Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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VACUUM ASSISTED SUSPENSION SYSTEM
[1] FIELD OF ART
[2] The disclosure relates to the field of prosthetic devices, and more
particularly to a
vacuum assisted suspension system.
[3] BACKGROUND
[4] In the field of prosthetics, an amputee can attach a prosthetic limb to
the residual
limb via a socket of the prosthesis using a variety of mechanical attachment
or suspension
mechanisms. A suspension system usually relies on creating a vacuum or
negative air
pressure in the space between the socket and the surface of the residual limb.
A seal is
created by covering the brims of the socket with a sleeve. The seal for the
vacuum space,
however, is not airtight, so air may leak into the vacuum space weakening the
attachment.
[5] As a result, there is a need for a system which can create and maintain
negative
air pressure during use.
[6] In some prosthetic systems, when weight is applied to a prosthetic
attachment
such as a prosthetic foot, the applied weight causes the vacuum pump to
decrease the
volume of the pump and expel air out of the pump. Then, when the compressive
force is
removed, the pump expands and draws air out of the vacuum space to create a
vacuum
effect. In these types of systems, the system relies on a complete compression
of the
pump in expelling air in each cycle to use the pump to its maximum capacity.
It is
difficult for complete compression to occur in every cycle using the gait of a
user as the
compressive force since the impact and displacement of the pump may not be
consistent
and can vary between users.
[7] SUMMARY
[8] The challenges of known vacuum assisted suspension systems are
addressed in
accordance with embodiments of the disclosure providing a vacuum assisted
suspension
system including a vacuum pump.
[9] In accordance with an embodiment of the method of creating vacuum in a
prosthetic socket, a compressive force is applied to a first end of a
compression transfer
element by applying weight or force to a prosthetic device or limb. The force
applied on
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the first end of the compression transfer element causes the volume of the
fluid chamber
to increase via a second end of the compression transfer element connected to
a movable
wall of the fluid compartment, and fluid is drawn into the fluid chamber from
a socket
space or cavity through an input port upon an increase in the volume of the
fluid
chamber. When the compressive force is removed the absence of the compressive
force
enables the volume of the fluid chamber to decrease thereby expelling fluid
out of the
fluid chamber through an output port.
[10] Preferably, the volume of the fluid chamber is zero or approximately zero
in the
absence of a compressive force. Having a compressive force increase the volume
of the
fluid chamber from zero and the absence of the compressive force enable a
return to a
volume of zero or near zero has been found to be advantageous since each pump
cycle is
fully utilized by fully expelling all or substantially all fluid drawn into
the fluid
compartment. This type of method and prosthetic system more effectively and
efficiently
uses the vacuum pump to increase or the vacuum or negative pressure within a
sealed
socket cavity. Smaller fluctuations in negative pressure are also achieved.
[11] In various embodiments of the vacuum assisted suspension system described
herein, the system includes a prosthetic foot, a prosthetic socket, an
elongate compression
transfer element connected to the prosthetic foot, and a vacuum pump connected
to the
prosthetic socket and the compression transfer element. The vacuum pump
includes a
housing defining an enclosed space to receive a fluid, at least one wall of
the housing and
at least one movable wall defining a fluid compartment, and the at least one
movable wall
is connected to the compression transfer element. The compression transfer
element
causes the at least one movable wall of the fluid compartment to move and
increase the
volume of the fluid compartment in response to a compressive force on the
prosthetic
foot to draw in fluid from the prosthetic socket, and in the absence of a
compressive
force, the movable wall is arranged to shift in a direction decreasing the
volume of the
fluid compartment thereby expelling fluid from the fluid compartment.
[12] In accordance with an embodiment of the vacuum pump, the enclosed space
in the
housing can be divided into a fluid compartment and a non-fluid compartment by
a
movable wall. The movable wall forms a seal with the interior wall of the
housing and
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reciprocates within the housing to change the volume of the compartments upon
application and removal of a compressive force. An embodiment of the vacuum
pump
can include a spring element which is compressed by the movable wall upon
application
of a compressive force and configured to expand in the absence of force on the
movable
wall to assist in expelling our out of the fluid compartment. The compression
transfer
element may be in the form of a wire which transfers force from a prosthetic
foot to the
movable wall by using pins on each end of the compression transfer element
which are
displaced by a compressive force.
