HK1065698B - Prosthetic foot with tunable performance - Google Patents

Description

Prosthetic foot with adjustable performance

Technical Field

The present invention relates to a high performance prosthetic foot that provides improved dynamic response capabilities, which capabilities are related to the force application mechanism.

Background

Martin et al in U.S. patent 5897594 disclose an jointless prosthetic foot for use on a leg prosthesis. Unlike previous solutions, in which the prosthetic foot has a rigid structure with joints to simulate the function of the ankle, the jointless prosthetic foot of Martin et al employs a resilient foot insertion member that is mounted inside the foot model. The insert part has a substantially C-shaped design in longitudinal section, which opens backwards and supports the prosthesis load with its upper C-limb, which load is transferred via its lower C-limb to the leaf spring connected thereto. The leaf spring has a convex design, seen from below, and extends substantially parallel to its base, forwardly beyond the foot insertion part, into the toe region. The invention of Martin et al is based on the object of improving an articulaless prosthetic foot, taking into account the shock of the heel, the elasticity, the heel-to-toe walking and the lateral stability, in order thus to carry it with it to walk in a natural way, with the aim of allowing the user to both walk normally and to carry out physical exercises and exercises. However, the dynamic response characteristics of this known prosthetic foot are limited. There is a need for a high performance prosthetic foot with an improved applied mechanical design that improves amputee athletic performance, including activities such as running, jumping, sprinting, starting, stopping and spanning, for example.

Another prosthetic foot has been proposed by VanL-Phillips and is said to provide amputees with the flexibility and mobility to perform a variety of activities that have not been possible in the past due to the structural limitations and corresponding performance limitations of existing prostheses. Running, jumping and other activities are said to be undertaken by existing prosthetic feet, which reportedly can be used by the user in the same manner as a normal foot. See, for example, U.S. patent 6071313; 5993488, respectively; 5899944, respectively; 5800569, respectively; 5800568, respectively; 5728177, respectively; 5728176, respectively; 5824112, respectively; 5593457, respectively; 5514185, respectively; 5181932, respectively; and 4822363.

Disclosure of Invention

In order for amputee athletes to achieve a higher level of performance, there is a need for a high performance prosthetic foot having an improved application mechanism that may be superior to the human foot, and possibly superior to existing prosthetic feet. It would be of interest to amputee athletes to have a high performance prosthetic foot with improved mechanics, high low dynamic response, and alignment adjustability, and possibly fine tuning to improve the horizontal and vertical components of motion, which itself may be a special task.

The prosthetic foot of the present invention meets the above-described needs. In accordance with one embodiment disclosed herein, the prosthetic foot of the invention comprises a longitudinally extending foot keel having an forefoot portion at one end and a hindfoot portion at an opposite end, and a longer midfoot portion extending between and upwardly arched from the forefoot and hindfoot portions. A calf shank including a downwardly convexly curved lower end is also provided. The curved lower end of the calf shank is attached to the upwardly arched midfoot portion of the foot keel in an adjustable fastening arrangement to form an ankle joint area of the prosthetic foot.

The adjustable fastening arrangement enables adjustment of the alignment of the calf shank and foot keel with respect to one another in the longitudinal direction of the foot keel for adjusting the performance of the prosthetic foot. By adjusting the alignment of the opposed upwardly arched midfoot portion of the foot keel and the downwardly convexly curved lower end of the calf shank with respect to one another in the longitudinal direction of the foot keel, the dynamic response characteristics and motion outcomes of the foot are altered to meet the particular needs of the desired/desired horizontal and vertical linear motions. A multi-purpose prosthetic foot is disclosed having high and low dynamic response capabilities, as well as biplanar motion characteristics, which improve the functional outcome of amputees engaged in athletic and/or recreational activities. A prosthetic foot particularly suited for sprinting is also disclosed.

These and other objects, features and advantages of the present invention will be better understood upon consideration of the detailed description of the disclosed embodiments of the invention and the accompanying drawings.

Drawings

Fig. 1 is a schematic representation of two adjacent radii of curvature R1 and R2, one next to the other, of the foot keel and calf shank of the prosthetic foot of the invention, which produce the dynamic response capabilities and motion outcomes of the foot in gait in the direction of arrow B, which is perpendicular to the tangent line A joining the two radii.

Fig. 2 is a schematic view similar to fig. 1, but showing the alignment of the two radii having been altered in the prosthetic foot of the invention to increase the horizontal component of the dynamic response capability and motion output of the foot in gait and to decrease the vertical component so that arrow B1, which is perpendicular to tangent a1, is more horizontal than in the state shown in fig. 1.

Fig. 3 is a side view of a prosthetic foot according to one embodiment of the invention having a pylon adapter and pylon connected thereto for securing the foot to the lower end of an amputee's leg.

Fig. 4 is a front view of a prosthetic foot having the pylon adapter and pylon of fig. 3.

Fig. 5 is a top view of the embodiment shown in fig. 3 and 4.

Fig. 6 is a side view of another foot keel of the invention particularly suited for sprinting and which may be used in the prosthetic foot of the invention.

Figure 7 is a top view of the foot keel of figure 6.

Fig. 8 is a bottom view of the foot keel of the prosthetic foot of fig. 3 providing high low dynamic response characteristics, as well as biplanar motion capabilities.

Fig. 9 is a side view of another foot keel of the invention for a prosthetic foot particularly suited for sprinting by an amputee having a Symes amputation of the foot.

Figure 10 is a top view of the foot keel of figure 9.

Fig. 11 is another variation of the foot keel for the prosthetic foot of the invention for a Symes amputee, the foot keel providing the prosthetic foot with high low dynamic response characteristics, as well as biplanar motion capabilities.

Figure 12 is a top view of the foot keel of figure 11.

Figure 13 is a side elevational view of the foot keel of the invention wherein the thickness of the tapered portion of the keel is tapered from the midfoot portion to the hindfoot portion of the keel.

Fig. 14 is a side view of another form of the foot keel wherein the thickness tapers from the midfoot portion to both the forefoot and hindfoot portions of the foot keel.

Fig. 15 is a side view of the anterior surface of a calf shank of the prosthetic foot of the invention from a slightly superior portion to a parabola shape, the thickness of the calf shank decreasing toward its upper end.

Fig. 16 is a side view similar to fig. 15, but showing another calf shank which tapers from the middle to both the upper and lower ends.

Fig. 17 is a side view of a C-shaped calf shank for the prosthetic foot, the calf shank thickness tapering from its middle portion to both the upper and lower ends.

