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INSOLE FOR SHOES
[0001] The invention is directed to an insole for shoes, which insole has a
flat back side in
direction of the shoe outsole with which the proposed insole is brought into
contact, and a
dome-shaped structure on the front side, respectively.
[0002] In order to allow a comprehensive appraisal of the present invention,
the closed
movement cycle of a walking human will first be considered analytically. This
closed
movement cycle involves not only the foot but also the entire lower extremity.
For this
purpose, the foot must contact the ground. When the foot contacts the ground,
each
movement of parts of this foot affects all of the other parts of the
corresponding leg.
[0003] The walking movement of each leg is divided into the stance phase and
the swing
phase. The stance phase is further differentiated into three component phases;
see Figure 1
which illustrates the human gait using the example of the right leg:
1. The contact phase, the first component phase of the stance phase, begins by
the foot
striking the ground with the outer edge of the heel. The tibia rotates
internally and the
inner side of the foot is raised slightly. In this phase, the foot rolls
further inward until
the metatarsus supports the full weight. The tibia rotates externally and the
ankle
pronates (rolls inward) by up to 8 so that the foot prepares for the
propulsive phase.
In short, the foot has absorbed the shock of contact with the ground, adapted
to the
uneven surface, and flattened out. The contact phase is concluded when the
forefoot
is in full contact with the ground. The primary function of this phase is to
absorb the
shock when striking the ground and adapt to different ground surfaces
(adaptation).
2. The second component phase of the stance phase, the midstance phase, begins
with
the forefoot fully contacting the ground and ends with the heel lifting off
from the
ground. Body weight travels over the foot when the tibia and the rest of the
body
move forward. The primary function of the foot in this phase is to store with
as little
loss as possible the energy gained during the first component phase and
reserve it for
the propulsive phase comparable to a bouncing rubber ball.
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3. The third component phase of the stance phase, the propulsive phase, begins
with the
lifting of the heel; the muscles, ligaments and tendons are flexed. The
forefoot and
hindfoot together form a springboard by which the toes can lift the weight of
the body
(forward) off the ground. The body is propelled forward during this component
phase, and the weight is shifted to the other foot when this other foot makes
contact
with the ground. This phase has a duration of approximately 2 seconds and
takes up
33% of the entire stance phase. At the start of this third component phase of
the
stance phase, the subtalar joint supinates (rolls outward) and ensures that
the center of
pressure remains under the outer side of the forefoot. This in turn ensures
that the
cuboid bone locks with the navicular bone. The foot transforms from mobile
adaptor
to rigid lever in order to propel the body forward during this phase. The
cuboid is
exceptional in that it is the only bone in the foot that articulates with both
the
metatarsal joint (tarsometatarsal articulation or Lisfranc joint) and the
tarsal joint
(midtarsal or Chopart's joint); further, it is the only bone that links the
lateral column
with the transverse foot arch. Consequently, the cuboid is the keystone of the
rigid,
static lateral column and thus imparts to the foot its own stability. The
locking of the
cuboid with respect to the navicular provides for a very strong support
through the
participating ligaments and, in so doing, spares the muscles which would
otherwise be
severely tasked, since the vertical forces at this moment can exceed 125% of
the body
weight. Towards the end of the propulsive phase, the unlocking of the cuboid
is
required after the locking has taken place at the start of the propulsive
phase. A co-
contraction of the fibularis longis (also known as peroneus muscle) and
tibialis
anterior takes place, which leads to counter-contractions and brings about a
transverse
pulling and supporting effect which substantially aligns the bones of the
midtarsal
region. The supporting effect of the tendons of the peroneus longus muscle
around
the cuboid is essential for control of the function of the transverse arch for
stability
and adaptability. To reach the end of the propulsive phase in which the big
toe leaves
the ground, the foot must now rotate internally - otherwise known as
pronation. If
the cuboid were not released or were unlocked, each joint would lose a small
portion
of its movement and, therefore, also a small portion of its forces needed for
toe-off-
this would lead to inhibition of muscular force, endurance, balance and
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proprioception. Moreover, there would be a tendency to lateral sprains because
this
structure is basically a raising structure (supination) and the person could
not achieve
a functional lowering (pronation). In such a case, the natural flow of force
through the
foot illustrated in Figure 2 would be interrupted or limited. Before the big
toe leaves
the ground, there occurs a dorsiflexion of the big toe together with the four
small toes
of the same foot and a plantarflexion of the first metatarsal bone together
with the
other metatarsal bones of the same foot. The dorsiflexion of the big toe is
known as
the windlass effect and is made possible because of the contraction of the
extensor
hallicus longus muscle. With the dorsiflexion of the big toe, the sesamoid
bones
move forward and upward around the head of the metatarsus and thus maximize
the
tension of the flexor hallicus longus muscle.