[13] In an embodiment of the system, a tensioned cable connected between a
prosthetic foot and the housing of the vacuum is arranged to enable a spring
element to
expand upon application of a compressive force to the tensioned cable thereby
increasing
the volume of the fluid chamber. When the compressive force is removed or is
absent, the
tensioned cable compresses the spring causing the volume of the fluid
compartment to
decrease.
[14] In accordance with an embodiment of the system, the system includes a
vacuum
pump having a housing comprising a pair of opposed movable walls with the
fluid
compartment defined by the movable walls and the elastomeric sidewalls. The
opposed
walls each include a wall extension to translate a compressive force into an
increase in
the volume of the fluid compartment. One of the wall extensions is connected
to a
proximal portion of the prosthetic foot and the second wall extension is
connected to a
distal portion of the prosthetic foot such as a heel portion.
[15] In an embodiment of the system, the system includes a vacuum pump
comprising
a base member and a pivoting member pivotally connected to each other at a
first end by
a joint. At a second end of the vacuum pump, opposite the joint end, a
protruding wall is
arranged on the base member opposite a recess of the pivoting member. The
protruding
wall can reciprocate within the recess of the pivoting member, and form a seal
with the
walls of the recess. The protruding wall and the recess form a fluid chamber
for the
vacuum pump. The base member is connected to the prosthetic foot and the
pivoting
member has a connector on the joint end to connect to a pylon or socket of a
residual
limb. When the base member and pivoting member rotate away from each other,
the
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volume of the fluid compartment is increased to draw in fluid from the socket
cavity, and
when the base member and pivoting member rotate towards each other, the volume
of the
fluid compartment is decreased to expel fluid from the fluid compartment.
[16] The numerous advantages, features and functions of the various
embodiments of
the vacuum assisted suspension system will become readily apparent and better
understood in view of the following description and accompanying drawings. The
following description is not intended to limit the scope of the prosthetic
system, but
instead merely provides exemplary embodiments for ease of understanding.
[17] BRIEF DESCRIPTION OF THE DRAWINGS
[18] The vacuum assisted suspension system is described with reference to the
accompanying drawings which show preferred embodiments according to the device
described herein. It will be noted that the device as disclosed in the
accompanying
drawings is illustrated by way of example only. The various elements and
combinations
of elements described below and illustrated in the drawings can be arranged
and
organized differently to result in embodiments which are still within the
spirit and scope
of the device described herein.
[19] Fig.1 is a schematic illustration of a vacuum assisted suspension system
according
to a first embodiment.
[20] Fig. 2 is an exploded view of the vacuum pump in Fig. 1.
[21] Fig. 3 shows a view of the vacuum pump of Fig. 2 in assembled form.
[22] Fig. 4 shows a cross-sectional view of an embodiment of the vacuum pump.
[23] Fig. 5 is a cross-sectional view of another embodiment of the vacuum
pump.
[24] Fig. 6 shows a cross-sectional view of another embodiment of the vacuum
pump.
[25] Fig. 7 shows a cross-sectional view of another embodiment of the vacuum
pump.
[26] Fig. 8 shows a variation of the vacuum assisted suspension system.
[27] Fig. 9a shows an embodiment of the vacuum assisted suspension system in
the
absence of a compressive force.
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[28] Fig. 9b shows an embodiment of the vacuum assisted suspension system
subjected to a compressive force.
[29] Fig. 10 is a side view of a fourth embodiment of the prosthetic system.
DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS
[30] A better understanding of different embodiments of the vacuum assisted
suspension system may be had from the following description read in
conjunction with
the accompanying drawings in which like reference characters refer to like
elements.
[31] While the disclosure is susceptible to various modifications and
alternative
constructions, certain illustrative embodiments are shown in the drawings and
will be
described below in detail. It should be understood, however, that there is no
intention to
limit the disclosure to the specific embodiments disclosed, but on the
contrary, the
intention is to cover all modifications, alternative constructions,
combinations, and
equivalents falling within the spirit and scope of the disclosure and defined
by the
appended claims.
[32] It will be understood that, unless a term is expressly defined in this
disclosure to
possess a described meaning, there is no intent to limit the meaning of such
term, either
expressly or indirectly, beyond its plain or ordinary meaning.