Fig. 18 is a side view of another example of a C-shaped calf shank for the prosthetic foot, the calf shank being progressively reduced in thickness from its midportion to its upper end.

Fig. 19 is a side view of an S-shaped calf shank for the prosthetic foot, the thickness of which is tapered from the midportion to each end.

Fig. 20 is another example of an S-shaped calf shank which is reduced in thickness only at its upper end.

Fig. 21 is a side view of a J-shaped calf shank, tapered at each end, for the prosthetic foot of the invention.

Fig. 22 is a schematic view similar to fig. 21, but showing a J-shaped calf shank which tapers in thickness only in a direction toward its upper end.

Fig. 23 is a side view, slightly above, of an aluminum or plastic coupling element used in the adjustable fastening arrangement of the invention to attach the calf shank to the foot keel as shown in fig. 3.

Fig. 24 is a side and slightly forward view of a pylon adapter for use on the prosthetic foot of Figs. 3-5 to attach the foot to a pylon for attachment to an amputee's leg.

Fig. 25 is a side view of another prosthetic foot of the invention similar to that of fig. 3, but showing the use of a coupling element having two releasable fasteners longitudinally spaced to attach the element to the calf shank and foot keel, respectively.

Fig. 26 is an enlarged side view of the connecting member shown in fig. 25.

Fig. 27 is an enlarged side view of the calf shank of the prosthetic foot of fig. 25.

Detailed Description

Referring to the drawings, the prosthetic foot 1 in the embodiment shown in Figs. 3-5 includes a longitudinally extending foot keel 2 having a forefoot portion 3 at one end thereof, a hindfoot portion 4 at an opposite end thereof, and an upwardly arched midfoot portion 5 extending between the forefoot and hindfoot portions. In the embodiment, midfoot portion 5 is convexly curved upward over its entire longitudinal extent between the forefoot and hindfoot portions.

The upstanding calf shank 6 of the foot 1 is attached at its downwardly convexly curved lower end 7 portion to the proximate posterior surface of the keel midfoot portion 5 by way of a releasable fastener 8 and coupling element 11. In the present embodiment, the fastener 8 is simply a bolt having a nut and washer, but could be a releasable clip or other fastener for securely positioning and retaining the calf shank to the foot keel when the fastener is tightened.

Referring to figure 8, a longitudinally extending aperture 9 is formed in the proximal posterior surface of the keel midfoot portion 5. For example, as shown in FIG. 15, a longitudinally extending aperture 10 is also formed in the curved lower end 7 of the calf shank 6. A releasable fastener 8 extends through the holes 9 and 10 which permit adjustment of the alignment of the calf shank and foot keel with respect to one another in the longitudinal direction A-A shown in fig. 5, at which time the fastener 8 is loosened or released to tailor the performance of the prosthetic foot to a particular task. Thus, the fastener 8, coupling element 11 and longitudinally extending holes 9 and 10 constitute an adjustable fastening arrangement for attaching the calf shank to the foot keel to form an ankle joint area of the prosthetic foot.

The effect of adjusting the alignment of the calf shank 6 and the foot keel 2 can be seen in Figs. 1 and 2, where the two radii R1 and R2, one next to the other, represent adjacent, facing, arched or convexly curved surfaces of the foot keel medial portion 5 and the calf shank 6. When such two radii are considered one next to the other, there is a motion capability perpendicular to the tangent line a in fig. 1 and perpendicular to the tangent line a1 in fig. 2, the tangent line being drawn between the two radii. The correlation between these two radii determines the direction of motion output. As a result, the dynamic response force application of the foot 1 depends on this relationship. The larger the radius of the recess, the higher the dynamic response capability. However, the smaller the radius, the faster it reacts.

The alignment capability of the calf shank and foot keel on the prosthetic foot of the invention enables the radii to be shifted to affect the horizontal or vertical linear velocity of the foot in athletic activities. For example, to improve the horizontal linear velocity capability of the prosthetic foot 1, alignment changes can be made to affect the relationship of the calf shank radius and the foot keel radius. That is, to improve the horizontal linear velocity profile, the bottom radius R2 of the foot keel is made further than its starting position in FIG. 2 as compared to FIG. 1. Thereby changing the dynamic response characteristics and making the motion output of the foot 1 more horizontal, as a result of which a greater horizontal linear velocity can be obtained by applying the same force.

The amputee can find the settings for each activity that meet his/her needs through exercise, as these needs are related to horizontal and vertical linear velocities. For example, high jump players and basketball players require a higher vertical jump height than sprinters. The coupling element 11 is a plastic or aluminum metal alignment coupling (see figures 3, 4 and 23) sandwiched between the attached foot keel 2 and calf shank 6. The releasable fastening member 8 extends through an aperture 12 in the attachment member. The coupling element extends along the proximal, posterior surface attachment portion of the calf shank and the keel midfoot portion 5.

The curved lower end 7 of the calf shank 6 is parabolic in shape with the smallest radius of curvature of the parabola located at its lower end and extending initially anteriorly and then upwardly on the parabola shape. As shown in fig. 3, a posterior facing concavity is formed by the curvature of the calf shank. The parabolic shape has the advantage of having a higher dynamic response characteristic which produces improved horizontal linear velocity associated with a larger radius proximal end while having a smaller radius of curvature at its lower end for faster response characteristics. As explained in fig. 1 and 2, the larger radius of curvature of the parabolic shape at its upper end causes the tangent line a to remain more vertical as the alignment changes, which can result in improved horizontal linear velocity.

Pylon adapter 13 is attached to the upper end of calf shank 6 by fasteners 14. Adapter 13 is then secured to the lower end of pylon 15 by fasteners 16. Pylon 15 is secured to the lower limb of the amputee by a support structure (not shown) attached to the residual limb of the leg.

In this embodiment, the forefoot, midfoot and hindfoot portions of the foot keel 2 are constructed from a single piece of resilient material. For example, a solid material of a plastic nature may be used which has shape-retaining characteristics when deflected by the ground reaction forces. In particular, high strength graphite laminated with a thermosetting epoxy or extruded plastic used under the trademark Delran or degassed polyurethane copolymers may be used to produce the foot keel and to produce the calf shank. The functional qualities associated with the material provide high strength with light weight and minimal creep. The thermosetting epoxy resin is laminated under vacuum conditions using the prosthesis industry standard. The polyurethane copolymer may be injected into a female mold and the extruded plastic article may be machined. Each material used has its advantages and disadvantages.

