Drawings
FIG. 1 is a schematic representation showing two adjacent and abutting radii of curvature R of the foot keel and calf shank of the prosthetic foot of the invention1And R2Which in gait produces a dynamic response capability and motion output of the foot in the direction of arrow B, which is perpendicular to the tangent line a connecting the two radii.
FIG. 2 is a view similar to FIG. 1, but showing the positioning of the two radii having been changed in a prosthetic foot according to the invention to increase the horizontal component of the dynamic response capability and motion output of the foot in gait while decreasing the vertical component thereof, and thus, perpendicular to tangent line A1Arrow B of1More towards the horizontal than in the situation shown in figure 1.
Figure 3 is a side view of a prosthetic foot according to one exemplary embodiment of the invention having a pylon adapter and pylon connected thereto for securing the prosthetic foot to the lower limb of an amputee.
FIG. 4 is a front view of the prosthetic foot with 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 for sprinting, 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 in the prosthetic foot of FIG. 3 providing high and low dynamic response characteristics and biplanar motion capabilities.
Fig. 9 is a side view of another foot keel of the invention for the prosthetic foot particularly useful for sprinting by an amputee who has had 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 and low dynamic response characteristics and biplanar motion capabilities.
FIG. 12 is a top view of the foot keel of FIG. 11.
Fig. 13 is a side view of the foot keel of the invention wherein the thickness of the keel tapers, e.g., tapers, 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 toward both the forefoot and hindfoot of the keel.
Fig. 15 is a side view from slightly above to the front of a parabolic shaped calf shank of the prosthetic foot of the invention, the calf shank thickness tapering toward its upper end.
Fig. 16 is a side view similar to fig. 15 but showing another calf shank which tapers from the middle toward both its 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 the middle toward its upper and lower ends.
FIG. 18 is a side view of another example of a C-shaped calf shank for the prosthetic foot, the thickness of the calf shank decreasing from its middle portion to its upper end.
Fig. 19 is a side view of an S-shaped calf shank for the prosthetic foot, the thickness of which tapers from the middle to both ends thereof.
Fig. 20 is another example of an S-shaped calf shank which is tapered 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 view similar to fig. 21 but showing a J-shaped calf shank which is progressively reduced in thickness only towards its upper end.
FIG. 23 is a side view, from slightly above, of an aluminum or plastic coupling element for use in the adjustable fastening arrangement of the invention for connecting the calf shank to the foot keel as shown in FIG. 3.
Fig. 24 is a side and slightly front view of a pylon adapter used on the prosthetic foot of Figs. 3-5, which adapter can also be used to attach the foot to a pylon to be attached to an amputee's leg.
Fig. 25 is a side view of another prosthetic foot of the invention similar to that shown in fig. 3, but showing the coupling element with two longitudinally spaced releasable fasteners connecting the coupling element to the calf shank and foot keel, respectively.
Fig. 26 is an enlarged side view of the connector shown in fig. 25.
Fig. 27 is an enlarged side view of the calf shank of the prosthetic foot of fig. 25.
Fig. 28 is a posterior view of a prosthetic foot according to another embodiment of the invention, wherein the posterior end of the arch shaped midportion of the foot keel is formed with a spring which is compressed to absorb vertical loads and expanded to restore vertical loads during various applications of the prosthetic foot.
Fig. 29 is a side view of the prosthetic foot of fig. 28 showing the calf shank attached to the posterior surface of the upwardly arched midportion of the foot keel.
Fig. 30 is a front view of the prosthetic foot of Figs. 28 and 29.
Fig. 31 is a bottom view of the foot keel of the prosthetic foot of Figs. 28-30.
Fig. 32 is a top view of the prosthetic foot of Figs. 28-30.
Fig. 33 is a side view of another form of the prosthetic foot of the invention similar to that shown in Figs. 28-32 except that the foot keel of the prosthetic foot has a fitting mounted to the dorsal surface of the posterior end of the arch shaped midportion for connecting the foot keel of the prosthetic foot directly to a support structure attached to a leg stump of a user.
Fig. 34 is a top view of the prosthetic foot of fig. 33.
Best Mode for Carrying Out The Invention
Turning now to the drawings, it can be seen from the exemplary embodiment in fig. 3 to 5 that the prosthetic foot 1 includes a longitudinally extending foot keel 2, the foot keel 2 having a forefoot portion 3 at one end, a hindfoot portion 4 at the other end, and an upwardly arched midfoot portion 5 extending between the forefoot and hindfoot portions. In this exemplary embodiment, the midfoot portion 5 is upwardly convexly curved over its entire longitudinal extent between the forefoot and hindfoot portions.
