Abstract
A prosthetic joint and a method of controlling dorsiflexion and plantarflexion of the hydraulic prosthetic ankle joint. The method includes generating ground reaction forces with a hydraulic prosthetic ankle, wherein the prosthetic hydraulic ankle comprises a first chamber and a second chamber, and the ankle is connected to a prosthetic foot; rotating the prosthetic foot in response to the ground reaction force; transferring fluid between the forward and rear chambers in response to rotation of the foot; providing a feature to occlude or partially occlude the fluid transfer between chambers; providing a non-electronic mechanism for controlling the flow responsive to both a position of the joint and a rate of change of position of the joint, and wherein the mechanism is arranged such that a dwell at a particular joint location or locations will occlude the flow path.
Claims
1. A prosthetic joint, comprising: a first and second connector and a pivot device that allows the first and second connector to rotate with respect to each other; a first chamber and a second chamber, wherein the chambers are connected via one or more fluid flow paths; an occlusion configured to restrict fluid flow between the chambers, and a non-electronic mechanism for controlling the flow responsive to a position of the joint and/or a rate of change of position of the joint.
2. The prosthetic joint of claim 1, wherein the mechanism is arranged such that a dwell at a particular joint location or locations will occlude the flow path.
3. The prosthetic joint of claim 1, wherein the occlusion is connected to a damping element that opposes movement of the occlusion when the occlusion moves to restrict fluid flow between chambers.
4. The prosthetic joint of claim 1, wherein the joint further comprises a cam driving a follower; the follower position drives closure of the occlusion through a compliant element.
5. The prosthetic joint of claim 4, wherein the cam shape provides simple harmonic motion.
6. The prosthetic joint of claim 4, wherein the cam and occlusion mechanism are configured to occlude the passage between the first and second chambers when the joint is stopped, or nearly stopped, at a particular angular location for a period of time defined by the mechanism dynamics.
7. The prosthetic joint of claim 1, wherein the first and second chambers are located anterior and posterior of a pivot.
8. The prosthetic joint of claim 1, wherein the joint includes a magnetic element; wherein the magnetic element drives the closure of the occlusion against an opposing damping element.
9. The prosthetic joint of claim 8, where a magnetic force at a predetermined joint location fully closes the occlusion at or before the mechanism reaches a steady state.
10. The prosthetic joint of claim 1, wherein the at least one fluid flow path comprises a bi-directional flow path connecting the first and second chambers.
11. The prosthetic joint of claim 1, wherein the at least one fluid flow path comprises a uni-directional flow path connecting the first and second chambers.
12. The prosthetic joint of claim 1, wherein the joint comprises at least one piston that is at least partially placed in the first chamber and/or in the second chamber, wherein the at least one piston is arranged to be moved by moving the first connector relative to the second connector in such a way, that fluid is moved from one chamber into the other chamber.
13. The prosthetic joint of claim 12, wherein the joint comprises precisely one piston that is placed partially in the first chamber and partially in the second chamber.
14. The prosthetic joint of claim 3, wherein the damping element is a hydraulic or pneumatic damping element.
15. The prosthetic joint of claim 14, wherein the damping element comprises at least one damping chamber and at least one damping piston, which is actuated in a predetermined range of the position of the first connector relative to the second connector to prevent closing of the fluid flow path.
16. A prosthetic system comprising the prosthetic joint of claim 1, comprising: a prosthetic foot connected to the joint at one of the connectors, and the second connector is connected to a prosthetic device.
17. A method of controlling rotation of a prosthetic joint comprising: applying an external force that causes rotation of a joint wherein the joint comprises a first and second chamber; transferring fluid between the first and second chambers in response to rotation of the joint; providing a feature to occlude or partially occlude the fluid transfer between chambers; providing a non-electronic mechanism for controlling the flow responsive to a position of the joint and/or a rate of change of position of the joint.