The physical characteristics of the elastomeric material associated with stiffness, elasticity and strength are all determined by the thickness of the material. Thinner materials deflect more easily than thicker materials for the same density. The material used, as well as its physical characteristics, is related to the stiffness of the prosthetic foot keel and the flexibility characteristics of the calf shank. In the embodiment of Figs. 3-5, the thickness of the foot keel and calf shank are uniform or symmetrical, however, as discussed below, the thickness along the length of the components may be varied, such as by making the hindfoot and forefoot areas thinner and more sensitive to deflection in the midfoot region.

To provide a prosthetic foot 1 with high and low dynamic response capabilities, the midfoot portion 5 is formed with a longitudinal arch such that the medial aspect of the longitudinal arch has a higher dynamic response capability than the lateral aspect of the longitudinal arch. To this end, in the embodiment, the radius of the inner portion of the longitudinal arc-shaped recess is larger than the radius of the outer side thereof. The rear end 17 of the hindfoot portion 4 is upwardly curved in the shape of an arc which reacts to the reaction force of the ground during impact with the heel caused by the compressive forces which absorb the impact. The heel formed by the hindfoot portion 4 has a posterior lateral corner 18 which is more posterior and lateral than the medial corner 19 to promote hindfoot eversion during the initial contact phase of gait. The anterior end 20 of the forefoot portion 3 is shaped in an upwardly curved arc to simulate the human toes being dorsiflexed in the heel-lift toe-off position of the post-stance phase of gait. Rubber or foam pads 53 and 54 are provided as cushioning material under the forefoot and hindfoot sections.

The improved biplanar motion capability of the prosthetic foot is created by the medial and lateral expansion joint holes 21 and 22 extending through the forefoot portion 3 between its dorsal and plantar surfaces. Expansion joints 23 and 24 extend forward from a respective one of the holes to the anterior edge of the forefoot portion to form medial, medial and lateral expansion struts 25-27 which create improved biplanar motion capability of the forefoot portion of the foot keel. The expansion joint holes 21 and 22 are located along the line B-B in figure 5 in the transverse plane and extend at an angle a of 25-35 to the longitudinal axis a-a of the foot keel with the medial expansion joint hole 21 being more anterior than the lateral expansion joint hole 22 and the expansion joint holes 21 and 22 as projected onto the sagittal plane being inclined at an angle of 45 to the transverse plane so that the dorsal aspect of the holes is more anterior than the plantar aspect. With this construction, the distance from the releasable fastener 8 to the lateral expansion joint hole 22 is shorter than the distance from the releasable fastener to the medial expansion joint hole 21, so that the lateral portion of the prosthetic foot 1 has a shorter toe lever than the medial portion to provide high and low dynamic response capabilities to the midfoot portion.

The anterior aspect of the hindfoot portion 4 of the foot keel 2 also includes an expansion joint hole 28 extending through the hindfoot portion 4 between its dorsal and plantar surfaces. An expansion joint 29 extends posteriorly from the hole 28 to the posterior edge of the hindfoot portion to form expansion struts 30 and 31. This results in improved biplanar motion capability of the hindfoot portion of the prosthetic foot.

As shown in figure 3, the dorsal aspect of the midfoot portion 5 and forefoot portion 3 of the foot keel 2 form an upwardly directed concavity 32 which mimics in function the fifth axis of motion (ray axis displacement) of the human foot. That is, the concavity 32 has a longitudinal axis C-C which is at an angle β of 20-35 degrees to the longitudinal axis A-A of the foot keel with the medial being more anterior than the lateral to encourage fifth axis motion in gait, as in the oblique low-speed axis of rotation of the second to fifth metatarsals of the human foot.

The importance of biplanar motion capability can be appreciated when the amputee walks on uneven terrain or when the athlete steps on the inside or outside of the foot. The direction of the ground force vector changes from a sagittal direction to have a forward planar component. The ground pushes the foot medially in the opposite direction to pushing the foot laterally. As a result, the calf shank is inclined medially and its weight is placed on the medial structure of the foot keel. In response to such pressure, the medial expansion joint struts 25 and 31 of the foot keel 2 dorsiflex (deflect upward) and invert, while the lateral expansion joint struts 27 and 30 plantar flex (deflect downward) and invert. This motion attempts to place the plantar surface of the plantar plate on the ground (plantar grade).

Referring to fig. 6 and 7, another foot keel 33 of the invention, particularly for sprinting, may be used on the prosthetic foot of the invention. The center of gravity of the human body becomes oriented only in the sagittal plane at sprinting. The prosthetic foot need not have a low dynamic response characteristic. As a result, a 35 degree outward rotational orientation of the longitudinal axis of the forefoot, midfoot concavity as in foot keel 2 is not required. Instead, the longitudinal axis D-D of the depression would become parallel to the frontal plane, as shown in FIGS. 6 and 7. This allows the sprint foot to react only in the sagittal direction. In addition, the expansion joint holes 34 and 35 are parallel to the frontal plane in the forefoot and midfoot portions along line E-E, i.e., the lateral hole 35 is moved forward and in line with and parallel to the frontal plane of the medial hole 34. The forward end 36 of the foot keel 33 is also parallel to the frontal plane. The rear heel portion 37 of the foot keel is also parallel to the frontal plane. This change negatively impacts the multi-use capabilities of the prosthetic foot. However, their performance characteristics become more suitable for the particular task. Another modification of the sprint foot keel 33 is in the toe axis area of the forefoot portion of the foot where 15 degrees of dorsiflexion on the foot keel 2 is increased to 25-40 degrees of dorsiflexion of the foot keel 33.

Fig. 9 and 10 illustrate another foot keel 38 of the invention for a prosthetic foot particularly suited for sprinting by an amputee who has had a Symes amputation through the foot. To this end, the midfoot portion of the foot keel 38 includes a posterior, upward facing concavity 39 in which the curved lower end of the calf shank is attached to the foot keel by way of a releasable fastener. Such foot keels may be used by all lower extremity amputees. The foot keel 38 accommodates the longer residual limb associated with the Symes level amputee. Its performance characteristics are significantly faster in terms of dynamic response capability. Its use is not specific to this level of amputation. It can be used on all tibial and femoral amputations. The foot keel 40 in the embodiment of figures 11 and 12 also has a concavity 41 for a Symes amputee, the foot keel providing the prosthetic foot with high low dynamic response characteristics, as well as biplanar motion capabilities, similar to the embodiment of figures 3-5 and 8.

