U.S. patent application number 09/829306 was filed with the patent office on 2001-08-23 for osmotic membrane and vacuum system for artificial limb.
Invention is credited to Caspers, Carl A..
Application Number | 20010016781 09/829306 |
Document ID | / |
Family ID | 25254138 |
Filed Date | 2001-08-23 |
United States Patent
Application |
20010016781 |
Kind Code |
A1 |
Caspers, Carl A. |
August 23, 2001 |
Osmotic membrane and vacuum system for artificial limb
Abstract
A hypobarically-controlled artificial limb for amputees includes
a single socket with a volume and shape to receive a substantial
portion of the residual limb. A liner with a volume less than the
residual limb is donned over the residual limb, with the liner
tensioned into a total contact relationship with the residual limb.
A sealed cavity is formed between the socket and the liner. A
vacuum source is connected to the socket cavity thereby drawing the
residual limb and liner into firm and total contact with the
socket. To compensate for some air leakage past the seal, there is
a mechanism to maintain the vacuum in the cavity. An osmotic
membrane encases the residual limb and creates a space between the
residual limb and the liner. The osmotic membrane allows passage of
water only in one direction: from the residual limb toward the
liner. Vacuum may be applied to the space between the osmotic
membrane and the liner to assist in wicking perspiration away from
the residual limb.
Inventors: |
Caspers, Carl A.; (Avon,
MN) |
Correspondence
Address: |
RIDER, BENNETT, EGAN & ARUNDEL
333 SOUTH SEVENTH STREET
SUITE 2000
MINNEAPOLIS
MN
55402
US
|
Family ID: |
25254138 |
Appl. No.: |
09/829306 |
Filed: |
April 9, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09829306 |
Apr 9, 2001 |
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09325297 |
Jun 3, 1999 |
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09829306 |
Apr 9, 2001 |
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09534274 |
Mar 23, 2000 |
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Current U.S.
Class: |
623/34 ; 623/32;
623/36 |
Current CPC
Class: |
A61F 2/601 20130101;
A61F 2210/0057 20130101; A61F 2002/7655 20130101; A61F 2013/15528
20130101; A61F 2/7812 20130101; A61F 2002/5052 20130101; A61F
2002/6614 20130101; A61F 2/5046 20130101; A61F 2/5044 20130101;
A61F 2002/7818 20130101; A61F 2002/5015 20130101; A61F 2/7843
20130101; A61F 2/74 20210801; A61F 2002/5053 20130101; A61F
2002/5003 20130101; A61F 2/80 20130101; A61F 2002/704 20130101;
A61F 2002/802 20130101 |
Class at
Publication: |
623/34 ; 623/36;
623/32 |
International
Class: |
A61F 002/80 |
Claims
What is claimed:
1. In an artificial limb for amputees who have a residual limb, the
residual limb being encased in a liner, the residual limb and liner
being inserted into the artificial limb socket, an apparatus for
wicking away perspiration from the residual limb, the apparatus
comprising: an osmotic membrane encasing the residual limb and
lying between the residual limb and the liner, thereby creating a
space between the residual limb and the liner, the membrane being
adapted to allow the passage of water vapor in one direction only,
from the residual limb towards the liner.
2. The apparatus of claim 1, further comprising: a) a vacuum source
connected to the space between the liner and the residual limb,
wherein application of the vacuum source to the space between the
liner and the residual limb lowers the partial water vapor pressure
in the space, allowing water vapor to pass more readily through the
osmotic membrane; and b) a seal means for sealing the space.
3. The apparatus of claim 2, further comprising a means to maintain
a vacuum in the space, in the presence of some air leakage past the
seal means.
4. The apparatus of claim 2, wherein the seal means further
comprises a nonfoamed, nonporous polyurethane suspension sleeve for
rolling over and covering the socket and a portion of the residual
limb.
5. The apparatus of claim 3, wherein the vacuum source is a vacuum
pump and the means to maintain the vacuum in the cavity is a
regulator, and further comprising a power source for the vacuum
pump and the regulator.
6. The apparatus of claim 3, wherein the vacuum source and the
means to maintain the vacuum in the cavity further comprise a
weight-actuated vacuum pump.
