Abstract:
A prosthetic coupling device for incorporation into a prosthetic socket and for coupling a prosthetic limb structural system to the prosthetic socket includes a deformable urethane cup to receive a positive model of an amputated limb and a coupling plate for attaching the prosthetic socket to prosthetic limb structural system. The deformable cup is flared at an end to allow it to accommodate a wide range of limb sizes. The coupling plate includes a surface for attaching to the deformable urethane cup, threaded standoffs that adjust the thickness of a laminate material formed around the end of the coupling plate during fabrication into a prosthetic socket, an o-ring that secures a sheet of PVA to the coupling plate during fabrication and a centered through hole for connecting to a pin from a suspension sleeve. The prosthetic coupling device may further include one or more magnets for releasably securing the prosthetic socket to a suspension sleeve.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention is directed generally to prosthetic limb systems and more specifically to a prosthetic coupling device for use with lower extremity prosthetic limb systems.  
         BACKGROUND OF THE INVENTION  
         [0002]    Lower extremity endoskeletal and exoskeletal prostheses, those prosthetic limb systems that are used to replace an amputated portion of a leg and to help restore the amputee&#39;s ability to use that leg, are commonly grouped into two categories; above-knee and below knee devices. Both of these types of lower extremity prosthetic limb systems are made to attach to the distal end of an amputated limb and will often include a roll-on suspension sleeve, which attaches directly to the limb, a prosthetic limb socket, which is mechanically or magnetically attached to the suspension sleeve and a prosthetic structural system, which is mechanically attached to a prosthetic coupling mechanism formed within the prosthetic limb socket.  
           [0003]    An important consideration in the design of lower extremity prosthetic systems is the strength of the prosthetic socket design and coupling system since the socket is the load-bearing interface between the residual limb and the load bearing prosthetic structural system. Other important considerations are the simplicity of the design and the method of fabrication of the prosthetic socket, as each prosthetic socket must be custom fit to an individual.  
           [0004]    Fabrication of lower extremity prostheses typically begins with the making of a positive model of the residual limb or stump. This may be accomplished by a variety of methods, the most common encompasses wrapping the limb with plaster-of-Paris bandages, allowing the bandages to dry thereby creating a negative mold and then filling the negative mold with a mixture of plaster-of-Paris and water and allowing it to harden. Other, more advanced methods for creating positive residual limb models include the use of computer-aided-design (CAD) and computer-aided-manufacturing (CAM) systems with three-dimensional printers. The positive model may then be modified in a number of ways by a skilled prosthetist to accommodate for various weight-bearing and non-weight-bearing surfaces.  
           [0005]    Using the modified positive model an intimate fitting prosthetic socket may be formed by means of thermo-molding or thermosetting techniques. During fabrication of the prosthetic socket, an attachment plate or similar coupling device is usually formed within an end of the prosthetic socket, which allows a prosthetic structural system to be bolted or otherwise connected to the prosthetic socket. A variety of prior art attachment plates (e.g. Grace Plate) are available, the most common of which include a standard four hole pattern (e.g., the Otto-Bock European pattern or the USMC pattern).  
           [0006]    Another important goal when making a prosthetic socket is that the coupling device most be properly positioned with respect to the positive model in order to fit and function properly. With prior art prosthetic systems this goal is often difficult to achieve. For example, one common prior art coupling system employs a three-prong adapter mechanism for positioning the coupling device on the positive model. This system requires that the three prongs be bent and shaped to the contours of a positive model. Because the three prongs do not create an intimate contact with the positive model a resin material is added to the coupling device to make up this space. After the resin hardens the three-prong adapter may not be repositioned, if it is later determined that the coupling device is not properly aligned with the positive model. Still other systems require that the positive model be reshaped so that an attachment plate will be at a correct degree.  
           [0007]    As a convenience in locating the attachment plate holes after the prosthetic socket is formed, cap head screws are typically placed in the holes. After fabrication of the socket, the thermo-molded or thermoset material will be higher over the screw heads than in surrounding areas and may be ground away to expose the screw heads. The screws may then be removed with an Allen Wrench exposing the plate holes. Even with the use of the cap head screws, finishing the end of the socket can be very time consuming.  
           [0008]    Other systems, such as the Becker Orthopedic Model 403000 Plate, which incorporates a knurled surface, eliminate the need to vacuum form plastic on the underside of the attachment plate. Although these attachment plates reduce the time and effort required to finish the plate they employ a fingertip type grip between the plate and the laminated material, which is a substantially weaker bond than the above-described fabrication methods.  