The functional characteristics of the several foot keels of the prosthetic foot 1 are related to their shape and design characteristics in that they are related to the concavity, convexity, radius size, expansion, compression and physical characteristics of the material, all of which are related to the reaction to ground forces during walking, running and jumping activities.

The foot keel 42 in fig. 13 is similar to the embodiment of fig. 3-5 and 8, except that the thickness of the foot keel decreases from the midfoot portion to the posterior of the hindfoot. The thickness of the foot keel 43 in fig. 14 is tapered or tapered at its anterior and posterior ends. Similar thickness variations are shown in the calf shank 44 of FIG. 14 and the calf shank 45 of FIG. 16, which can be used on the prosthetic foot 1. Each design of the foot keel and calf shank produce different functional outcomes because these functional outcomes are related to horizontal and vertical linear velocities that are characteristic of improving performance in tasks associated with various sports. The ability to accommodate a variety of calf shank designs and adjustments in the settings between the foot keel and the calf shank create a prosthetic foot calf shank relationship that gives the amputee and/or prosthetist the ability to tune the prosthetic foot for optimum performance in a particular one of a variety of athletic and recreational activities.

Other calf shanks for the prosthetic foot 1 are illustrated in Figs. 17-22 and include C-shaped calf shanks 46 and 47, S-shaped calf shanks 48 and 49 and J-shaped calf shanks 50 and 51. The upper end of the calf shank may also have a vertical end with a tapered web attached at the proximal end. A male pyramid can be bolted to and through the vertical end of the calf shank. Plastic or aluminum padding may also be provided in the elongated openings at the proximal and distal ends of the calf shank for receiving the proximal male pyramid and the distal foot keel. The prosthetic foot of the invention is a modular system, preferably made of standardized units or sizes for flexibility and versatility.

All running activities associated with the runway are performed in a counter-clockwise direction. Another optional feature of the invention takes into account forces acting on the foot moving along such a curved path. When the object moves along a curved path, centripetal acceleration acts towards the center of rotation. Newton's third law applies to this energy effect. This is an equal and opposite effect. Thus, for each "centripetal" force, there is one "centrifugal" force. The action of the centripetal force is directed towards the centre of rotation, while its reaction, the action of the centrifugal force, is directed away from the centre of rotation. If the athlete is running around a curve on a runway, centripetal force pulls the athlete towards the center of the curve while centrifugal force pulls it away from the center of the curve. To counteract the centrifugal forces that tend to lean the runner outward, the runner's body leans inward. If the runner is turning on the track in a counterclockwise direction all the time, the left side is the inside of the track. As a result, according to a feature of the present invention, the left side of the left and right prosthetic foot calf shanks can be made thinner than the right side and the amputee athlete's curve performance can be improved.

In several embodiments, the foot keels 2, 33, 38, 42, 43 are all 29 centimeters long, and are proportioned to the shoe 1 in figures 3, 4 and 5, as well as in the schematic views of several different calf shanks and foot keels. However, the skilled artisan will appreciate that the specific dimensions of the prosthetic foot may vary depending on the size, weight and other characteristics of the amputee fitted with the foot.

The operation of the prosthetic foot 1 during the walking and running stance phases of the gait cycle will be discussed below. Newton's three laws of motion, related to the laws of inertia, acceleration and reaction force, are the basis of the dynamics of motion of the foot 2. According to Newton's third law, the law of force-reaction force, the thrust of the ground pushing the foot is equal to and opposite to the thrust of the foot pushing the ground. This force is referred to as ground reaction force. Various scientific studies have been conducted on human walking, running and jumping activities. Force plate studies tell us that newton's third law appears in gait. Through the above studies, we know the direction of the ground pushing feet.

The stance phase of the walking/running activity may be further divided into deceleration and acceleration phases. When the prosthetic foot touches the ground, the foot pushes forward on the ground, while the ground pushes back the foot equally in the opposite direction, that is, the ground pushes back on the prosthetic foot. This force causes the prosthetic foot to move. The stance phase analysis of walking and running activities begins at the contact point of the posterior lateral corner 18 in fig. 3 and 18, which is more posterior and lateral than the medial part of the foot. This offset at initial contact causes the foot to evert and the calf shank to plantar flex. The calf shank is always looking for a position to transfer body weight through its shank, for example, it tends to have its long vertical component in a position opposite to ground forces. This is why the plantar flexion is moved backwards so as to oppose the ground reaction force which pushes the foot backwards. The ground forces cause the calf shank to compress, moving its proximal end posteriorly. The tight radius of the lower portion of the calf shank compresses, simulating the plantar flexion of the human ankle joint, and lowers the forefoot to the ground through compression. At the same time, the rear of the upper part of the foot keel 2 is pressed upwards by compression. Both of these compressive forces act as shock absorbers. This shock absorption is further enhanced by the offset posterior lateral heel 18 which can cause the foot to roll over once the calf shank has stopped moving to plantar flexion and is pushing the foot posteriorly by the ground, which also acts as a shock absorber.

The compression members of the foot keel and calf shank then begin to unload, that is, seek their original shape, and release the stored energy which causes the proximal end of the calf shank to move anteriorly in an accelerated manner. As the calf shank approaches its vertical starting condition, the ground forces change from pushing posteriorly to pushing vertically upward against the foot. Since the prosthetic foot has posterior and anterior plantar surface weight bearing areas, and these areas are connected by a long, non-weight bearing arch shaped midportion, vertically directed forces from the prosthesis will cause the long arch shaped midportion to be loaded by expansion. The rear and front load bearing surfaces are spaced apart. The vertical force is maintained in the long, arched midsection of the foot, while the temporal force is transferred from the vertical to the forward direction. The calf shank expands, resembling ankle dorsiflexion. This can result in the prosthetic foot rotating off the anterior plantar weight bearing surface. The long arch of the midfoot changes from being compressed to expanding. This releases the stored vertical compressive force energy into an improved expansion capacity.

The long arc of the foot keel and calf shank resist expansion of their respective structures. As a result, the calf shank is restrained from advancing and the foot begins to rotate off the anterior plantar surface weight bearing area. The expansion of the midfoot portion of the foot keel has the same high low response capabilities as the foot keels of the embodiments shown in figures 3-5 and 8, figures 11 and 12, and figures 13 and 14. Because of the midfoot forefoot transition of the foot keel, the angle is 25-35 outward relative to the long axis of the foot, with the medial long arch being longer than the lateral long arch. This is important because on a normal foot, during acceleration or deceleration, the medial portion of the foot is used.

