Abstract:
The present invention in one embodiment is a vacuum pump including a compressible elastomeric member with an internal reservoir enclosing a volume of fluid, an outlet port providing fluid communication between the internal reservoir and a fluid sink, and an inlet port providing fluid communication between the internal reservoir and a fluid source. The pump further includes first and second pressure elements coupled to the elastomeric member on opposing sides. At least one of the first and second pressure elements is adapted to apply a longitudinal force along, and a rotational force about, an axis extending through the compressible elastomeric member. Upon the application of a longitudinal compression force to the compressible elastomeric member, fluid flows from the internal reservoir to the fluid sink and upon the application of a longitudinal expansion force, fluid flows from the fluid source to the internal reservoir. Upon the application of a rotational force, the elastomeric member exerts a counter-rotational force.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit under 35 U.S.C. §119(e) of Provisional Application No. 60/953,400, filed Aug. 1, 2007, which is herein incorporated by reference in its entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates generally to prosthetic devices, and more particularly to vacuum pumps used to generate a vacuum attachment of the prosthetic device to the residual limb of a user. 
       BACKGROUND 
       [0003]    An ongoing challenge in the development of prosthetic limbs is the attachment of the prosthetic limb to the residual limb of a user. For prosthetic legs, it is often difficult to securely attach the prosthetic leg to the residual leg without exerting too much or uneven pressure on the residual limb. On the one hand, the lack of a secure attachment can adversely affect the user&#39;s ability to walk. On the other hand, an improper fit can cause sores, swelling and pain for the user. 
         [0004]    One approach for overcoming this challenge has been the application of a negative pressure vacuum in a space between the limb (or a liner donned on the limb) and a socket or receptacle coupled to the prosthetic limb (see  FIG. 1  generally). Two conventional ways to apply such a vacuum are by a mechanical pump or an electronic pump. 
         [0005]    Mechanical pumps are often in-line systems that utilize the movement of the user to generate the negative pressure vacuum in the socket. For example, the force generated by contacting the ground during a user&#39;s walking motion can be used to generate a vacuum in the socket space to hold the prosthesis to the user&#39;s limb. However, in utilizing the motion of the user, such pumps should not inhibit, and should ideally aid in, as natural and pain-free of a movement as possible for the user. 
       SUMMARY 
       [0006]    One embodiment of the present invention provides a vacuum pump including a compressible elastomeric member. The compressible elastomeric member includes an internal reservoir enclosing a volume of fluid, an outlet port providing fluid communication between the internal reservoir and a fluid sink, and an inlet port providing fluid communication between the internal reservoir and a fluid source. The pump further includes first and second pressure elements coupled to the elastomeric member on opposing sides. 
         [0007]    At least one of the first and second pressure elements is adapted to apply a longitudinal force along, and a rotational force about, an axis extending through the compressible elastomeric member. Upon the application of a longitudinal compression force to the compressible elastomeric member, fluid flows from the internal reservoir to the fluid sink and upon the application of a longitudinal expansion force, fluid flows from the fluid source to the internal reservoir. Upon the application of a rotational force, the elastomeric member exerts a counter-rotational force. The inlet may be attached to an enclosed space such that upon the application of the expansion force, a negative pressure vacuum is applied to the enclosed space. 
         [0008]    Another embodiment of the present invention provides a prosthetic device for attachment to a residual limb. The prosthetic device includes a vacuum pump having a compressible elastomeric member including an internal reservoir enclosing a volume of fluid, an outlet port providing fluid communication between the internal reservoir and a fluid sink and an inlet port providing fluid communication between the internal reservoir and a fluid source. The prosthetic device also includes a first support member having a proximal end configured for attachment to the residual limb and a distal end coupled to a first side of the elastomeric housing, and a second support member having a proximal end coupled to a second opposing side of the elastomeric member. 
         [0009]    One or both of the first and second support members are adapted to apply a longitudinal force along, and a rotational force about, an axis extending through the compressible elastomeric member. Upon the application of a longitudinal compression force to the compressible elastomeric member, fluid flows from the internal reservoir to the fluid sink and upon the application of a longitudinal expansion force, fluid flows from the fluid source to the internal reservoir. Additionally, upon the application of a rotational force the elastomeric member exerts a counter-rotational force. The fluid source may be an enclosed space formed between the residual limb of a user and a receptacle attached to the upper support, such that a negative pressure vacuum is formed in the enclosed space to maintain the attachment of the prosthesis. 
