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 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. A liner for a hypobarically-controlled socket for an artificial limb, with an adhering interface attaching the liner to the inner wall of the socket and forming a seal between the liner and the socket. The liner may be permanently attached to the socket.

Description:
[0001]    This is a divisional of U.S. patent application Ser. No. 09/670,853, filed Sep. 27, 2000, which is a continuation-in-part of U.S. patent application Ser. No. 09/492,406, filed Jan. 27, 2000, which is a continuation-in-part of U.S. patent application Ser. No. 09/325,297, filed Jun. 3, 1999. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The present invention relates to prosthetic devices and more particularly to a hypobarically-controlled artificial limb for amputees.  
           [0003]    An amputee is a person who has lost part of an extremity or limb such as a leg or arm that 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. I 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 that 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  that 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]    Historically, artificial limbs typically used by a leg amputee were for the most part all made out of wood such as an Upland Willow. The limbs were hand carved with sockets for receiving the stump  14  of the residual limb  10 . Below the socket would be the shin portion with the foot below the shin. These wooden artificial limbs were covered with rawhide, which often were painted. The sockets of most wood limbs were hollow as the limbs were typically supported in the artificial limb by the circumferential tissue adjacent the stump  14  rather than at the distal end of the stump  14 .  
           [0008]    Some artificial limbs in Europe were also made from forged pieces of metal that were hollow. Fiber artificial limbs were also used which were stretched around a mold after which they were permitted to dry and cure. Again, these artificial limbs were hollow and pretty much supported the residual limb about the circumferential tissue adjacent the stump  14 .  
           [0009]    All of these various artificial limbs have sockets to put the amputee&#39;s stump  14  thereinto. There are generally two categories of sockets. There are hard sockets wherein the stump goes right into the socket actually touching the socket wall without any type of liner or stump sock. Another category of sockets is a socket that utilizes a liner or insert. Both categories of sockets typically were opened ended sockets where they had a hollow chamber in the bottom and no portion of the socket touched the distal end of the stump  14 . So, the stump was supported about its circumferential sides as it fits against the inside wall of the sockets.  
           [0010]    These types of sockets caused a lot of shear force on the stump  14  as well as had pressure or restriction problems on the nerve bundles and vascular flow of fluid by way of the circumferential pressure effect of the socket on the limb. This pressure effect could cause a swelling into the ends of the socket where an amputee may develop severe edema and draining nodules at the end of their stump  14 .  
           [0011]    With time, prosthetists learned that by filling in the socket&#39;s hollow chamber and encouraging a more total contact with the stump and the socket, the swelling and edema problems could be eliminated. However, the problematic tissue configurations, such as bony prominences, required special consideration such as the addition of soft or pliable materials to be put into the socket.  
           [0012]    Today, most artificial limbs are constructed from thermoset plastics such as polyester resins, acrylic resins, polypropylenes and polyethylenes, which are perhaps laminated over a nylon stockinette that also may be impregnated by the various resins.  
           [0013]    In the past, most artificial limbs were suspended from the amputee&#39;s body by some form of pulley, belt or strap suspension often used with various harnesses and perhaps leather lacers or lacings. Another method of suspending artificial limbs is known as the wedge suspension wherein an actual wedge is built into the socket that is more closed at its top opening. The wedge in the socket cups the medial femoral condyle or knuckle at the abductor tubical. Yet another form of suspension is referred to as the shuttle system or a mechanical hookup or linkup wherein a thin suction liner is donned over the stump that has a docking device on the distal end which mechanically links up with its cooperative part in the bottom of the socket chamber. Sleeve suspensions were also used wherein the amputee may use a latex rubber tube which forms into a rubber-like sleeve which would be rolled on over both the top of the artificial limb and onto the amputee&#39;s thigh. The sleeve suspensions have been used in combination with other forms of suspensions techniques.  
           [0014]    Both the use of a positive pressure system and the use of a negative pressure system (or hypobaric closed chamber) have been utilized in the field of prosthetics. At one time, for pressure systems “inflatable inner tubes” were used to fit into sockets. Presently, there are pneumatic “bags” which are strategically placed over what people consider to be good weight-bearing areas to increase pressure to help accommodate for volume changes within the socket.  
           [0015]    The problem with this is that it is a very specific pressure and creates atrophy and loss of tissue dramatically over these high pressure areas. None of these systems employs positive pressure distributed over the total contact area between the residual limb and the artificial limb socket to accommodate volume changes within the socket.  
           [0016]    The negative pressure aspects have been utilized for a closed chamber in that a socket is donned by pulling in with a sock, pulling the sock out of the socket and then closing the opening with a valve. This creates a seal at the bottom and the stump is held into the socket by the hypobaric seal. However, there are no systems that employ a negative pressure produced by a vacuum pump to lock the residual limb to the artificial limb.  
