Abstract:
A prosthetic foot includes a heel member having a heel member shaft extending upwardly from a heel end thereof and a forefoot member having a forefoot member shaft extending upwardly from a toe end thereof. An ankle member receives the heel member shaft and forefoot member shaft so as to allow the heel member shaft and forefoot member shaft to translate in a direction of a wearer&#39;s leg in response to an upward force thereon. At least one compressible member is coupled to the ankle member and is in compressible contact with the heel member shaft and/or forefoot member shaft so as to compress in response to the translation thereof.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This is a continuation of application Ser. No. 14/051,746, filed Oct. 11, 2013, which claims priority to U.S. provisional application 61/712,981, filed Oct. 12, 2012 and titled “Prosthetic Foot with Interchangeable Components.” The priority documents are incorporated by reference in their entireties. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to prosthetic feet and, more particularly, to prosthetic feet made of interchangeable components. 
       BACKGROUND 
       [0003]    Amputees that wear a prosthetic foot to enhance their mobility must choose a prosthetic foot that is appropriate for their size and lifestyle. Unfortunately, prosthetic feet that are designed for day-to-day activities such as walking are not ideal for performing vigorous exercise. For this reason, many amputees will have different prosthetic feet for different activities. In order to change between the different prosthetic feet when using conventional prosthetics, the amputee must completely remove the foot attached to the leg and replace it with a different foot. This is inefficient, expensive, and may change gait adjustments originally set by the attending prosthetist. 
         [0004]    Conventional prosthetic feet are usually made of a plurality of components that are fastened together mechanically or with an adhesive to form a single structure. These are not designed to allow the wearer to replace different components, nor are they engineered to allow the amputee to replace, for example, walking foot components with running foot components without replacing the entire foot. 
       SUMMARY 
       [0005]    In view of these problems, we have developed a prosthetic foot designed so that its components can easily be removed and replaced. The foot effectively allows wearers to have a single prosthetic foot that is adaptable to many different activities and sizes by selecting interchangeable components. 
         [0006]    A first example of a prosthetic foot embodying these principles comprises a heel member having a heel member shaft extending upwardly from a heel end thereof and a forefoot member having a forefoot member shaft extending upwardly from a toe end thereof. An ankle member receives the heel member shaft and forefoot member shaft therein so as to allow the heel member shaft and forefoot member shaft to translate in a direction of a wearer&#39;s leg in response to an upward force thereon. At least one compressible member is coupled to the ankle member and in compressible contact with the heel member shaft and/or forefoot member shaft so as to compress in response to the translation of the heel member shaft and/or forefoot member shaft. 
         [0007]    Other features of this first example may include the following. 
         [0008]    The ankle member may apply inward force to the heel member shaft and forefoot member shaft to maintain an alignment of the heel member shaft and forefoot member shaft therealong. 
         [0009]    The heel member shaft and forefoot member shaft may be translatable along the ankle member independently of one another. 
         [0010]    The ankle member may form a sleeve around the heel member shaft and forefoot member shaft and the heel member shaft and forefoot member shaft may translate upwardly within the sleeve when upward force acts, respectively, on the heel member or forefoot member. In this case, the compressible member may be positioned above the heel member shaft and forefoot member shaft within the sleeve. 
         [0011]    The ankle member may apply inward force to the compressible member when the compressible member is compressed to maintain the compressible member&#39;s alignment with the heel member shaft and forefoot member shaft. 
         [0012]    The heel member shaft and forefoot member shaft may translate upwardly along the ankle member along or more guide slots defining the direction of translation, each guide slot having a corresponding pin inserted therein to restrict translation within a length of the one or more guide slots. 
         [0013]    A second example of a prosthetic foot embodying these principles comprises an ankle member having a sleeve defining an interior extending along an axis defined by a wearer&#39;s leg and having a compressible member positioned therein; a heel member having a heel member shaft extending upwardly from a heel end thereof and along the axis within the interior; a forefoot member having a forefoot member shaft extending upwardly from a toe end and along the axis within the interior. The heel member shaft and forefoot member shaft are translatable along the axis in response to an upward force thereon. The compressible member compresses in response to the upward force. 
