Patent Publication Number: US-2005137717-A1

Title: Prosthetic foot with rocker member

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates in one embodiment to lower limb prostheses in general, and, in particular, to a prosthetic foot having an ankle section with a rocker member connected to a foot member, where the rocker member facilitates the flexion of the foot member.  
      2. Description of the Related Art  
      Prosthetic feet of different designs are well known in the art. The various conventional designs have sought to solve various limitations associated with prosthetic feet.  
      Common to many conventional prosthetic foot designs is the desire to approximate the feel and fluid range of motion of a human foot&#39;s natural stride. One aspect of said natural stride is the ability to fluidly transition from heel-strike to toe-off during motion of the foot.  
      Some conventional designs attempt to provide said fluid transition by incorporating springs to store and release energy during motion of the prosthetic foot. The springs can be of different shapes, such as C-shaped or U-shaped, and of different types, such as leaf springs. However, such foot designs tend to be bulky and may be difficult to wholly contain in a cosmesis. Additionally, in some instances, the efficiency of the springs may deteriorate following prolonged use, resulting in less efficient energy storage and release during motion of the foot.  
      Other designs employ an ankle module pivotally connected to the foot member with bumpers disposed between each end of the ankle module and the foot member. In such designs, the bumpers store and release energy during heel-strike and toe-off. However, such designs also have disadvantages.  
      Additionally, existing prosthetic foot designs do not provide the desired degree of stride fluidity during foot motion. For example, existing designs do not adequately adapt the degree of flexion of the foot based on the load being applied to the foot. Such foot designs thus allow the same degree of flexion for lighter and heavier individuals, resulting in a less fluid foot motion for both individual types.  
      Some existing designs are difficult to fit into and remove from a cosmesis. Such ease of removal and introduction is particularly useful for performance of maintenance on the foot. For example, in foot designs that utilize bumpers, a user may want to replace the bumpers to vary the stiffness of the foot. Ease of removal of the foot from the cosmesis facilitates such replacement.  
      Accordingly, there is a need for an improved prosthetic foot that solves some of the problems discussed above.  
     SUMMARY OF THE INVENTION  
      In at least one embodiment, the prosthetic foot is configured to provide an improved fluid transition between heel-strike and toe-off. The foot has a rocker member having an anterior section and a posterior section, wherein the anterior section is elongated in shape. The rocker member is preferably removably connected in cantilever fashion at the posterior section thereof to a foot member, wherein the foot member has a toe section and a heel section. In one embodiment, the posterior section of the rocker member has a generally planar lower surface, whereas the anterior section has a generally curved lower surface. In another embodiment, the front and posterior sections of the rocker member have generally planar lower surfaces.  
      As the foot transitions from heel-strike to toe-off, flexion of the foot member increases and the rocker member gradually rolls-up onto the foot member. This roll-up effect advantageously adjusts the stiffness of the foot to the load being applied. The greater the applied load, the more the rocker member rolls-up onto the foot member, and the greater the increase in the flexion and stiffness of the foot member. The stiffness of the foot member can also be varied based on the location along the foot member where the rocker member is connected. The further the rocker member is connected from the heel of the foot member, the greater the increase in stiffness during roll-up of the rocker member onto the foot member.  
      In one embodiment, the foot member is made of layers of composite material, wherein the layers define a certain foot member thickness. Optionally, the foot member may be tapered, for example, at the heel section. The taper and thickness of the lay-up design is preferably configured to provide a foot member designed for a target applied toe load. Additionally, the taper and thickness of the lay-up design are configured so that the rocker member rolls-up onto the foot member a desired amount when the target toe load is applied.  
      In another preferred embodiment, the anterior section of the rocker member is advantageously tapered for easier introduction into and removal from a cosmesis. Similarly, the posterior section of the rocker member can also be tapered. Moreover, the foot blade can also be tapered at the heel section thereof to facilitate the initial roll-up of the rocker member onto the foot member. Also, the length of the anterior section of the rocker member can be advantageously varied to provide an increased roll-up effect. In another embodiment, the anterior section can have a recessed or indented surface to decrease the weight of the rocker member.  
      In some embodiments, the prosthetic foot also comprises an ankle module having an anterior portion and a posterior portion, the module movably connected to the rocker member about an axis. Bumpers can be disposed between the ankle module and rocker member to provide energy storage and release during foot motion. Preferably, at least one of the bumpers is made of compressible material. Optionally, at least one of the bumpers can be made of a rigid or semi-rigid material. More preferably, at least a portion of the bumpers is compressible. In one embodiment, the bumpers are advantageously configured to reduce any clicking or other noise generated during the transition from heel-strike to toe-off of the foot. For example, at least one of the bumpers can be configured to function as a muffler or damper. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a perspective view of one embodiment of a prosthetic foot.  