           [0017]    The older systems were initially started in Germany. They were an open-ended socket, meaning there was an air chamber in the bottom of the socket. This did not work particularly well because it would cause swelling of the residual limb into the chamber created by the negative draw of suspending the weight of the leg and being under a confined area. This would lead to significance edema that would be severe enough to cause stump breakdown and drainage.  
           [0018]    It was later discovered in America that total contact was essential between the residual limb and the socket and once you had total contact the weight was distributed evenly or the suspension was distributed over the whole surface of the limb rather than just over the open chamber portion of the socket.  
           [0019]    The human body as a whole is under approximately one atmosphere of pressure at sea level. It keeps and maintains a normal fluid system throughout the body. When an amputee dons a prosthesis and begins taking the pressures of transmitting the weight of the body through the surface area of the residual limb to the bone, there is increased pressure on the residual limb equal to one atmosphere plus whatever additional pressures are created by weight bearing. This increased pressure causes the eventual loss of fluids within the residual limb to the larger portion of the body that is under less pressure. This loss of fluids causes the volume of the residual limb to decrease during the day. It varies from amputee to amputee, but it is a constant among all amputee and the more “fleshy” and the softer the residual limb, the more volume fluctuation there will be. The greater the weight and the smaller the surface area, the greater the pressures will be and the more “swings” there will be in fluids. In the past, the amputee had to compensate for this volume decrease by removing the artificial limb and donning additional stump socks to make up for the decreased residual limb volume.  
           [0020]    While some of these devices addressed some of the problems associated with prosthetics, none of the artificial limbs, liners and socket, individually or in combination, offered a prosthesis that presented a total contact relationship with the residual limb; absorbed and dissipated shear, shock and mechanical forces transmitted to the limb tissues by the artificial limb; controlled residual limb volume; and used negative pressure as a locking device to hold the residual limb into the socket.  
           [0021]    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; and to totally adjust and adapt the internal socket environment to changes in residual limb volume; and control stump volume changes by a negative pressure system which is also capable of providing positive pressure. Ideally, the vacuum system should be automatically regulated.  
           [0022]    There is also a need for an improved hypobarically-controlled artificial limb with a positive mechanical interlock between an inner socket, which receives the residual limb, and an outer socket that attaches to the shin and foot of the artificial limb. Both the inner socket and the outer socket should have a rigid lower portion for weight-bearing and a substantially flexible upper portion to allow movement of the residual limb.  
           [0023]    In the past, artificial limbs had to be custom-built for the amputee. The custom building process generally consisted of: placing a singly ply thin cotton casting sock over the residual limb; making a first negative mold of the residual limb for forming an orthopedic plaster wrap about the residual limb and casting sock; making a first positive model of the residual limb by filling the negative mold with plaster; forming a thermoplastic foam about the positive model to create a space for a liner; adding additional thermoplastic foam to form a distal end cap as well as other areas which may require additional thicknesses due to tissue configurations; forming a second enlarged negative plaster mold about the foam; removing the foam; pouring a liquid and moldable liner into the space between the positive model and the second negative mold; allowing the liner to harden; removing the liner from the second negative mold; having the amputee don the liner over the residual limb; placing another single ply thin casting sock over the liner; making a third plaster wrap or negative mold of the artificial limb socket about the residual limb and the liner; removing the liner from the third plaster wrap; making a plaster cast or positive model of the socket from dental plaster; milling or shaving the positive model to create a reduced positive model to create weight bearing areas and compression of the liner against the residual limb and the socket; and making the socket from the reduced positive model.  
           [0024]    This custom-building process is expensive, time-consuming, and requires the constant attention of a skilled prosthetist.  
           [0025]    There is a need for a generic artificial limb socket that can be fitted to the contours of the residual limb without the need for a lengthy, expensive custom-molding process. The socket should contain a semi-compressible molding material which can be molded to the contours of the residual limb under vacuum and/or positive air pressure.  
         SUMMARY OF THE INVENTION  
         [0026]    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 seal between the socket and the residual limb. A sealed cavity is formed between the socket and the residual limb. Optionally, 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.  
           [0027]    A liner for a hypobarically-controlled socket for an artificial limb, the socket having a volume and shape to receive a substantial portion of an amputee&#39;s residual limb with a cavity therebetween and a partial vacuum in the cavity tending to draw the residual limb into firm contact with the socket and the artificial limb having a suspension sleeve for rolling over and covering the socket and a portion of the residual limb, the liner comprising:  
           [0028]    a) an inner layer adapted to contact the residual limb;  
           [0029]    b) an outer fabric layer engaging said inner layer; and  
           [0030]    c) an annular seal extending outwardly from said outer fabric layer and adapted to sealingly engage the suspension sleeve, thereby making a seal between the residual limb and the socket to minimize air leakage into the cavity.  
           [0031]    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.  
           [0032]    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.  
           [0033]    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.  
           [0034]    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.  