[33] The anatomical terms described herein are not intended to detract from
the normal
understanding of such terms as readily understood by one of ordinary skill in
the art of
prosthetics. For example, the term "distal" is used to denote the portion or
end of a limb
that is farthest from the central portion of the body. The term distal is the
opposite of
"proximal" which is used to denote that the end or portion of the limb is
nearer to the
central portion of the body.
[34] Embodiments of a vacuum assisted suspension system include a vacuum pump
having a fluid connection with a socket, and the vacuum pump assists in
creating a
vacuum between a residual limb and the socket by pumping fluid out of the
socket. The
fluid is pumped out of the socket when the user puts his weight on a
prosthetic foot such
as upon a heel strike. The compressive force of the heel strike causes a
compression
transfer element of the pump to increase the volume of a fluid chamber in the
pump. The
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increase in volume of the pump draws in fluid from the vacuum space between
the
residual limb and the socket of a prosthetic limb. In this manner, the pump
decreases the
air pressure within the vacuum space causing a vacuum effect.
[35] After the compressive force is removed, for example, during toe-off and
the swing
phase of gait, the volume of the fluid chamber in the pump is decreased. The
connection
between the vacuum space of the socket and the pump may have a one-way valve,
so all
of the air within the volume of the pump is expelled out of an outlet to
another space or to
atmosphere. The inlet can be provided with a one-valve so that the vacuum
space of the
socket is the only source of air or fluid.
[36] This method of producing a vacuum effect in the prosthetic socket is
advantageous over prior method of compressing the pump to expel air and
decompressing
the pump to draw in air. The method described herein achieves smaller
fluctuations in air
pressure, so the difference between the greatest pressure and least pressure
in the vacuum
space is less in the method described herein compared to prior art methods.
[37] The efficiency of the pump is determined partially by how effectively the
volume
of the fluid chamber is reduced. Since the pump returns to the original state
of zero or
near-zero volume at the beginning or end of each cycle, the volume of the
fluid chamber
is determined by the degree of compressive force applied to the pump. In the
method
described herein, all fluid drawn into the pump is expelled afterwards, thus,
fully utilizing
each cycle. Additionally, the method described herein may be implemented using
a pump
that does not have any spring type elements which may affect the bio-
mechanical
function of the prosthetic system.
[38] The benefits of using a vacuum suspension system include increased blood
flow
to the residual limb since there is less pressure on the residual limb. The
vacuum
suspension system also reduces volume fluctuations of the residual limb, and
wounds on
the residual limb heal faster. The vacuum assisted suspension system allows
for increased
proprioception and reduced pistoning since there is a better attachment
between the
socket and the residual limb. The socket trim lines can also be lowered with a
vacuum
suspension system resulting in a lighter, smaller prosthetic system.
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[39] It may also be beneficial to produce hypobaric pressure below a certain
level in
the socket. This may be achieved using a seal between the residual limb and
the socket,
instead of the conventional sealing method of using a sleeve to form an
airtight
connection between the residual limb and the proximal end of the socket. The
seal may
be provided as in an exemplary prosthetic liner taught in U.S. patent no.
8,034,120 issued
October 11, 2011.
[40] The benefit of using, for example a liner having a seal, is to reduce the
volume of
air to be drawn out of the socket and therefore, a better suspension may be
achieved in a
shorter time period. Using a silicone liner with integrated seal also provides
the added
benefit that the hypobaric region is not directly applied to the skin.
[41] The various embodiments of the vacuum assisted suspension system will now
be
described with respect to the figures.
[42] Fig. 1 is a schematic illustration of an embodiment of a vacuum assisted
suspension system. Fig. 1 shows a cross-sectional view of an exemplary
embodiment of a
vacuum pump 2 and the connections of the vacuum pump 2 to a socket 4 and a
prosthetic
foot 6. The vacuum pump 2 has a housing 8 which forms an enclosed interior
space
including a fluid chamber 12 and a non-fluid chamber 14. The chambers 12 and
14 are
separated by a movable wall 10 which forms a seal with the sides of the
housing 8. One
side of the movable wall 10 forms part of the fluid chamber 12 and the
opposite side of
the movable wall 14 forms part of the non-fluid chamber 14.
