U.S. patent application number 09/761258 was filed with the patent office on 2002-07-18 for leg and knee support devices for squatting and kneeling.
Invention is credited to Michalow, Alexander.
Application Number | 20020092098 09/761258 |
Document ID | / |
Family ID | 25061666 |
Filed Date | 2002-07-18 |
United States Patent
Application |
20020092098 |
Kind Code |
A1 |
Michalow, Alexander |
July 18, 2002 |
Leg and knee support devices for squatting and kneeling
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) |
Correspondence
Address: |
GARDNER, CARTON & DOUGLAS
321 N. CLARK STREET
SUITE 3400
CHICAGO
IL
60610
US
|
Family ID: |
25061666 |
Appl. No.: |
09/761258 |
Filed: |
January 16, 2001 |
Current U.S.
Class: |
5/648 |
Current CPC
Class: |
A41D 13/065
20130101 |
Class at
Publication: |
5/648 |
International
Class: |
A47G 009/00 |
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.degree., 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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