The upstanding calf shank 6 of the foot 1 is connected at a portion of its downwardly convexly curved lower end 7 to the proximate posterior surface of the keel midfoot portion 5 by way of a releasable fastener 8 and coupling element 11. In the exemplary embodiment, the fastener 8 is a single bolt with a nut and washer, however, it could also be a releasable clamp or other fastener for securely positioning and retaining the calf shank to the foot keel as the fastener is tightened.
Referring to figure 8, a longitudinally extending opening 9 is formed in the proximate rear surface of the keel midfoot portion 5. A longitudinally extending opening 10, such as that shown in fig. 15, is also formed in the curved lower end 7 of the calf shank 6. The releasable fastener 8 extends through the openings 9 and 10 so that the alignment of the calf shank and the foot keel with respect to one another can be adjusted in the longitudinal direction A-A in FIG. 5 when the fastener 8 is loosened or released to tune the performance of the prosthetic foot for a particular task. Thus, the fastener 8, the coupling element 11, and the longitudinally extending openings 9 and 10 constitute an adjustable fastening arrangement for attaching the calf shank to the foot keel to form the 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 R are closely adjacent to each other1And R2Representing adjacent and facing arcuate or convex curvatures of the foot keel midportion 5 and the calf shank 6. When two such radii are considered to be immediately adjacent to each other, a tangent line A shown in FIG. 1 and a tangent line A shown in FIG. 2 drawn between the two radii1There is motion capability in the vertical direction. The correlation between these two radii determines the direction of motion output. As a result, the application of the dynamic response force of the foot 1 depends on this relationship. The larger the radius of the concave surface, the stronger the dynamic response capability. However, the smaller the radius, the faster the response.
The alignment capabilities of the calf shank and foot keel in the prosthetic foot of the invention allow for radial shifting and thus can affect the horizontal or vertical linear velocity of the foot during athletic activities. For example, to enhance the horizontal linear velocity capability of the prosthetic foot 1, positioning alterations can be made to affect the relationship of the calf shank radius and the foot keel radius. That is, to enhance the horizontal linear velocity characteristic, the bottom radius R of the foot keel is as shown in comparing FIG. 2 with FIG. 12Closer to the distal end than its starting position. This changes the dynamic response characteristics and motion output of the foot 1 to be closer to horizontal, so that greater horizontal linear velocities can be achieved with the same applied force.
When the amputee's needs involve horizontal and vertical linear velocities, he/she can find settings for various exercises that meet his/her needs through practice. For example, high jump athletes and basketball athletes require more vertical lift than sprinters. The coupling element 11 is a plastic or aluminum retaining coupling element sandwiched between the attached foot keel 2 and calf shank 6 (see figures 3, 4 and 23). The releasable fastener 8 extends through an aperture 12 in the connector. The coupling element extends along the adjoining portion of the calf shank and the proximate posterior surface of the keel midfoot portion 5.
The curved lower end 7 of the calf shank 6 is parabolic with the smallest radius of curvature of the parabola lying at the lower end and extending initially anteriorly and then upwardly in the parabola shape. As shown in FIG. 3, the curvature of the calf shank forms a posterior concavity. The parabolic shape is advantageous because it has enhanced dynamic response characteristics, resulting in an increased horizontal linear velocity associated with its proximal end of relatively larger radius, while having a smaller radius of curvature at its lower end to achieve faster response characteristics. The larger radius of curvature at the upper end of the parabolic shape allows the tangent line a described with reference to fig. 1 and 2 to remain more vertically oriented during positioning changes, which may result in an improved horizontal linear velocity.
A pylon adapter 13 is attached to the upper end of the calf shank 6 by fasteners 14. Adapter 13 is in turn 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 leg stump.
In this exemplary embodiment, the forefoot, midfoot and hindfoot portions of the foot keel 2 are formed of a single piece of resilient material. For example, a solid piece of material that is plastic in nature may be employed that has shape-retaining properties when deflected by ground reaction forces. In particular, high strength graphite laminated with a thermosetting epoxy or extruded plastic known under the trade name Delran or degassed polyurethane copolymers may be used to form the foot keel as well as the calf shank. The functional properties associated with these materials provide high strength with relatively low weight and minimal creep. The thermosetting epoxy is laminated under vacuum using prosthesis industry standards. The polyurethane copolymer can be cast into a female mold and the extruded plastic machined. The use of each material has its advantages and disadvantages.