18. A method of controlling dorsiflexion and plantarflexion of a hydraulic prosthetic ankle joint, comprising: generating ground reaction forces with a hydraulic prosthetic ankle, wherein the prosthetic hydraulic ankle comprises a first chamber and a second chamber, and the ankle is connected to a prosthetic foot; rotating the prosthetic foot in response to the ground reaction force; transferring fluid between the first and second chambers in response to rotation of the foot; providing a feature to occlude or partially occlude the fluid transfer between chambers; providing a non-electronic mechanism for controlling the flow responsive to a position of the joint and/or a rate of change of position of the joint.
19. The method of claim 17, wherein the mechanism is arranged such that a dwell at a particular joint location or locations will occlude the flow path.
20. The method of claim 17, wherein the first and second chambers are located anterior and posterior of a joint.
21.-29. (canceled)
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0045] The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:
[0046] FIG. 1 is a diagrammatical illustration representing one embodiment of an application for the joint described herein;
[0047] FIG. 2 is a diagrammatical illustration of a prosthesis representing one embodiment of an application for the joint described herein;
[0048] FIG. 3 is a diagrammatical illustration of a joint in accordance with one embodiment;
[0049] FIG. 4 is a time response graph plotting time verses percent of closure during standing for one embodiment of a joint;
[0050] FIG. 5 is a time response graph plotting time verses percent of closure during walking for one embodiment of a joint;
[0051] FIG. 6 is a diagrammatical illustration of a joint in accordance with one embodiment with the ground reaction force during standing,
[0052] FIG. 7 is an illustration of a state space diagram for a joint in accordance with one embodiment;
[0053] FIG. 8 is graph of plantarflexion and dorsiflexion of a healthy joint;
[0054] FIG. 9 is a diagrammatical illustration of a joint in accordance with one embodiment in different phases of the gait cycle;
[0055] FIG. 10 is a diagrammatical illustration of portions of a joint in accordance with one embodiment;
[0056] FIG. 11 is a diagrammatical illustration of portions of a joint in accordance with one embodiment;
[0057] FIG. 12 is a diagrammatical illustration of portions of a joint in accordance with one embodiment;
[0058] FIG. 13 is a diagrammatical illustration of portions of a joint in accordance with one embodiment;
[0059] FIG. 14 is a diagrammatical illustration of a joint in accordance with one embodiment;
[0060] FIG. 15 is a diagrammatical illustration of a non-electrical mechanism in accordance with one embodiment; and
[0061] FIG. 16 is a diagrammatical illustration of a non-electrical mechanism in accordance with one embodiment.
[0062] FIG. 17 is a diagrammatical illustration of a joint according to an embodiment of this invention,
[0063] FIGS. 18 to 21 show diagrammatical illustrations of the non-electrical mechanism in different stages during “walking” and
[0064] FIGS. 22 to 24 show the non-electrical mechanism from FIGS. 18 to 21 in different stages during “standing”.
BEST MODE(S) FOR CARRYING OUT THE INVENTION
[0065] Referring to FIG. 1, a diagrammatical illustration of a person wearing a below-the-knee prosthesis 114 with an ankle joint 100 is illustrated. In FIG. 2, the below-the-knee prosthesis 114 includes a socket 102 for receiving the amputated limb, a shank (or pylon) 104 connecting the base of the socket to a connector 106. The connector 106 can be the “inverted pyramid” connector. The connector 106 is received within a receiver 108. The receiver 108 can have set screws that lock the connector 106 in place. The receiver 108 is then connected to the joint 100, which in turn is connected to a prosthetic foot 112 via a hinge 110. The socket 102, shank 104, connector 106, and foot 112 can all be well-known components. The joint 100 is illustrated functioning as an ankle, however, the joint can have other applications, such as a knee or hip joint.