The longer medial arch of the prosthetic foot has a higher dynamic response characteristic than the lateral arch. When walking or running at slower speeds, the lateral shorter toe rod is used. The center of gravity of the body moves through a sinusoidal space. It moves medial, lateral, proximal and distal. When walking or running at a slower speed, the center of gravity of the body moves more to the medial and lateral sides than when walking or running at a higher speed. In addition, momentum or inertia is lower and the ability to overcome higher dynamic response capabilities is lower. The prosthetic foot of the invention is adapted to employ the principles described herein in a manner that applies machinery.

The foot pushes posteriorly on the ground as the force of the ground pushes anteriorly on the foot, and the long, arch-shaped anterior profile of the midfoot portion applies this posteriorly directed force vertically on its plantar surface as the heel begins to lift. This is the most efficient and useful way to apply such force. The same occurs in the posterior aspect of the hindfoot portion of the prosthetic foot. It is also shaped so that the posterior ground forces at initial contact are opposite the plantar surface of the foot keel, perpendicular to the direction of the applied force.

Late in the heel lift, the toes leave the walking and running motion, with the axial region of the forefoot portion dorsiflexed 15-35 degrees. This upwardly extending curvature causes forward ground forces to press against this part of the foot. The resistance to such compressive forces is less than the resistance to the expansion and smooth transition that occurs during the swing phase of prosthetic foot gait and running. In the late stance phase of gait, the expanded calf shank and the expanded midfoot long arch release their stored energy, enhancing the thrust on the amputee's body center of gravity.

In several of the embodiments previously mentioned, the posterior aspect of the hindfoot and forefoot portions of the foot keel incorporate expansion joint holes and expansion joint struts. The orientation of the expansion joint holes acts as a mitered hinge and improves biplanar motion capability to improve the overall contact characteristics of the plantar surface of the foot when walking in uneven terrain.

The dynamic response capabilities of the Symes foot keel as shown in FIGS. 9-12 are significantly different because such capabilities are associated with walking, running and jumping activities. The foot keels differ in 4 different ways. Including the presence of a concavity in the proximal posterior of the midfoot portion to better accommodate the Symes distal residual limb shape than flat. The alignment recess requires that the respective anterior and posterior radii of the medial portion of the curved foot keel be deeper and smaller in size. As a result, all of the midfoot long arc radii and the hindfoot radii are more compact and smaller. This significantly affects the dynamic response characteristics. Smaller radii result in lower dynamic response potential. However, the prosthetic foot responds more quickly to all of the walking, running and jumping ground forces described above. The result is a faster foot with a lower dynamic response.

With the prosthetic foot of the invention, improved task-specific motion performance can be achieved through alignment changes that can affect the vertical and horizontal components of each motion. The human foot is a multi-functional unit that can walk, run, and jump. On the other hand, the human tibial fibular calf shank structure is not a multifunctional unit. It is a simple lever that exerts its force parallel to its longitudinal proximal-distal direction during walking, running and jumping activities. It is an incompressible structure and has no potential to store energy. On the other hand, the prosthetic foot of the invention has dynamic response capabilities because such dynamic response capabilities are associated with the horizontal and vertical linear velocity components of athletic walking, running and jumping activities, and are superior to the human tibia and fibula. As a result, there is a possibility of improving the amputee's athletic performance. To this end, in accordance with the invention, the fastener 8 is loosened and the alignment of the calf shank and the foot keel with respect to one another is adjusted in the longitudinal direction of the foot keel. This variation is illustrated in figures 1 and 2. The calf shank is then secured in the adjusted position on the foot keel by the fastener 8. During this adjustment, the bolts of the fastening member 8 slide relative to one or both of the opposed, longer, longitudinally extending holes 9 and 10 in the foot keel and calf shank, respectively.

An alignment change that improves the performance characteristics of a runner when starting to contact the ground with the plane of his foot during sprinting, for example, is one in which the foot keel is slid anteriorly relative to the calf shank and the foot plantar flexed on the calf shank. This new relationship improves the horizontal component of running. That is, the calf shank plantar flexes to the foot and the foot contacts the ground in a foot flat condition, the ground immediately pushing the foot backwards as opposed to the initial heel contact, while the foot pushes forward on the ground. Thereby causing the calf shank to move rapidly anteriorly (through expansion) and downwardly. The expansion creates a dynamic response force that resists the direction of the calf shank's initial motion. As a result, the foot rolls over the plantar surface weight-bearing area of the metatarsals. This causes the midfoot portion of the foot keel to expand, which resists more than compression. The net effect of calf shank expansion and midfoot expansion is that further anterior advancement of the calf shank is resisted, which causes the knee expander and hip expander of the user's body to move the body's center of gravity anteriorly and proximally in a more efficient manner (i.e., increased horizontal velocity). In this case, further forward and upward than in the case of a heel toe runner whose calf shank forward propulsion is less resisted by the calf shank which initially has more dorsiflexion (vertical) than a foot flat runner.

To study the function of the sprint foot, the alignment of the calf shank and foot keel was changed. The foot keel has the advantage that the longitudinal axes of all of its depressions are oriented parallel to the frontal plane. The calf shank is plantar flexed and slid posteriorly on the foot keel. This further reduces the distal arc compared to a flat foot runner, for example, with a multi-purpose foot keel similar to that shown in figures 3-5 and 8. As a result, there is greater horizontal motion potential and dynamic response in its improved horizontal capabilities.

Sprinters have a large range of motion, force and momentum (inertia), momentum being the prime mover. Since the deceleration time of the standing period is shorter than the acceleration time, a higher horizontal linear velocity is obtained. This means that at initial contact, when the toes make contact with the ground, the ground pushes the foot backward and the foot pushes the ground forward. The calf shank, with greater force and momentum, is forced to make greater flexion and downward movement than the initial contact foot flat runner. The result of the force is that the long, arch-shaped concavity of the foot is loaded by expansion and the calf shank is loaded by expansion. The expansion force is resisted to a greater extent than all other previously mentioned forces associated with running. As a result, the dynamic response capability of the foot is proportional to the force applied. The human tibia fibula calf shank response is only related to energy force potential, is a straight structure, and is not capable of storing energy. In sprinting, the expansion forces on the prosthetic foot of the invention are greater than all other previously mentioned forces associated with walking and running. As a result, the dynamic response capabilities of the foot are proportional to the applied force, and the amputee athlete's athletic performance may be enhanced compared to human body function.

