Note: Descriptions are shown in the official language in which they were submitted.
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Flip Flop Sandal
The present invention relates to a sandal, in particular in the form of a so-
called flip-flop, having
a shoe sole and a big toe compartment for separately accommodating the big toe
separated from
the other toes. The invention thus relates in particular to flip-flops having
orthopedic means for
correcting and/or preventing hallux valgus.
Painful defective positioning of toes that frequently must be treated
surgically can result from
various causes, especially wearing shoes that are too tight or too high.
Frequently in particular
the big toe moves into a bent defective position towards the outside of the
foot, and this is
associated with changes in the tissue in the area of the metatarsophalangeal
joint or the
metatarsus.
To correct such defective toe positioning, especially hallux valgus, normally
a corrective splint is
applied to the foot, by means of which splint the toe to be corrected is, so
to say, correctively
bent, i.e. forced in or into its proper position and held there. Appropriate
splints are used both
post-operatively and during conservative therapy that does not involve
surgical intervention.
However, sometimes there is a reluctance to wear such foot splints, especially
in the summer in
open shoes like sandals because the splints are visible when socks and
stockings are not worn
and sometimes there is the perception of a stigma attached to wearing them.
In the framework of such therapies for toe correction there has been a growing
understanding
that it is important to strengthen the muscles in the foot region - muscles
that are frequently
atrophied, however - in order for the foot to be able to hold itself in the
proper shape even
without splints, at least in the long term. Since appropriate exercises that
are performed
deliberately during physical therapy frequently are often perceived as
bothersome and are not
continued for long, it would be desirable to have a shoe that trains the foot
automatically, as it
were, builds ups the foot's muscles, especially in the metatarsal area, and
holds the big toe in its
proper natural position, but that nevertheless permits appropriate movements
to attain the desired
exercise effect.
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Proceeding from this point, the object of the underlying invention is to
create an improved sandal
of the aforesaid type that does not suffer from the disadvantages of the prior
art and that further
advantageously refines the prior art. In particular, a flip-flop sandal is to
be created that supports
therapy for hallux valgus and/or has a preventive effect in this regard in
that when walking the
big toe is held in its proper natural position and at the same time
a.supporting effect is provided
to the arch of the foot. It should also attain more vigorous exercising of the
foot muscles in the
metatarsal area that control movement of the big toe.
This object is attained in accordance with the invention using a sandal in
accordance with claim
1. Preferred embodiments of the invention are the subject-matter of the
dependent claims.
Thus, centering the shoe sole relative to the foot and in a certain
orientation is proposed in order
to prevent the lateral slipping and twisting that is normally experienced with
flip-flops so that the
big toe compartment acts like a corrective toe positioning aid and keeps the
big toe in its proper
natural position or can at least exert corrective force in that direction. The
shoe sole is centered
using a specially embodied attachment of the shoe sole in the metatarsal area,
which attachment
simultaneously supports and aligns the metatarsus. In accordance with the
invention, the flip-
flop has a metatarsal strap for supporting the metatarsus, to which strap the
shoe sole is attached
in a predetermined orientation by means of a centering apparatus, the
aforesaid metatarsal strap
having lateral foot sole support segments that extend laterally underneath the
foot sole and/or
over the shoe sole and can be raised from the shoe sole in order to support
the metatarsus from
the foot sole using upwardly oriented, lateral pressure forces and in order to
support it in the
upright position, even when the foot sole rolls and lifts up from the shoe
sole.
The aforesaid centering means are embodied especially such that, as is usual
with flip-flops, they
permit the foot sole to lift up during the rolling movement of the foot during
walking, but such
that they still prevent lateral slipping and twisting of the shoe sole
relative to the foot such that
the shoe sole, when seen from a top view, always remains essentially in its
pre-specified proper
position under the foot sole so that the big toe compartment can act as a
corrective toe
positioning aid and hold the big toe in its proper natural position.
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In a refinement of the invention, the aforesaid centering apparatus
advantageously includes at
least one pair of connecting straps that are for connecting the shoe sole to
the metatarsal strap
and that run on an incline in opposite directions in order to center the shoe
sole with respect to
the metatarsal strap. The aforesaid connecting straps are in particular each
inclined at an acute
angle relative to a center longitudinal plane that runs upright through the
shoe sole so that overall
there is a somewhat V-shaped arrangement of the connecting straps that has a
centering effect.