         [0010]    A further embodiment of the present invention provides a leg prosthesis for attachment to a residual portion of a leg. The leg prosthesis includes a receptacle for receiving the limb, a foot portion and a vacuum pump. The vacuum pump includes a housing having an interior compartment and a shaft member having a portion disposed in the interior compartment of the housing. The housing and shaft member are coupled to provide reciprocating movement along a longitudinal axis extending through the housing and shaft member. 
         [0011]    The vacuum pump further includes a compressible elastomeric member having an internal reservoir enclosing a volume of fluid, an outlet port providing fluid communication between the internal reservoir and a fluid sink and an inlet port providing fluid communication between the internal reservoir and a fluid source. Upon the application of a compression force along the longitudinal axis, the shaft moves relative to the housing to compress the elastomeric member such that fluid flows from the internal reservoir to the fluid sink, and upon the application of an expansion force, the shaft moves relative to the housing to expand the elastomeric member such that fluid flows from the fluid source to the internal reservoir. 
         [0012]    Yet another embodiment of the present invention provides a foot prosthesis including an upper plate configured for attachment to a lower leg prosthesis or residual limb and a lower plate adapted to contact a walking surface. The upper plate extends between an ankle portion and a toe portion and the lower plate extends between a heel portion and a toe portion. The lower and upper plates are coupled such that a space is defined between the ankle portion and the heel portion. Upon the application of a compression force to the ankle portion or heel portion, the space is reduced. 
         [0013]    The foot prosthesis also includes a vacuum pump disposed in the space between the ankle and heel portions. The vacuum pump includes an elastomeric member with an internal reservoir adapted to enclose a volume of fluid, an outlet port in fluid communication with the internal reservoir and a fluid sink, and an inlet port in fluid communication with the internal reservoir and a fluid source. Upon the application of the compression force the elastomeric member compresses such that fluid flows from the reservoir to the fluid sink, and wherein upon the termination of the compression force, the upper or lower plate cause the application of an expansion force to the elastomeric member such that fluid flows from the fluid source into the reservoir. 
         [0014]    A further embodiment provides a vacuum pump including an elongated upper pylon and an elongated lower pylon adapted to move axially and rotationally with respect to said upper pylon, wherein the longitudinal axis of the upper pylon and the longitudinal axis of the lower pylon are maintained in a generally colinear alignment. The vacuum pump further includes a resilient compressible elastic member coupled to and disposed between respective ends of the upper and lower pylons to resist the axial and rotational movement of the lower pylon The elastic member includes an internal reservoir enclosing a volume of fluid, which may be formed by a substantially continuous elastic wall enclosing the internal reservoir. 
         [0015]    An outlet port provides fluid communication between the internal reservoir and a fluid sink and an inlet port providing fluid communication between the internal reservoir and a fluid source. Upon the application of a compression force along the longitudinal axis, the upper pylon moves relative to the the lower pylon to compress the elastomeric member such that fluid flows from the internal reservoir to the fluid sink. Upon the application of an expansion force, the upper pylon moves relative to the lower pylon to expand the elastomeric member such that fluid flows from the fluid source to the internal reservoir. 
         [0016]    The present invention also provides methods of using the vacuum pump described above to apply a vacuum to a space between a user&#39;s residual limb and a receptacle of a prosthetic device. While multiple embodiments are disclosed, still other embodiments of the present invention will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  shows an artificial limb engaged with a residual limb and including a socket, vacuum pump, pylon and prosthetic foot. 
           [0018]      FIG. 2  shows a vacuum pump according to a first embodiment of the present invention. 
           [0019]      FIG. 3  shows a cross-section of the vacuum pump of  FIG. 1  attached to a prosthetic foot. 
           [0020]      FIG. 4  shows another cross-section of the vacuum pump of  FIG. 1 . 