7. A method of wicking away perspiration from a residual limb in an
artificial limb, comprising the steps of: a) inserting the residual
limb into an osmotic membrane adapted to allow the passage of water
vapor in only one direction away from the residual limb; b)
inserting the residual limb and osmotic membrane into a flexible
liner wherein a space is created between the osmotic membrane and
the liner; b) inserting the residual limb and liner into a socket
having a volume and shape to receive the residual limb and the
liner, the socket having a cavity into which the residual limb and
liner are inserted; c) sealing the socket cavity; d) applying a
vacuum to the socket cavity between the liner and the socket,
thereby drawing the residual limb and liner into firm and total
contact with the socket; and e) applying a vacuum to the space
between the osmotic membrane and the liner.
8. The method of claim 7, further comprising the step of: f)
maintaining a vacuum in the socket cavity, in the presence of some
air leakage into the socket cavity.
9. The method of claim 7, wherein the liner is of a non-foamed,
non-porous polyurethane.
10. The method of claim 7, wherein a vacuum of at least ten inches
of mercury is maintained in the cavity.
Description
BACKGROUND OF THE INVENTION
[0001] This is a continuation-in-part of U.S. patent application
Ser. No. 09/325,297, filed Jun. 3, 1999, and U.S. Pat. No.
09/534,274, filed Mar. 23, 2000.
[0002] The present invention relates to prosthetic devices and more
particularly to a hypobarically-controlled artificial limb for
amputees and to a method for removing perspiration from the space
between the residual limb and the liner by means of an osmotic
membrane and an applied vacuum.
[0003] An amputee is a person who has lost part of an extremity or
limb such as a leg or arm which commonly may be termed as a
residual limb. Residual limbs come in various sizes and shapes with
respect to the stump. That is, most new amputations are either
slightly bulbous or cylindrical in shape while older amputations
that may have had a lot of atrophy are generally more conical in
shape. Residual limbs may further be characterized by their various
individual problems or configurations including the volume and
shape of a stump and possible scar, skin graft, bony prominence,
uneven limb volume, neuroma, pain, edema or soft tissue
configurations.
[0004] Referring to FIGS. 1 and 2, a below the knee residual limb
10 is shown and described as a leg 12 having been severed below the
knee terminating in a stump 14. In this case, the residual limb 10
includes soft tissue as well as the femur 16, knee joint 18, and
severed tibia 20 and fibula 22. Along these bone structures
surrounded by soft tissue are nerve bundles and vascular routes
which must be protected against external pressure to avoid
neuromas, numbness and discomfort as well as other kinds of
problems. A below the knee residual limb 10 has its stump 14
generally characterized as being a more bony structure while an
above the knee residual limb may be characterized as including more
soft tissue as well as the vascular routes and nerve bundles.
[0005] Referring to FIG. 2, amputees who have lost a part of their
arm 26, which terminates in a stump 28 also may be characterized as
having vascular routes, nerve bundles as well as soft and bony
tissues. The residual limb 10 includes the humerus bone 30 which
extends from below the shoulder to the elbow from which the radius
34 and ulna 36 bones may pivotally extend to the point of
severance. Along the humerus bone 30 are the biceps muscle 38 and
the triceps muscle 40 which still yet may be connected to the
radius 34 and the ulna, 36, respectively.
[0006] In some respects, the residual limb amputee that has a
severed arm 26 does not have the pressure bearing considerations
for an artificial limb but rather is concerned with having an
artificial limb that is articulable to offer functions typical of a
full arm, such as bending at the elbow and grasping capabilities.
An individual who has a paralyzed limb would also have similar
considerations wherein he or she would desire the paralyzed limb to
having some degree of mobility and thus functionality.
[0007] During the day, as the residual limb amputee walks on an
artificial limb, perspiration builds up between the residual limb
and the liner which cushions the residual limb in the artificial
limb socket. As this perspiration buildup continues, the residual
limb begins to slip around within the liner, causing a feeling to
the wearer of losing contact with the artificial limb. This
slippage often also causes irritation to the residual limb, which
may be worsened by a growth of bacteria in the warm, moist
environment between the residual limb and the liner.
[0008] There is a need for an improved hypobarically-controlled
artificial limb that will offer total contact relationship with the
residual limb; absorb and dissipate shock, mechanical and shear
forces typically associated with ambulation, twisting and turning
and weight bearing with an artificial limb; control residual limb
volume by way of even weight distribution; use negative pressure as
a locking device to hold the residual limb into the socket without
causing swelling of the residual limb into the socket; and control
the buildup of perspiration on the residual limb. One of the ways
of controlling the buildup of perspiration is to use a vacuum
system to wick away this perspiration from the residual limb.