The physical properties of an elastic material, for example relating to stiffness, flexibility and strength, are all determined by the thickness of the material. Thinner materials deflect more easily than thicker materials of the same density. The materials used, as well as the physical properties, are related to the stiffness and flexibility characteristics of the prosthetic foot keel and calf shank. In the exemplary embodiment shown in figures 3 through 5, the thickness of the foot keel and calf shank are uniform or symmetrical, however, the thickness can vary over the length of these components in a manner to be discussed below, e.g., the hindfoot and forefoot regions can be made thinner and more sensitive to deflection in the midfoot region.
To help provide the prosthetic foot 1 with high and low dynamic response capabilities, the midfoot portion 5 is formed in a longitudinal arch such that the medial side of the longitudinal arch has a relatively higher dynamic response capability than the lateral side of the longitudinal arch. To this end, in the exemplary embodiment, the medial side of the concave surface of the longitudinal arch is larger in radius than the lateral side thereof. The rear end 17 of the hindfoot portion 4 is shaped in an upwardly curved arch that reacts to ground reaction forces during heel strike by compressing the cushioning. The heel formed by the hindfoot portion 4 is formed with a posterior lateral corner 18, which corner 18 is more posterior and lateral than the medial corner 19 to promote eversion of the hindfoot in the initial contact phase of gait. The anterior end 20 of the forefoot portion 3 is shaped as an upwardly curved arch to simulate the human toes being dorsiflexed in the heel-raised toe-off position in the last stance phase of gait. Rubber or foam pads 53 and 54 are provided as cushioning pads on the lower portions of the forefoot and hindfoot.
Extending through the medial expansion joint hole 21 and the lateral expansion joint hole 22 of the forefoot portion 3 between the dorsal and plantar surfaces of the forefoot portion 3 creates an enhanced biplanar motion capability of the prosthetic foot. The expansion joints 23 and 24 extend anteriorly from the respective holes to the anterior edge of the forefoot portion to form medial, medial and lateral expansion struts 25, 26 and 27 which provide enhanced 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 FIG. 5 in a transverse plane extending at an angle α of 350 relative to the longitudinal axis A-A of the foot keel with the medial expansion joint hole 21 more anterior than the lateral expansion joint hole 22. The expansion joint holes 21 and 22 projected on the sagittal plane are inclined at an angle of 450 to the transverse plane with the dorsal aspect of the holes more anterior than the plantar aspect. With this arrangement, 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 (toe lever) than the medial to achieve the midfoot high and low dynamic response.
The anterior portion of the hindfoot portion 4 of the foot keel 2 also includes an expansion joint hole 28 extending through the hindfoot portion 4 between the dorsal and plantar surfaces of the hindfoot portion 4. An expansion joint 29 extends rearwardly from the aperture 28 to the rear edge of the hindfoot portion to form expansion struts 30 and 31. This provides enhanced biplanar motion capability to the hindfoot portion of the prosthetic foot.
As shown in FIG. 3, the dorsal aspect of the midfoot portion 5 and the forefoot portion 3 of the foot keel 2 form an upwardly facing concavity, 32, which enables it to functionally mimic the fifth ray axis of motion of a human foot. That is, the concavity 32 has a longitudinal axis C-C which is positioned at an angle 13 of 20 to 35 relative to the longitudinal axis A-A of the foot keel with the medial being more anterior than the lateral to encourage fifth ray motion in gait as in the oblique low gear axis of rotation of the second to fifth metatarsals in the human foot.
The importance of biplanar motion capability is understood when amputees walk on uneven terrain or when athletes stop sharply inward or outward on the feet. The direction of the ground force vector changes from a sagittal orientation to having a frontal plane component. The ground will act inwardly in a direction opposite to the foot's outward action. As a result, the calf shank leans medially and gravity is applied to the medial structure of the foot keel. In response to these pressures, 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 evert. This motion is used to place the plantar surface of the sole of the foot on the ground (plantar-contacting).