[43] A compression transfer element 15 is connects to the housing 8 of the
vacuum
pump 2 and to the prosthetic foot 6. The compression transfer element 15
includes a wire
16 which has a first pin 18 on the end attached to the heel portion of the
prosthetic foot 6
and a second pin 20 on the end connected to the housing 8. The second pin 20
enters the
fluid chamber 12 through an opening in the housing 8 to adjust the position of
the
movable wall 10 and connects with the side of the movable wall 10 which forms
the fluid
chamber 12. The wire 16 may be a flexible wire placed within a tubular casing
which
forms an airtight connection between the wire 16, the second pin 20, the
housing 8
including the fluid chamber 12. The opening in the housing 8 for the second
pin 20 may
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also be provided with a sealer such as an elastomeric ring which
simultaneously allows
reciprocation of the second pin 20 through the opening while providing an
airtight
connection between compression transfer element 15 and the vacuum pump 2.
Alternatively, the compression transfer element 15 may be a stiff wire within
a tubular
casing. The compression transfer element 15 translates a compressive force
into a force
applied to the movable wall 10 to cause the movable wall 10 to reciprocate in
the housing
8.
[44] A compressive force can be a force created during gait on the prosthetic
foot, in
particular, by applying weight to a portion of the prosthetic foot 6. In an
embodiment of
the system, the compressive force is created upon heel strike when the user
applies
weight to the heel area of the prosthetic foot 6 to which one end of the
compression
transfer element is attached. The compression transfer element 15 translates
the heel
strike force into a force to cause the movable wall 10 to reciprocate.
[45] In the absence of a compressive force, the movable wall 10 rests on the
housing
surface having an input port 24 and output port 26 such that the fluid chamber
12 has
zero or near zero volume. The input port 24 and output port 26 may be
positioned
anywhere on the surface of the housing 8. It is preferred that the ports 24
and 26 be
placed opposite the movable wall 10 for the most efficient pumping mechanism
and on
the same side as the opening for the second pin 20.
[46] To create or increase the vacuum effect, a user places his weight on the
prosthetic
foot 6, which creates a compressive force that causes the first pin 18 to push
on the wire
16 and slide into the tubular casing. When the first pin 18 pushes on the wire
16, the wire
16 is displaced and pushes on the second pin 20. The second pin 20 applies a
force which
may be substantially perpendicular to the movable wall 10 to increase the
volume of the
fluid chamber 12. Due to the increase in the volume of the fluid chamber 12,
fluid is
drawn into the fluid chamber 12 via an input port 24 from the socket 4 through
a tube 44.
[47] When the compressive force is removed, the movable wall 10 returns to its
original state of resting on the housing surface which simultaneously returns
the fluid
chamber 12 to its original state of approximately zero volume. When the volume
of the
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fluid chamber 12 is decreasing, fluid drawn in from the socket 4 previously is
now forced
out of the output port 26. The output port 26 is provided with a one-way valve
which only
allows fluid out of the output port 26. The input port 24 may also have a one-
way valve
which prevents fluid in the fluid chamber 12 from returning to the socket and
only allows
fluid to enter the fluid chamber 12.
[48] The pump 2 may optionally have a spring element 22 in the non-fluid
chamber
which assists in returning the fluid chamber 12 to a volume of zero or
approximately
zero. The spring element 22 may be substantially perpendicular to the movable
wall 10
and is compressed when the fluid chamber 12 is enlarged. In other words, the
direction of
compression and expansion of the spring element is arranged to be
perpendicular to the
movable wall 10. When the compressive force is removed, the spring element 22
decompresses and pushes the movable wall 10. The addition of a spring element
22
increases the efficiency of the pump by allowing the pump to more quickly
decompress
due to the added force on the movable wall 10 provided by the spring element
22. The
spring element 22 may be a coil or a spring, or formed from an elastomeric
material.
[49] In this manner, hypobaric pressure may be created or enhanced in the
space
enclosed by the residual limb and socket 4.
[50] Fig. 2 is an exploded view of the embodiment of the vacuum pump 2 in Fig.
1.
The pump housing 8 in this embodiment is shown to be formed of two pieces. The
pump
housing 8 may be formed of a single continuous housing. Further, while the
vacuum
pump housing 8 is shown to have a cylindrical shape, the pump housing 8 may
take any
form including any polygonal prism such as a rectangular prism. The movable
wall 10, as
seen in Fig. 2, has a circular shape corresponding to the base shape of the
interior volume
which is cylindrical in this embodiment. Similar to the vacuum pump housing 8,
the
movable wall 10 may have a variety shapes depending on the shape of the
enclosed
interior space of the housing 8. The shape of the movable wall 10 should
correspond to
the base shape of the housing 8 to create two completely separate chambers.