           [0021]      FIG. 5  shows a lower support portion of the vacuum pump of  FIG. 1 . 
           [0022]      FIG. 6  shows a resilient portion of the vacuum pump of  FIG. 1 . 
           [0023]      FIG. 7  shows a cross-section of the resilient portion shown in  FIG. 6 . 
           [0024]      FIG. 8  shows a partial cross-section of a vacuum pump according to a second embodiment of the present invention. 
           [0025]      FIG. 9  shows a partial cross-section of a vacuum pump according to a third embodiment of the present invention. 
           [0026]      FIG. 10  shows a partial cross-section of a vacuum pump according to a fourth embodiment of the present invention. 
           [0027]      FIG. 11  shows a cross-section of a vacuum pump according to a fifth embodiment of the present invention. 
           [0028]      FIG. 12  shows a cross-section of a vacuum pump according to a sixth embodiment of the present invention. 
           [0029]      FIG. 13  shows a cross-section of a resilient portion of the vacuum pump of  FIG. 12 . 
           [0030]      FIG. 14  shows a vacuum pump according to a seventh embodiment of the present invention. 
           [0031]      FIG. 15  shows a vacuum pump according to an eighth embodiment of the present invention. 
           [0032]      FIG. 16  shows a cross-section of the vacuum pump of  FIG. 15 . 
           [0033]      FIG. 17  shows a vacuum pump according to an ninth embodiment of the present invention. 
           [0034]      FIG. 18  shows a cross-section of the vacuum pump of  FIG. 17 . 
           [0035]      FIG. 19  shows the vacuum pump of  FIGS. 17 and 18  incorporated into a prosthetic foot. 
           [0036]      FIG. 20 . shows a vacuum pump according to an tenth embodiment of the present invention incorporated into a prosthetic foot. 
           [0037]      FIG. 21 . shows a cross-section of the vacuum pump and prosthetic foot of  FIG. 19 . 
           [0038]      FIG. 22 . shows a vacuum pump incorporated into a prosthetic foot according to an eleventh embodiment of the present invention. 
           [0039]      FIG. 23  shows the vacuum pump for incorporation into a prosthetic foot according to  FIG. 22 . 
       
    
    
     DETAILED DESCRIPTION 
       [0040]    Various modifications and additions can be made to the exemplary embodiments discussed below without departing from the scope of the present invention. For example, while the embodiments described below refer to particular features, the scope of this invention also includes embodiments having different combinations of features and embodiments that do not include all of the above described features. 
         [0041]    One embodiment of the present invention is a vacuum pump that can be used with an artificial limb, such as an artificial leg, artificial arm or other prosthetic device.  FIG. 1  shows an artificial leg  50  including a socket  52  coupled to one end of a pylon  54  via a vacuum pump  100  in accordance with the present invention. An artificial foot  56  is coupled to the other end of the pylon  54 . A residual limb, or residuum  60 , of a user is encased in a liner  62  and is received within the socket  52  that has been configured in size and shape to accept the residuum  60 . A fluid connection, such as tube  53 , connects the vacuum pump  100  to a space formed between the socket  52  and the liner  62  and/or residuum  60  when the artificial leg is attached. 
         [0042]    As further shown in  FIGS. 1-7 , the vacuum pump  100  includes a shaft or upper pylon  120  with an end attachment  130 ; a housing or lower pylon  140  and a hollow, elastomeric structure  160  that is shaped like a toroid. The hollow elastomeric structure  160 , hereinafter referred to as the toroid  160 , is interposed or sandwiched between the end attachment  130  and the housing  140 , with the shaft  120  passing through a central opening  170  of the toroid  160 . As further shown in  FIG. 6-7 , the toroid  160  includes two generally flat top and bottom surfaces  161  and two outwardly bowed side walls  163  defining an internal reservoir  162 . 