         [0014]    Other features of the second example may include the following. 
         [0015]    The ankle member may apply inward force to the heel member shaft and forefoot member shaft to maintain alignment of the heel member shaft and forefoot member shaft therealong. 
         [0016]    The heel member shaft and forefoot member shaft may be translatable along the axis independently of one another. 
         [0017]    The compressible member may be positioned above the heel member shaft and forefoot member shaft and intersect the axis. 
         [0018]    The ankle member may apply inward force to the compressible member when the compressible member is compressed to maintain the compressible member&#39;s alignment with the heel member shaft and forefoot member shaft. 
         [0019]    The extent of translatability may be defined by one more guide slots within the sleeve, extending along the axis, and having a corresponding pin inserted therein. 
         [0020]    A third example of a prosthetic foot embodying these principles comprises an ankle member having a sleeve defining an interior extending along an axis defined by a wearer&#39;s leg, the interior being at least partially defined by anterior and posterior lubricated sidewalls; a heel member having a heel member shaft within the sleeve, a heel end extending downwardly out of the sleeve, and opposed lubricated anterior and posterior heel member surfaces, the lubricated posterior heel member surface being in slidable contact with the ankle member posterior lubricated sidewall; a forefoot member having a forefoot member shaft within the sleeve, a toe end extending downwardly and forwardly out of the sleeve, and opposed lubricated anterior and posterior forefoot member surfaces, the lubricated anterior forefoot member surface being in slidable contact with the ankle member anterior lubricated sidewall, the lubricated posterior forefoot member surface being in slidable contact with the lubricated anterior heel member surface; and a compressible member positioned within the interior above and in contact with the heel member shaft and forefoot member shaft so as to compress when upward force acts on the heel member and/or forefoot member. 
         [0021]    Other features of the third example may include the following. 
         [0022]    The heel member shaft and forefoot member shaft may together define a pair of opposed guide slots, each having a pin inserted therein to restrict the movement of the heel member and forefoot member to a length of the guide slots. 
         [0023]    The pins may extend through opposed lateral sidewalls of the ankle member. 
         [0024]    A pin securing member may apply inward force against the pins to maintain the pins within the guide slots. 
         [0025]    The ankle member may apply inward force to the compressible member when the compressible member is compressed to maintain the compressible member&#39;s alignment with the heel member shaft and forefoot member shaft. 
         [0026]    These and other objects, aspects, and advantages of the invention will be better appreciated in view of the following detailed description of preferred embodiments. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]      FIG. 1  is a side anterior perspective view of a prosthetic foot connected to a limb connector, according to an embodiment of the invention; 
           [0028]      FIG. 2  is a side view thereof with a lateral side of the ankle member cutaway; 
           [0029]      FIG. 3  is a front view thereof with the anterior side of the ankle member cutaway; 
           [0030]      FIG. 4  is a side anterior perspective view of an exemplary forefoot member useful with the prosthetic foot of  FIG. 1 ; 
           [0031]      FIG. 5  is a side elevation of the forefoot member of  FIG. 4 ; 
           [0032]      FIG. 6  is a bottom view of the forefoot member of  FIG. 4 ; 
           [0033]      FIG. 7  is an anterior elevation view of the forefoot member of  FIG. 4 ; 
           [0034]      FIG. 8  is a posterior elevation view of the forefoot member of  FIG. 4 ; 
           [0035]      FIG. 9  is a side posterior perspective view of an exemplary heel member useful with the prosthetic foot of  FIG. 1 ; 
           [0036]      FIG. 10  is a side elevation view of the heel member of  FIG. 9 ; 
           [0037]      FIG. 11  is a bottom view of the heel member of  FIG. 9 ; 
           [0038]      FIG. 12  is a posterior elevation view of the heel member of  FIG. 9 ; 
           [0039]      FIG. 13  is an anterior elevation view of the heel member of  FIG. 9 ; 