       FIG. 2A  is a side elevational view of the prosthetic foot shown in  FIG. 1  with the heel in a neutral position.  
       FIG. 2B  is a side elevational view of the prosthetic foot in  FIG. 1  having a foot member heel section with a tapered thickness.  
       FIG. 2C  is an exploded side view of the prosthetic foot shown in  FIG. 1 .  
       FIG. 3  is a front elevational view of the prosthetic foot illustrated in  FIG. 1 .  
       FIG. 4  is a top elevational view of the prosthetic foot illustrated in  FIG. 1 .  
       FIG. 5  is a longitudinal cross-sectional view of one embodiment of an ankle module and rocker member.  
       FIG. 6  is a transverse cross-sectional view of the ankle module and rocker member shown in  FIG. 5 .  
       FIG. 7A  is a side elevational view of the prosthetic foot shown in  FIG. 1  attached to a pylon and having one heel height.  
       FIG. 7B  is a side elevational view of the prosthetic foot in  FIG. 7A  at a different heel height.  
       FIG. 8A  is a side elevational view of another embodiment of a prosthetic foot with a different ankle module.  
       FIG. 8B  is a cross-sectional view of the proximal end of the ankle module shown in  FIG. 8A .  
       FIG. 9A  is a side elevational view of the prosthetic foot shown in  FIG. 8A  attached to a pylon and having one heel height.  
       FIG. 9B  is a side elevational view of the prosthetic foot shown in  FIG. 8A  at a different heel height.  
       FIG. 10  is a side elevational view of the prosthetic foot in  FIG. 7A  in a flexed state. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       FIGS. 1-2A  illustrate one embodiment for a prosthetic foot  100  extending between a toe section  2  and a heel section  4 . Preferably, the prosthetic foot  100  comprises a foot member or support  10  which may have an elongate configuration having a length L extending between a front end  12  and a rear end  14 . As used herein, length L refers to the horizontal length of the foot member  10  along a plane parallel to a support surface S on which the prosthetic foot  100  rests. Preferably, the length L can be between about 18 and 40 cm, corresponding to the size of the prosthetic foot  100 , when the foot  100  has a neutral heel height position, as described below. In one embodiment, the length L is about 25 cm. However, the length L can have other values and can vary as the heel height position of the prosthetic foot  100  is adjusted. The foot member  10  also preferably comprises an anterior portion  12   a , a posterior portion  14   a , and an intermediate portion  16 . In one embodiment, the anterior portion  12   a  can include a front toe portion configured to operatively contact the support surface S. The posterior portion  14   a  can comprise a heel portion, and the intermediate portion  16  can comprise an arch portion. Additionally, in one embodiment the foot member  10  can be generally shaped like the sole of the human foot, wherein the length L is approximately equal to that of a natural human foot. Alternatively, the foot member  10  may be shorter. In some embodiments, the foot member  10  may comprise multiple pieces separated, for example, transversely or longitudinally from each other. In other embodiments, the foot member  10  may be an integral piece, may be substantially flat, and may have a substantially rectangular traverse cross-section along its length L.  
      The foot member  10  as shown in  FIG. 2A  is preferably made of a material adapted to flex during motion from heel-strike through toe-off and has the desired strength. In one embodiment, the foot member  10  can be fabricated using a carbon filament with a polymer binder, for example, epoxy. However, other filament types can be used, such as glass, Kevlar, and nylon to ensure lightweight and structural and dynamic characteristics consistent with the amputee. Preferably, the foot member  10  is constructed using a combination of longitudinal (lengthwise) filaments interspersed with a fraction of transverse filament to bind the longitudinal filaments together and prevent the separation thereof under load. For example, in one embodiment, longitudinal or 90-degree filament, and transverse or 0-degree filament, can be used. However, in other embodiments, the longitudinal and transverse filaments can be arranged in other configurations, such as at 45 degrees relative to each other. Preferably, the longitudinal and transverse filaments are arranged together with the polymer binder in laminae that are located in immediate contact with one another. For example, the laminae can be superimposed on each other, maintained in operative relationship by the polymer binder, or additionally by encapsulating polymer or filaments arranged in the thickness direction, and be susceptible to a bending stress determined by the thickness of the superimposed laminae. The number of laminae preferably varies with the size of the prosthetic foot  100 . For example, the foot member  10  of a smaller prosthetic foot  100  can comprise a lower number of laminae than the foot member  10  of a larger prosthetic foot  100 . Accordingly, a thickness T of the foot member  10  will vary with the number of laminae used to fabricate the foot  100 . Further details of material suitable for use in fabricating the foot member  10  can be found in U.S. Pat. Nos. 4,547,913 and 4,822,363, both of which are hereby incorporated by reference.  