[0004] Figure 1 shows the right-foot gait and the stance phase subdivided into
its three
subphases: the contact phase, midstance phase and propulsive phase.
[0005] Figure 2 illustrates the natural flow of force through the foot in more
detail. The
flow of force begins slightly to the side in the heel and then flows forward
between the first
and second metatarsal bones and exits the foot through the big toe.
[0006] Numerous authors who have addressed problems relating to heath,
particularly
problems of the lower extremities in humans, have been convinced through their
own
observations that precisely those disabilities which are frequently
encountered in humans who
wear shoes consistently and for long periods are absent in the feet of
primitive peoples who
do not wear shoes: hallux valgus, plantar fasciitis, bunions, hammertoe, and
generally painful
feet are typical examples of such disabilities.
[0007] In short, it may be stated that in societies in which shoes are not
worn, the foot
muscles have freedom of movement and the joints remain flexible. Therefore,
functional
disorders are found in these humans only extremely rarely.
[0008] In shoe-wearing humans, shoes commonly in their way limit the natural
movements of the foot and the sequences for adaptive muscle activation
required for
stabilization of the foot structure before and during full weight bearing and
during toe-off.
[0009] Various rehabilitative insoles have already been proposed for
alleviating the health
problems described above. For example, US 5,404,659 suggests an insole for a
shoe in which
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a very extensive dome-shaped structure is provided for stimulating the golgi
tendon organ.
This dome-shaped structure makes up almost 50% of the entire surface area of
the insole and
accordingly forces the foot into a concave compulsory posture enclosing the
arch. A
disadvantage in this known insole consists in the inhibition of the windlass
effect described in
paragraph [0003] and, therefore, of the final and very important part of the
stance phase: the
propulsive phase. With its dome-shaped structure, the known insole aims at a
region defined
as the apex of the arch of the foot by the lateral cuneiform, cuboid and
navicular bones.
However, in the inventor's opinion, the dynamic locking/unlocking of the
cuboid bone, which
is inhibited by the known insole, is fundamentally important for a natural
gait with shoes.
Since the peroneus longus embraces the cuboid, it is important that the cuboid
yields.
Otherwise, the peroneus is weakened. This highlights the inventor's insight
that it is
important to assist the foot in optimally performing the function intended for
it by nature
rather than artificially build up the foot posture enclosing the arch by an
excessively large
dome-shaped structure. Further, it has been shown that it is rather
uncomfortable to wear a
shoe having the known insole.
[0010] European patent applications EP 1 041 947 and EP 1 423 062 referred to
as the
prior art coming closest ultimately attempt to optimize the insole suggested
in US 5,404,659.
In both cases, however, a very extensive dome-shaped structure is proposed
which has the
disadvantages already mentioned above; in both cases, the golgi tendon organ
is to be
stimulated by a dome-shaped structure whose target is defined by the point of
articulation of
the lateral cuneiform, cuboid and navicular bones. This also applies to US
2002/0014024 Al
by the same applicant.
[0011] US 2,423,622 A also discloses a flat shoe insole having a virtually
square-shaped
elevation exactly and exclusively beneath the cuboid bone of the shoe wearer
which is aligned
laterally alongside the longitudinal axis of the suggested shoe insole. To
this extent, the
known shoe insole is the prior art coming closest to the present invention
because it is
designed entirely correctly insofar as the basic idea is concerned and was
merely unable to
take into account the current insights of the inventor which underlie the
present invention or
fundamentally new considerations spanning more than 60 years. The document,
which was
certainly already very much ahead of its time, completely overcomes the
misleading teachings
of US 2,287,341 A according to which a shoe insole has elevations on the outer
side in the
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elongated position of the cuboid of the shoe wearer. The inventor is convinced
that shoe
insoles designed in this way have poor health benefits.