It would be possible for the connecting straps to be arranged in a completely
different manner;
for instance, the connecting straps could be spaced farther apart from one
another at their
fastening points on the shoe sole than in the area of their connecting points
to the metatarsal strap
so that the result would essentially be a pitched roof-shaped arrangement of
the connecting
straps. However, in a refinement of the invention the connecting straps are
advantageously
arranged in the opposite manner, i.e. the connecting straps are spaced farther
apart from one
another at their connecting points to the metatarsal strap than at their
connecting points to the
shoe sole.
The V-shaped spreading can vary in its severity. An arrangement of the
connecting straps at a
spread angle of 45 to 150 , preferably about 60 to 120 , and in particular
about 75 to 100 can
be advantageous for effecting sufficiently strong centering and for not
introducing into the strap
tensile forces that are too strong. The distance between the connecting points
for connecting the
connecting straps to the shoe sole is advantageously less than 2/3 of the
distance between the
connecting points for the strap.
It can be advantageous when the connecting straps, seen in section through the
metatarsal strap,
are connected to the metatarsal strap approximately in the area of 7 o'clock
to 10 o'clock and 2
o'clock to 5 o'clock, preferably in the area of about 8 o'clock to 9 o'clock
and 3 o'clock to 4
o'clock, in order to effect adequate centering, but also to permit the foot
sole to lift up
sufficiently from the shoe sole, which is crucial to the feeling of wearing
flip-flops.
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The connecting straps can advantageously be embodied sufficiently elastic and
extensible to
attain both lifting up of the foot sole from the shoe sole and also adequate
centering for the shoe
sole.
In order to prevent torsion on the connecting straps, the latter are embodied
with sufficient width
and are connected to the metatarsal strap and shoe sole across their entire
width, wherein the
width of the connecting straps can advantageously be in the range of 2/3 to
3/3 of the width of
the metatarsal strap. The width of the connecting straps can preferably be
between 3 cm and 10
cm, in particular 4 cm to 7 cm.
When viewed from the side of the sandal, the aforesaid connecting straps
advantageously extend
essentially vertically or at only a slight incline from the metatarsal strap
downward to the shoe
sole so that the center section of the connecting points for connecting the
connecting straps to the
shoe sole corresponds to the metatarsus.
In a refinement of the invention, the lateral foot sole support segments of
the metatarsal strap are
not directly connected to the lateral edges of the shoe sole at their segments
that are adjacent to
the outer edges of the foot sole, as is normally the case with a conventional
upper, but rather are
drawn inward unconnected to the edges of the sole so that the lateral foot
sole support segments
of the metatarsal strap run free of the shoe sole in the area of the lateral
sole edges so that the
metatarsal strap on the left and on the right in an area between about 6
o'clock and 9 o'clock or
about 6 o'clock and 3 o'clock can be stretched away from the shoe sole and
spaced apart
therefrom or can exert a corresponding tightening force on the sole area of
the metatarsus.
The aforesaid foot sole segments can be drawn inward, spaced apart from the
shoe sole edges,
towards the center of the shoe interior delimited by the upper and the shoe
sole, and due to this
can be positioned against the lateral edges of the foot sole in order to
provide upright support
there, specifically even when the foot sole lifts up from the shoe sole during
a rolling motion.
In a refinement of the invention, tensioning means for tightening the
metatarsal strap are
provided so that in particular the aforesaid lateral foot sole support
segments of the metatarsal
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strap can be tightened inward and upward in order to attain the desired
support. The aforesaid
tensioning means advantageously include length adjusting means for adjusting
the length of the
aforesaid strap. In order ensure simple operation, the tensioning means and/or
the length
adjusting means can have an actuating part on a top side of the metatarsal
strap, or an exterior
side thereof, that faces away from the shoe sole. For instance, the metatarsal
strap can be fixed
in a tightened position using a velcro fastener or similar retention means.
In a refinement of the invention the at least one connecting point for
connecting the shoe sole to
the metatarsal strap using the aforesaid centering apparatus is arranged
spaced apart from the
sole edges at least 1/4 of the width of the shoe sole, preferably 1/3 of the
width or more, i.e.
inwardly offset toward the center of the shoe sole.
