embodiment, the cushions 35 may be permanently affixed to the garment by, for example, sewing or gluing or bonding, or they may be fit into pockets or attached by other reversible means such as snaps or velcro.

[0047] The cushions of the invention comprise one or more layers of lightweight, flexible, durable material that is sufficiently firm to support adequate body weight and provide pressure distribution without collapse, and sufficiently resilient to deforming to retain the desired shape. For example, suitable materials include but are not limited to polyurethane, cellular foams or other foams, rubber, silicone, and vinyl compounds. A number of suitable materials are commercially available, and it is anticipated that different suitable materials will be developed in the future that are also within the scope of the invention. The cushions are shaped as described above and as illustrated in the preferred embodiments in FIGS. 3c-3k, and may further have a covering, which may be waterproof.

[0048] Optionally, where the cushions are multilayered as depicted in FIGS. 4a-c, the layers may have different densities suitable for different applications (such as but not limited to weight-supporting and pressure distribution), with both layers encased in a suitable flexible casing, such as, for example, an elastomeric or nylon net casing. The layers may optionally be attached to each other with any suitable flexible adhesive, or the layers may be contained in a covering that prevents shifting of the layers.

[0049] In the multi-layered, single cushion embodiments of the invention as depicted in FIG. 4, at least one pressure distribution layer 29 forms each of the fronts 25 of the cushion (the layer that opposes the body), while at least one weight-supporting layer 30 forms the back 26 of the cushioning device of the invention, as depicted in FIGS. 4a-c. Additional layers may optionally may be inserted between these two, but it is critical that a pressure distribution layer face and be shaped to accommodate each body part to be cushioned, and that the weight-supporting layer be shaped to fit its opposing surface. In the embodiment depicted in FIG. 4, the single cushion device (similar to that illustrated in FIG. 3e) has two pressure distribution layers 29 with a weight-supporting layer 30 between them. The pressure distribution layers 29 are concavely shaped with respect to their facing body parts. The double cushion embodiments of the device such as those depicted in FIGS. 3a, c, f, h and j, comprise a concavely shaped pressure distribution layer facing the body part to be cushioned, with a generally planar weight-supporting layer on the back surface.

[0050] This pressure distribution layer 29 serves to distribute contact point stresses to decrease peak pressure at the contact points, decreasing discomfort and fidgeting, and therefore decreasing muscle contraction. In general, the weight-supporting layer 30 is more dense or stiff or firm than the pressure distribution layer 29, which serves to cushion the body part protected by the device with maximum contact with the body.

[0051] The pressure distribution layer 29 must be compressible to provide maximum coverage for all contact points with the body, and to more effectively disperse the force of pressure during squatting and kneeling. In addition, this material must be readily shaped. This material may be made of different substances, such as cellular foams of differing densities, with the greatest density placed at the point of greatest pressure. Cellular foams, such as high-density polyurethane foams, are one example of a suitable compressible pressure distribution material that may be obtained in multiple densities. The pressure distribution layer 29 may or may not comprise the same material as the weight-supporting layer 30, but formed at a lower density. For example, most cellular materials can be formed in multiple densities, and could be used for both layers in the multi-layered device of the invention. In such an embodiment, encapsulating materials and multiple chambers are optional.

[0052] In a 2-layer cushion of the invention, the weight-supporting layer 30 may comprise a single generally homogeneous layer (FIG. 4a), or it may optionally contain multi-chambered (FIG. 4b) or layered structures (FIG. 4c), where in each case the chambers 31 are filled with, or the layers 33 comprise, a material of generally higher density or pressure than the pressure distribution layer 29.

[0053] By way of example and not as a limitation, materials such as a fluid (including a semi-solid such as a gel) may be used as the weight-supporting layer if encased in a covering sufficiently strong to withstand the weight of the body without allowing the fluid to leak. Suitable fluids include but are not limited to water, semi-liquid gels, oils, waxes, silicone, and any other liquid or semi-liquid material, including but not limited to thixotropic materials, suitable for providing weight-support in the cushion of the invention. Pressurized gas, for example, may also comprise the weight-supporting layer 30, wherein the gas may be, for example, air, nitrogen or other non-toxic gas capable of encapsulation without degrading the encapsulating material. Additionally, lightweight beads may be used for the weight support layer, such as but not limited to microbeads made of styrofoam or other plastic or polymer material. The beads must be small enough to be packed densely to provide a smooth surface sufficiently resilient to support the weight of the body, yet large enough to accommodate a containment mechanism without leaking, such as but not limited to a sewn or sealed pouch. Generally, the beads can range from one to five millimeters in diameter, most preferably from one to three millimeters. In all cases, if encapsulation of the material used in the weight supporting layer is desired (such as for a liquid, gas or bead, for example), the material may optionally be encased in a single encapsulating chamber, or may be encased in multiple encapsulating chambers.

[0054] The chambers 31 or layers 33 may optionally be encased with a flexible encapsulating material 32 that is sufficiently strong to withstand the weight of the body and impermeable to the substance being encapsulated. A variety of suitable encapsulating materials are commercially available and include plastics, vinyls, rubbers or polyurethanes, including but not limited to polyvinlychloride. It is anticipated that new suitable encapsulating materials will also be developed, and these are considered within the scope of the invention. In some embodiments, the chambers may be formed from the material that surrounds the chambers (as described below), in which case the encapsulating material is unnecessary.

[0055] The encapsulated chambers 31 or layers 33 may be surrounded by any suitable material 34 (including materials of the same or greater density than the pressure distribution layer) which may include but is not limited to encapsulating material, the material used for the pressure distribution layer 29 or any other material sufficiently durable and chemically compatible for surrounding the chambers 31 or layers 33. It is anticipated that materials will be developed in the future that are suitable for this purpose, and such materials are considered within the scope of the invention.

[0056] In general, if a foam or other solid material is used for the pressure distribution layer, the same material, if used as a solid layer for the weight-supporting layer 30, will have a greater density than that of the pressure distribution layer 29. In the chambered or layers embodiments depicted in FIGS. 4b and 4c respectively, the surrounding material 34 may be the same density material as that used for the pressure distribution layer, 29 and may even be the same material. The surrounding material may also be of greater density than the material used for the pressure distribution layer 29.

[0057] From the foregoing, it will be apparent that the present invention provides a unique and improved cushioning device for use when squatting or kneeling. The particular configuration of the device may be adapted to all situations where squatting, kneeling, simultaneous squatting and kneeling or shifting positions during squatting and kneeling is performed. Accordingly, it will be obvious to one skilled in the art to make various changes, alterations and modifications to the cushioning devices described above. These and other changes, alterations and modifications will be obvious to one skilled in the art, and are accordingly intended to be compassed within the spirit and scope of the invention and the appended claims.





 
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