The prosthetic foot 53 illustrated in fig. 25 is similar to that illustrated in fig. 3, except for the adjustable fastening arrangement between the calf shank and the foot keel and the arrangement for the upper end of the calf shank for attachment to the lower end of a pylon. In this embodiment, the foot keel 54 is adjustably connected to the calf shank 55 by way of a plastic or aluminum coupling element 56. The coupling element is connected to the foot keel and calf shank by respective releasable fasteners 57 and 58 which are spaced from one another in the coupling element in a direction along the longitudinal direction of the foot keel. The fastener 58 connecting the coupling element to the calf shank is posterior to the fastener 57 connecting the foot keel and the coupling element. By increasing the effective length of the calf shank in this manner, the dynamic response capability of the calf shank can be improved. As with the other embodiments, alignment changes are made in cooperation with the longitudinally extending holes in the calf shank and foot keel.

An elongated hole 59 is provided in the upper end of the calf shank 55 for receiving the pylon 15. Once received in the hole, the pylon can be securely clamped to the calf shank by tightening bolts 60 and 61, drawing the free side edges 62 and 63 of the calf shank together along the hole. The pylon connection can be easily adjusted by loosening the bolts, telescoping the pylon to a desired position relative to the calf shank, and re-clamping the pylon in the adjusted state by tightening the bolts.

The description of the embodiments ends here. While the invention has been described in connection with various illustrative embodiments, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this invention. More particularly, reasonable variations and modifications are possible in the component parts and/or arrangements of the subject composite structure within the scope of the foregoing description, the drawings, and the appended claims without departing from the inventive concepts. In addition to variations and modifications in the component parts and/or arrangements, other uses will also be apparent to those skilled in the art.

Claims (72)

1. A prosthetic foot, comprising:

a longitudinally extending foot keel;

a resilient integrally formed calf shank connected at a lower end of the shank to the foot keel for fixedly positioning the shank and foot keel relative to one another in the longitudinal direction of the foot keel, the shank extending upwardly from the foot keel in a substantially curvilinear manner to form an ankle joint area of the prosthetic foot and a generally vertically oriented lower prosthetic part of the leg above the ankle joint area for connection with a support structure on a human leg stump;

wherein at least a portion of the shank extending upwardly from the foot keel is convexly curved anteriorly, and wherein the ankle joint area and the prosthetic portion of the leg of the shank are compressible and expandable during gait in response to ground reaction forces thereon to store and release energy to improve the dynamic response of the prosthetic foot in gait.

2. The prosthetic foot according to claim 1, further comprising means for adjusting the alignment of said calf shank and said foot keel with respect to one another in the longitudinal direction of said foot keel to adjust the performance of the prosthetic foot for a particular task, wherein said means for adjusting the alignment includes a longitudinally extending aperture in at least one of said foot keel and said calf shank, and a releasable fastener extends through said aperture to adjustably connect said calf shank to said foot keel for adjusting said alignment.

3. The prosthetic foot according to claim 2, wherein each of said foot keel and said calf shank are provided with a longitudinally extending hole through which said releasable fastener extends.

4. The prosthetic foot according to claim 1, further comprising a coupling element between said calf shank and said foot keel, and a releasable fastener extends through an aperture in said coupling element to connect said calf shank to said foot keel therethrough.

5. The prosthetic foot according to claim 4, wherein said releasable fastener connects said coupling element to said foot keel and wherein another releasable fastener is provided which connects said coupling element to said calf shank for connecting said calf shank to said foot keel.

6. The prosthetic foot according to claim 5, wherein said releasable fastener and said another releasable fastener are spaced from one another in said connection component in a direction along said longitudinal direction of said foot keel.

7. The prosthetic foot according to claim 6, wherein said another releasable fastener is more posterior than said releasable fastener.

8. The prosthetic foot according to claim 1, wherein said forward facing convexly curved portion is in the shape of a parabola having its smallest radius of curvature located at the lower end of the calf shank and extending upwardly in said parabola shape.

9. The prosthetic foot according to claim 1, wherein said calf shank is S-shaped with a lower portion of said S-shape forming said anterior facing convexly curved portion of said calf shank.

10. The prosthetic foot according to claim 1, wherein said calf shank is J-shaped with a lower portion of said J-shape forming said anterior facing convexly curved portion of said calf shank.

11. The prosthetic foot according to claim 1, wherein each of the two vertically spaced ends of said calf shank is convexly rounded to a respective free end extending in the same direction along said longitudinally extending foot keel, a relatively straight upstanding portion of said calf shank connecting said rounded ends being located on a side of the calf shank opposite to the side of said free end.

12. The prosthetic foot according to claim 1, wherein the calf shank forming the lower prosthetic portion of the leg extends upwardly in a substantially curvilinear manner, the curve being reversely curved to merge with the straight vertical upper end of the calf shank.

13. The prosthetic foot according to claim 1, wherein said foot keel has a forefoot portion at one end, a hindfoot portion at an opposite end, and an upwardly arched midfoot portion between said forefoot and hindfoot portions, and wherein each of said forefoot and hindfoot portions are concavely curved upwardly.

14. The prosthetic foot according to claim 1, wherein said foot keel has an forefoot portion at one end, a hindfoot portion at an opposite end, and an upwardly arched midfoot portion between said forefoot and hindfoot portions, and wherein said midfoot portion of said foot keel is convexly curved upwardly throughout its longitudinal extent between said forefoot and hindfoot portions.

15. The prosthetic foot according to claim 1, wherein said foot keel has an forefoot portion at one end, a hindfoot portion at an opposite end, and an upwardly arched midfoot portion between said forefoot and hindfoot portions, and wherein said midfoot portion of said foot keel includes a posterior, upwardly facing concavity in which said curved lower end of said calf shank is connected to said foot keel.

16. The prosthetic foot according to claim 1, wherein said foot keel has a forefoot portion at one end, a hindfoot portion at an opposite end, and an upwardly arched midfoot portion between said forefoot and hindfoot portions, and wherein said hindfoot portion includes a heel with a posterior lateral corner that is more posterior and lateral than the medial corner of the heel to promote hindfoot rollover during initial contact phase of gait.

17. The prosthetic foot according to claim 1, wherein said foot keel has a forefoot portion at one end, a hindfoot portion at an opposite end, and an upwardly arched midfoot portion between said forefoot and hindfoot portions, and wherein a plantar surface of the midfoot portion of said foot keel has a longitudinal arch concavity with a medial portion having a greater radius than a lateral portion thereof.