      The foot member  10  in  FIG. 2A  can be fabricated using, for example, injection molding and/or the use of thermoplastic materials and processes or any of a range of combinations thereof. In one preferred embodiment, chopped fiber may be blended in a thermoplastic or a thermoset resin and the resulting mixture injection molded into an appropriate configuration. In another preferred embodiment, thermoplastic or thermoset laminae may be alternatively or additionally wound around an injection molded core or a thermoplastic resin may be injected between thermoplastic or thermoset laminae whereby the laminates are bonded onto the injected material.  
      The foot member  10  in one embodiment is a generally flat plate-like member, which may or may not have some curvature. As shown in  FIG. 2A , the posterior and intermediate sections  14   a ,  16  are generally planar while the anterior section  12   a  is generally curved. The posterior and intermediate sections  14   a ,  16  are generally inclined with respect to the support surface S. For example, the posterior portion  14   a  can extend at an angle α relative to the support surface S. The angle α can be between about 10 and 30 degrees when the foot  100  is at rest and has a neutral heel height position, as described below. In the illustrated embodiment, the angle α is about 15 degrees with the foot  100  at rest and in a neutral heel height position. However, the angle α can have other values and can vary during motion of the prosthetic foot  100  and when the heel height position of the foot  100  is adjusted. In another embodiment, the foot member  10  can be generally planar and extend substantially parallel to the support surface S from the toe section  2  to the heel section  4 . In another embodiment, the posterior and intermediate sections may also be curved.  
      As shown in  FIG. 2A , the thickness T of the foot member  10  tapers between a maximum at the rear end  14  and a minimum at the front end  12 . In some embodiments, the thickness T can vary from between about 7 and 10 millimeters at the rear end  14  to between about 2.5 and 5 millimeters at the front end  12 . In one embodiment, the thickness T varies between about 8 millimeters at the rear end  14  to about 3 millimeters at the front end  12 . In another embodiment (not shown), the thickness T of the foot member  10  may be uniform from the rear end  14  to the front end  12 . In one embodiment, the foot member  10  has a uniform thickness T of about 7 mm. In still another embodiment, the thickness T of the foot member  10  can taper between a maximum at the intermediate section  16  and minimums at the front and the rear ends  12 ,  14 , as shown in  FIG. 2B .  
      As best seen in  FIG. 3 , in one preferred embodiment, the anterior portion  12   a  of the foot member  10  comprises at least two toe members  18   a ,  18   b . The toe members  18   a ,  18   b  are preferably defined by at least one longitudinal slot  20  in the foot member  10  extending rearwardly from the front end  12 . In the illustrated embodiment, the longitudinal slot  20  extends into the foot member  10  about two to three centimeters from the front end  12 . However, in other embodiments, the slot  20  can extend further or less into the foot member  10 . In the illustrated embodiment, the longitudinal slot  20  is offset from a major axis X extending generally longitudinally along the midline of the foot member  10  to resemble either a left foot or a right foot. The left foot embodiment is illustrated in  FIG. 3 . In other embodiments, the longitudinal slot  20  can be substantially aligned with the axis X. In one embodiment, the slot  20  is adapted to receive a thong of a sandal or similar footwear. In another embodiment, the slot  20  is adapted to receive a foot cover (not shown) having a corresponding slot between the toe members  18   a ,  18   b  to provide a more aesthetically pleasing foot cover, or a cover adapted to receive a thong of a sandal or similar footwear.  
       FIG. 4  shows a top view of the prosthetic foot  100  illustrated in  FIG. 2A . In the illustrated embodiment, the posterior section  14   a  of the foot member  10  is tapered relative to the intermediate section  16  of the foot member  10  so that the posterior section  14   a  is less wide. For example, the foot member can have a width W that tapers toward the rear end  14 . The anterior section  12   a  of the foot member  10  can also be tapered relative to the intermediate section  16 . In one embodiment, the width W may taper gradually and continuously from the intermediate section  16  to the front and rear ends  12 ,  14 . In another embodiment, the foot member  10  can have a generally constant width W along the intermediate section  16  and taper thereafter towards the front and rear ends  12 ,  14 . In still another embodiment, the foot member  10  can have a generally constant width W from the front end  12  to the rear end  14 .  
      As best shown in  FIG. 2A , the prosthetic foot  100  also comprises a rocker member  30  mounted to the foot member  10  near the posterior section  14   a  of the foot member  10 . The rocker member  30  can have an elongate configuration having a length L′ extending between a front end  32  and a rear end  34 . In one embodiment, the length L′ is less than about 45% of the length L of the foot member  10 . In another embodiment, the length L′ is about 45% or more of the length L of the foot member  10 . In still another embodiment, the length L′ is about 50% or more of the length L of the foot member  10 . In the illustrated embodiment, the length L′ is about 55% of the length L of the foot member  10 . In a preferred embodiment, the front end  32  of the rocker member  30  extends past the transverse midline of the foot member  10 . The length L′ is preferably between about 40 and 60 mm. In the illustrated embodiment, the length L′ is about 50 mm. The rocker member  30  also defines an anterior section  32   a , a posterior section  34   a , and an intermediate section  35 . A base  36  extends along a lower portion  30   a  of the rocker member  30 , from the posterior section  34   a  to the anterior section  32   a.    