[0012] US 3,421,518 A likewise merely suggests an elevation on the outer side
in the
elongated position of the cuboid bone of the shoe wearer for the insole of a
shoe and
therefore, with respect to medical engineering, does not go beyond the
insights and
disclosures of the above-cited US 2,287,341 A.
[0013] The technical teaching of US 2,154,997 A consists in the construction
of a bottom
foot lining in the elongated position of the cuboid bone of the shoe wearer
which is now not
only on the outer side but over the full width of the foot. On the one hand,
this inhibits any
inward rolling of the foot during the contact phase - see paragraph [0003] -
and on the other
hand is quite rightly uncomfortable to wear because it is contrary to the
natural gait. Further,
a comparable teaching is disclosed in US 2,421,088 A. In this respect, it
remains to be noted
that constructions such as these are diametrically opposed to the present
invention.
[0014] Finally, reference is made to US 6,510,626 B1 which, with respect to
the insole for
a shoe, likewise merely discloses outside elevations in the elongated position
of the cuboid
bone of the shoe wearer and to this extent does not go beyond the disclosures
of US
2,287,341 A and US 3,421,518 A.
[0015] After intensive observations in everyday practice as a chiropractor,
the inventor
became convinced that all of the references evaluated above either lead away
from the
solution to the underlying problem or at least do not solve it convincingly.
This problem can
be summarized by the object of making available to the public an insole for a
shoe which
enables natural walking without pain or fatigue.
[0016] According to the invention, the problem is solved by an insole for a
shoe, wherein
the insole has a flat back side in direction of the shoe outsole and a dome-
shaped structure
(12) on the front side, and wherein
^ the dome-shaped structure (12) has a base surface of a maximum of 25% of the
insole
surface,
^ the dome-shaped structure (12) is positioned under the cuboid bone (4) of
the shoe
wearer,
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wherein the insole according to the invention for a shoe is characterized by
the following
features:
^ a longitudinal axis (16) can be associated with the dome-shaped structure
(12) at its
apex, wherein the longitudinal axis (16) of the dome-shaped structure (12)
encloses an
angle ((p) in a range from 5 to 75 with the longitudinal axis of the insole.
[0017] A particularly preferred range for the angle (<p) between the
longitudinal axis (16)
of the dome-shaped structure (12) and the longitudinal axis of the insole is
from 5 to 50 ,
particularly preferably from 5 to 35 .
[0018] In a preferred embodiment form, the dome-shaped structure (12) of the
insole
according to the invention is positioned under the medial side of the cuboid
bone (4) of the
shoe wearer where the cuboid bone (4) borders the navicular bone (3) on one
side and the
calcaneus bone (2) on the other side. In this connection, reference is made on
the one hand to
Figure 3 which shows the bone structure of a human foot and names all of the
important
bones mentioned herein. On the other hand, reference is made to Figure 4 which
likewise
shows the human foot in which all of the bones essential to the invention are
designated and,
further, shows the goal of the dome-shaped structure corresponding to the
present invention
in one of the preferred embodiments thereof.
[0019] The dome-shaped structure (12) is constructed so as to be elastic - for
example, it
is produced from permanently elastic plastics and/or gel materials,
constructional variations
of various hardness being preferred. It was shown in numerous trials upon
which the present
document is based that in a preferred embodiment the base surface of the dome-
shaped
structure (12) of the insole according to the invention for a shoe can even
have a base surface
of only a maximum of 20%, or even a maximum of 15%, of the insole surface. In
particularly preferred embodiments, it is even possible to reduce the base
surface of the
dome-shaped structure (12) to a surface of 10% or less, particularly
preferably even to a
surface in a range from less than 4% to 8%, of the insole surface. In this
case, however, the
wearer of a shoe of this kind should train intensively to run on these insoles
according to the
invention with dome-shaped structure (12) which have a particularly
drastically reduced base
surface because otherwise it could be less comfortable under certain
circumstances.