Referring to fig. 6 and 7, another foot keel 33 of the invention, which is particularly useful for sprinting, can be used in the prosthetic foot of the invention. In sprinting, the center of gravity of the body becomes located substantially only along the sagittal plane. The prosthetic foot need not have a low dynamic response characteristic. As a result, the longitudinal axis of the forefoot, midfoot concavity does not need to be oriented in a 35 external rotational orientation as in foot keel 2. Instead, as shown in FIGS. 6 and 7, the orientation of the longitudinal axis D-D of the concave surface should become parallel to the frontal plane. This allows the sprint foot to react only in the sagittal direction. In addition, the orientation of the expansion joint holes 34 and 35 in the forefoot and midfoot portions is parallel to the frontal plane along line E-E, i.e., the lateral hole 35 is moved anteriorly into alignment with the medial hole 34 and parallel to the frontal plane. The anterior extremity 36 of the foot keel 33 is also made parallel to the frontal plane. The rear distal heel region 37 of the foot keel is also parallel to the frontal plane. These modifications can adversely affect the multi-purpose performance of the prosthetic foot. However, its performance characteristics are task specific. Another variation of the sprint foot keel 33 is in the toe area of the forefoot portion of the prosthetic foot where 15 of dorsiflexion in the foot keel 2 is increased to 25-40 of dorsiflexion in the foot keel 33.
Figures 9 and 10 show another foot keel 38 of the invention which can be used in a prosthetic foot particularly suited for sprinting by an amputee who has undergone a Symes amputation. To this end, the midfoot portion of the foot keel 38 includes a posterior, upwardly facing concavity 39 in which the curved lower end of the calf shank is attached to the foot keel by way of the releasable fastener. The foot keel is available to all lower extremity amputees. The foot keel 38 is adapted for use with the longer residual limb associated with the Symes level amputee. Its performance characteristics are much faster in terms of dynamic response performance. Its application is not specific to this degree of amputation. It can be applied in all cases of amputation through the tibia and through the femur. In the exemplary embodiment of Figs. 11 and 12, the foot keel 40 also has a concavity 41 for a Symes amputee, the foot keel providing the prosthetic foot with high and low dynamic response characteristics, as well as biplanar motion capabilities, similar to those of the exemplary embodiment of Figs. 3-5 and 8.
The functional characteristics of several foot keels for the prosthetic foot 1 are related to the shape and design characteristics, which relate to the concavity, convexity, radius size, extension, compression, and physical properties of the material, all of which relate to reacting to ground forces in walking, running, and jumping activities.
The foot keel 42 in fig. 13 is similar to that of the exemplary embodiment of Figs. 3-5 and 8, except that the thickness of the foot keel tapers from the midfoot portion toward 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. The calf shank 44 of FIG. 14 and the calf shank 45 of FIG. 16 show similar variations in thickness which can be used in the prosthetic foot 1. Each design of the foot keel and calf shank produce different functional outcomes because these functional outcomes relate to horizontal and vertical linear velocities that are specific to improving performance in different athletic tasks. The ability to adjust the configuration of the calf shank and the arrangement between the foot keel and the calf shank creates a prosthetic foot calf shank relationship that enables the amputee and/or prosthetist the ability to tune the prosthetic foot to maximum performance in a selected one of a variety of athletic and leisure activities.
Other calf shanks for the prosthetic foot 1 are illustrated in figures 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 can also include a straight vertical end with a prismatic connecting plate attached to the proximal-most end. A male pyramid (male pyramid) may be passed through the vertical end of the calf shank to form a bolted joint. Plastic or aluminum fillers for receiving the adjacent male pyramid and the distal foot keel may also be provided in the extended openings at the proximal and distal ends of the calf shank. The prosthetic foot of the invention is a modular system preferably constructed from standardized units or dimensions to meet flexibility and versatility in use.
All track-related racing movements are performed in a counter-clockwise direction. Another optional feature of the invention takes into account forces acting on the foot following such a curved path. When the object moves along a curved path, centripetal acceleration acts towards the center of rotation. Newton's third law is suitable for energy action. There are equal and opposite reaction forces. Thus, for each "centripetal" force, there is one "centrifugal" force. The centripetal force acts toward the center of rotation, and the centrifugal force, i.e., the reaction force, acts away from the center of rotation. As the athlete runs around a curve on a track, centripetal force may pull the runner toward the center of the curve, while centrifugal force may pull the runner away from the center of the curve. To counteract the centrifugal force that attempts to lean the runner outward, the runner leans inward. If the direction of rotation of the runner on the track is always counter-clockwise, the left side is the inside of the track. As a result, according to a feature of the invention, the left side of the left and right prosthetic foot calf shanks can be made thicker than the right side to enhance the curvilinear performance of the amputee runner.