           [0009]    These and other prior art systems are effective in attaching a lower extremity prosthetic limb system to an amputated limb, however, because each prosthetic socket must be custom designed to an individual, these systems can be difficult and time-consuming to manufacture. Therefore, it is desirable to have a prosthetic limb system that is more quickly and easily fabricated without sacrificing the structural integrity of the prosthetic socket. It is also desirable to have a prosthetic limb system that has enhanced structural features and that is easier to attach to an amputated limb.  
         SUMMARY OF THE INVENTION  
         [0010]    Embodiments of the present invention provide an apparatus and method for coupling a prosthesis limb structural assembly to a prosthetic limb socket.  
           [0011]    In accordance with one embodiment of the present invention, a coupling system includes a deformable cup and a coupling plate operatively connected to the deformable cup.  
           [0012]    In another embodiment the deformable cup is constructed of urethane.  
           [0013]    In another embodiment the deformable cup is constructed and arranged to allow for use with a wide range of prosthetic limbs.  
           [0014]    In another embodiment the connecting plate further includes a plurality of threaded standoffs.  
           [0015]    In another embodiment the coupling system further comprises a finishing plate that is constructed and arranged to operatively connect to the threaded standoffs.  
           [0016]    In another embodiment the coupling plate includes a circumferential groove for receiving an o-ring.  
           [0017]    In another embodiment the coupling system includes an o-ring coupled to the circumferential groove.  
           [0018]    In another embodiment the coupling plate includes a centering hole for operatively connecting to a suspension sleeve assembly.  
           [0019]    Another embodiment of the present invention is directed to a coupling system for coupling a prosthetic limb socket to a prosthetic limb structural assembly. The coupling system includes a deformable cup including an amount of magnetic material disposed within the deformable cup and a coupling plate operatively connected to the deformable cup.  
           [0020]    In one embodiment the coupling system includes a magnetic disc constructed to attach to a suspension sleeve. In another embodiment the coupling system includes a metallic disc constructed to attach to a suspension sleeve.  
           [0021]    Another embodiment of the present invention is directed to a method of making a prosthesis for attachment to an amputated limb. The method includes steps of preparing a positive model of the amputated limb, providing a prosthetic coupling device comprising a deformable cup operatively connected to an attachment plate comprising a bottom surface and a top surface having a plurality of threaded standoffs and a groove for receiving an o-ring, placing the prosthetic coupling device on the positive model, pulling a first sheet of polyvinyl alcohol over the prosthetic coupling device and the positive model, securing a first end of the first sheet of polyvinyl alcohol to the coupling plate with an o-ring, trimming the first sheet of polyvinyl alcohol, securing a second end of the first sheet of polyvinyl alcohol to a vacuum pump, pulling a vacuum with the vacuum pump, pulling at least one layer of dry lamination material over the first sheet of polyvinyl alcohol and interweaving the dry lamination material between the threaded standoffs, attaching a finishing plate to the threaded standoffs with a plurality of set screws, pulling a second sheet of polyvinyl alcohol over the dry lamination material and securing on a first end to a vacuum pump and tying or clamping a second end, introducing a resin material between the first sheet of polyvinyl alcohol and the second sheet of polyvinyl alcohol, pulling a vacuum on the second sheet of polyvinyl alcohol and removing the finishing plate.  
           [0022]    In another embodiment of the present invention the method of making a prosthesis for attachment to an amputated limb further includes the step of releasing the vacuum on the first sheet polyvinyl alcohol and repositioning the coupling system prior to pulling the vacuum on the second sheet of polyvinyl alcohol.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0023]    For a better understanding of the present invention, reference is made to the drawings, which are incorporated herein by reference, and in which:  
         [0024]    [0024]FIG. 1 is a side view of a prosthetic coupling device in accordance with a first embodiment of the present invention;  
         [0025]    [0025]FIG. 2 is a top view of the prosthetic coupling device of FIG. 1;  
         [0026]    [0026]FIG. 3 is a top view of a finishing plate in accordance with a first embodiment of the present invention;  
         [0027]    [0027]FIG. 4 is a side view of the prosthetic coupling device of FIG. 1 in cooperation with the finishing plate of FIG. 3;  
         [0028]    [0028]FIG. 5 illustrates the prosthetic coupling device of FIG. 1 cooperating in a first position with a positive model of an amputated limb having received a sheet of PVA material;  
         [0029]    [0029]FIG. 6 illustrates the prosthetic coupling device of FIG. 1 receiving an o-ring for securing the PVA sheet of FIG. 5;  
         [0030]    [0030]FIG. 7 illustrates a layer of dry material encompassing the prosthetic coupling device, the positive model and the PVA sheet of FIG. 6;  
         [0031]    [0031]FIG. 8 illustrates the prosthetic coupling device receiving the finishing plate of FIG. 3;  
         [0032]    [0032]FIG. 9 illustrates the prosthetic coupling device and other components of FIG. 8 receiving a second sheet of PVA material;  
         [0033]    [0033]FIG. 10 illustrates a finished prosthetic socket incorporating the prosthetic coupling device of FIG. 1;  
         [0034]    [0034]FIG. 11 is a side view of a prosthetic coupling device in accordance with a second embodiment of the present invention;  
         [0035]    [0035]FIG. 12 is a top view of a release mechanism for use with the prosthetic coupling device of FIG. 11; and  
         [0036]    [0036]FIG. 13 is side view of a release mechanism in accordance with a third embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION  
       [0037]    For purpose of illustration, and not to limit generally, the present invention will now be described with specific reference to lower extremity prosthetic coupling systems, which are used for attaching an endoskelatal or exoskeletal prosthetic limb structural assembly to a prosthetic limb socket and for connecting a prosthetic limb socket to a suspension sleeve. One skilled in the art will appreciate, however, that embodiments of the present invention are not limited to lower extremity prosthetic devices, but rather, the coupling apparatus and methods in accordance with embodiments of the present invention may be used in other applications requiring coupling of orthotic and prosthetic devices.  