           [0035]    Another object and advantage of the present invention is that it uses vacuum pressure to lock the residual limb into the socket and reduce socket volume to compensate for fluid loss in the residual limb.  
           [0036]    Another object and advantage of the present invention is that both vacuum and positive pressure may be created by a miniaturized pump with a mechanical or motor drive.  
           [0037]    Another object and advantage of the present invention is that it includes a digital computer system to control the miniaturized pump to regulate both negative pressure and positive pressure, when used.  
           [0038]    Another object and advantage of the present invention is that is includes a semicompressible molding material between the outer socket and the inner socket which may be molded to the contours of the artificial limb under the influence of vacuum pressure, thereby avoiding the need for a custom-building process.  
           [0039]    Another object and advantage of the present invention is that the inner socket and outer socket are interlockable with each other to prevent relative movement. The interlocking may be achieved by any of a variety of mechanisms, such a pins or detents. The inner socket is removable from the outer socket.  
           [0040]    Another object and advantage of the present invention is that vacuum pump and the vacuum regulator may be enclosed in the space between the outer socket and the inner socket, thereby preventing damage to these components. The vacuum regulator may be controlled by an externally-accessible vacuum control.  
           [0041]    Another object and advantage of the present invention is that both the inner socket and the outer socket may be constructed of a lower, rigid portion and an upper substantially flexible portion. The lower rigid portion provides the necessary rigidity to support the person&#39;s weight, while the upper flexible portion accommodates movement of the residual limb.  
           [0042]    Another object and advantage of the present invention is that it includes an outer sheath between the inner socket and the suspension sleeve, to prevent abrasion of the suspension sleeve by the inner socket.  
           [0043]    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.  
           [0044]    Another principal object and advantage of the present invention is that it includes a large vacuum reservoir 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. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0045]    [0045]FIG. 1 is a side elevational view of the tissue and skeletal structure of an amputee&#39;s residual limb;  
         [0046]    [0046]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;  
         [0047]    [0047]FIG. 3 is an exploded elevational view of the residual limb donning the polyurethane sleeve, stretchable nylon sleeve, liner, nylon sheath and socket of an artificial limb;  
         [0048]    [0048]FIG. 4 is a cross-section of the artificial limb in FIG. 3, which is a first embodiment of the artificial limb;  
         [0049]    [0049]FIG. 5 is a cross-section of the artificial limb similar to FIG. 4, showing a second embodiment of the artificial limb;  
         [0050]    [0050]FIG. 6 is the same as FIG. 5, but showing compression of the inner socket under the influence of positive air pressure;  
         [0051]    [0051]FIG. 7 is a cross-section of the artificial limb showing a third embodiment of the artificial limb;  
         [0052]    [0052]FIG. 8 is a cross-section of the artificial limb showing a fourth embodiment of the artificial limb;  
         [0053]    [0053]FIG. 9 is an elevational view of the polyurethane sleeve and second stretchable nylon sleeve rolled over the socket and residual limb with clothing shown in broken outline;  
         [0054]    [0054]FIG. 10 is a cross-section of the artificial limb showing a fifth embodiment of the artificial limb;  
         [0055]    [0055]FIG. 11 is a cross-section of the artificial limb showing a sixth embodiment of the artificial limb;  
         [0056]    [0056]FIG. 12 is a detailed view of the vacuum mechanism in FIG. 11;  
         [0057]    [0057]FIG. 13 is a cross-section of the artificial limb showing a seventh embodiment of the artificial limb;  
         [0058]    [0058]FIG. 14 is a detailed view of the vacuum mechanism and suspension sleeve of FIG. 13;  
         [0059]    [0059]FIG. 15 is a cross-section of the artificial limb showing an eighth embodiment of the artificial limb;  
         [0060]    [0060]FIG. 16 is a cross-section of the artificial limb showing a ninth embodiment of the artificial limb;  
         [0061]    [0061]FIG. 17 is a cross section of the artificial limb showing a liner with an annular seal;  
         [0062]    [0062]FIG. 18 is a cross-section of the artificial limb showing a second embodiment of the liner of FIG. 17;  
         [0063]    [0063]FIG. 19 is a partial cross-section of the artificial limb showing a third embodiment of the liner of FIG. 17;  
         [0064]    [0064]FIG. 20 is a partial cross-section of the artificial limb showing a fourth embodiment of the liner of FIG. 17; and  
         [0065]    [0065]FIG. 21 is a partial cross-section of the artificial limb showing a liner with an adhering interface attaching the liner to the inside of the socket. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0066]    [0066]FIG. 3 shows the hypobarically-controlled artificial limb  50  of the present invention. The hypobarically-controlled artificial limb  50  includes an outer socket  52 , shin  54 , and foot  56 . The outer socket  52  has a volume and shape to receive a substantial portion of the residual limb  14  with a space  58  therebetween.  