In several embodiments, the foot keels 2, 33, 38, 42 and 43 are each 29 centimeters long, proportional to the length of the shoe 1, and shown to scale in FIGS. 3, 4 and 5 and several views of the various calf shanks and foot keels. However, those of ordinary skill in the art will readily appreciate that the specific dimensions of the prosthetic foot may vary depending on the size, weight and other characteristics of the amputee to be fitted with the foot.
The operation of the prosthetic foot 1 during walking and running stance phase gait cycles will now be described. Newton's three laws of motion involving inertia, acceleration, and forces and reactions are the basis of the kinematics of the foot 2. It is known from newton's third law, the law of force and reaction, that the force of the ground on the foot is equal and opposite in magnitude to the force of the foot on the ground. They are referred to as ground reaction forces. Much scientific research has been conducted on human gait, running and jumping activities. Research on force plates has shown that newton's third law is followed in gait. The direction of the ground to the foot's force is known from these studies.
The stance phase of the walking/running activity can be further broken down into deceleration and acceleration phases. When the prosthetic foot contacts the ground, the foot applies a force forward on the ground, which reacts in an equal and opposite manner, that is, the ground applies a force backward on the prosthetic foot. This force moves the prosthetic foot. The stance phase analysis of walking and running activities begins with the contact point being the posterior lateral corner 18 in fig. 3 and 18, which is offset more posteriorly and laterally than the medial side of the foot. Upon initial contact, this offset causes the foot to evert and the calf shank to plantar flex. The calf shank is always looking for a position through which body weight can be transferred through its tibia, for example, it tends to place its longer vertical member in a position to resist ground forces. This is why it moves the rearward plantar flexion to resist the ground reaction forces acting rearwardly on the foot. The ground forces cause the calf shank to compress and its proximal end to move posteriorly. The calf shank smaller radius compresses to simulate human ankle joint plantar flexion and the forefoot is placed on the ground by compression. At the same time, the top posterior side of the foot keel 2 is pressed upward by compression. These two compressive forces act as shock absorbers. This shock absorption is further enhanced by the offset of the lateral rear heel 18 which causes eversion of the foot and also acts as a shock absorber once the calf shank has stopped moving into plantar flexion and the ground has exerted posteriorly on the foot.
The compressed pieces of the foot keel and calf shank then begin to unload, i.e., they try to return to their original shapes 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 initial position, the ground reaction force changes from acting posteriorly to acting vertically upward on the foot. Since the prosthetic foot has posterior and anterior plantar surface weight bearing areas, and they are connected by a non-weight bearing long arch shaped midportion, vertical forces from the prosthesis cause the long arch shaped midportion to bear load by expansion. The rear and front load bearing surfaces are spaced apart. These vertically directed forces are stored in the long arch shaped midportion of the foot as the ground forces change in nature from vertical to anteriorly directed. The calf shank can be extended to simulate dorsiflexion of the ankle. This causes the prosthetic foot to pivot away from the anterior plantar weight bearing surface. The long arch of the hindfoot changes from a compressed state to an extended state. This releases the stored vertical compressive force energy to enhance stretch performance.
The long arch of the foot keel and calf shank resist expansion of their respective structures. As a result, the calf shank anterior motion is prevented and the foot begins to pivot off the anterior plantar weight-bearing surface. In the foot keel of the exemplary embodiment of figures 3-5 and 8, figures 11 and 12, figure 13 and figure 14, extension of the midfoot portion of the foot keel has high and low response capabilities. Since the midfoot forefoot transition area of these foot keels is offset 25 to 35 outwardly from the longitudinal axis of the foot, the medial long arch is longer than the lateral long arch. This is important because in a normal foot, the medial side of the foot is used during acceleration or deceleration.
The longer medial arch of the prosthetic foot has greater dynamic response characteristics than the lateral. The lateral shorter toe lever is used in slow walking or running. The center of gravity of the body moves in space in a sinusoidal curve. It moves medially, laterally, proximally and distally. When walking or running at a slow speed, the center of gravity of the body moves more medial and lateral than when walking or running at a fast speed. In addition, momentum or inertia is less and the ability to overcome higher dynamic response capabilities is less. The prosthetic foot of the invention is adapted to accommodate these principles in applied mechanics.