      The base  36  of the rocker member  30 , as shown in  FIG. 2A , defines a contact surface  36   a  that contacts the foot member  10  and a roll-up surface  36   b  that does not contact the foot member  10  when the prosthetic foot  100  is at rest. In the illustrated embodiment, the contact surface  36   a  extends generally along the posterior and intermediate sections  34   a ,  35  of the rocker member  30 . In other embodiments, the contact surface  36   a  can extend along the posterior section  34   a  and partially along the intermediate section  35 . In one embodiment, the contact surface  36   a  can extend solely along the posterior section  34   a . In the illustrated embodiment, the roll-up surface  36   b  extends along the anterior section  32   a , between the intermediate section  35  and the front end  32  of the rocker member  30 . In other embodiments, the roll-up surface  36   b  can additionally extend partially along the intermediate section  35 . In one embodiment, the roll-up surface  36   b  can extend generally along the anterior and intermediate sections  32   a ,  35 .  
      As shown in the embodiment illustrated in  FIG. 2A , the roll-up surface  36   b  is preferably curved. However, in other embodiments, the roll-up surface  36   b  can be generally planar. In one embodiment, the roll-up surface  36   b  can have a radius of curvature (not shown) corresponding to a radius of curvature (not shown) of the intermediate section  16  of the foot member  10 . As illustrated, the anterior tip of the roll-up surface  36   b  may be rounded.  
      The contact surface  36   a  is preferably configured to mate with the surface of the posterior section  14   a  of the foot member  10 . In one embodiment the contact surface  36   a  can also be curved and have a radius of curvature. In one embodiment, the radius of curvature of the contact surface  36   a  can be equal to the radius of curvature of the roll-up surface  36   b . In another embodiment, the contact surface can be generally planar.  
      As shown in the embodiment illustrated in  FIG. 2A  when the rocker member  30  is connected to the foot member  10  and the foot  100  is at rest, the roll-up surface  36   b  extends relative to the contact surface  36   a  and the foot member  10  so as to define a longitudinal slot  22  between the anterior section  32   a  of the rocker member  30  and the foot member  10 . For example, in one embodiment, the roll-up surface  36   b  can extend generally at an angle β relative to the contact surface  36   a  and to the posterior section  14   a  of the foot member  10 . In another embodiment (not shown), where the roll-up surface  36   b  is generally planar, the roll-up surface  36   b  can be inclined relative to the foot member  10 , but not relative to the contact surface  36   a . The angle β is preferably between about 10 and 20 degrees. In the illustrated embodiment, the angle β is about 15 degrees.  
      In one embodiment, as shown in  FIG. 2C , the rocker member  30  can be removably mounted to the foot member  10  via at least one connector  37 . In some embodiments, the connector  37  may comprise one or a plurality of bolts connecting the foot member  10  to the posterior section  34   a  of the rocker member  30 . However, the connector  37  can comprise other structures, such as rivets and screws. In other embodiments, the rocker member  30  can be permanently or releasably fixed to the foot member  10  via, for example, adhesives, straps, resins or welds. In one embodiment, the rocker member  30  is connected to the foot member  10  in cantilever form. Accordingly, the anterior section  32   a  of the rocker member  30  can move relative to the foot member  10 , and the roll-up surface  36   b  can roll-up onto the foot member  10 , during motion of the prosthetic foot  100 . In one embodiment, such a cantilever connection can be achieved by connecting the rocker member  30  to the foot member  10  solely at the posterior section  34   a  of the rocker member  30 .  
      The prosthetic foot  100  shown in  FIG. 2A  can have a roll-up surface  36   b  that is about 10% or more of the length L′ of the rocker member  30 . In another embodiment, the length of the roll-up surface  36   b  can be about 20% or more of the length L′ of the rocker member  30 . In still another embodiment, the length of the roll-up surface  36   b  can be about 30% or more of the length L′ of the rocker member  30 . In yet another embodiment, the length of the roll-up surface  36   b  can be about 40% or more of the length L′ of the rocker member  30 . In another embodiment, the length of the roll-up surface  36   b  can be about 50% or more of the length L′ of the rocker member  30 . In another embodiment, the length of the roll-up surface  36   b  can be about 70% or more of the length L′ of the rocker member  30 . In the illustrated embodiment, the length of the roll-up surface  36   b  is about 60% of the length L′ of the rocker member  30 .  