         [0067]    A first embodiment of the hypobarically-controlled artificial limb  50  is shown in FIG. 4. The hypobarically-controlled artificial limb  50  further includes a flexible inner socket  60  with a cavity  62  with a volume and shape for receiving a substantial portion of the residual limb  14  and fitting in the space  58  between the outer socket  52  and the residual limb  14 . The inner socket  60  has an inner surface  64  opposing the residual limb  14  and an outer surface  66  opposing the outer socket  52 .  
         [0068]    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  is connected to a power source  83 , which may be a battery.  
         [0069]    A vacuum valve  74  is suitably connected to the vacuum source  70 . The vacuum valve  74  may preferably be disposed on the outer socket  52 . 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 inner socket  60 .  
         [0070]    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.  
         [0071]    A seal means  84  makes an airtight seal between the residual limb  14  and the outer socket  52 . Preferably, the seal means  84  is a nonfoamed, nonporous polyurethane suspension sleeve  86  which rolls over and covers the outer socket  52  and a portion of the residual limb  14 . Alternatively, the seal means  84  maybe any type of seal which is airtight.  
         [0072]    The hypobarically-controlled artificial limb  50  may also include a thin sheath  90  between the residual limb  14  and the inner surface  64  of the inner 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 residual limb  14  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.  
         [0073]    The hypobarically-controlled artificial limb  50  may also include a nonfoamed, nonporous polyurethane liner  92  receiving the residual limb  14  and disposed between the sheath  90  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.  
         [0074]    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 .  
         [0075]    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 .  
         [0076]    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 . Thereafter, the liner  92  is optionally donned.  
         [0077]    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 inner socket  60 . Alternatively, the sheath  90  may be avoided and the liner  92  simply inserted into the inner socket  60  of the artificial limb  50 .  
         [0078]    Next, the amputee simply grasps the rolled over portion of the polyurethane sleeve  86  and rolls it over a substantial portion of the outer socket  52 . The sleeve  86  makes an airtight seal between the residual limb  14  and the outer socket  52 .  
         [0079]    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 .  
         [0080]    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 inner 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 fifteen to twenty inches).  
         [0081]    It will be seen that the vacuum within the inner 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 inner socket  60  without causing swelling of the residual limb into the socket, because of the total contact of the residual limb  14  with the inner socket  60 . That is, there is no open chamber between the residual limb  14  and the inner socket  60  which would draw on the residual limb.  
         [0082]    As the volume of the residual limb  14  decreases during the day due to weight-bearing pressures, the regulator means  70  may appropriately adjust the vacuum source  70  to draw the residual limb  14  more firmly against the inner socket  60  and thus compensate for the loss of residual limb volume. The vacuum may also partially oppose the loss of fluids from the residual limb caused by weight-bearing pressures.  
         [0083]    A second embodiment of the hypobarically-controlled artificial limb  50  is shown in FIGS. 5 and 6. The second embodiment of the hypobarically-controlled artificial limb  50  is as described above, with the exception that the inner socket  60 A is compressible as well as being flexible. Instead of a vacuum source, the second embodiment has a positive air pressure source  100 , which may preferably be a motor-driven pump  102 . The regulator means  80 , which may be a digital computer  82 , controls the positive air pressure source  100 . The regulator means and positive air pressure source  100  are connected to a power source (not shown), which may be a battery. A positive pressure valve  104  connects the space  58  to the positive air pressure source  100 , for compressing the inner socket  60 A as the volume of the residual limb decreases.  
         [0084]    It will be seen that as the volume of the residual limb  14  decreases during the day due to weight-bearing pressures, the regulator means  80  may control the positive air pressure source  100  to cause air pressure to compress the inner socket  60 A to compensate for the decreased volume of the residual limb, as shown in FIG. 6.  
         [0085]    A third embodiment of the hypobarically-controlled artificial limb  50  is shown in FIG. 7. The third embodiment is a combination of the first and second embodiments described above.  
         [0086]    The mechanical motor-driven pump  72  may act as both the vacuum source  70  and the positive air pressure source  100 . The regulator means  80 , vacuum source  70  and positive air pressure source  100  are connected to a power source (not shown), which may be a battery.  
         [0087]    The vacuum source  70 , under control of the regulator means  80 , will compensate for reduced residual limb volume up to a certain point. From that point on, the regulator means  80  will cause the positive air pressure source  100  to further compensate for reduced residual limb volume as described above. The third embodiment thus uses both vacuum and positive air pressure working together to lock the residual limb  14  into the inner socket  60  and reduce socket volume to compensate for fluid loss in the residual limb  14 . The exact point at which the changeover is made between vacuum compensation and positive air pressure compensation is controlled by the regulator means  80 , which as described may be a digital computer appropriately programmed for the socket environment.  