[0009] U.S. Pat. No. 5,888,230 discloses the use of a vacuum pump
connected between the limb and a liner. However, this invention is
essentially inoperable because the liner will conform to the stump
at all times, by an interference fit, so that there is no space
between the residual limb and the liner against which to draw a
vacuum. In any case, the patent does not disclose application of
vacuum to the socket cavity in such a manner as to draw the
residual limb firmly and totally against the interior of the
socket. Instead, the patent discloses the use of shims between the
liner and the socket. Without total contact between the residual
limb and the socket, the limb may swell into the space between the
limb and the socket. Also, the patent does not disclose the use of
vacuum to remove perspiration.
[0010] U.S. Pat. No. 5,549,709 discloses several embodiments of a
hypobarically-controlled artificial limb. However, all of these
embodiments required two sockets: an outer socket and an inner
socket. Applicant has found that the present invention offers
improved performance without the requirement for two sockets. A
single socket works equally well or better than two sockets. Also,
this patent does not disclose a mechanism for maintaining vacuum in
the presence of air leakage into the socket.
[0011] It has been found that it is essentially impossible to
maintain a perfect, airtight seal between the residual limb and the
sockets disclosed in U.S. Pat. No. 5,549,709, with the result that
slow air leakage into the sockets diminishes the vacuum in the
sockets. With the reduction in vacuum, the beneficial effects of
the vacuum also slowly diminish. Consequently, there is a need for
a means for maintaining the vacuum in the socket cavity in the
presence of some air leakage past the seal.
SUMMARY OF THE INVENTION
[0012] A hypobarically-controlled artificial limb for amputees
includes a single socket with a volume and shape to receive a
substantial portion of the residual limb. A sealed cavity is formed
between the socket and the residual limb. The wearer may use a
liner over the residual limb for comfort. A vacuum source is
connected to a vacuum valve connected to the cavity to suspend the
artificial limb from the residual limb and to control and minimize
volumetric and fluid changes within the residual limb. To
compensate for some air leakage past the seal, there is a mechanism
to maintain the vacuum in the cavity. An osmotic membrane
encompasses the residual limb, between the residual limb and the
liner, allowing perspiration to pass one way through the osmotic
membrane. Vacuum may be applied to the space between the osmotic
membrane and the liner to wick away perspiration.
[0013] A principle object and advantage of the present invention is
that it uses vacuum within the artificial limb socket to suspend
the artificial limb from the residual limb.
[0014] Another object and advantage of the present invention is
that it uses vacuum within the artificial limb socket to assist in
socket fit and minimizes volumetric limb changes within the
socket.
[0015] Another object and advantage of the present invention is
that it uses vacuum within the socket to lock the residual limb
into the socket while preventing negative draw within the socket
from causing swelling of the residual limb into the socket.
[0016] Another object and advantage of the present invention is
that it uses vacuum within the socket to oppose the loss of fluids
from the residual limb caused by weight-bearing pressures.
[0017] Another object and advantage of the present invention is
that the vacuum may be created by a pump with a mechanical or motor
drive.
[0018] Another principal object and advantage of the present
invention is that it may comprise only a single socket, rather than
two sockets, simplifying construction and reducing cost and
complexity.
[0019] Another principal object and advantage of the present
invention is that it includes a mechanism that can be used to
maintain vacuum in the cavity between the residual limb or liner
and the socket as air leaks into the cavity.
[0020] Another principal object and advantage of the present
invention is that it includes an osmotic membrane that allows
perspiration to pass in only one direction from the residual limb
outward toward the liner.
[0021] Another principal object and advantage of the present
invention is that vacuum may be applied to the space between the
osmotic membrane and the liner to assist in wicking away
perspiration.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 is a side elevational view of the tissue and skeletal
structure of an amputee's residual limb;
[0023] FIG. 2 is a side elevational view of a residual limb in the
form of an amputated arm showing the skeletal and muscular
structure of the residual limb;
[0024] FIG. 3 is an exploded elevational view of the residual limb
donning the polyurethane sleeve, stretchable nylon sleeve, liner,
osmotic membrane, nylon sheath and socket of an artificial
limb;
[0025] FIG. 4 is a cross-section along the lines 4 of FIG. 3.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0026] FIGS. 3 and 4 show one embodiment of the apparatus 50 of the
present invention. The hypobarically-controlled artificial limb 50
includes a single socket 60, shin 54, and foot 56. The socket 60
has a volume and shape to receive a substantial portion of the
residual limb 14 with a space 58 therebetween.