      As best shown in  FIGS. 3-4 , the rocker member  30  has a width W′ that varies between a maximum at the intermediate section  35  to minimums at the anterior and posterior sections  32   a ,  34   a . For example, in one embodiment, the width W′ may taper at a constant angle from the intermediate section  35  to the anterior and posterior sections  32   a ,  34   a . In another embodiment, the width W′ may taper at a gradually increasing slope between the intermediate section  35  and the anterior and posterior sections  32   a ,  34   a , such as in the form of a curve. In one embodiment, the width W′ tapers from about 4 cm at the intermediate section  35  to about 2 cm at the anterior section  32   a  and about 1 cm at the posterior section  34   a . In yet another embodiment, the width W′ of the rocker member  30  may be generally uniform between the front and rear ends  32 ,  34  of the rocker member  30 .  
      As best seen in  FIGS. 4-5 , the rocker member  30  can have recessed sections formed thereon configured to lower the weight of the rocker member  30 . For example, in one embodiment, the anterior section  32   a  of the rocker member  30  may have a recessed portion  38  formed on an upper surface thereof. In another embodiment, the intermediate section  35  may have a recessed section  38   a  formed on an upper surface thereof.  
      As seen in  FIG. 3  and  FIG. 6  the intermediate section  35  of the rocker member  30  defines two opposite walls  35   a ,  35   b  which preferably extend generally parallel to each other. The rocker member  30  also defines an axial opening  40  formed on both walls  35   a ,  35   b  and adapted to receive an axle  42  therethrough. The axle  42  is configured to connect an ankle module  50  to the rocker member  30  such that the ankle module  50  is capable of pivoting about the axle  42  between the anterior and posterior sections  32   a ,  34   a  of the rocker member  30 . At least one bearing  44  can be disposed between the axle  42  and the ankle module  50 . In the embodiment illustrated in  FIG. 6 , two bearings  44  are disposed between the axle  42  and ankle module  50 , with a bearing spacer  46  disposed between the two bearings  44 .  
      As shown in  FIGS. 2A and 5 , the ankle module  50  in one embodiment comprises a housing  52  defining an anterior cylinder  54   a  and a posterior cylinder  56   a  therein. In one embodiment, the cylinders  54   a ,  56   a  have the same length. As shown in  FIG. 2A , the ankle module  50  is operatively connected to the foot member  10  via rocker member  30 . The anterior and posterior cylinders  54   a ,  56   a  are preferably sized to slidingly receive an anterior piston  54  and a posterior piston  56 , respectively. In one embodiment, the pistons  54 ,  56  have the same length. Additionally, each of the cylinders  54   a ,  56   a  is preferably longer than its corresponding piston  54 ,  56  and defines a gap  57  between the piston  54 ,  56  and a wall  52   a  of the housing  52 . Preferably, the anterior piston  54  is aligned with the anterior section  32   a  of the rocker member  30 . Likewise the posterior piston  56  is preferably aligned with the posterior section  34   a  of the rocker member  30 . The housing  52  also comprises a valve  58  disposed on the wall  52   a  and between the cylinders  54   a ,  56   a . The valve  58  can be operated to selectively permit communication between the cylinders  54   a ,  56   a . In the illustrated embodiment, the valve  58  is a spool valve. However, other valve types can be used.  
      When the valve  58  shown in  FIG. 5  is in an open position, such that the cylinders  54   a ,  56   a  communicate with each other, a fluid contained in the cylinders  54   a ,  56   a  can flow between the cylinders  54   a ,  56   a . The housing  52  can thus move relative to the pistons  54 ,  56  and be selectively pivoted about the axle  42  to a different position relative to a generally vertical axis Y. When the valve  58  is in a closed position, there is no communication between the cylinders  54   a ,  56   a  so that the fluid cannot flow between the cylinders  54   a ,  56   a . As a result, the housing  52  cannot move relative to the pistons  54 ,  56  and is held in a substantially fixed position relative to the vertical axis Y.  
      In one embodiment, the volume of the gap  57  in each cylinder  54   a ,  56   a , as shown in  FIG. 5 , will preferably vary when the valve  58  is in the open position and the housing  52  is moved relative to the pistons  54 ,  56  to a different position. For example, when the heel of the foot  100  is in a neutral heel height position, the gap  57  in each cylinder  54   a ,  56   a  generally has the same volume. However, when the housing  52  is rotated toward the anterior section  32   a  of the rocker member  30  (see e.g.,  FIG. 7B ) to achieve a lower heel height, the gap  57  in the anterior cylinder  54   a  will have a lower volume than the gap  57  in the posterior cylinder  56   a . Likewise, when the housing  52  is rotated toward the posterior section  34   a  of the rocker member (see e.g.,  FIG. 7A ) to achieve a higher heel height, the gap  57  in the anterior cylinder  54   a  will have a greater volume than the gap  57  in the posterior cylinder  56   a.    