18. The prosthetic foot according to claim 1, wherein said foot keel has an forefoot portion at one end, a hindfoot portion at an opposite end, and an upwardly arched midfoot portion between said forefoot and hindfoot portions, and wherein said midfoot portion and a dorsal portion of said forefoot portion of said foot keel are formed with an upwardly facing concavity which mimics the function of the fifth axis of motion of the human foot, the longitudinal axis of said concavity being oriented at an angle of 20 ° -35 ° to the longitudinal axis of the foot keel with the medial being more anterior than the lateral to encourage fifth axis motion in gait as is the oblique low speed axis of rotation of the second through fifth metatarsals in the human foot.

19. The prosthetic foot according to claim 1, wherein said foot keel has an forefoot portion at one end, a hindfoot portion at an opposite end, and an upwardly arched midfoot portion between said forefoot and hindfoot portions, and wherein a posterior portion of the forefoot portion of said keel includes medial and lateral expansion joint holes extending through the medial and lateral sides of said forefoot portion between dorsal and plantar surfaces thereof, the expansion joints extending forwardly from respective ones of said holes to the anterior edge of the forefoot portion to form medial, medial and lateral expansion struts which create improved biplanar motion capability of the forefoot portion of said foot keel.

20. The prosthetic foot according to claim 19, wherein said expansion joint holes are located along a line in the transverse plane extending at an angle of 25 ° -35 ° to the longitudinal axis of the foot keel with the medial expansion joint hole more anterior than the lateral expansion joint hole.

21. The prosthetic foot according to claim 19, wherein said expansion joint holes as projected on the sagittal plane are inclined at an angle of 45 ° to the transverse plane, the dorsal portions of these holes being more anterior than the plantar portions.

22. The prosthetic foot according to claim 19, wherein the distance from the releasable fastener to the lateral expansion joint hole is shorter than the distance from the releasable fastener to the medial expansion joint hole, such that the lateral portion of the prosthetic foot has a shorter toe lever than the medial portion to enable high and low dynamic response of the midfoot portion.

23. The prosthetic foot according to claim 1, wherein the anterior end of said foot keel is shaped in an upwardly curved arc to simulate the toes of a person who dorsiflexes during the heel-lift toe-off position of late stance phase of gait.

24. The prosthetic foot according to claim 1, wherein said foot keel has an forefoot portion at one end, a hindfoot portion at an opposite end, and an upwardly arched midfoot portion between said forefoot and hindfoot portions, and wherein a posterior portion of the forefoot portion of said keel includes at least one expansion joint hole extending through said forefoot portion between dorsal and plantar surfaces thereof, an expansion joint extending forwardly from said expansion joint hole to a forward edge of the forefoot portion to form a plurality of expansion struts which create improved biplanar motion capability of the forefoot portion of said foot.

25. The prosthetic foot according to claim 1, wherein said foot keel has an forefoot portion at one end, a hindfoot portion at an opposite end, and an upwardly arched midfoot portion between said forefoot and hindfoot portions, and wherein said forefoot, midfoot and hindfoot portions of said keel are formed from a single piece of resilient material.

26. The prosthetic foot according to claim 25, wherein said resilient material is a semi-rigid plastic.

27. The prosthetic foot according to claim 1, wherein said foot keel is formed of a semi-rigid material with a longitudinal arch shaped to create a dynamic response capability of said foot in gait such that a medial aspect of the longitudinal arch has a relatively higher dynamic response capability and a lateral aspect of said longitudinal arch has a relatively lower dynamic response capability.

28. The prosthetic foot according to claim 1, wherein the posterior end of said foot keel is shaped in an upwardly curved arc which reacts with ground reaction forces to absorb shock during compression induced heel strike.

29. The prosthetic foot according to claim 1, wherein said foot keel has an forefoot portion at one end, a hindfoot portion at an opposite end, and an upwardly arched midfoot portion between said forefoot and hindfoot portions, and wherein an anterior portion of the hindfoot portion of said keel includes an expansion joint hole extending through said hindfoot portion between a dorsal and plantar surface thereof, an expansion joint extending posteriorly from said expansion joint hole to a posterior edge of the hindfoot portion to form a plurality of expansion struts which create improved biplanar motion capability of the hindfoot portion of said foot.

30. A prosthetic foot, comprising:

a longitudinally extending foot keel having a forefoot portion at one end and a hindfoot portion at an opposite end, and a relatively longer midfoot portion extending between and upwardly arched from said forefoot and hindfoot portions;

a calf shank including a forward facing convexly curved lower end; and

an adjustable fastening arrangement connecting said curved lower end of said calf shank to said midfoot portion of said keel to form an ankle joint area of said prosthetic foot; and

wherein the adjustable fastening arrangement can adjust the alignment of the calf shank and the foot keel with respect to one another in the longitudinal direction of the foot keel for adjusting the performance of the prosthetic foot.

31. The prosthetic foot according to claim 30, wherein said adjustable fastening arrangement includes at least one releasable fastener and a coupling element between said calf shank and said keel, said coupling element and said at least one adjustable fastener connecting said calf shank to said foot keel.

32. The prosthetic foot according to claim 31, wherein said adjustable fastening arrangement includes longitudinally extending holes in each of said calf shank and said foot keel which receive respective releasable fasteners and permit said calf shank and said keel to be slid relative to one another along said longitudinal direction over a range of adjustment to adjust the performance of the prosthetic foot.

33. The prosthetic foot according to claim 30, wherein said convexly curved lower end of said calf shank extends anteriorly superior therefrom.

34. The prosthetic foot according to claim 1, further comprising an adapter connected to the upper end of the calf shank for connecting the prosthetic foot to a support structure on a human leg stump.

35. The prosthetic foot according to claim 1, wherein the foot keel has an anterior plantar surface weight bearing portion including laterally spaced expansion struts which create the biplanar motion capabilities of the foot keel.

36. The prosthetic foot according to claim 1, wherein the calf shank is formed of a single piece of resilient material.

37. The prosthetic foot according to claim 1, wherein the foot keel has posterior and anterior plantar surface weight bearing portions and a non-weight bearing midportion extends between the weight bearing portions.

38. The prosthetic foot according to claim 37, wherein the anterior plantar surface weight bearing portion is oriented at an angle to the longitudinal axis of the foot keel with its medial side more anterior than its lateral side.

39. The prosthetic foot according to claim 1, wherein the shank extends upwardly in a substantially curvilinear manner above the ankle joint area.

40. The prosthetic foot according to claim 1, wherein the shank has a straight vertical upper end.

41. The prosthetic foot according to claim 1, wherein the foot keel includes an forefoot portion, a midfoot portion and a hindfoot portion.