         [0038]    FIGS.  1 - 9  show various side and top views of a prosthetic coupling device. Referring now to FIGS. 1 and 2, a prosthetic coupling device  10  in accordance with a first embodiment of the present invention is shown. The prosthetic coupling device  10  comprises a deformable cup  12  operatively connected to a coupling plate  14 . Deformable cup  12  includes a lower cupped portion  16  having a flared rim  18  and an upper surface  20 . The flared rim  18  is designed to allow the prosthetic coupling device  10  to accommodate a variety of different shaped positive limb models (not shown). Deformable cup  12  is preferably made from a flexible material such as urethane, however, other suitable materials such as rubber and the like may be used.  
         [0039]    The coupling plate  14  includes a lower surface  30  for receiving and connecting to the upper surface  20  of deformable cup  12 . In the present embodiment, the coupling plate  14  is adhered to the deformable cup with an adhesive layer (not shown) however other methods are contemplated. The coupling plate  14  further includes an upper surface  32 , an o-ring groove  34  located between the lower surface  30  and upper surface  32  and a set of threaded standoffs  42 ,  44 ,  46  and  48 , which are shown protruding from the upper surface  32 . The coupling plate  14  may further include a centered opening  50  passing between the upper surface  32  and the lower surface  30 .  
         [0040]    Referring now to FIGS. 3 and 4, the prosthetic coupling device  10  further includes an array of setscrews  52 ,  54 ,  56  and  58  with corresponding nuts  62 ,  64 ,  66  and  68  and a finishing plate  70 . The setscrews  52 ,  54 ,  56  and  58  are constructed and arranged to threadably engage threaded standoffs  40 ,  42 ,  44  and  46 . The finishing plate  70  includes an array of through holes  72 ,  74 ,  76  and  78  that are arranged to correspond with the placement of threaded standoffs  42 ,  44 ,  46  and  48  and a centered through hole  80 .  
         [0041]    Referring now to FIGS. 5 through 10, the prosthetic coupling device  10  is incorporated into a prosthetic socket. First, a positive model  90  of a residual limb (not shown) is made by one of many known prior art techniques. The positive model  90  acts as a mold for the prosthetic socket. Next, the prosthetic coupling device  10  is set on an end  92  of positive model  90  and a sheet of polyvinyl alcohol (PVA)  100 , which has a first side  102  and a second side  104 , is pulled over the prosthetic coupling device  10  and positive model  90 . The PVA sheet  100 , which may be wetted with water to make it more pliable and easier to work with, is secured to the coupling plate  14  with an o-ring  110 , thereby forming a bag that completely surrounds the prosthetic coupling device  10  and positive model  90 . The o-ring  110  creates an airtight seal and eliminates the need of adding and gluing additional PVA material, a common technique for this prior art prosthetic socket fabrication method. A first end  112  of PVA sheet  100  is then trimmed up to the o-ring  110 . A second end of the PVA sheet  100  is secured to a vacuum pump (not shown) and a vacuum is pulled. When the vacuum is pulled, the PVA sheet  100  shapes the deformable cup  12  to the positive model  90 . Unlike the prior art apparatus and methods discussed above, if the alignment between the positive model  90  and the prosthetic coupling device  10  needs to be adjusted, the vacuum may be released, the prosthetic coupling device  10  repositioned and the vacuum drawn again.  