The movable
wall 10 may also be outlined with an elastomeric material to create an
airtight partition
between the fluid chamber 12 and the non-fluid chamber 14 while still allowing
the
movable wall 10 to easily reciprocate between the two chambers 12 and 14.
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[51] The input and output ports are not shown in this view. The spring element
22 is
arranged between one side of the movable wall 10 and the housing 8. The spring
element
22 may be received in corresponding recesses 28 on the movable wall 10 and
housing 8
to maintain the positioning of the spring element 22 within the vacuum pump 2.
[52] Because the vacuum pump housing 8 may take such a large variety of
shapes, the
vacuum pump 2 can be placed in numerous locations on the prosthetic foot.
Further, the
ability of the vacuum pump 2 to create a negative pressure effect is not
limited by the size
of any cavity in which the vacuum pump 2 may be placed. This allows the vacuum
pump
to be compatible with a wide range of prosthetic foot forms. The vacuum pump 2
also
adds minimal weight to the prosthetic foot 6.
[53] Fig. 3 shows the embodiment of Fig. 2 assembled with the first pin 18,
the wire
16 within a casing and the outer housing 8 of the vacuum pump 2.
[54] The wire 16 has a housing connector, and the housing 8 has a
corresponding
compression transfer element connector. The attachment between the compression
transfer element 15 and the housing 8 may be a threaded attachment or
interlocking
connector or other types of attachments known in the art.
[55] The wire 16 of the compression transfer element 15 may be made of any
type of
material which would provide the compression transfer element 15 with some
rigidity
and stiffness including metal, plastic, or fiberglass. The outer tubular
casing for the wire
16 may be made of a variety of materials including plastic or an elastomeric
material.
[56] Additionally, the compression transfer element 15 may take the form of a
shaft
which is connected to the heel section of the prosthetic foot. The vertical
displacement of
the heel caused upon heel strike would generate the compressive force acting
on the
pump.
[57] The vacuum pump may also be placed inside the prosthetic foot. During the
stance phase of gait, the weight of the user would apply a compressive force
to the pump
to increase the volume of the fluid chamber and draw in air from the socket as
similarly
described above.
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[58] Figs. 4-7 show other variations of the vacuum pump 2.
[59] Fig. 4 shows a movable wall 10 with a recess outlining the shape of the
spring
element 22 to receive the spring element 22 in the fluid compartment. For
example, the
spring element 22 may be cylindrical such that the recess is a circular
indentation in the
movable wall 10. The input port 24 and output port 26 are arranged on the side
of the
housing 8 opposite the side in which the second pin 20 enters the vacuum pump.
The
vacuum pump in Fig. 4 is shown in a compressed state with the second pin 20
extending
from the wire 16 into the non-fluid compartment to push the movable wall 10
against the
opposing side to expel fluid out of output port 26. Once pressure on the
second pin 20 is
released, the spring element 22 decompresses to push the movable wall 10
towards the
pin receiving side of the housing 8 and draw fluid into the pump 2 through
input port 24.
[60] Fig. 5 shows another arrangement of the elements of the vacuum pump 2. In
Fig.
5, the ports 24, 26 are arranged adjacent or on the same side of the housing 8
as the
second pin 20 similar to the embodiment shown in Figs. 1-3. The movable wall
10 in Fig.
is provided with a cylindrical recess having a depth to receive approximately
half of the
spring element 22 in its uncompressed state. When the second pin 20 receives
pressure or
force, the second pin 20 pushes the movable wall 10 towards the opposing wall
until the
movable wall 10 comes into contact with the housing 8. The second pin 20
extends into
the fluid compartment and connects with the movable wall 10 on the fluid
compartment
side.
[61] Fig. 6 shows another embodiment of the vacuum pump 2. Fig. 6 is similar
to the
embodiment shown in Fig. 4, but the second pin 20 is arranged on the same side
as the
ports 24, 26. In this embodiment, the pin 20 can extend from wire 16 into the
fluid
compartment to push the movable wall 10 and draw in fluid through input port
24. The
spring element 22 in the fluid compartment can serve the opposite effect of
the pin 20 and
pull the movable wall 10 towards the ports 24, 26 to expel air out of output
port 26.