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[0020] The dome-shaped structure (12) is generally constructed in the form of
a truncated
cone or truncated pyramid which is rounded on the base side and apex side,
wherein the
height (15) of the dome-shaped structure (12) is preferably in a range from 3
to 20 mm. The
rounded apex (13) of the truncated cone or truncated pyramid facing the cuboid
bone (4) of
the shoe wearer can accordingly be circular or square. In an embodiment form
which is
particularly preferred and which is considered by the inventor to be the best,
the truncated
cone or truncated pyramid has a rectangle or an ellipse at least at its
rounded apex (13) facing
the cuboid bone (4) of the shoe wearer, wherein the rectangle or ellipse has a
longitudinal-
transverse ratio in a range of 1:1, or greater than 1:1, to 4:1 and
particularly preferably in a
range of 1.2:1 to 3:1.
[0021] When the truncated cone or truncated pyramid has a rectangle or ellipse
at its
rounded apex (13) facing the cuboid bone (4) of the shoe wearer with a
longitudinal-
transverse ratio at least in a range of 1:1, or greater than 1:1, to 4:1, it
was shown to be
particularly effective in the trials upon which the present document is based
when the
longitudinal axis (16) of the dome-shaped structure (12) extends along the
medial edge of the
cuboid bone (4) and particularly and preferably then encloses an angle (gyp)
of 5 to 35 ,
particularly preferably an angle ((p) of 25 to 35 , with the longitudinal
axis of the insole.
[0022] For an illustration of the dome-shaped structure (12) as truncated
cone, reference is
made particularly to Figure 5 which shows a corresponding truncated cone. The
position of
the angle (gyp) is further illustrated particularly in Figure 4.
[0023] In a first possible constructional variant of the insole according to
the invention,
this insole is permanently connected to the dome-shaped structure (12). This
can be achieved
in that the insole and dome-shaped structure (12) are fabricated separately
and subsequently
indissolubly glued; this can also be achieved in that the insole and dome-
shaped structure (12)
are cast integral from a suitable plastics material without limiting in any
way to these two
possibilities.
[0024] In a second possible constructional variant of the insole according to
the invention,
the insole and dome-shaped structure (12) both have connection components, and
the
connection components of the insole are formed with the connection components
of the
dome-shaped structure (12) in such a way that insole and dome-shaped structure
(12) are
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connected to one another so as to be difficult to detach. This detachability
is desirable when
the possibility of exchanging the dome-shaped structure (12) while retaining
the insole is
afforded as is preferred by the inventor. When exchange of the dome-shaped
structure (12) is
possible, the latter can be replaced in a particularly simple and convenient
manner in case of
wear or when a different hardness and/or a different outer shape or dimension
is desired.
[0025] In this case, the connection components between insole and dome-shaped
structure
(12) are preferably selected from the list comprising:
^ hook-and-loop strips,
^ recessed grooves in the insole and springs engaging in the grooves under the
base (14)
of the dome-shaped structure (12),
^ recessed grooves in the base (14) of the dome-shaped structure (12) and
springs
engaging in the grooves at the front side of the insole.
[0026] In case recessed grooves in the insole are selected as connection
components
between insole and dome-shaped structure (12), a preferred embodiment form
consists in that
these recessed grooves in the insole extend at an angle of 80 to 100 to the
longitudinal axis
(16) of the dome-shaped structure (12). Given this choice of angle at which
the recessed
grooves in the insole and the springs engaging in the grooves in a
corresponding manner
below the base (14) of the dome-shaped structure (12) extend virtually at
right angles to the
longitudinal axis (16) of the dome-shaped structure (12), the insole and dome-
shaped
structure (12) are connected to one another in a particularly resistant manner
so that such an
alignment of grooves and springs is particularly suitable for athletic shoes.
In a particularly
preferred constructional variant of the described embodiment form, the grooves
which are
recessed in the insole extend up to at least an outer edge of the insole so
that the springs
below the base (14) of the dome-shaped structure (12) can be inserted into the
recessed
grooves of the insole proceeding from the outer edge of the insole.