In order to be able to finely adjust the position of the big toe and precisely
adjust the correcting
forces, in a refinement of the invention an adjusting apparatus for adjusting
the position and/or
orientation of the big toe compartment relative to the shoe sole can be
provided and/or a big toe
strap can be provided in the area of the big toe compartment by means of which
a correcting
force can be exerted on the big toe toward the interior of the shoe. Instead
of a big toe strap that
completely encircles the big toe, where necessary alternatively embodied
tensile/pressure means
for applying a corrective force toward the interior of the shoe can also be
provided, for instance
in the form of a displaceably arranged bar that extends on the side of the big
toe facing the
adjacent toe. Alternatively or in addition, the entire big toe accommodation
on the sole could be
borne transversely and adjustable. However, what is preferred is the aforesaid
big toe strap that
is connected to the interior of the shoe sole at a fixed strut and can
comfortably exert a
corresponding corrective force on the big toe using longitudinal displacement.
In an
advantageous embodiment of the invention, tensioning means for tightening the
big toe strap to
the interior of the foot are provided that in particular include length
adjusting means for adjusting
the length of the aforesaid strap. The big toe strap in the form of a
tightenable velcro loop can
preferably be fixed to the shoe sole or to itself.
In order to attain an enhanced exercise effect for the muscles that control
movement of the big
toe, in a refinement of the invention it can be provided that the big toe
movement when the foot
CA 02728009 2010-12-14
rolls upward is essentially mechanically disconnected from the movement of the
other toes so
that the big toe assumes the majority of the balance work, as is provided when
walking barefoot,
and especially the muscles that hold the big toe receive more intense
exercise, and at the same
time the big toe can be prevented from moving incorrectly towards the outside
of the foot. The
shoe sole is advantageously distinguished in that a big toe segment of the
shoe sole is separated
from an adjacent toe segment in the shoe sole by a notch in the sole that runs
in the longitudinal
direction of the shoe, and nevertheless can be bent in the rolling direction.
Because of the notch
in the sole in the longitudinal direction of the sole between the big toe and
adjacent toes, the
segment of the shoe sole that is disposed under the big toe can simply be
folded compared to the
adjacent segment of the shoe sole that is beneath the adjacent toes, i.e., can
simply be bent
upward and downward about a transverse axis without the aforesaid adjacent
segment of the shoe
sole having to bend, as well.
No direct transfer of force between torsion forces and bending torques occurs
between the big
toe segment of the shoe sole and the adjacent toes segment of the shoe sole so
that the big toe is
not assisted in keeping balance by the adjacent toe segment of the shoe sole,
which leads to
increased exercise for the muscles that control big toe movement. Due to the
notch in the sole
between big toe and adjacent toes, walking in the shoe feels like walking
barefoot because the
big toe rolls up regardless of the other toes. At the same time, accommodating
the big toe in the
big toe compartment separately from the other toes in conjunction with the
centering apparatus
that centers the shoe sole alignment on the metatarsal strap ensures that the
big toe does not
project out towards the outside of the foot, but rather is held in its
straight, natural, and proper
position. Thus despite the aforesaid notch in the sole, and more precisely
because of its
orientation and course, the flip-flop and in particular also the shoe sole,
have sufficient stiffness
transversely, i.e. with respect to bending about a vertical axis, to fix the
big toe towards the
inside of the foot and to prevent its undesired movement to the outside of the
foot.
The big toe compartment can advantageously be provided in the form of an
essentially
cylindrical sleeve that is open toward the tip of the toe. Alternatively a
compartment can be
provided that encircles the big toe on all sides and is closed at the tip of
the toe so that, seen from
the end of the shoe, the big toe compartment roughly forms a nearly
cylindrical hollow unit that
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is open to the side from which the toe is inserted and closed to the tip of
the toe, and seen in
cross-section this cylindrical hollow unit is encircled by the sole and
corresponding arches that
run in a curve above the sole.