      The valve  58  shown in  FIG. 5  may be actuated in one of a variety of ways. In the embodiment illustrated in  FIG. 2A , a push button  60  is adapted to move upon receipt of a force to actuate the valve  58  between an open and a closed position. Said actuation allows the movement and fixation of the housing  52  relative to the pistons  54 ,  56  to reposition the ankle module  50  relative to the axis Y, as described above. However, other actuation mechanisms may be used, such as a lever (not shown). Further details of the ankle module  50  can be found in U.S. Pat. No. 5,957,981, which is hereby incorporated by reference in its entirety.  
      As best shown in  FIG. 2A  a front bumper  70  is disposed between the anterior piston  54  and the anterior section  32   a  of the rocker member  30 . Similarly a rear bumper  76  is disposed between the posterior piston  56  and the posterior section  34   a  of the rocker member  30 . In some embodiments, one or both of the bumpers  70 ,  76  can be removably disposed between the ankle module  50  and the rocker member  30 .  
      In the embodiment illustrated in  FIG. 2A , the front bumper  70  comprises a generally compressible portion  70   a  and a generally rigid portion  70   b . In one embodiment, the generally compressible portion  70   a  can be about 2 cm long. The compressible portion  70   a  and rigid portion  70   b  can be made of materials having different durometers. For example, in one embodiment, the compressible portion  70   a  can have a durometer of 95 Shore A and the rigid portion  70   b  can have a durometer of 70 Shore D. In another embodiment, the entire length of the front bumper  70  is incompressible.  
      Similarly, the rear bumper  76  shown in  FIG. 2A  can be made of a generally compressible material, such as a hard rubber or polyurethane, having one of a variety of durometers. In one embodiment, a kit can be provided comprising a plurality of rear bumpers  76 , wherein each rear bumper  76  has a different durometer varying between a soft and an extra firm consistency. For example, the durometer of the rear bumper  76  can vary between 60 Shore A and 95 Shore A.  
      Preferably, the bumpers  70 ,  76  shown in  FIG. 2A  can be replaced. In one embodiment, the bumpers  70 ,  76  can be removed by applying a force to rotate the housing  52  of the ankle module  50  to expose the space between the pistons  54 ,  56  and the bumpers  70 ,  76 . The bumpers  70 ,  76  can then be replaced with new bumpers or bumpers having a different durometer. For example, to remove the front bumper  70 , the actuator  60  can be actuated to allow rotation of the housing  52  toward the posterior section  34   a  of the rocker member  30  via application of a force, thus exposing a space between the anterior piston  54  and the front bumper  70 . The front bumper  70  can then be removed from between the anterior piston  54  and the anterior section  32   a  of the rocker member  30 . Following replacement of the front bumper  70 , a user can apply a force to rotate the housing  52  toward the anterior section  32   a  of the rocker member  30 . Similarly, the actuator  60  can be actuated to allow rotation of the housing  52  toward the anterior section  32   a  of the rocker member  30  via application of a force, to expose a space between the posterior piston  56  and the posterior section  34   a  of the rocker member  30 . The rear bumper  76  can then be removed from between the posterior piston  56  and the posterior section  34   a  of the rocker member  30 . Following replacement of the rear bumper  76 , the user can apply a force to the housing  52  to rotate the housing  52  toward the rear section  34   a  of the rocker member  30 .  
      As illustrated in  FIG. 2A , the ankle module  50  comprises a pyramid  62  having a top surface  64  and a side surface  66  and configured to receive a pylon or other prosthesis thereon. In the illustrated embodiment, the side surface  66  consists of a plurality of generally flat faces extending an angle γ relative to the generally vertical axis Y. In another embodiment the side surface  66  can comprise a generally cylindrical surface also extending at said angle γ. In other embodiments the side surface  66  can extend generally parallel to the vertical axis Y. As described above, the ankle module  50  can be selectively moved relative to the axis Y by actuating the valve  58  to allow the housing  52  to rotate relative to the pistons  54 ,  56 . However, the pyramid  62  is to be oriented generally vertically when connected to a user&#39;s pylon or prosthesis. Accordingly, the movement of the housing  52  relative to the axis Y effectively adjusts the heel height of the prosthetic foot  100 , wherein the heel height is defined as the distance between the support surface S and the pyramid  62 . If the ankle module  50  is moved toward the posterior section  34   a  of the rocker member  30 , the heel height is increased. Similarly, if the ankle module  50  is moved toward the anterior section  32   a  of the rocker member  30 , the heel height is decreased.  