         [0043]    When the pump  100  is compressed by an external force along a longitudinal axis extending through the pump, such as during the step phase of the user, the toroid  160  is compressed and a substantial volume of the fluid within its internal reservoir  162  is forced out through an outlet  164  to a fluid sink, which may be an external fluid atmosphere. When the external force on the pump  100  lessens or is removed, the elastomeric material, and particularly the side wall  163 , of the toroid  160  causes the toroid  160  to return or expand back to its initial configuration due to its elastic memory and/or resiliency. As a result, the toroid  160  draws fluid from a fluid source into the internal cavity  162  through an inlet  166 . An outlet check valve  165 , such as a one-way expulsion valve, and a one-way intake check valve  167 , can be connected to the internal cavity  162  at the outlet  164  and the inlet  166 , respectively. 
         [0044]    When the intake valve  167  is connected to a vessel, such as the space adjacent to socket  52 , fluid is evacuated from the vessel/socket  52  by the pump  100 . Since the residuum  60  and liner  62  are substantially sealed to the socket  52  about the periphery of the residuum  60 , evacuation of fluid from the sealed socket  52  results in negative pressure or a vacuum being formed in the socket  52  about the residuum  60 . As a result, the pump  100 , functions as a vacuum pump that holds the socket  52  to the liner  62  and/or residuum  60 . In this manner, the vacuum pump  100  removes the fluid, in this case air (which may include moisture from the limb), from the space between the prosthetic liner  62  and the socket  52  after placement of the residuum  60  and liner  62  within the socket  52 . The socket  52  can also be arranged so that fluid is removed from between the liner  62  and skin of the residuum  60 , which would further facilitate removal of perspiration. 
         [0045]    In an artificial limb, such as the limb  50  shown in  FIG. 1 , the compression force results from the weight of the user being transmitted through the residuum  62 . In a standing position, the weight of the user is distributed between the artificial limb  50  and the user&#39;s other lower limb. However, when the user takes a step while walking, the majority of the weight is placed onto the limb  50  as it engages the ground at the foot  56 . The force continues until toe-off, when the foot  56  is lifted from the ground. The force remains removed through a swing phase, as the limb  50  is swung forward for another step. The compression force is then reapplied to the limb  50  and the pump  100  upon contact of the foot  56  to the ground. Thus, as the user walks, the compression force is repeatedly applied to and removed from the toroid  160  in a reciprocating manner. This process results in a generally continuous draw of fluid from the socket  52  creating the advantageous vacuum in the socket  52 , as described above, which is particularly useful during the swing phase to maintain the attachment between the limb  50  and the socket  52 . 
         [0046]    Besides aiding in the retention of the artificial leg  50  on the residuum  60 , removal of the fluid from between the socket  52  and liner  62  increases the intimacy of the socket fit, improving the user&#39;s ability to feel shock waves passed through the prosthetic structure, or artificial leg  50 , and into the residuum  60 . This can result in a “feeling” sensation and in increased awareness as to the location of the artificial leg  50  under the user. Although the fluid described with respect to  FIG. 1  is air, fluid may mean any appropriate type of gas, including oxygen, nitrogen or air, with or without the addition of moisture. 
         [0047]    The elastomeric toroid  160  is preferably formed from an elastomeric material, including but not limited to thermoset urethane, thermoplastic urethane or other suitable elastomers. In one embodiment, the toroid  160  is molded from a thermoset urethane in two halves that are bonded together to form an air-tight seal  171  around the circumference of outer wall  163  and a similar seal (not shown) along the circumference of inner wall  163 . Other than the seals formed during production, the toroid  160 , the inner and outer wall  163  form a substantially continuous elastomeric wall enclosing the internal reservoir  162 . 
         [0048]    In one embodiment the toroid  160  has an outer diameter of about 2.00 to 2.50 inches and an inner diameter of about 1.00 to about 1.50 inches, more particularly, about 1.13 inches. The wall thickness is about 0.10 to about 0.20 inches, more particularly, about 0.13 inches thick. The wall thicknesses of the toroid  160  determine its compression and expansion properties, as well as its rotational resilience about the longitudinal access extending through the pump  100 , which is discussed in greater detail below. The rotational resilience is dependent primarily on the outer wall thickness, and the compression/expansion resilience is dependent primarily on the total wall thickness. 