The notch in the sole that effects the desired mechanical decoupling of the
big toe segment in the
shoe sole from the adjacent toe segment in the shoe sole can be embodied
fundamentally
different. The aforesaid notch in the sole is advantageously formed from a cut
and/or a slit in the
sole that essentially cuts into and separates the shoe sole from the tip of
the shoe part way
towards the back of the shoe in the longitudinal direction of the shoe until
about the point when it
reaches the metatarsophalangeal joint. This yields completely separated sole
areas under the big
toe and the adjacent toes, attaining maximum decoupling during the rolling
movement. Instead
of such a complete removal of material, it is also possible to leave a thin
layer of material in the
area of the notch in the sole, which layer does not interfere with mechanical
decoupling or
provides only minimal interference. It can especially be provided that a
connecting membrane is
provided in the area of the notch in the sole between the big toe segment and
the adjacent toe
segment on the shoe sole, and then joins the two aforesaid segments to one
another. The
connecting membrane can in particular form a seal that prevents dirt or liquid
from entering the
slit between big toe and adjacent toes. In this case, compared to the material
for the shoe sole,
the aforesaid connecting membrane is significantly more extensible and where
necessary also
much thinner, wherein the aforesaid connecting membrane may be embodied using
a different
material than the rest of the shoe sole. For instance, it would be possible to
use an extensible,
water-tight textile membrane, the extensibility of which does not interfere
with the desired
decoupling.
The invention shall be described in greater detail in the following using a
preferred exemplary
embodiment and associated drawings.
Fig. 1: is a lateral elevation of a flip-flop sandal having a foot disposed
therein, as seen
from the outside side of the foot, in accordance with one advantageous
embodiment of the invention;
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Fig. 2: is a lateral elevation of the sandal in Fig. 1, as seen from the
outside of the foot;
Fig. 3: is a top view of the sandal from Figs. 1 and 2, as seen from above,
including the
foot;
Fig. 4: is a schematic section through the sandal in the area of the
metatarsal strap from
Fig. 1 in accordance with the line A-A in Fig. 1;
Fig. 5: is a top view of the sole of the flip-flop in accordance with one
embodiment of the
invention, according to which the sole has a notch between the big toe and
adjacent toes; and,
Fig. 6: is a schematic section through the sandal in the area of the
metatarsal strap from
Fig. 1 in accordance with the line AA- in Fig. 1 and having a strap connection
that
is in accordance with another advantageous embodiment of the invention and
that
has been modified with respect to Fig. 4.
The sandal 1 depicted in the figures is embodied in the form of a so-called
flip-flop and includes
a shoe sole 2 and a separate big toe compartment 7 that is at its front end in
the area of the toes
and that in the area of the shoe sole 2 - as seen in Fig. 5 - can be separated
from the shoe section
that surrounds the adjacent toes by a sole notch 8. As Fig. 5 illustrates, the
sole notch 8 in the
embodiment depicted is formed by a slit-like cut 10 in which the material of
the shoe sole 2 is
completely removed. The aforesaid cut 10 reaches from the tip of the shoe to
about the
metatarsophalangeal joint and extends essentially parallel to the longitudinal
direction of the
shoe.
As Figure 1, 2, and 3 depict, the big toe compartment 7 is formed by a big toe
strap 14 that is
connected to the shoe sole segment 2a beneath the big toe and is
advantageously embodied with
a modifiable length so that the position of the big toe can be adjusted
exactly on the shoe sole 2.
For instance, the big toe strap 14 can be tightened and fixed by means of a
hook-and-loop closure
16. Where necessary it can be provided that the position of the big toe strap
and thus of the big
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toe compartment 7 is adjusted relative to the shoe sole 2, and especially can
be changed
transverse to the longitudinal direction of the sole, by means of suitable
adjusting means in order
to be able to exert different strength corrective forces 15 on the big toe
towards the inside of the
foot or to be able to adapt the sandal to the defective positioning.
A metatarsal strap 17 is provided in the area of the metatarsus, as Figures 1,
2, and 3 depict. The
metatarsal strap 17 completely encircles the metatarsus and is embodied
independent of the shoe
sole. The strap 17 includes two lateral foot sole support segments 18 and 19
that encircle and
support the metatarsus to be supported from its sides at the foot sole. The
aforesaid foot sole
support segments 18 and 19 are detached from the shoe sole 2 and in particular
are not directly
attached to the lateral edges of the shoe sole 2 so that the metatarsus can be
supported from
below using lateral upwardly and inwardly oriented support forces 20. Because
the aforesaid
foot sole support segments 18 and 19 are not connected to the lateral edges of
the shoe sole 2, it
is specifically the metatarsal segment that is to be addressed with respect to
hallux valgus
disorder that is supported and shaped by the support forces 20.