       FIG. 7A  shows the prosthetic foot  100  with a pylon  80  attached to the ankle module  50 . The pylon  80  can be cylindrical in shape, or have any other suitable shape, and be made of any material suitable for use in prosthetic pylons. In the illustrated embodiment, the ankle module  50  has been moved toward the posterior section  34   a  of the rocker member  30  so that the housing  52  rotates relative to the pistons  54 ,  56 . As a result, the heel height from the support surface S to the junction of the pylon  80  and the ankle module  50  is increased to a heel height H 1 . In this configuration, a user can advantageously use the prosthetic foot  100  with shoes that have high heels.  
       FIG. 7B  shows another configuration of the prosthetic foot in  FIG. 7A  with a different heel height. In the illustrated embodiment, the ankle module  50  has been moved toward the anterior section  32   a  of the rocker member  30  so that the housing  52  rotates relative to the pistons  54 ,  56 . As a result, the heel height from the support surface S to the junction of the pylon  80  and the ankle module  50  is decreased to a heel height H 2 . In this configuration, a user can advantageously use the prosthetic foot with shoes that have low heels or when walking barefoot.  
       FIG. 8A  shows another embodiment of the prosthetic foot  100  wherein the ankle module  50 ′ comprises a tube clamp  62 ′ having a generally cylindrical body  66 ′. The tube clamp  62 ′ preferably extends a height H′ from the housing  52 ′ to an upper end  62   a ′ and may be integrally formed with the housing  52 ′. Optionally, the tube clamp  62 ′ can have at least one support member extending between the upper end  62   a ′ and the housing  52 ′. In the illustrated embodiment, the tube clamp  62 ′ has two support members  68 ′. The tube clamp  62 ′ is configured to receive a pylon or other prosthesis therein. The clamp  62 ′ comprises a clamp bore  62   b ′ that extends through two clamp arms  62   c ′, as shown in  FIG. 8B . The clamp arms  62   c ′ define a slot  63 ′ therebetween. The clamp bore  62   b ′ is configured to receive a connector (not shown) therethrough, such as a bolt or the like, to urge the clamp arms  62   c ′ toward each other. Accordingly, by urging the clamp arms  62   b ′ toward each other, an inner surface  62   d ′ of the clamp tube  62 ′ can be clamped about a surface of a pylon or other prosthesis.  
      The embodiment of the prosthetic foot  100  shown in  FIG. 8A  can also be adjusted to provide different heel heights.  FIG. 9A  shows one embodiment of the prosthetic foot  100  with a pylon  80 ′ attached to the tube clamp  62 ′ of the ankle module  50 ′. In the illustrated embodiment, the ankle module  50 ′ has been moved toward the posterior section  34   a  of the rocker member  30  so that the housing  52 ′ rotates relative to the pistons  54 ,  56 , as described above. As a result, the heel height from the support surface S to the junction of the pylon  80 ′ and the ankle module  50 ′ is increased to a heel height H 1 ′. In this configuration, a user can advantageously use the prosthetic foot  100  with shoes that have high heels.  
       FIG. 9B  shows another configuration of the prosthetic foot in  FIG. 9A  with a different heel height. In the illustrated embodiment, the ankle module  50 ′ has been moved toward the anterior section  32   a  of the rocker member  30  so that the housing  52 ′ rotates relative to the pistons  54 ,  56  (as shown in  FIG. 5 ). As a result, the heel height from the support surface S to the junction of the pylon  80 ′ and the ankle module  50 ′ is decreased to a heel height H 2 ′. In this configuration, a user can advantageously use the prosthetic foot with shoes that have low heels.  
      The prosthetic foot  100  of  FIGS. 1-9B  advantageously provides a fluid heel-to-toe movement as compared to other prosthetic foot designs. As a user proceeds from heel-strike to toe-off, the rocker member  30  rolls up onto the foot member  10 , causing the posterior portion  14   a  of the foot member  10  to flex toward the anterior section  12   a , as illustrated in  FIG. 10 . In the embodiments described in  FIGS. 1-10  above, the roll-up is provided because the anterior section  32   a  of the rocker member  30  is free to move relative to the foot member  10 , so that the roll-up surface  36   b  rolls-up onto the foot member  10 . The roll-up effect provides flexion and gradual stiffening of the foot member  10  in comparison to conventional prosthetic foot designs, thus providing an improved fluid foot motion. The roll-up effect also facilitates more efficient energy storage and release during heel-strike through toe-off. The initial roll-up of the rocker member  30  onto the foot member  10  is further facilitated in embodiments where the thickness T of the foot member  10  is tapered at the posterior section  14   a  (see  FIG. 2B ) because the tapered thickness provides a lower resistance to flexion.  