         [0049]    In the embodiment shown in  FIGS. 1-7 , and more particularly in  FIG. 4 , the shaft  120  is received within the housing  140  in a compartment  142 . The shaft  120  and the compartment  142  are preferably sized and shaped in a complementary manner, such that the shaft  120  smoothly rides axially within the compartment  142  as the compressive force is applied and removed. Bearings  144 ,  145  are provided to facilitate the smooth movement of the shaft  120 , with bearings  144  provided within the compartment  142  and bearings  145  embedded within an inner wall  141  of the housing  140  adjacent to the compartment  142 . A fastener  124  attaches to the shaft  120  at an end  122  opposite the end attachment  130 . This fastener  124 , such as a screw with a wide head shown in  FIG. 4 , engages an interior portion  146  of the housing  140  to restrict the movement of the shaft  120  and keep it in the interior compartment  142 . 
         [0050]    At the other end of the shaft  120 , the end attachment  130  moves with the shaft  120  as it moves within the compartment  142 . The end attachment  130  includes a mounting structure  132  configured for attachment to another prosthetic component using a prosthetic coupler, including but not limited to a pyramid connector (not shown). The mounting structure  132  includes a plurality of screws  134  for securing the pump  100  to the other prosthetic component, for example, a socket, a pylon, a foot and/or any other suitable component. 
         [0051]    The housing  140  is also configured for connection to another prosthetic component. As shown in  FIGS. 2 ,  4  and  5 , the housing end  148  opposite from the toroid  160  is configured to be clamped to another prosthetic component, especially one having a pipe or pylon-type end. The housing  140  includes a cylindrical recess  150  sized and shaped to receive the pipe end. A split  152  in the housing wall  149  works with a clamp  154  to provide for a secure attachment of the housing  140  to the component. In  FIG. 3 , The housing  140  is shown with the end  148  formed for direct attachment to a prosthetic foot  156 . In this manner, the need for additional coupling components is removed and the overall weight and height of the artificial limb may be reduced. 
         [0052]    The prosthetic end attachments of the pump  100  can vary significantly depending on the components to which the pump  100  is intended to be attached. However, the current tube clamp in the housing is a space efficient design which allows a continuous length adjustment by cutting the attachment tube to the correct length. 
         [0053]    In the embodiment shown in  FIGS. 1-7 , the pump  100  is not only designed to pump fluid and/or generate vacuum due to the application and removal of axial compressive forces, but it also provides shock absorption to the artificial limb and/or rotational resistance between the shaft  120  and the housing  140 . In particular, the toroid  160  acts as a compression spring, a torsion spring, and as a vacuum generating device. With the toroid  160  sandwiched between the upper components of the artificial limb and the lower components of the limb, the elastomeric material helps absorb shocks due to impacts or other sharp forces. As a result, these forces are reduced and softened for the user and the artificial limb. 
         [0054]    The toroid  160  is provided with a plurality of protrusions, such as torsion ribs  168 ,  169  extending from both surfaces of the toroid. One set of protrusions  168  engage or interlock with recesses or grooves (not shown) in the end attachment  130 , which are sized and shaped to receive the ribs  168 . In a similar manner, the other set of torsion ribs  169  engage with openings or grooves  155  formed in the top surface  143 , or toroid end, of the housing  140 . These torsion ribs  168 ,  169  keep the end attachment  130  and the housing  140  from rotating independently. However, when a torsional force is applied to the artificial limb, the components connected to the pump  100  at the end attachment  130  can twist relative to the components connected to the pump  100  at the housing  140 . The resilient, elastomeric material of the toroid  160  allows for the twisting motion and also returns the components to their initial alignment upon withdrawal of the torsional force. In one embodiment, the toroid  160  provides gradually increasing resistance to the rotation. This ability also increased the comfort and usability of the artificial limb for the user. The amount of rotation can be controlled by the geometry of the ribs  168 ,  169  and toroid  160 , or by the material and/or durometer of the toroid  160 . 
         [0055]    The pump  100  in accordance with the present invention has significant advantages over previous pump designs. One advantage is the small number of parts required, which means that the pump is more simple and cost effective to manufacture, and service. Another advantage is that the fluid passing through the pump is only in contact with the interior of the toroid  160  and the check valves  165 ,  167 . The toroid  160  is constructed of an elastomer which has excellent corrosion resistance. Thus, the design can pump corrosive fluids without significant deleterious effects. In the example shown in  FIG. 1 , not only will air be drawn from the socket  52  into the internal cavity  162  of the toroid  160 , but also moisture, such as perspiration, which is corrosive. 