[62] Fig. 7 shows an embodiment of the vacuum pump 2 with elements similar to
those of Fig. 5. In Fig. 7, the second pin 20 extends out of the wire 16 into
the non-fluid
compartment to push the moveable wall 10 towards the ports 24, 26. When
pressure on
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the second pin 20 is released, the spring element 22 in the non-fluid
compartment can
serve to draw the moveable wall 10 away from the ports 24, 26 to draw in fluid
into the
pump 2 through input port 24.
[63] Fig. 8 depicts a variation of the vacuum assisted suspension system. The
vacuum
assisted suspension system shown in Fig. 8 includes an enlarged cross-
sectional view of
the vacuum pump 2 as well as the connections between the pump 2, the socket 4,
and
prosthetic foot 6. Vacuum pump 2 has a housing 8 which may comprise two
pieces. The
two pieces may use a threaded connection to attach to each other. The housing
8 forms an
interior enclosed space and within the interior enclosed space is a movable
wall 10 which
divides the enclosed space into a fluid chamber 12 and a non-fluid chamber 14.
One side
of the movable wall 10 forms the fluid chamber 12 and the opposite side forms
the non-
fluid chamber 14. The movable wall 10 reciprocates within the enclosed space
to change
the volume of the fluid chamber 12 and the non-fluid chamber 14. The vacuum
pump 2
may be attached to the shank or the pylon of the prosthetic foot above the
ankle area as
shown in Fig. 8.
[64] The compression transfer element 15 includes a tensioned cable or wire 34
having
an end pin 38 which interacts with a protruding pin 30 of the movable wall 10
by pulling
and releasing a wire loop 39. The protruding pin 30 is positioned on the side
of the
movable wall 10 forming part of the fluid chamber 12 and extends through the
fluid
chamber 12. The protruding pin 30 may extend outside of the housing 8 and the
opening
through which the protruding pin 30 reciprocates can be provided with a sealer
such as an
elastomeric ring to provide an airtight connection.
[65] In the absence of a compressive force which is a force directed towards
the
vacuum pump 2, the tensioned cable 34 is taut and pulls the movable wall 10
towards the
output port 26 which compresses the spring element 32 and changes the volume
of the
fluid chamber 12 to zero or approximately zero. Similar to the previous
embodiment, the
ports 24 and 26 may be placed anywhere on the surface of the housing 8 and are
preferably placed opposite the movable wall 10.
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[66] When the user places his weight on the prosthetic foot, such as during a
heel
strike, the tension in the cable 34 is reduced allowing the spring element 32
to
decompress and push the movable wall 10 away from input port 24 and output
port 26.
The cable 34 is attached to the heel portion of the prosthetic foot 6 by a
cable anchor 36
at the distal end of the cable 34. The proximal end of the cable 34 has the
end pin 38
which is located in the wire loop 39. The wire loop 39 is looped around the
end pin 38
such that one end of the wire loop 39 is attached to the outside of the
housing 8 and the
other end of the wire loop 39 is attached to the protruding pin 30 of the
movable wall 10.
The end pin 38 of the cable 34 is located on the interior of the loop 39 acts
like an
adjustable weight for the movable wall 10 by applying weight on the middle
portion of
the loop 39 to pull or release the movable wall 10.
[67] The compression transfer element 15 may include a cable guide 40 at the
end of a
pump arm 42 protruding from the bottom of the housing 8. The pump arm 42 may
have a
perpendicular extension at the distal end to have the general shape of an "L"
with the
cable guide 40 attached to the end of the perpendicular extension. The cable
guide 40
positions the proximal end of the cable 34 to be substantially parallel to the
protruding
pin 30. The spring element 32 may coil or wrap around the protruding pin 30.
The spring
element 32 may be a spring or may be formed from an elastomeric material.
[68] The alternative arrangements of elements of the vacuum pump 2 shown in
Figs. 4-
7 may also be used in the vacuum pump 2 of the second embodiment of the
prosthetic
system described herein. The protruding pin 30 may be used in Figs. 4-7
instead of pin
20. A skilled person would have known how to adapt the various embodiments of
the
vacuum pump 2 to be used in the embodiments of the prosthetic system described
herein.