[0027] The apparatus 50 further includes a cavity 62 in the socket
60 with a volume and shape for receiving a substantial portion of
the residual limb 14.
[0028] A vacuum source 70 may conveniently be attached to the shin
or pylon 54. The vacuum source 70 may preferably be a mechanical or
motor-driven pump 72. The vacuum source 70 may be connected to a
power source 83, which may be a battery.
[0029] A vacuum valve 74 is suitably connected to the vacuum source
70. The vacuum valve 74 may preferably be disposed on the socket
60. A vacuum tube 76 connects the vacuum valve 74 to the cavity 62.
It will be seen that the vacuum source will cause the residual limb
14 to be drawn into firm contact with the inner surface 64 of the
socket 60.
[0030] The hypobarically-controlled artificial limb 50 also
includes a regulator means 80 for controlling the vacuum source 70.
Preferably, the regulator means 80 may be a digital computer 82.
Alternately, the regulator means may be a vacuum regulator. The
regulator means 80 is connected to a power source 83, which may be
a battery.
[0031] A seal means 84 makes an airtight seal between the residual
limb 14 and the socket 60. Preferably, the seal means 84 is a
nonfoamed, nonporous polyurethane suspension sleeve 86 which rolls
over and covers the socket 60 and a portion of the residual limb
14. Alternatively, the seal means 84 may be any type of seal which
is airtight.
[0032] The apparatus 50 may also include a nonfoamed, nonporous
polyurethane liner 92 receiving the residual limb 14 and disposed
between the socket 60 and the residual limb 14. The liner 92
provides a total-contact hypobaric suction, equal weight
distribution socket liner. The liner 92 readily tacks up to the
skin of the residual limb 14 and provides total contact with the
limb 14. The liner 92 absorbs and dissipates shock, mechanical and
shear forces typically associated with ambulation.
[0033] The hypobarically-controlled artificial limb 50 may also
include a thin sheath 90 between the liner 92 and the inner surface
64 of the socket 60. As vacuum is applied to the cavity 62, the
sheath 90 will allow the vacuum to be evenly applied throughout the
cavity 62. Without the sheath 90, the liner 92 might "tack up"
against the inner surface 64 and form a seal which might prevent
even application of the vacuum to the cavity 62. The sheath 90 may
also be used to assist the amputee into a smooth and easy fitting
into the inner socket 60. The sheath 90 is preferably made of thin
knitted nylon.
[0034] The hypobarically-controlled artificial limb 50 may also
include a stretchable nylon second sleeve 94 for rolling over and
covering the suspension sleeve 86 to prevent clothing from sticking
to and catching the suspension sleeve 86.
[0035] The hypobarically-controlled artificial limb 50 may also
include an osmotic membrane 100 encompassing the residual limb 14
and creating a space 102 between the residual limb 14 and the liner
92. The osmotic membrane 100 allows perspiration to pass in one
direction only from the residual limb outward toward the liner
92.
[0036] This beneficial effect of the osmotic membrane is achieved
as follows. The osmotic membrane allows water vapor to pass through
the membrane from the side of the membrane with a higher partial
water vapor pressure (the residual limb side) to the side of the
membrane with a lower partial water vapor pressure (the liner
side), but not in the opposite direction. Eventually, the partial
water vapor pressure on the two sides of the osmotic membrane would
become equal, and transmission of vapor through the membrane would
cease. However, application of vacuum to the space 102 will
continually lower the partial water vapor pressure on the liner
side of the membrane 100, so that water vapor will continue to pass
through the membrane. In turn, this lowers the partial water vapor
pressure on the residual limb side of the membrane 100, allowing
perspiration on the residual limb to change from the liquid state
to the vapor state.
[0037] Appropriate materials for the osmotic membrane 100 are the
Sympatex hydrophylic polyester block copolymer from Sympatex
Technologies, One Merrill Industrial Drive, Suite 201, Hampton,
N.H. 03842; the Goretex.RTM. material from A.W. Gore &
Associates, www.gore.com; the Gill 02 Fabric from Gill North
America, 1025 Parkway Industrial Park, Buford, Ga. 30581; and the
SealSkinz product from Porvair, Estuary Road, King's Lynn, Norfolk,
PE30 2HS, United Kingdom.