         [0056]    The pump  200  shown in  FIG. 8  is similar in operation to the pump  100  shown in  FIGS. 1-7 , except that the pump  200  includes a toroid  220  positioned within an interior compartment  203  of a housing  202 . A hollow shaft  210  is also received within the housing  202  and positioned adjacent to the toroid  220 . The shaft  210  reciprocates within the interior compartment  203  along a bushing  205  and a post  215  that passes through an end of the shaft  210  and is positioned through a center of the toroid  220 . The post  215  is attached to the housing  202  at a first end  216  and a second end  217  is positioned within a compartment  212  in the interior  211  of the shaft  210 . A spring  218  is positioned about the post  215  for applying a return force upon compression of the toroid  220 . A one-way valve  222  extends through the toroid  220 . Upon application of a compression force, the shaft  210  moves toward the toroid  220 , compressing the toroid  220  and the spring  218 . The compartment  212  moves relative to the second end  217  of the post  215 . As the toroid compresses, fluid is transferred through an outlet  224  into the interior compartment  211 . Upon reduction or removal of the compression force, fluid is drawn into the toroid  220  through an inlet  226  as the spring  218  returns the shaft  210  to its initial position. As stated above, if the inlet  226  is fluidly connected to a sealed vessel/socket, the pump  200  may be used to apply a vacuum within the prosthetic socket, as discussed with respect to  FIGS. 1-7 . 
         [0057]    In the embodiment shown in  FIG. 9 , a one-way valve  240  extends through a toroid  250 . The one-way valve  240  includes an intake  242  to receive fluid from an external source, an inlet  244  to receive fluid from the toroid  250  upon compression of the toroid  250  and an outlet  246  through which the transferred fluid is expelled. 
         [0058]    The embodiment shown in  FIG. 10  is similar to the embodiments shown in  FIGS. 8 and 9 , except that it includes an elastomeric structure  280 , which is not toroidal in shape, positioned between an interior of the housing  260  and a reciprocating shaft  265 . The elastomeric structure  280  includes an one-way valve  282 , including an inlet  284  and an outlet  286 , which extends approximately through the center of the elastomeric structure  280  to transfer fluid into and out of the elastomeric structure  280  upon compression/expansion. 
         [0059]      FIG. 11  shows a pump  300  including a shaft  320  positioned within a housing  340 . The shaft  320  and the housing  340  include mounting structures  322 ,  342 , respectively, for connection to other prosthetic components. An elastomeric toroid  330  is positioned about the shaft  320  and is sandwiched between the shaft  320  and the housing  340  within flanges  321 ,  341 , respectively, on the outer diameter of each tube. A resilient member  325  is coupled to the shaft  320  and positioned to contact the housing  340 . Upon application of the compression force, the shaft  320  and housing  340  move relative to each other, compressing the toroid  330  and the resilient member  325 . Upon release of the force, the resilient member  325  returns the shaft  320  to its initial position, allowing the toroid  330  to re-expand. This embodiment allows for a reduced wall thickness for toroid  300  because the resilient member  325  is capable of providing the primary return force. 
         [0060]      FIGS. 12 and 13  show a pump  350 , which is very similar to the pump  100  shown in  FIGS. 1-7 , However, the pump  350  includes an elastomeric structure  360  that does not include an inner wall. Instead, the structure  360  is formed with a generally ‘C’ shaped outer wall  362  that seals against an outer surface  355  of the shaft  354  to form a hollow internal cavity  364 . The structure  360  remains sealed with the outer shaft surface  355  even as the shaft  354  moves relative to the structure  360  and the housing  370 . 
         [0061]      FIG. 14  shows a pump  380 , which is also similar to the pump  100  shown in  FIGS. 1-7 . However, pump  380  includes a toroid  390  having an internal wall  392  that, due to a thickness differential, is bowed inwardly toward the shaft  382  and away from the outer wall  394 . As a result, the inner wall  392  requires a thickness that is less than the thickness of the outer wall  394 , in order to achieve the desired rotational, compression and expansion resilience of the toroid  390 . 