      Advantageously, the degree of roll-up of the foot  100  shown in  FIGS. 1-10  can be varied by varying the length of the roll-up surface  36   b . As noted above, in the illustrated embodiment, the roll-up surface  36   b  is about 60% of the length L′ of the rocker member  30 . However, the roll-up surface  36   b  can be about 10% or more of the length L′. Additionally, in the illustrated embodiment, the length L′ of the rocker member  30  is advantageously greater than about 50% of the length L of the foot member  10 , which also contributes to an increased roll-up effect. Accordingly, in at least one embodiment, the front end  32  of the rocker member  30  extends forward of a midline of the foot member  10 .  
      As discussed above with respect to  FIG. 4 , the foot member  10  can have a width W that tapers toward the posterior section  14   a , or heel section  4 , of the foot member  10 . Such a tapered posterior section  14   a  or heel section  4  advantageously facilitates the roll-up of the rocker member  30  onto the foot member  10  during motion of the foot  100 .  
      As best shown in  FIGS. 2A, 2B ,  5  and  7 A- 10 , the bumpers  70 ,  76  are advantageously disposed between the rocker member  30  and the housing  52 . In embodiments where the rocker plate  30  is removably mounted on the foot member  10 , such a configuration also allows the ankle module  50 , bumpers  70 ,  76 , and rocker member  30  to be detached from the foot member  10  as a unit. Therefore this configuration advantageously facilitates the assembly and disassembly of the prosthetic foot  100 , as well as the replacement of the bumpers  70 ,  76 .  
      As noted above, the front bumper  70  shown in  FIG. 2A  advantageously comprises a generally compressible portion  70   a  and a generally rigid portion  70   b . The front bumper  70  is thus adapted to operate as a muffler or damper, substantially preventing a “clicking” noise when the rear bumper  76  is compressed and released during motion of the foot  100 .  
      Further, the rocker member  30 , as shown in  FIG. 3 , can advantageously be tapered in width toward the front end  32  thereof, facilitating insertion and removal of the rocker member  30  from a cosmesis or foot cover. Additionally, the anterior section  32   a  of the rocker member  30  can have a recessed section  38  formed thereon, advantageously reducing the weight of the rocker member  30 .  
      As noted above, the prosthetic foot  100  of  FIGS. 1-10 , can advantageously be adjusted to different heel heights. This allows the prosthetic foot  100  to be used in conjunction with a variety of footwear, each having a different heel height. Additionally, the adjustable heel height of the prosthetic foot  100  provides a user with increased comfort and security when walking up or down hills by allowing the user to adjust the orientation of the foot  100  as best suited for the grade of the hill&#39;s incline.  
      In  FIGS. 1-10 , as the user proceeds from heel-strike to toe-off, the pylon  80  or other prosthesis applies a forward force onto the housing  52  of the ankle module  50 . However, when the valve  58  is in a closed position, there is no communication between the cylinders  54   a ,  56   a . Accordingly, the housing  52  is not allowed to move relative to the pistons  54 ,  56 . Instead, the wall  52   a  of the housing  52  hydraulically transfers said force to the anterior piston  54 , which in turn transfers the force to the front bumper  70 . The front bumper  70  transfers the force to the anterior section  32   a  of the rocker member  30 , which causes the rocker member  30  to roll-up onto the foot member  10 , as discussed above. Likewise, during heel-strike, the pylon  80  or other prosthesis applies a rearward force onto the housing  52  of the ankle module  50 . The wall  52   a  of the housing hydraulically transfers said force to the posterior piston  56  when the valve  58  is closed, and the posterior piston  56  transfers the force to the rear bumper  76 . The rear bumper  76  then transfers the force to the posterior section  34   a  of the rocker member  30 , which transfers it to the posterior section  14   a  of the foot member  10 .  
      For purposes of summarizing the invention and the advantages achieved over the prior art certain objects and advantages of the invention have been described hereinabove. Of course it is to be understood that not necessarily all such objects or advantages may be achieve in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied but carried out in a manner that achieves or optimizes one advantage or a group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein. The embodiments illustrated in  FIGS. 1-10  show the length L of the foot member  10  substantially coinciding with the length of the prosthetic foot  100  so that the foot member  10  extends from the toe section  2  to the heel section  4  of the foot  100 . However the foot member  10  need not extend the full length of the prosthetic foot  100 . In some embodiments the foot member  10  can extend to a point rearward of the toe section  2  of the prosthetic foot  100  and/or connect to another member (not shown) that extends to the toe section  2  of the foot  100 . Likewise, in some embodiment the foot member  10  can extend to a point frontward of the heel section  4  of the prosthetic foot  100  and/or connect to another member (not shown) that extends to the heel section  4  of the foot  100 .  
      All of these aspects are intended to be within the scope of the invention herein disclosed. These and other aspects of the present invention will become readily apparent to those skilled in the art from the appended claims and from the preceding detailed description of the preferred embodiments having referenced the attached figures, the invention not being limited to any preferred embodiments disclosed.