As the ground forces act anteriorly on the prosthetic foot and the prosthetic foot is acted upon posteriorly on the ground, the anterior portion of the long arch of the midfoot portion is contoured to apply these posteriorly directed forces perpendicular to its plantar surface as the heel begins to rise. This is the most efficient and effective way to apply these forces. The same holds true for the posterior hindfoot portion of the prosthetic foot. It is also shaped so that the posterior ground forces at initial contact are opposed by the plantar surface of the foot keel perpendicular to the direction of its application of force.
The toe region of the forefoot portion undergoes dorsiflexion of 15-35 during the subsequent phases of heel-lift, toe-off walking and running activities. This upwardly extending arch allows forward ground forces to compress this area of the foot. This compression ratio provides less resistance to extension and a smooth transition during the swing phase of gait and running of the prosthetic foot. During the subsequent stance phase of gait, the expanded calf shank and the expanded midfoot long arch release their stored energy to promote propulsion of the amputee's body center of gravity.
In several of the aforementioned embodiments, the hindfoot and hindfoot regions of the foot keel incorporate expansion joint holes and expansion joint struts. When walking on uneven terrain, the orientation of the expansion joint holes act as mitered hinges, enhancing biplanar motion performance to improve the overall contact characteristics of the plantar surface of the foot.
The Symes foot keels in FIGS. 9-12 are significantly different in dynamic response performance because these properties are related to walking, running and jumping activities. These foot keels differ in four notable features. These include the presence of a concavity in the proximate posterior of the midfoot portion that can accommodate the Symes distal residual limb shape better than a flat surface. The alignment concavity requires the corresponding anterior and posterior radii of the medial portion of the arch foot keel to be more mobile and smaller in size. As a result, all of the midfoot long arch radii and the hindfoot radii are denser and smaller. This can significantly affect the dynamic response characteristics. Smaller radii result in a smaller dynamic response. However, the prosthetic foot responds more quickly to all of the above walking, running and jumping ground forces. The result is a faster foot with less dynamic response.
Enhanced task-specific athletic performance can be achieved with the prosthetic foot of the invention through alignment changes that affect the vertical and horizontal components of each task. The human foot is a multifunctional unit that can walk, run and jump. On the other hand, the human tibiofibula calf shank structure is not a multifunctional unit. It is a simple lever that can exert its force parallel to its longer proximal-distal orientation during walking, running and jumping activities. It is an incompressible structure and cannot store energy. On the other hand, the prosthetic foot of the invention has dynamic response capabilities because these dynamic response capabilities are associated with the horizontal and vertical linear velocity components of the athlete's walking, running, and jumping activities, and are superior to the human tibia and fibula. As a result, amputee athletic performance may be enhanced. To this end, in accordance with the present 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 shown in fig. 1 and 2. The calf shank is then secured to the foot keel in the adjusted position with the fastener 8. During adjustment, the bolt of the fastener 8 can slide relative to one or both of the opposed and longer longitudinally extending openings 9 and 10 in the foot keel and calf shank, respectively.
An alignment change that enhances the performance characteristics of a runner who makes initial contact with the ground with the foot flat, as in a sprint, is one in which the foot keel is slid anteriorly relative to the calf shank and the foot sole flexes on the calf shank. This new relationship increases the horizontal component of running. In other words, since the calf shank underside flexes to the foot and contacts the ground in a position sufficient for ball-on-foot contact as opposed to initial heel contact, the ground will act directly posteriorly on the foot which will act anteriorly on the ground. This causes the calf shank to move rapidly anteriorly (by extension) and inferiorly. Dynamic response forces are created by expansion that will resist the calf shank's initial direction of motion. As a result, the foot pivots on the metatarsal plantar surface weight bearing area. This can result in stretching of the midfoot region of the keel which is more impeded than compression. The net effect of the calf shank expansion and the midfoot expansion is that further anterior motion of the calf shank is resisted which allows the knee and hip extensions in the user's body to move the body's center of gravity forward and proximally in a more efficient manner (i.e., increased horizontal velocity). In this case, the center of gravity is more forward than upward than for a heel toe runner whose calf shank's forward motion is less impeded by the calf shank and begins to be dorsiflexed (upright) more than a foot flat runner.