         [0088]    A fourth embodiment of the hypobarically-controlled artificial limb  50  is shown in FIG. 8. The fourth embodiment is like the first embodiment, but includes two vacuum valves: a first vacuum valve  106  and a second vacuum valve  110 , both connected to the vacuum source  70 . The first vacuum valve  106  connects the vacuum source  70  to the space  58 . The space  58  contains a semi-compressible material  108 , such as polystyrene beads, as disclosed in U.S. Pat. No. 4,828,325, herein incorporated by reference.  
         [0089]    To don the artificial limb  50 , the amputee proceeds as described above. After inserting the residual limb  14  (with optional coverings) into the inner socket  60 B, which is both compressible and expandable, and rolling the suspension sleeve  86  over the outer socket  52 , the amputee activates the regulator means  80 , causing the vacuum source  70  to apply a vacuum to the space  58 . This causes the material  108  to lock mechanically together into a rigid mass, conforming to the shape of the residual limb  14 . The inner socket  603  may expand slightly under the weight of the residual limb  14  and under the influence of vacuum.  
         [0090]    It will be seen that the semi-compressible molding material  108  can be molded to the contours of the residual limb  14  without using a custom-building process to produce a custom socket. The outer socket  52  may appropriately occur in standard sizes, such as small, medium, and large. The inner socket  60 B may also occur in standard sizes such as small, medium, and large. Adaptation of the inner socket  60 B to the contours of the residual limb  14  occurs through solidifying the material  108  under the influence of vacuum.  
         [0091]    The second vacuum valve  110  connects the vacuum source  70  to the cavity  62  as previously described, for locking the residual limb  14  into the inner socket  60 B.  
         [0092]    The fourth embodiment may also include a positive air pressure source  100  as previously described, to adjust the size of the inner socket  60 B to compensate for decreased residual limb volume.  
         [0093]    The fourth embodiment may also include a thin sheath  90 , liner  92 , and second sleeve  94 , as previously described (see FIG. 3).  
         [0094]    The positive air pressure source  100  may also be used for shock absorption and a dynamic response in the ankle and foot sections of the artificial limb  50 , by means of a connection  120 .  
         [0095]    A fifth embodiment of the hypobarically-controlled artificial limb  50  is shown in FIG. 10. This embodiment is the same as the first embodiment shown in FIG. 4, with some changes. First, vacuum source  71  may be a hand-operated vacuum pump  71  which may remove air from the cavity  62  down to approximately 15-25 inches of mercury. A suitable hand-operated vacuum pump is marketed under the trademark MITY VAC IT® by Neward Enterprises, Inc. of Cucamonga, Calif.  
         [0096]    The fifth embodiment also includes the seal means  84  which preferably consists of a non-foamed, nonporous polyurethane suspension sleeve  86  for rolling over and covering a portion of the residual limb  14 . A portion of the seal means  86  is adapted to be disposed between the outer socket  52  and the inner socket  60 . The sleeve may be made of any of a variety of air-impervious elastomers.  
         [0097]    The fifth embodiment, shown in FIG. 10 also includes a mechanical interlock  67 ,  59  for interlocking the inner socket  62  with the outer socket  52 . Preferably, the mechanical interlock consists of a first detent  67  in the inner socket  62  and a second detent  59  in the outer socket  52 . The first detent  67  engages the second detent  59  to lock the inner socket  60  into the outer socket  52 .  
         [0098]    A sixth embodiment of the hypobarically-controlled artificial limb of the present invention is shown in FIGS. 11 and 12. The sixth embodiment is like the first embodiment shown in FIG. 4, with some changes.  
         [0099]    First, the inner socket is specifically intended to be removably from the outer socket. To provide a positive mechanical connection between the inner socket and outer socket and yet allow the inner socket to be easily removed, the sixth embodiment includes a mechanical interlock  103  engaging the inner socket  60  and the outer socket  52 . Preferably, the mechanical interlock may be an extension  104  which is attached to the inner socket  60  and a docking device  106  attached to the outer socket  52  and receiving the extension  104 , and a locking mechanism  105  engaging the extension  104  and the docking device  106 .  
         [0100]    The extension may be any sort of protrusion from the inner socket, such as a bulge or tab. Preferably, the extension  104  comprises a shuttle pin  108 .  
         [0101]    The locking mechanism may be any sort of member which engages both the extension  104  and the docking device  106 , such as a screw, wire, or pin. Preferably, the locking mechanism  105  comprises a second pin  110  which extends outside the outer socket  52  as to be accessible.  
         [0102]    Second, the sixth embodiment includes two thin sheaths, rather than one. A first inner sheath  90  may preferably be disposed between the residual limb  14  and the inner surface  64  of the inner socket  60 . As vacuum is applied to the cavity  62 , the inner sheath  90  will allow the vacuum to be evenly applied throughout the cavity  62 . Without the inner sheath  90 , the residual limb  14  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 inner sheath  90  may also be used to assist the amputee into a smooth and easy fitting into the inner socket  60 .  