[69] Figs. 9a and 9b show a different version of the vacuum assisted
suspension
system including the vacuum pump 44. Fig. 9a depicts the vacuum pump 44 in its
original, decompressed state where the vacuum pump 44 is not subject to any
compressive forces. In Fig. 9b, a compressive force 56 has been applied to the
vacuum
pump 44.
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[70] The housing 8 of vacuum pump 44 is formed of at least one pair of
parallel
movable walls 46 and 48 which are preferably rigid. Between the movable walls
46 and
48 is a fluid chamber 54 which may be formed of an elastomeric material. The
fluid
chamber 54 also has sidewalls 47, 49 which can be formed of the elastomeric
material.
The elastomeric material may have an accordion-like structure to enable the
fluid
chamber 54 to expand and contract. The housing of the vacuum pump 44 may have
the
shape of a rectangular prism when expanded.
[71] The first movable wall 46 has an extension 60 which extends from the
chamber
area of the wall and attaches to proximal portion of the prosthetic foot 6. On
the wall
extension 60, one end of a first hinge 50 is connected to the first movable
wall 46 outside
of the fluid chamber area. The second end of the first hinge 50 is connected
diagonally to
the second movable wall 48 in the fluid chamber area of the second movable
wall 48. The
second hinge 52 is attached to the distal end of the first movable wall 46,
and the wall
extension 62 of the second movable wall 48. The second wall 48 has a distal
extension 62
which connects to the heel of the prosthetic foot. As shown in Fig. 9a, the
fluid chamber
areas of the walls 46 and 48 are offset when the fluid chamber 54 has no
volume.
[72] The wall extensions 60 and 62 may be formed together with the walls 46
and 48,
respectively, or the wall extensions 60 and 62 may be separate components
which are
rigidly attached to the walls 46 and 48 such as rigid or stiff cables, wires,
or plates. The
wall extension 62 is shown as being attached to the heel of the prosthetic
foot 6. Wall
extensions 60, 62 may be rearranged such that wall extension 60 is attached to
the heel
portion of the prosthetic foot 6, and wall extension 62 is attached to the
proximal portion
of the prosthetic foot 6.
[73] The compression transfer element includes the wall extension 62 attached
to or
integrated with the wall 48. When a compressive force in the direction 56
occurs such as
during a heel strike, the volume of the fluid chamber 54 increases by having
at least the
wall extension 62 push or shift the movable wall 48 diagonally away from
movable wall
46 to increase the volume between the two movable walls 46 and 48. The
movement of
the walls 46 and 48 is guided by the hinges 50 and 52. The direction of the
fluid chamber
expansion 58 may also be substantially perpendicular to the compressive force
56.
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[74] After the heel strike, a compression element such as an elastomer or a
spring
system compresses the pump 44 by reducing the volume of the fluid chamber 54
to being
zero or near zero and returns the pump 44 to the state shown in Fig. 9a.
[75] Similar to the previous embodiments, the input port and output port of
the fluid
chamber 54 may be located on any surface of the pump.
[76] The vacuum pump 44 may comprise two pairs of opposing parallel walls. The
first pair of walls may have a placement similar to those of movable walls 46
and 48. The
second pair of walls may be parallel to the hinges 50 and 52.
[77] As shown in Fig. 9b, the vacuum pump 44 may have a rectangular cross-
section.
The vacuum pump 44 may also have a fluid chamber 54 with a diamond cross-
section.
[78] Fig. 10 shows a side view of another embodiment of the vacuum assisted
suspension system including a vacuum pump 64 on a prosthetic foot 6. The
vacuum
pump 64 functions through a pivoting mechanism. The pivoting mechanism
generally
involves a base member and a pivoting member that pivot about or rotate around
a
common joint to cause a protruding wall or piston to reciprocate within a
fluid chamber.
The base member and the pivoting member are arranged such that the rotation
occurs
between the prosthetic foot and the residual limb. In this manner, the
pivoting of the
pump helps make the gait process smoother by functioning similar to a regular
heel.
Thus, the fourth embodiment is advantageous in that the fourth embodiment aids
the gait
of the user and also assists in maintaining negative pressure in the sealed
cavity of a
socket.
[79] In the embodiment shown in Fig. 10, the vacuum pump 64 has a connector 66
on
the proximal end to connect the pump 64 to, for example, a pylon or in the end
a residual
limb. The pump 64 further includes an elongate base member 68, an elongate
pivoting
member 70, a joint 72, a fluid chamber 76, and a protruding wall or piston 80.