To functionally analyze the sprint foot, a change in the alignment of the calf shank and foot keel is made. A foot keel having all concavities with a longitudinal axis orientation parallel to the frontal plane can be utilized. The calf shank is plantar flexed and slid posteriorly on the foot keel. This allows the distal end circle to be further reduced as compared to a flat foot runner with a multi-purpose foot keel like that shown, for example, in figures 3-5 and 8. As a result, further enhanced horizontal motion is achieved and dynamic response is incorporated into this enhanced horizontal capability.
Sprinters have an increased range of motion, effort and momentum (inertia), where momentum is the dominant force. Since the deceleration phase in their stance phase is shorter than its acceleration phase, an increased horizontal linear velocity can be achieved. This means that in initial contact, when the toes make contact with the ground, the ground will act posteriorly on the foot, which will act anteriorly on the ground. The calf shank, with increased force and momentum, is forced into still greater flexion and downward motion than the initial contact of the foot flat runner. As a result of these forces, the long arch concavity of the foot is loaded by extension and the calf shank is loaded by extension. These stretching forces are resisted to a greater extent than all other aforementioned forces associated with running. As a result, the dynamic response capability of the foot is proportional to the force applied. The human tibiofibular calf-tibial response is only related to energy force potential, it is a straight structure and does not store energy. In sprinting, these extension forces are greater in the prosthetic foot of the invention than all other forces described above in connection with walking and running. As a result, the dynamic response capabilities of the foot are proportional to the applied force and enhanced amputee athletic performance is possible as compared to human 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 upper end structure of the calf shank for attachment to the lower end of a pylon. In this exemplary 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 the calf shank by respective releasable fasteners 57 and 58 with these fasteners 57 and 58 being spaced apart 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 itself can be increased. As in the other exemplary embodiments, can cooperate with the longitudinally extending openings in the calf shank and foot keel for positioning changes.
The upper end of the calf shank 55 defines an extended opening 59 for receiving pylon 15. Once received in the opening, the pylon can be securely clamped to the calf shank by tightening bolts 60 and 61 to draw the free edges 62 and 63 of the calf shank together along the opening. The pylon connection can be easily adjusted by loosening the bolts, sliding the pylon into a desired position relative to the calf shank, and retightening the pylon into the adjusted position by tightening the bolts.
A prosthetic foot 64 according to another embodiment of the invention is shown in fig. 28-32. The prosthetic foot 64 includes a resilient, longitudinally extending foot keel 65 having posterior 66 and anterior 67 plantar surface weight bearing areas, and a non-weight bearing arch shaped midportion 68 extending between the weight bearing areas. To enhance the ability of the high performance prosthetic foot to absorb and recover vertical loads or vertical impact forces, the intermediate portion can be formed with a spring 69 that can be compressed to absorb vertical loads and expanded to recover vertical loads during use of the prosthetic foot. This elastic loading of the spring 69 is an additional part of the elastic loading of the arched length of the intermediate part, which is produced by stretching as described in the previous embodiments. When the vertically directed force on the prosthetic foot is reduced, the energy stored by the arch length of the medial portion and the compression spring 69 of the medial portion is released.
These features enhance the ability of the prosthetic foot to remain fully functional without damage under vertical forces during various activities, wherein the vertical forces that can be applied range from a minimum vertical force (three times body weight) to a maximum vertical force (13 times body weight). In this embodiment, the rear end of the arched middle portion is rolled downward and forward to form a spring 69. The posterior plantar surface weight bearing area or hindfoot 66 of the foot keel may be attached to the arch shaped midportion 68 by means of the spring, for example, using two threaded fasteners 70, 70 as shown in FIG. 31.
Foot keel 65 has a system of combined radii that begins to absorb vertical forces by compressing when heel-toe contact is made. The upwardly concave curved hindfoot or heel lever forms a hindfoot plantar surface weight bearing area 66 which begins to compress when the heel contacts, e.g., its radius of curvature will become shorter, 66. The midfoot 68 initially expands but it is immediately arrested because the radii of the resilient foot keel provide greater resistance to expansion than compression. As the foot moves to midstance, the vertical load increases, the midfoot long arch length expands, while the spring 69 at the rear end of the midfoot is compressed for storing energy. As the foot moves into the heel-off phase of gait and the vertical load decreases, the foot keel spring 69 and arch length restore the energy stored therein to enhance the dynamic response of the foot.