           [0040]      FIG. 14  is a bottom perspective view of an exemplary ankle member useful with the prosthetic foot of  FIG. 1 ; 
           [0041]      FIG. 15  is a bottom view of the ankle member of  FIG. 14 ; 
           [0042]      FIG. 16  is anterior or posterior side elevation view of the ankle member of  FIG. 14  with the facing side cutaway; 
           [0043]      FIG. 17  is a lateral side elevation view of the ankle member of  FIG. 14  with the facing side cutaway; 
           [0044]      FIG. 18  is a top view of the of an exemplary compressible member useful with the prosthetic foot of  FIG. 1 ; 
           [0045]      FIG. 19  is a side elevation view of the compressible member of  FIG. 18 ; 
           [0046]      FIG. 20  is a side elevation view of an exemplary pin useful with the prosthetic foot of  FIG. 1 ; 
           [0047]      FIG. 21  is a top or bottom view of the pin of  FIG. 20 ; 
           [0048]      FIG. 22  is a rear elevation view of the pin of  FIG. 20 ; 
           [0049]      FIG. 23  is a front elevation view of the pin of  FIG. 20 ; 
           [0050]      FIGS. 24A-C  illustrate an example of how components of the prosthetic foot of  FIG. 1  can be interchanged; and 
           [0051]      FIG. 25  is a side anterior perspective view of the prosthetic foot of  FIG. 1  including a pin securing member. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0052]    In the Summary above and in the Detailed Description of Preferred Embodiments, reference is made to particular features (including method steps) of the invention. Where a particular feature is disclosed in the context of a particular aspect or embodiment of the invention, that feature can also be used, to the extent possible, in combination with and/or in the context of other particular aspects and embodiments of the invention, and in the invention generally. 
         [0053]    The term “comprises” is used herein to mean that other ingredients, features, steps, etc. are optionally present. When reference is made herein to a method comprising two or more defined steps, the steps can be carried in any order or simultaneously (except where the context excludes that possibility), and the method can include one or more steps which are carried out before any of the defined steps, between two of the defined steps, or after all of the defined steps (except where the context excludes that possibility). 
         [0054]    In this section, the invention will be described more fully with reference to certain preferred embodiments. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will convey preferred embodiments of the invention to those skilled in the art. 
         [0055]      FIG. 1  generally illustrates a prosthetic foot  20  according to an embodiment of the invention. The foot  20  includes a forefoot member  30 , a heel member  60 , and an ankle member  90 . In practice, the foot  20  is attached to a limb connector  130  designed to connect the foot to the wearer&#39;s leg. The wearer&#39;s leg defines a vertical axis L along which the ankle member  90  is aligned. The limb connector  130  is shown in broken lines to indicate that its design does not form a key component of the foot  20 . The foot  20  may function regardless of the type of limb connector  130  used. 
         [0056]    The prosthetic foot  20  is modular and includes parts that can be removed and substituted very easily to meet the individual needs of the wearer. This allows the components to be interchanged with other components for the purpose of replacement or for the purpose of substituting one component for another component having different properties. For example, the original forefoot and heel members may be interchanged with different forefoot and heel members suited to a particular activity, the wearer&#39;s gait, the wearer&#39;s lifestyle, a particular shoe size, the wearer&#39;s height, the wearer&#39;s weight. 
         [0057]    In  FIGS. 2 and 3  the facing side of the ankle member is cutaway so that the mechanical functionality of various components is revealed. The details of each component are discussed in turn. 
         [0058]    The ankle member  90  forms a sleeve into which a forefoot member shaft  32  and heel member shaft  62  are positioned. The ankle member  90  applies inward force against the forefoot member shaft  32  and heel member shaft  62  to maintain alignment of the respective shafts  32 ,  62  along the vertical axis of the ankle member  90 . The forefoot member shaft  32  and heel member shaft  62  slide independently along the ankle member when upward force acts on the forefoot member  30  or heel member  60 . 