[0027] In case recessed grooves in the base (14) of the dome-shaped structure
(12) are
selected as connection components between insole and dome-shaped structure
(12), it is
preferable when these recessed grooves extend along the longitudinal axis (16)
of the dome-
shaped structure (12). The springs corresponding to the recessed grooves along
the
longitudinal axis (16) of the dome-shaped structure (12) are formed on the
front side of the
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insole. Insofar as the grooves are guided into the base (14) of the dome-
shaped structure (12)
up to the outer edge of the dome-shaped structure (12), it is particularly
simple and
convenient to insert the grooves proceeding from the end of the springs. Snap-
in elements in
the grooves and associated springs prevent an unintentional slipping of the
dome-shaped
structure (12) relative to the insole on one hand and facilitate an exact
alignment of the dome-
shaped structure (12) relative to the insole on the other hand.
[0028] Insofar as the connection components between the insole and dome-shaped
structure (12) are realized by means of grooves and springs to be inserted
into the grooves, it
is particularly preferable when the recessed grooves are undercut and the
springs are formed
so as to widen outward in a corresponding manner.
[0029] In another preferred embodiment form, the construction of the dome-
shaped
structure (12) and the connection thereof to the insole is realized by means
of a preferably
three-part component structure comprising base (12-1), center piece (12-2) and
dome (12-3).
In this case, the base (12-1) which is generally made from an inelastic,
durable plastic or from
carbon fibers is positioned under the insole ideally in the middle of a bottom
structure of the
insole which corresponds in an exactly fitting manner to the base (12-1) and
which receives
the base (12-1), and the base (12-1) comprises connection elements for
connecting to the
center piece (12-2) by frictional engagement. These connection elements for
connecting base
(12-1) and center piece (12-2) by frictional engagement can be constructed,
for example, as
matching eyelet/pin elements having a snap-in function.
[0030] Like the base (12-1), the center piece (12-2) itself is preferably
produced from an
inelastic, durable plastic or from carbon fibers and is positioned above the
base (12-1) in the
plane of the insole; to this end, the insole has a continuous hole in the
outer shape of the
center piece (12-2). Ideally, the center piece (12-2) can be inserted by
guiding through the
hole in the insole in an exactly fitting manner from above until it is pressed
onto the base (12-
1) for connecting to the latter.
[0031] On top, the center piece (12-2) preferably has:
^ either at least one recessed groove, in which case the dome (12-3) has the
at least one
matching spring engaging in this groove,
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or at least one spring, in which case the dome (12-3) has the at least one
matching
groove in which the spring of the center piece (12-2) can engage.
The above-mentioned dome (12-3) is constructed so as to be elastic and, for
example, is
produced from permanently elastic plastic and/or from gel material which may
be covered
with a suitable outer material if required.
[0032] In a specific instance of the preferred embodiment form described
above, the base
(12-1) and center piece (12-2) can also be constructed as a cohesive workpiece
which is either
assembled before being inserted in an exactly fitting manner through the hole
in the insole,
this time from below, from the two individually fabricated pieces, base (12-1)
and center
piece (12-2), and possibly glued, or is fabricated directly in one piece, in
which case this
workpiece has a bottom part as base (12-1) and a top part as center piece (12-
2).
[0033] It is possible to form the insole as an integral component part of a
shoe. In this
case, the insole according to the invention is glued and/or sewed to the
outsole of a shoe and,
as the case may be, also to the outer material of this shoe.
[0034] In a particularly preferred embodiment form of the present invention,
it is also
possible that the insole is constructed as an insert for certain shoes. In
this case, it is also
possible for the insole to be produced and offered as a so-called 3/4 sole
which can be
fastened to a complete insole inside a specific shoe by means of double-sided
adhesive tapes.
In so doing, it is common to shorten 3/4 soles of this kind in the front and,
if necessary, on
the sides until they fit into the given shoe.
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Reference Numbers
(1) ankle bone (talus)
(la) articulation surface of the ankle bone
(1b) neck of ankle bone
(1c) head of ankle bone
(2) heel bone (calcaneus)
(3) navicular bone
(4) cuboid bone
(5-7) cuneiform bones I-III
(8) largest metatarsal bone (metatarsal I)
(9-10) toe bones (phalanges)
(11) smallest metatarsal bone (metatarsal II)
((p) angle between the longitudinal axis of the dome-shaped structure and the
longitudinal
axis of the insole
(12) dome-shaped structure
(13) apex of the dome-shaped structure formed as truncated cone
(14) base of the dome-shaped structure formed as truncated cone
(15) height of the dome-shaped structure
(16) longitudinal axis at the apex of the dome-shaped structure