         [0103]    An outer sheath  93  is preferably disposed between the suspension sleeve  86  and the inner socket  60 , thereby preventing the suspension sleeve from tacking to the inner socket  60 . Such tacking would cause friction between the inner socket  60  and the sleeve  86  which would cause the sleeve to wear out. Such tacking might also cause restrictions in the movement of the residual limb. The outer sheath  93  also protects the suspension sleeve  86  from being damaged by friction with the inner socket  60 .  
         [0104]    The sixth embodiment also preferably includes an adhesive pressure tape  95  adapted to cover the outer sheath  93 , suspension sleeve  86 , and the second sleeve  94  and sealing the outer sheath  93 , suspension sleeve  86 , and the second sleeve  94  to the inner socket  60 . The tape  95  locks all of these layers to the inner socket so that they do not come loose during movement.  
         [0105]    In the sixth embodiment, the suspension sleeve  86  goes between the inner socket  60  and the outer socket  52 , so that the sleeve  86  is protected from damage.  
         [0106]    In the sixth embodiment, the inner socket  60  has a rigid lower portion  98  and a substantially flexible upper portion  96 . The rigid lower portion assists in weight-bearing while the substantially flexible upper portion allows for movement of the residual limb  14 . As the knee is bent from fully straight to fully flexed, the width of the knee changes rather significantly and in a hard, non-flexible socket brim, there can be excessive pressure on the residual limb  14 . The substantially flexible upper portion  96  makes the artificial limb  50  more comfortable and more adaptive to these changes. For the same reason, the outer socket  52  has a rigid lower portion  102  and a substantially flexible upper portion  100 .  
         [0107]    Preferably, the top edge of the inner socket  60  is below the top edge of the outer socket  52  so that the sleeve  86  is protected from impact. Preferably, the top edge of the inner socket  60  may be {fraction (3/16)} inch below the top edge of the outer socket  52 .  
         [0108]    The sixth embodiment includes extensive modifications to the vacuum system.  
         [0109]    First, a vacuum fitting  78  has been added to the inner socket  60  to attach the vacuum tube  76 . The vacuum fitting  78  allows the attachment of a vacuum sensor  79  adapted to sense the amount of vacuum in the cavity  62  and a sensor lead  81  is attached to the sensor  79  connecting the sensor  79  to the regulator means  80 , thus conveying the sensed vacuum to the regulator means  80 .  
         [0110]    A vacuum valve  74  is placed between the cavity  62  and the vacuum source  70  to maintain vacuum in the cavity  62 . Typically, the vacuum valve  74  is a one-way valve or non-return valve.  
         [0111]    In the sixth embodiment, the vacuum source  70 , vacuum tube  76 , vacuum valve  74 , regulator means  80 , and power source  83  are all attached to the outer socket  52  in the space  58  between the outer socket  52  and inner socket  60 . In this way, these delicate components are protected against being damaged by impact. Because of the placement of the regulator means  80  within the outer socket  52 , a vacuum control  77  is provided extending outside the outer socket  52  to allow manual control of the regulator means  80 .  
         [0112]    The amputee dons the sixth embodiment in a manner similar to that earlier described, with some modifications. First, the outer sheath  93  is put on the residual limb  14  after rolling the suspension sleeve  86  upward over the residual limb and before donning the liner  92 . After donning the inner sheath  90  over the liner  92 , the amputee inserts the residual limb  14  into the inner socket  60 . Next, the outer sheath  93 , suspension sleeve  86 , and second sleeve  94  are rolled down over the inner socket  60 , and the adhesive pressure tape  95  is applied. Next, the wearer sets the regulator means  80  to an appropriate vacuum level by means of the vacuum control  77 , and connects the vacuum tube  76  to the vacuum fitting  78 . The inner socket  60  is then placed within the outer socket  52  so that the shuttle pin  108  engages the docking device  106  and the locking pin  110  is set to engage the shuttle pin  108  and the docking device  106 , providing a positive mechanical interlock.  
         [0113]    A seventh embodiment of the hypobarically-controlled artificial limb of the present invention is shown in FIG. 13. The seventh embodiment is similar to the sixth embodiment, with some changes.  
         [0114]    First, the mechanical interlock  103  does not engage the inner socket  60 . Instead, the mechanical interlock engages the outer socket  52  and the suspension sleeve  86 . To accomplish this, the suspension sleeve  86  covers the entire inner socket  60 , and the suspension sleeve  86  has the extension  104  or shuttle pin  108  embedded in the suspension sleeve at the distal end of the suspension sleeve, as shown in FIG. 14. Preferably, the extension  104  has a portion  104 A embedded in the suspension sleeve. This portion  104 A may be a disk or umbrella  104 A. The extension  104  then engages the docking device  106  as previously described.  
         [0115]    Second, the suspension sleeve  86  is modified to support the additional weight imposed on the suspension sleeve  86  due to the outer socket  52  and artificial limb. In particular, the suspension sleeve  86  is fabricated from a material which allows circumferential expansion but resists longitudinal stretching under the weight of the artificial limb. Such a material is described in U.S. Pat. No. 5,571,208, herein incorporated by reference.  