         [0059]    A compressible member  110  is coupled to the ankle member  90  and is in compressible contact with the heel member shaft  62  and forefoot member shaft  32  so as to compress when upward force acts on the heel member  60  and/or forefoot member  30 . The vertical arrow A in  FIGS. 2 and 3  illustrates that the compressible member  110  compresses along the direction of the vertical axis of the ankle member  90 . The vertical arrows B and C illustrate the direction the shafts  32 ,  62  slide along the ankle member  90 . 
         [0060]    When upward force acts on the heel member  60  or forefoot member  30 , the respective shaft  32 ,  62  slides vertically within the ankle member  90  and compresses the compressible member  110 , which absorbs the shock due to the force. The heel member shaft  62  and forefoot member shaft  32  slide independently of one another along the ankle member  90  because the only mechanical link between the shafts  32 ,  62  is the inward force applied by ankle member  90 . 
         [0061]    The heel member  60  can easily be removed from the ankle member  90  by sliding it out of the ankle member  90 . Likewise, the forefoot member  32  can easily be removed from the ankle member  90  by sliding it out of the ankle member  90 . Either of these components can then be replaced with a different heel member  60  and/or forefoot member  30  that suits a certain activity or weight without needing to remove the ankle member  90  from the wearer&#39;s limb. This also allows worn components to be replaced without needing to replace the entire foot or send the foot back to the manufacturer for repair. 
         [0062]    Additional details of a preferred forefoot member  30  are shown in  FIGS. 4-8 . The forefoot member  30  includes the forefoot member shaft  32  and extends from a forefoot member upper end  34  through a curved forefoot section  36  to a toe section end  38  and terminates at a toe end  40 . A forefoot member top surface  42  and forefoot member bottom surface  44  are positioned on opposite sides. 
         [0063]    At the shaft section  32 , the forefoot member top surface  42  includes a lubricated forefoot member anterior surface  46 . Also at the shaft section  32 , the forefoot member bottom surface  44  includes a lubricated forefoot member posterior surface  48 . 
         [0064]    The opposed lateral sides of the forefoot member each include an elongated depression  50  formed along the shaft  32  adjacent to the lubricated forefoot member posterior surface  48 . 
         [0065]    Additional details of a preferred heel member  60  are shown in  FIGS. 9-13 . The heel member  60  includes the heel member shaft  62  and extends from a heel member upper end  64  through a curved heel section  72  to a heel end  66 . A heel member top surface  68  and heel member bottom surface  70  are positioned on opposite sides. 
         [0066]    At the shaft section  62 , the heel member top surface  68  includes a lubricated heel member posterior surface  74 . Also at the shaft section  62 , the heel member bottom surface  70  includes a lubricated heel member anterior surface  76 . 
         [0067]    The opposed lateral sides of the heel member  60  each include an elongated depression  78  formed along the shaft  62  adjacent to the lubricated heel member anterior surface  76 . 
         [0068]    Additional details of a preferred ankle member  90  are shown in  FIGS. 14-17 . The ankle member  90  forms a sleeve having opposed anterior and posterior sidewalls  92   a  and opposed lateral side walls  92   b  that together define an interior  100 . The interior surface along the anterior and posterior sidewalls  92   a  is lubricated to form anterior and posterior lubricated sidewalls  104 . In the embodiment shown, the ankle member  90  is symmetric about a vertical plane bisecting the anterior and posterior sidewalls  92   a  and a vertical plane bisecting the lateral side walls  92   b.    
         [0069]    Both lateral sidewalls  92   b  define a respective opening  102  that passes through to the interior  100 . The purpose of the openings  102  is described in detail below. 