A patient wearing the prosthetic foot 64, who can perform activities of various levels, from as simple as walking to as complex as basketball games, does not need to sacrifice any of the functions of the prosthetic foot and does not need to make manual changes. The anterior portion of the posterior weight bearing area 66 includes an expansion joint hole 71 which extends through the foot keel between the dorsal and plantar surfaces thereof. The expansion joint 72 extends posteriorly from the hole 71 to the posterior edge of the foot keel to form multiple expansion struts which provide enhanced biplanar motion capability to the posterior weight bearing area of the prosthetic foot in gait. The hindfoot 66 may also have a posterior lateral corner shaped as shown in fig. 5, 17 and 18. The forefoot 67 and midfoot 65 portions of the foot keel may also have offset plantar weight bearing surfaces as indicated by the diagonal lines in FIG. 8. The forefoot 67 may also include a plurality of extension supports as shown in fig. 5, 23 and 24.
The prosthetic foot 64 further includes a resilient, upstanding calf shank 73 having a downward and anteriorly convexly curved lower end connected to the foot keel 65 to form an ankle joint area 74 of the prosthetic foot. The calf shank extends upwardly to form a lower prosthetic portion of the leg above the ankle joint area for attachment to a support structure on the leg stump of a user. An adapter, not shown, can be provided for this purpose at the upper end of the calf shank. The calf shank above the ankle joint area is also anteriorly convexly curved. The upper end of the calf shank can also have a straight vertical end with a prismatic link plate or other adapter connected to the proximal-most end as described above for the other calf shanks used in the prosthetic foot of the invention.
The fastening arrangement 75 for attaching the calf shank to the foot keel includes a footplate 76 having releasable fasteners 77, 78 at opposite ends for loosening and tightening the footplate. Loosening the compression plate allows the alignment of the calf shank and the foot keel with respect to one another to be adjusted in the longitudinal direction of the foot keel, while adjusting the inclination of the calf shank where it connects to the foot keel in the longitudinal direction of the foot keel. As described above, this allows the direction of the dynamic response of the prosthetic foot to be changed. As in the previous embodiment, the upper portion of the calf shank 73 forms the lower prosthetic part of the leg. The upper portion may also extend upwardly in a generally curvilinear manner to expand and compress in response to ground reaction forces acting thereon in gait for storing and releasing energy to enhance the dynamic response of the prosthetic foot in gait. The prosthetic foot 64 can have rubber or foam pads, not shown, as cushioning pads on the lower forefoot and hindfoot portions of the foot keel. Additionally, as in the other embodiments, a cosmetic covering may be provided on the prosthetic foot, as will be readily understood by those skilled in the art.
As shown in FIG. 29, a wedge 79, formed for example of plastic or rubber, is adhesively bonded to the foot keel at the anterior juncture of the foot keel and the lower end of the calf shank. The wedge acts as a stop to limit dorsiflexion of the upwardly extending calf shank in gait. The size of the wedge can be selected to be wider or narrower in a plane containing the longitudinal axis of the foot to allow adjustment of the amount of dorsiflexion desired. Of course, the flexibility of the calf shank can be selected first for optimal dynamic performance of the calf shank and foot.
The embodiment of the invention illustrated in figures 33 and 34 is a prosthetic foot 75 similar to the prosthetic foot illustrated in figures 28-32, except that the prosthetic foot is provided with an attachment fitting 76 mounted to the dorsal surface of the posterior end of an arch shaped midportion 77 for attaching the foot keel of the foot directly to a support structure attached to the leg stump of a user. In the exemplary embodiment, joint 76 is in the form of an inverted prismatic connection joint connected to a tie plate 78, wherein tie plate 78 is connected to the upper surface of intermediate portion 77 near its rear end. The prismatic joint is received by a complementary shaped socket joint on the depending prosthetic socket to connect the prosthetic foot to the prosthetic socket. The prosthetic foot 64 and calf shank can be made of various resilient materials. These elastic materials may include, but are not limited to, plastics, polymer impregnated and encapsulated laminates (carbon fibers, fiberglass, Kevlar impregnated with thermosetting epoxy), and alloys such as spring steel, aluminum, titanium, or other soft metals such as Flexon (trade name for soft titanium).
This concludes the description of the exemplary embodiments. Although the present invention has been described with reference to a number of 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 combination arrangement within the scope of the foregoing disclosure, the drawings and the appended claims without departing from the spirit of the invention. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.