         [0042]    At least one layer of dry lamination material  120  is then pulled over the PVA sheet  100  and is interwoven over the upper surface  32  of coupling plate  14  such that the dry lamination material  120  is interlaced between the threaded standoffs  42 ,  44 ,  46  and  48 . Multiple layers of dry lamination material may be used, depending upon the desired thickness of the prosthetic socket. With the dry lamination material  120  in place, the setscrews  52 ,  54 ,  56  and  58  are threaded into threaded standoffs  42 ,  44 ,  46  and  48 . It should be noted that the threaded standoffs could be inserted into the threaded standoffs earlier in the fabrication process. Next, the finishing plate  70  is placed over the setscrews  52 ,  54 ,  56  and  58 , and is bolted in place with nuts  62 ,  64 ,  66  and  68 .  
         [0043]    With the finishing plate  70  secured in place, a second PVA sheet  130  is pulled over the dry lamination material  120  and secured on one end to the vacuum pump. Next, a liquid laminating resin (not shown) is introduced beneath the second PVA sheet  130 . Two types of liquid laminating resin are generally used-polyester and acrylic. It should be noted that other materials may be added to the lamination to increase the strength of the prosthetic socket. These materials include carbon fiber, rayon, Dacron and others.  
         [0044]    After the liquid laminating resin is introduced, the PVA sheet  130  is tied off or alternatively clamped at an end  132  with clamp  134  as shown. A vacuum is pulled by the vacuum pump at the other end of PVA sheet  130 . The pressure created by the vacuum pump draws the laminating resin into the dry lamination material  120 , thereby impregnating the material. In the present invention, the PVA sheet  100  acts as a parting agent and keeps the liquid resin from coming in contact with the positive model  90 . After the lamination process is completed the vacuum is released. Next, the nuts  62 ,  64 ,  66  and  68 , the finishing plate  70  and the setscrews  52 ,  54 ,  56  and  58  are removed, revealing a finished prosthetic socket  122  having a uniform laminate layer over the upper surface  32  of the coupling plate  14  that is flush with the openings to threaded standoffs  42 ,  44 ,  46  and  48  and that requires little or no adjustment. The length of threaded standoffs  42 ,  44 ,  46  and  48  dictate the thickness of the laminate layer over the upper surface  32  of the coupling plate  14 .  
         [0045]    Also, because urethane has a memory it will want to return to its prevacuumed state. This will cause the deformable cup  12  to spread out tight against the first side  102  of the PVA sheet  100  after the lamination process is completed. The finished prosthetic socket  122  may be attached to a metal pin  124  from a suspension sleeve  126  by any of a number of prior art locking mechanisms (not shown). It should be noted that in addition to the lamination techniques previously described, it is contemplated that the prosthetic coupling device  10  could also be incorporated in a prosthetic socket using thermo-molded plastics, such as polypropylene. Using thermo-plastics would avoid the need to laminate the prosthetic socket and could be done directly over the positive model  90 .  
         [0046]    Referring now to FIGS. 11 through 12, an alternative embodiment of the present invention is disclosed. In this embodiment, an alternative method of attaching a prosthetic socket  130  to a suspension sleeve  126 ′ includes a first magnet  140 , which is encapsulated in a deformable cup  12 ′ prior to formation of prosthetic socket  130 . The magnet  140  is designed to work in conjunction with a second magnet  144 . The second magnet  144  includes a through hole so that it can be easily attached to a metal pin  124 ′ from a suspension sleeve  126 ′. The magnetic force between the first magnet  140  and the second magnet  144  should be sufficient to secure the prosthetic socket to the suspension sleeve  126 ′ during use. While a two-magnet system is disclosed, other combinations, such as a single magnet and a piece of metal are contemplated. An advantage of this embodiment is that it is both an after-fabrication and an after-market solution and thus may be used in conjunction with prior art locking mechanisms and or prior art suspension sleeves.  
         [0047]    In order to release the magnetic bond between the first magnet  140  and the second magnet  144  when removing the prosthetic socket an optional release plate  150  is disclosed. The release plate may include one or more slots  146  to which a release strap (not shown) may be attached. The release strap, when pulled, will allow the wearer to more easily remove the prosthetic device.  
         [0048]    Referring now to FIG. 13, an alternative release system for the prosthetic socket  130  is disclosed. In this embodiment, a washer  160  is attached to the end of the metal pin  124 ′ of the suspension sleeve  126 ′. A hole (not shown) may then be drilled through the side of the prosthetic socket  130  so that a rod or similar device may be inserted between the first magnet  140  and the second magnet  144  to pry them apart. Again, as described above, while a two-magnet system is disclosed in this embodiment, other combinations, such as a single magnet and a piece of metal are contemplated.  
         [0049]    Having thus described various embodiments of the present invention, various alterations, modifications and improvements will readily occur to those skilled in the art. Such alterations, modifications and improvements are intended to be within the scope and spirit of the invention. Accordingly, the foregoing description is by way of example only and is not intended as limiting. The invention&#39;s limit is defined only in the following claims and the equivalents thereto.