The base
member 68 is affixed to a portion of the prosthetic foot 6 preferably the shin
area of the
foot 6, and the connector 66 is attached to the pivoting member 70 such that
the
prosthetic foot 6 pivots separately from the pylon and the residual limb. Near
the
proximal end of the base member 68 is a joint 72 which connects the base
member 68 to
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the pivoting member 70. The joint 72 enables the base member 68 and the
pivoting
member 70 to rotate or pivot with respect to each other in the direction shown
by arrow
74. The joint 72 may be in the form of two partial elements such as a
cylindrical pin on
one member inserted through a pin holder of the other member. The pivoting or
rotation
of the base member 68 and the pivoting member 70 preferably occurs in a plane
parallel
to the anterior-posterior plane. The axis of rotation for the joint 72 is
preferably
perpendicular to the anterior-posterior plane.
[80] At the end opposite the joint 72 which is shown as the distal end in Fig.
10, the
base member 68 has a protruding wall or piston 80 positioned opposite to a
recess in the
pivoting member 70. The protruding wall or piston 80 is received within the
recess, and
the protruding wall 80 forms a seal with the interior of the recess. Together
the protruding
wall 80 and the recess form a fluid chamber 76. The fluid chamber 76 is
preferably
located at the opposite end of the joint 72 or the distal end of the pump 64
to maximize
the difference between the maximum and minimum volume of the fluid chamber 76.
Arrow 80 shows the direction of reciprocation of the piston 80 within the
recess of the
pivoting member 70. Arrow 82 which is parallel to arrow 80 represents the
overall
direction of expansion and contraction of the fluid chamber 76. When the base
member
68 and the pivoting member 70 are rotated towards each other, the piston 80 is
inserted
deeper within the recess causing the volume of the fluid chamber 76 to
decrease. When
the base member 68 and the pivoting member 70 are rotated away from each
other, the
piston 80 is pulled away from the interior of the recess and causes the volume
of the fluid
chamber 76 to increase.
[81] The fluid chamber 76 has openings 78 which are preferably connected to
one-way
valves to control the direction of fluid flow into and out of the chamber. For
example, one
opening may be connected to a one-way valve which only allows fluid into the
fluid
chamber 76. This valve is in fluid communication with the cavity of the socket
to
increase the vacuum or negative pressure within a sealed socket cavity. The
other
opening is connected to a one-way valve which only allows fluid to be expelled
from the
fluid chamber 76, for example, to atmosphere.
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[82] During gait such as at heel strike, the base member 68 and the pivoting
member
70 rotate away from each other to cause an expansion of the fluid chamber 76
and an
increase of the volume of the fluid chamber 76 which draws fluid into the pump
64 from
the socket cavity. After the toe off, the base member 68 and pivoting member
70 rotate
towards each other to decrease the volume of the fluid chamber 76 and expel
fluid out of
one of the openings. The rotation of the base member 68 and pivoting member 70
towards each other may be accomplished with a spring element or other element
which
applies an external force.
[83] Similar to the other embodiments described herein, the fluid chamber 76
of the
vacuum pump 64 preferably has minimum volume of zero or approximately zero
such
that during gait, any fluid drawn into fluid chamber 76 in one cycle is
substantially
expelled before more fluid is drawn into the fluid chamber 76.
[84] The resistance of the joint 72 is adjustable to increase or decrease the
amount of
rotational force required to pivot the base member 68 and the pivoting member
70 based
on the user's preference. The angle of the pump 64 and the degree with which
the
member 68, 70 are able to rotate is also adjustable to accommodate different
situations
such as different shoes.
[85] The embodiments described herein may be used with an exemplary prosthetic
socket as taught in U.S. patent no. 7,427,297 issued September 23, 2008.
[86] The embodiments described herein may be used with an exemplary prosthetic
foot as taught in U.S. patent no. 6,969,408 issued November 29, 2005.
[87] The embodiments described herein may be used with a pressure regulator to
insure the safety and comfort of the user which may be achieved using
mechanical and/or
electronic methods known in the industry.
[88] While the foregoing embodiments have been described and shown, it is
understood that alternatives and modifications of these embodiments, such as
those
suggested by others, may be made to fall within the scope of the invention.
Any of the
principles described herein may be extended to other types of prosthetic or
orthopedic
devices.