[0038] The osmotic membrane may be laminated onto a supporting
fabric, such as a cloth stump sock.
[0039] An important aspect of the osmotic membrane 100 is that it
should have no pores into which the skin of the residual limb 14
may be drawn under the influence of vacuum.
[0040] Optionally, vacuum from the vacuum source may be applied to
the space 102 between the osmotic membrane 100 and the liner 92.
Application of vacuum lowers the boiling point of water, allowing
perspiration passing through the osmotic membrane 100 to evaporate
and be removed from the space 102.
[0041] Referring to FIG. 3, the polyurethane tubular sleeve 86 may
be appreciated alone and in combination with the urethane liner 92
together with the optional nylon sheath 90 and second stretchable
nylon sleeve 94.
[0042] More specifically, the amputee takes the stretchable nylon
second sleeve 94, suitably made of a spandex-like material and
rolls it up over the stump 14 to the upper portions of the residual
limb suitably as the thigh of a leg 12. Next, the polyurethane
sleeve 86 is also rolled upwardly over the residual limb 10. The
amputee than places the osmotic membrane 100 over the residual limb
14. Thereafter, the liner 92 is donned.
[0043] Next, the amputee may optionally utilize the nylon sheath 90
which is suitably of a non-stretching, thin, friction reducing
nylon. As stated, this sheath 90 optionally may be used to assist
the amputee into a smooth and easy fitting into the socket 60.
Alternatively, the sheath 90 may be avoided and the liner 92 simply
inserted into the socket 60 of the artificial limb 50.
[0044] Next, the amputee simply grasps the rolled over portion of
the polyurethane sleeve 86 and rolls it over a substantial portion
of the socket 60. The sleeve 86 makes an airtight seal between the
residual limb 14 and the socket 60.
[0045] As can be appreciated, the polyurethane sleeve 86 is tacky.
Consequently, the stretchable nylon second sleeve 94 may be
utilized and rolled over the polyurethane sleeve 86.
[0046] The amputee then sets the regulator means 80 to cause the
vacuum source 70 to apply vacuum through the vacuum valve 74 and
vacuum tube 76 to the cavity 62. Enough vacuum is applied to cause
the residual limb (with optional coverings) to be drawn firmly
against the inner surface 64 of the socket 60, which is flexible.
The vacuum source 70 may preferably maintain a vacuum in the range
of 0 to 25 inches of mercury (ideally ten to twenty five
inches).
[0047] It will be seen that the vacuum within the socket 60 will
cause the hypobarically-controlled artificial limb 50 to be
suspended from the residual limb 14. The vacuum will lock the
residual limb 14 into the socket 60 without causing swelling of the
residual limb into the socket, because of the total contact of the
residual limb 14 with the socket 60. That is, there is no open
chamber between the residual limb 14 and the socket 60 which would
draw on the residual limb.
[0048] As the volume of the residual limb 14 decreases during the
day due to weight-bearing pressures, the regulator means 80 may
appropriately adjust the vacuum source 70 to draw the residual limb
14 more firmly against the socket 60 and thus compensate for the
loss of residual limb volume. The vacuum may also partially or
completely oppose the loss of fluids from the residual limb caused
by weight-bearing pressures.
[0049] The vacuum within the socket 60 is also applied to the space
102 between the osmotic membrane 100 and the liner 92. Application
of vacuum to the space 102 lowers the boiling point of water,
causing perspiration wicking through the osmotic membrane to
evaporate and be drawn out of the space 102.
[0050] The vacuum source 70 may be a weight-actuated vacuum pump
and shock absorber as disclosed in U.S. patent application Ser. No.
09/534,274, filed Mar. 23, 2000 and herein incorporated by
reference.
[0051] To maintain the vacuum in the cavity, either a regulator
means 80, or a weight-actuated vacuum pump and shock absorber as
disclosed in U.S. patent application Ser. No. 09/534,274, may be
employed.
[0052] The present invention may be embodied in other specific
forms without departing from the spirit or essential attributes
thereof, and it is therefore desired that the present embodiment be
considered in all respects as illustrative and not restrictive,
reference being made to the appended claims rather than to the
foregoing description to indicate the scope of the invention.
* * * * *
References