         [0116]    The sleeve  86  preferably contains fabric threads which may be oriented circumferentially around the sleeve. The threads preferably are comprised of double-knit polyurethane. The threads may also include nylon. The threads permit the sleeve  86  to expand circumferentially so that the sleeve may be slipped onto the residual limb  14  and so that the lower portion may be slipped over the inner socket  52 . The threads are preferably connected together with cross-links, which also may be preferably comprised of polyurethane. The cross-links and threads form a matrix which allows circumferential expansion but resists longitudinal stretching under the weight of the artificial limb. By example, the sleeve  86  may have a 4-to-1 ratio of circumferential stretch relative to longitudinal stretch.  
         [0117]    The sleeve  86  may have a portion above the inner socket  52  which is manufactured of material which allows both vertical and horizontal stretching, to increase flexibility.  
         [0118]    An eighth embodiment of the hypobarically-controlled artificial limb of the present invention is shown in FIG. 15.  
         [0119]    Unlike earlier embodiments, the artificial limb  50  of the eighth embodiment has only a single socket  60  rather than inner and outer sockets and is thus considerably simpler.  
         [0120]    The socket  60  has a volume and shape to receive a substantial portion of the residual limb  14  with a cavity  62  therebetween.  
         [0121]    A nonfoamed, nonporous polyurethane liner  92  is preferably adapted to receive the residual limb  14  and to be disposed between the residual limb  14  and the socket  60 .  
         [0122]    A vacuum source  70  is connected to the cavity  62  by a vacuum valve  78 , thereby drawing the residual limb  14  into firm contact with the socket  60 .  
         [0123]    A seal means  84  makes a seal between the residual limb  14  and the socket  60  to minimize air leakage into the cavity  62 . It has been found that it is impossible to make a perfect seal, with the result that air leakage can occur at rates up to 30 cc per minute. As air leaks into the cavity  62 , it is necessary to activate the vacuum source  70  to restore vacuum in the cavity. Furthermore, it has been found that when the vacuum in the cavity is about 5 inches of mercury, the residual limb may lose up to 6 to 15% of its volume during the day, whereas if the vacuum in the cavity is 15-25 inches of mercury, the residual limb loses only about 1% of its volume during the day.  
         [0124]    To minimize the time that the vacuum source, such as a vacuum pump  72 , needs to run to maintain vacuum in the cavity, a ninth embodiment of the artificial limb  50  is shown in FIG. 16. The ninth embodiment is the same as the eighth embodiment, but a vacuum reservoir  110  is added between the vacuum source  70  and the vacuum valve  78 . The vacuum reservoir  110  has a volume substantially larger than the cavity  62 . Suitably, the vacuum reservoir may have a volume of 2 gallons or 9000 cc while the volume of the cavity  62  may be only about 100 cc or even less.  
         [0125]    It will be seen that as air leaks into the cavity  62 , the air will be pulled into the vacuum reservoir  110 , thereby maintaining the vacuum in the cavity  62 .  
         [0126]    When the vacuum in the reservoir  110  reaches a certain minimum threshold, the vacuum source  70  may be activated to restore vacuum to the vacuum reservoir  110 . The vacuum source  70  may be activated either manually or by a regulator means (not shown).  
         [0127]    The artificial limb  50  typically includes a shin or pylon  54  and a foot  56 , as shown in FIG. 3. Preferably, the vacuum reservoir  110  is attached to the shin  54  between the socket  60  and the foot  56 . However, the vacuum reservoir may also be carried separately, as for example in a backpack. Depending on the placement of the vacuum reservoir  110 , a vacuum tube  76  may be necessary to connect the vacuum reservoir  110  to the vacuum valve  78 .  
         [0128]    If the volume of the vacuum reservoir  110  is about 9000 cc and air leaks into the cavity  62  at about 75 cc per minute, it will be seen that the intervals between activation of the vacuum source  70  can be up to about 120 minutes.  
         [0129]    The artificial limb  50  of the eighth and ninth embodiments may preferably further comprise the following.  
         [0130]    An inner sheath  90  may be adapted to be disposed between the liner  92  and the socket, to ensure even distribution of vacuum in the cavity  62 , as earlier described. Preferably, the inner sheath  90  may be thin knitted nylon. The sheath  90  may also be affixed to the outside of the liner  92 .  
         [0131]    The seal means  84  is preferably a nonfoamed, nonporous polyurethane suspension sleeve  86  for rolling over and covering the socket  60  and a portion of the artificial limb  14 , as earlier described. Seal means may also be an external annular abutting flange or ring  140  shown in FIG. 17. Again, seal means may also be an internal annular abutting flange or ring  140  shown in FIG. 18.  