         [0070]    Additional details of the preferred compressible member  110  are shown in  FIGS. 18 and 19 . The compressible member  110  is adapted to compress in the vertical direction and return to its original shape when the compression force is removed. Accordingly, the compressible member  110  functions in a spring-like manner to absorb the shock on the heel member  60  and forefoot member  30  when the wearer uses the prosthetic foot. 
         [0071]    In the example shown, the compressible member  110  forms an elongated disk-like shape with a compressible material  112  in a high flexure and fatigue resistant material sheath  114 . The compressible material  112  is preferably rubber, plastic, or the like. The sheath  114  is preferably also rubber, plastic, or the like. The make-up of the compressible material  112  is specifically selected for the degree of energy recovery required to match the wearer&#39;s lifestyle and body weight. The material property combinations for the compressible material  112  material and sheath  114  determine the energy recovery performance of the compressible member  110 . These materials may be selected to provide a specific type of shock-absorbing performance tuned to a wearer&#39;s preference. 
         [0072]    When the compressible member  110  compresses, it recovers energy from the heel member  60  and forefoot member  30  and returns a significant amount of that energy back to the heel member  60  and forefoot member  30  to allow the wearer to have a more natural stride. The compressible member  110  also returns rapid shock induced energy, from jumping for example, in a controlled manner. If the compressible member  110  becomes overloaded or fatigued and the sheath  114  fails, the compressible member  110  will not totally fail because the compressible material  112  will remain intact. 
         [0073]    The shape of the compressible member  110  is selected to fit within the interior  100  of the ankle member  90  so that when the compressible member  110  is compressed, it deforms and presses against the interior sidewalls  92   a,b  of the ankle member, which, in turn, maintain its alignment with the forefoot member  30  and heel member  60 . For this reason, it is preferred that the height H, width W, and thickness T of the compressible member  110  be such that it fits snugly within the ankle member  90  so that the ankle member&#39;s interior walls either touch it or nearly touch it when the compressible member  110  is not compressed. The preferred arrangement of the compressible member  110  with respect to the ankle member  90  is best shown in  FIGS. 2 and 3 . The shape of the compressible member  110  can be altered to correspond to the shape of the interior  100  of the ankle member  90 . Accordingly, the compressible member  110  need not have the shape shown in every embodiment. 
         [0074]    Limiting the lateral expansion of the compressible member  110  within the ankle member  90  is advantageous for many reasons, which include preventing destructive overstressing of the sheath  114  and changing the wearer&#39;s “feel” while walking to identify the need to replace the compressible member  110 . 
         [0075]    Although the compressible member  110  shown in the drawings and described here is particularly preferred, the compressible member  110  is not limited to this specific example. There are various other types of spring-like or shock absorbing devices that one having skill in the art, using this disclosure as guidance, may use to serve the same purpose. 
         [0076]    Referring back now to  FIG. 2 , when the forefoot member  30  and heel member  60  are coupled to the ankle member  90  the lubricated posterior heel member surface  74  is in slidable contact with the ankle member posterior lubricated sidewall  104 , the lubricated anterior forefoot member surface  46  is in slidable contact with the ankle member anterior lubricated sidewall  104 , and the lubricated posterior forefoot member surface  48  is in slidable contact with the lubricated anterior heel member surface  76 . 
         [0077]    The lubricated surfaces are preferably formed from a solid lubricating material inlaid into the material that makes up the respective component part. The lubricating material allows the surfaces to slide quietly against each other with little wear. A particularly preferred lubricating material is polytetrafluoroethylene, commonly sold under the name TEFLON® by E.I. DuPont de Nemours and Company, Corp. Other suitable lubricating materials include, but are not limited toother families of fluoropolymers, polyethylene polymers of various molecular weights, acetal resins (commonly sold under the name DELRIN® by E.I. DuPont de Nemours and Company, Corp), or any other polymer that has good resistance to wear due to sliding. 