As Figure 4 depicts, the metatarsal strap 17 is advantageously detached from
the lateral edges of
the shoe sole 2 across at least 1/4 of the shoe sole width and from the
connection between upper
3 and shoe sole 2 across at least 1/4 of the height of the upper 3 in order to
be able to apply the
desired support forces 20.
The metatarsal strap 17 has tensioning means 21 in the form of a length
adjusting apparatus 22 in
order to be able to fit the metatarsal strap 17 to different foot widths and
to adjust the support
force 20. The tensioning means 21 or length adjusting means 22 can for
instance have a hook-
and-loop closure 24 by means of which the overlapping segments of the strap 17
on top can be
fixed to strap segments thereunder (see Figure 4).
The aforesaid metatarsal strap 17 is joined via a centering apparatus 3 to the
shoe sole 2 that is
embodied such that the shoe sole 2 can lift up when the foot rolls off during
walking but such
that, at least when it returns to the ground, it remains positioned centered
under the foot sole and
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cannot slip to the side or transversely. Because of this the big toe
compartment 7 can act as a
corrective toe positioning aid and hold the big toe in its proper natural
position.
In a refinement of the invention, the aforesaid centering apparatus 3
advantageously includes at
least one pair of connecting straps 4, 5 that are for connecting the shoe sole
2 to the metatarsal
strap 17 and that run on an incline in opposite directions in order to center
the shoe sole with
respect to the metatarsal strap 17. In particular the aforesaid connecting
straps 4, 5 are each
inclined at an acute angle relative to a center longitudinal plane that runs
upright through the
shoe sole so that overall there is a somewhat V-shaped arrangement of the
connecting straps 4, 5
(see Figs. 4 and 6).
In a refinement of the invention, the connecting straps 4, 5 are
advantageously arranged such that
the connecting straps 4 and 5 are spaced farther apart from one another at
their connecting points
6 to the metatarsal strap than at their connecting point 9 to the shoe sole 2.
The arrangement of the connecting straps in the embodiment depicted in Fig. 4
is at a spread
angle of about 90 in order to effect sufficiently strong centering and in
order not to introduce
tensile forces that are too strong into the strap. The distance between the
connecting points for
connecting the connecting straps to the shoe sole is advantageously less than
2/3 of the distance
between the connecting points for the strap.
The embodiment depicted in Fig. 6 depicts a comparatively more widely spread
arrangement of
the connecting bands 4 and 5, which in accordance with Fig. 6 are arranged in
a V-shape at about
a 120 angle.
It can be advantageous when the connecting straps 4 and 5, seen in section
through the
metatarsal strap 17, are connected to the metatarsal strap 17 approximately in
the area of 7
o'clock to 10 o'clock and 2 o'clock to 5 o'clock, preferably in the area of
about 8 o'clock to 9
o'clock and 3 o'clock to 4 o'clock, in order to effect adequate centering, but
also to permit
sufficient lifting up of the foot sole from the shoe sole 2, which is crucial
to the known feeling of
wearing flip-flops.
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The embodiment in accordance with Fig. 4 depicts a connection of the
connecting straps 4 and 5
to the metatarsal strap 17 in the area of about 9 o'clock and 3 o'clock, while
the more widely
spread arrangement in accordance with Fig. 6 has a connection in the area of
about 7:30 and
4:30.
The connecting straps 4 and 5 can advantageously be embodied sufficiently
elastic and
extensible to attain both lifting up of the foot sole from the shoe sole 2 and
also an adequate
centering for the shoe sole 2.
In order to prevent torsion of the connecting straps 4 and 5, the latter are
embodied with
sufficient width and are connected to the metatarsal strap and shoe sole
across their entire width,
wherein the width of the connecting straps advantageously equals the width of
the metatarsal
strap 17. The width of the connecting straps 4, 5 can preferably be between 4
cm and 7 cm.
When viewed from the side of the sandal (see Figs. 1 and 2), the aforesaid
connecting straps 4, 5
advantageously extend essentially vertically or at only a slight incline from
the metatarsal strap
17 downward to the shoe sole 2 so that the center section of the connecting
points 9 for
connecting the connecting straps 4, 5 to the shoe sole 2 corresponds to the
metatarsus.
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