         [0062]      FIGS. 15 and 16  show a pump  400 , which does not include a shaft reciprocating within a housing. Instead the pump  400  includes a housing  405  having a top connecting component  410  and a bottom connecting component  420 . As shown, the top connecting component  410  includes a pyramid connector  412 , and the bottom connecting component  420  includes a coupler  422  for receiving a pyramid connector. A bottom element  414  of the top component  410  is configured to engage a top element  424  of the bottom component  420  forming an eye-shaped spring portion  406  within which a resilient hollow member  430  is positioned. 
         [0063]    The resilient member  430  performs a similar function to the toroid in the above described embodiments. Intake and outlet one-way check valves  431 ,  432  are positioned in fluid connection with the hollow interior space  434  of member  430 . Both the top component  410  and the bottom component  420  include connecting members  415 ,  425 , respectively, that engage the resilient member  430  and transfer compression forces to it. When the pump  400  is subjected to a compression force, the top component  420  and the bottom component  420  move relative to each other causing compression of the resilient member  430  and transfer of fluid from the interior space  434 . Upon removal of the compression force, the eye-shaped spring portion  406  aids in the expansion of the resilient member  430 , transferring fluid out of a fluidly connected vessel and into the interior space  434 . 
         [0064]      FIGS. 17 and 18  show a pump  450  similar to the pump shown in  FIGS. 15 and 16 . A hollow resilient member  480  is positioned within a spring portion  455  formed between top and bottom connecting components  460 ,  470 . Top and bottom connecting members  465 ,  475  engage the resilient member  480 , and intake and outlet valves  481 ,  482  are in fluid connection with an interior space  484 . Instead of an eye-shaped spring portion, the spring portion  455  is generally ‘C’ shaped and formed of a single component. As with the eye-shaped spring, the C-spring  455  aids during expansion of the resilient member  480  after removal of a compression force. 
         [0065]      FIG. 19  shows the pump  450  positioned within a prosthetic foot  490 . The bottom component  470  in this embodiment includes structure for positioning and coupling directly to the prosthetic foot  490 . As shown, the pump  450  is provided in the heel portion of the foot  490 , such that the compression force is applied to the pump  450  upon heel strike during the walking cycle. 
         [0066]      FIGS. 20 and 21 , also show a pump  500  positioned within the heel portion of a prosthetic foot  510 . The pump  500  includes a resilient wedge component  520  having a hollow internal reservoir  522  in fluid connection with intake and outlet valves  524 ,  525 . As with the other embodiments, a compression force, primarily applied during heel strike, compresses the resilient wedge  520  forcing fluid from the hollow internal space  522 . Upon release of the force, the wedge  520  expands drawing fluid from a fluidly connected vessel. In this embodiment, the spring characteristics of the prosthetic foot  510  itself aid in the expansion of the wedge  520 . 
         [0067]      FIGS. 22 and 23 , show a pump  550  again positioned in the heel portion of a prosthetic foot  560  having a resilient heel wedge  562 . In this embodiment, the pump  550  is formed from a resilient cylinder  551  having intake and outlet valves  552 ,  553 , respectively, positioned axially at opposite ends of the cylinder  551 . The resilient cylinder  551  is received within the resilient heel wedge  562 , such that a compression force is applied to the cylinder  551  during walking, especially at heel strike. In this case, the resilient heel wedge  562  not only transmits the compression force to the pump  550 , but also aids in expansion of the resilient cylinder  551  to draw fluid from a fluidly connected vessel. 
         [0068]    The vacuum pump of the present invention basically includes a resilient hollow member fluidly connected to intake and outlet valves. This resilient member is positioned within a structure having at least two surfaces that move relative to each other in a reciprocating manner. The resilient member repeatedly compresses and expands between the two surfaces due to the application and removal of a compression force applied to the pump. Each compression forces fluid out of the hollow internal space within the resilient member and each expansion draws fluid back into the internal space through the intake valve. When the intake valve is fluidly connected to a vessel, the compressive action of the pump will draw fluid out of the vessel. If the vessel is