         [0132]    A stretchable nylon second sleeve  94  (see FIG. 3) for rolling over and covering the suspension sleeve  86  may be added to prevent clothing from sticking to and catching on the suspension sleeve  86 , as earlier described.  
         [0133]    The vacuum source  70  is preferably a motor or mechanical driven vacuum pump  72 , as earlier described. A vacuum tube  76  may be necessary to connect the vacuum pump  72  to the vacuum valve  78 , depending on the placement of the vacuum pump  72 .  
         [0134]    Applicant has found that many of the embodiments discussed earlier share a common problem. The vacuum which holds the residual limb (and liner) in firm contact with the socket tends to cause edema and blistering at the point on the residual limb where the suspension sleeve contacts the residual limb. This problem occurs because the vacuum (perhaps 7½ pounds of negative pressure) in cavity  62  draws against the suspension sleeve  86  at the point where the suspension sleeve  86  contacts the skin of the residual limb. However, because the liner  92  often has an outer fabric cover  130  to prevent the liner from adhering to the socket  60  or clothing, the suspension sleeve cannot make a good seal at the point where it contacts the outer fabric cover  120 . This has left the residual limb as the only point at which to make the seal.  
         [0135]    [0135]FIG. 17 shows one solution to this problem. The liner  92  is improved by adding an annular seal  140  extending outwardly from the fabric cover  130 . The annular seal, which may be made from the same material as the inner layer  92  of the liner, is adapted to sealingly engage the suspension sleeve  86 , producing a seal against the vacuum in cavity  62  at the point of contact with the suspension sleeve  86 . Therefore, the vacuum in cavity  62  now draws against the annular seal  130  rather than against the skin of the residual limb  14 .  
         [0136]    An alternative solution to the above problem is shown in FIG. 18. Here, the annular seal  140  does not make contact with the suspension sleeve  86 , but rather makes contact with the inner wall  63  of the socket  60 , and makes a seal at that point. No suspension sleeve is used in this variation, it being found that sufficient holding force is provided by the vacuum in cavity  62 . FIG. 18 also shows that the annular seal  140  may simply be an extension of the liner  92 , passing through the fabric cover  130 .  
         [0137]    A second alternative is shown in FIG. 19. This alternative is like that of FIG. 18, with the exception that a mechanical interlock  103  is provided which is adapted to interlock with the socket  60 . Preferably, as shown, the mechanical interlock  103  comprises a shuttle pin  108  adapted to connect the liner  92  with the socket  60 , and a locking mechanism  105  such as a second pin  110  extending through the socket  60  to the exterior of the socket  60  for access by the amputee as earlier described. More particularly, the liner  92  may have an extension  104  or shuttle pin  108  embedded in the liner at the distal end of the liner. Preferably, the extension  104  has a portion  104 A which may be a disk or umbrella which engages a docking device  106  as earlier described.  
         [0138]    To keep air from entering the cavity  62 , the invention of FIG. 19 also preferably includes a locking mechanism seal  150  adapted to engage the inner wall  63  of the socket  60  about the locking mechanism  105 . The seal  150  could alternatively be on the outer surface of the socket  60 .  
         [0139]    Another alternative is shown in FIG. 20. Here, the fabric cover  130  stops below the annular seal  140 . The annular seal  140  may also be made of the same material as the liner  92 .  
         [0140]    Applicant has found that, by bonding the liner  92  directly to the inside surface  63  of the socket  60 , a seal may be produced that maintains the vacuum in the cavity  62  without the need for a separate annular seal or vacuum seal. FIG. 21 shows this embodiment.  
         [0141]    In FIG. 21, the liner  92  is bonded directly to the inside surface  63  of the socket  60  by an adhering interface  64 .  
         [0142]    The adhering interface  64  may be such as to provide a permanent attachment of the liner  92  to the socket  60 , or a semi-permanent attachment that allows the liner  92  to be removed and replaced.  
         [0143]    The adhering interface  64  may be any interface that has two adhering surfaces. One adhering surface  64   a  preferably adheres to the liner  92  while the other adhering surface  64   b  preferably adheres to the inside surface  63  of the socket  60 .  
         [0144]    Possible embodiments of a permanent attachment for the adhering interface  64  are: a laminating adhesive, i.e., a thin film placed on the surface of the liner and the liner  92  then being inserted into the socket  60 ; contact cement; or any type of paint-on glue.  
         [0145]    Possible embodiments of a semi-permanent attachment for the adhering interface  64  are: a hook and loop fastener fabric such as Velcro®; or cooperating magnets in both the liner  92  and the socket  60 .  
         [0146]    To don the artificial limb, the wearer inserts the residual limb into the liner, which is already attached to the socket by the adhering interface.  
         [0147]    Additional connections may be employed between the residual limb and the socket, such as the nonfoamed, nonporous polyurethane suspension sleeve earlier described and the mechanical interlock also previously described.  
         [0148]    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.