42. The prosthetic foot according to claim 1, wherein the ankle joint region simulates plantar flexion and dorsiflexion of a human ankle joint.

43. A calf shank for a prosthetic foot, comprising:

an elongated, semi-rigid resilient member having a forward facing convexly curved portion at one end of the member for attachment to a foot keel to form a forward facing convexly curved ankle region of the prosthetic foot, the opposite end of the member having means for attaching the calf shank to a supporting structure on an amputee's leg, and wherein the forward facing convexly curved portion at said one end of the member is provided with an adjustable fastening arrangement for attaching the member to the foot keel during use of the prosthetic foot, the adjustable fastening arrangement permitting a prosthetic foot user to vary the alignment of the calf shank with respect to the foot keel in the longitudinal direction of the foot keel to adjust the performance of the prosthetic foot.

44. The calf shank according to claim 43, wherein the fastening arrangement includes a longitudinally extending hole in the convexly curved portion of the member along which a fastener for connecting the calf shank to a foot keel can be slid.

45. The calf shank according to claim 43, wherein the anterior facing convexly curved portion is parabola-shaped.

46. The calf shank according to claim 43, wherein the calf shank is S-shaped.

47. The calf shank according to claim 43, wherein the calf shank is J-shaped.

48. The calf shank according to claim 43, wherein each of the one end and the opposite end of the calf shank component is convexly rounded in the same direction to a respective free end of the component, and wherein a relatively straight portion of the component connects with the rounded end on a side of the component opposite the side of the free end.

49. A method of adjusting the performance of a prosthetic foot for a specific task, wherein the prosthetic foot includes a longitudinally extending foot keel having an forefoot portion at one end and a hindfoot portion at an opposite end, and a relatively long midfoot portion extending between and upwardly arched from the forefoot and hindfoot portions, and a calf shank including a forwardly facing convexly curved lower end connected at a portion thereof to the foot keel by adjustable fastening structure to form an ankle joint area of the prosthetic foot, the method comprising the steps of: adjusting the alignment of the calf shank and the foot keel with respect to one another in the longitudinal direction of the foot keel and securing the calf shank and the foot keel to one another in the adjusted position with the fastening structure.

50. A calf shank for use with a foot keel in a prosthetic foot, the calf shank comprising:

an elongated resilient member having a lower end for connection to a foot keel in the prosthetic foot, a forwardly facing convexly curved lower portion of said member extending upwardly from the foot keel to form an ankle joint area of the prosthetic foot; and

wherein the members extend upwardly in a substantially curvilinear manner above the ankle joint location to form a lower prosthetic portion of the leg above the ankle joint location which may expand and compress in response to ground reaction forces thereon during walking to store and release energy to improve the dynamic response of the prosthetic foot in gait.

51. The calf shank according to claim 50, further comprising an adapter connected to an upper portion of the member for connection with a support structure on an amputee's leg stump.

52. The calf shank according to claim 50, wherein the member extending upwardly in a substantially curvilinear manner above the ankle joint area is reversely curved so as to merge with a straight vertical upper end of the member.

53. The calf shank according to claim 50, wherein the member above the ankle joint area is also anteriorly facing convexly curved.

54. The calf shank according to claim 53, wherein the convexly curved lower portion of the member has a relatively smaller radius of curvature than the convexly curved member above the ankle joint area.

55. The calf shank according to claim 50, wherein the member is J-shaped, a lower portion of the J-shape forming a forward-facing convexly curved lower portion of the member.

56. The calf shank according to claim 50, wherein the member is parabolic in shape.

57. The claim 50 merges with the straight vertical upper end of the member.

58. The calf shank according to claim 50, further including a fastening arrangement for attaching the lower end of the member to the foot keel.

59. The calf shank according to claim 58, wherein the fastening structure can change the effective length of the calf shank and thereby change the dynamic response capability of the calf shank.

60. The calf shank according to claim 58, wherein the fastening arrangement is adjustable so that alignment of the member and the foot keel with respect to one another in the longitudinal direction of the foot keel can be adjusted.

61. The calf shank according to claim 58, wherein the fastening arrangement includes means for adjusting the inclination of the member in connection with the foot keel in the longitudinal direction of the foot keel.

62. The calf shank according to claim 50, wherein the member is S-shaped with a lower portion of the S-shape forming a forward-facing convexly curved lower portion of the member.

63. The calf shank according to claim 50, wherein each of the upper and lower ends of the member is convexly rounded to a respective free end extending in the same direction along the foot keel, a relatively straight upstanding portion of the member connecting the rounded ends being located on a side of the member opposite the side of the free end.

64. The calf shank according to claim 50, wherein the member is formed from a single piece of resilient material.

65. The calf shank according to claim 50, wherein the member is formed of a material having shape-retaining properties.

66. A prosthesis, comprising:

a foot;

an ankle;

an elongated upstanding shank located above the ankle;

wherein the ankle and shank are integrally formed as a resilient member which is connected at a lower end of the member to the foot so as to securely locate the member and the foot relative to each other in the longitudinal direction of the foot, the resilient member being forward facing convexly curved at least in the ankle region and curving during gait so as to store and release energy to improve the dynamic response of the prosthesis in gait.

67. The prosthesis of claim 66, wherein the shank has a straight vertical upper end.

68. The prosthesis of claim 66, wherein the foot includes a foot keel.

69. The prosthesis of claim 68, wherein the lower end of the resilient member is coupled to the foot keel.

70. A method of improving the dynamic response of a prosthetic foot in gait, comprising:

providing a prosthetic foot comprising: a longitudinally extending foot keel having a forefoot portion, a midfoot portion, and a hindfoot portion; and a resilient, upstanding, elongated, integrally formed shank securely positioned and retained at a lower end on the foot keel and extending anteriorly upwardly from the foot keel with a anteriorly facing convexly curved portion of the shank so as to form an ankle joint area of the prosthetic foot curved to simulate plantar flexion and dorsiflexion of a human ankle joint, the shank having a substantially curvilinear portion above the ankle joint area; and

the prosthetic foot utilizes the curved portion of the resilient elongated shank to store and release energy in response to ground reaction forces thereon during gait to improve the dynamic response of the prosthetic foot.

71. The method of claim 70, wherein each curved portion is a forward-facing convex curve.

72. The method of claim 70, wherein a radius of curvature of the curved upper portion of the shank is relatively larger than a radius of curvature of the curved lower portion of the shank to increase dynamic response capability.