         [0078]    Although not preferable, if desired, a liquid or gel-type lubricant can be applied to the lubricated surfaces for extra lubrication. One must be careful, however, in choosing the lubricant because grit trapped in the lubricant may damage the solid lubricating material. 
         [0079]    As shown in  FIGS. 1 and 2 , pins  120  are positioned through the opposed lateral sidewalls  92   b  of the ankle member  90 . Preferred pins  120  are shown in greater detail in  FIGS. 20-23 . Each pin  120  includes a cylindrical body  122  extending from a first end  123  to a wedge shaped second end  124 . The pins  120  are preferably made from the same lubricating material as the lubricated surfaces, most preferably polytetrafluoroethylene, to allow the wedge shaped second end  124  to slide easily against the heel member  90  and forefoot member  30 . 
         [0080]    As best shown in FIGS.  2  and  24 A-C, within the ankle member  90 , the respective depressions  50 ,  78  of the forefoot member  30  and heel member  60  meet to form a pair of vertical guide slots that define the sliding direction in which the forefoot member  30  and heel member  60  slide. As best shown in  FIG. 3 , the pins  120  are positioned through the openings  102  in the ankle member  90  so that the wedge shaped second end  124  of each pin  102  fits within a respective guide slot. The pins  120  restrict the distance the forefoot member  30  and heel member  90  can slide to the length of the guide slots. 
         [0081]    As mentioned above, the various components of the prosthetic foot  20  can easily be removed from the ankle member  90  without removing the ankle member  90  from the wearer&#39;s leg. This is advantageous for many reasons, some of which have already been described. 
         [0082]    One of the particular advantages of the foot&#39;s modularity is that is allows one to easily replace the heel member  60  and forefoot member  30 . An example of this is illustrated in  FIGS. 24A-C  in which a height of the heel end above ground G is adjusted by replacing heel member  60 ′ with shorter heel member  60 ″. This is achieved by sliding heel member  60 ′ out of the ankle member  90  and sliding heel member  60 ″ into the ankle member  90  as illustrated by the arrows in  FIG. 24B . The guide pins (not shown) are installed as previously described.  FIG. 24C  shows the shorter heel member  60 ″ installed on the prosthetic foot  20 . 
         [0083]    Referring now to  FIG. 25 , it may be useful to include a pin securing member  140  to maintain the position of the pins  120 . In the example shown, the pin securing member  140  is an annular strap that extends completely around the ankle member  90  and presses inwardly on the pins  120 . There many different strap-type pin securing members  140  that are suitable, including resilient straps that can be stretched over the pins  120  or belt-like straps that include a fastener for joining two ends together. A preferred pin securing member  140  is a belt-like strap with a hook and loop type fastener. When used, the pin securing member  140  is preferably tightened around the pins  120  to prevent the pins from sliding out of the openings  102  while pressing the second end  124  of the pins  120  into the guide slots, which, in turn, causes the anterior lubricious surface  46  of the forefoot member and the posterior lubricious surface  74  of the heel member  90  to press against the lubricious surfaces  104  on the interior of the ankle member  90 . 
         [0084]    The prosthetic foot  20  may be made from any material suitable for making components parts of prosthetic devices and that can allow each of the components to perform its desired functions. The forefoot member  30 , heel member  60 , and ankle member  90  may be primarily made of the same or a different material. A particularly preferred material for making the forefoot member  30 , heel member  60 , and ankle member  90  is carbon fiber composite because it is lightweight, strong, and resilient. The properties of carbon fiber are also tunable to meet a desired need by varying the ply schedule, layer orientation, resins, and fabrication process employed to make each part. 
         [0085]    The scope of the invention is not limited to the particular shape of the component shown in the drawings and described. The shape of each component may vary to account for a wearer&#39;s activity level and/or weight or may vary to be suited to a particular activity such as running. 
         [0086]    The invention has been described in some detail, but it will be apparent that various modifications and changes can be made within the spirit and scope of the invention as described in the foregoing specification and the appended claims.