[0066] Referring to FIG. 3, a prosthetic joint 100 suitable to be used as the ankle joint 100 in FIGS. 1 and 2 is illustrated. The joint of FIG. 3 is highly schematic to illustrate major components of one embodiment of the prosthetic joint. The joint 100 includes an outer hydraulic case 116. The case is provided with an interior first chamber 128, an interior second chamber 130, a first piston 120 within the first chamber 128, and a second piston 122 within the second chamber 130. The chambers 128 and 130 are filled with a hydraulic fluid. A passage 132 between the first chamber and the second chamber is provided. The first piston 120 and the second piston 122 each includes a cam follower 124 and 126, respectively, that rests on cams 118, 148. The prosthetic joint 100 is rotatably connected to the foot 112 via a pivot 134. The foot may dorsiflex and plantarflex with respect to the joint 100 about the pivot 134. The foot is driven to rotate by engaging in a walking gait motion, for example. Of course, the first piston 120 and the second piston 122 can also be two ends of only one piston which can be shaped in form of a part of a ring. It is also possible to use only one cam.
[0067] In one embodiment, a cam assembly is provided to regulate or stop the flow between chambers. The cam assembly can provide controlled dorsiflexion and plantar flexion when walking and also provide stability when standing without the use of electronics. Other embodiments can use a magnetic device to regulate and stop the flow.
[0068] The cam assembly may include a cam 136, a follower 138 in contact with the cam surface, a primary spring 140 that is connected between the follower and the lever arm 142. The lever arm is connected to a damping device 144 and a secondary spring 146 that opposes the damping device. The lever arm is also connected to an occlusion 150. The occlusion 150 is configured to variably block the passage 132 between chambers 128 and 130. This passage 132 is the fluid flow path between the two chambers 128, 130. Thus, with the increasing blockage, the resistance to fluid flow between chambers increases until the occlusion 150 fully blocks the passage 132 and fluid transfer between chambers 128 and 130 is stopped so the ankle becomes locked into position. The amount of restriction to fluid flow can depend on the shape and configuration of the cam 136. In one embodiment, less resistance occurs the greater the plantarflex or dorsiflex angle is or becomes. Greater resistance occurs as the angle (between foot and shank, for example) approaches zero or near zero, corresponding to midstance or when the body's center of gravity is in line with the center of rotation of the joint. The occlusion is damped so that a faster gait results in less resistance to flow compared to a slower gait which increases the resistance. The damping reaction can be adjusted to be slower or faster based on the user of the joint. The cam 138 can be symmetric or asymmetric with respect to the nose of the cam. The cam sides can be linear or nonlinear and can define an involute shape. The nose of the cam 138 is the top or maximum point of the cam from the point of rotation. The lobe length is defined as the length between the point of rotation to the nose. The dimensions and placement of the cam 138 and the shape can be modified to fit a particular user of the joint to coincide with the user's walking characteristics. In order to effectuate the standing state, the cam 138 is adjusted such that when the angle of the ankle is at or near zero, corresponding to at or about midstance, and the rate of rotation is at or near zero, corresponding to standing still, then the cam 138 can line up to exert the maximum lift on the occlusion 150 and coupled with the damping response will fully restrict the flow between chambers 128, 130 to support the joint in the standing position. Resuming a walking gait will move the cam 138 out of maximum lift and allow the occlusion 150 to permit flow between chambers once again. FIG. 4 shows a graph of one embodiment of the response of a joint at steady state occurring when a person is standing still, i.e., when the rotation angle is at or near pre-selected zero and the rate of rotation is at or near zero. As the graph shows, the fully closed position is reached in about 0.5 seconds or less. However, it is to be appreciated that the response of the joint can be changed depending on the intended user of the joint.
[0069] The foot rotates in relation to the joint via the application of external forces, such as the ground reaction forces. A walking gait includes the stance and swing phase. The stance phase, i.e., when any part of the foot is in contact with the ground, begins with heel strike when the end of the heel first strikes the ground. This causes a slight plantarflexion movement initially, as shown in FIG. 8 as a negative rotation. As the stance phase continues, dorsiflexion occurs, the angle becomes zero approximately at midstance. However, zero angle is relative and can vary between persons. Dorsiflexion continues to a maximum after midstance, and is followed by planterflexion in preparation for toe-off. plantarflexion reaches a maximum at toe-off. Then, dorsiflexion occurs to lift the toe during swing phase to avoid stubbing the toe into the ground, and can end with the angle approximately at zero in preparation for the next cycle. See FIG. 9 for the controlled phases of planterflexion and dorsiflexion of the joint. FIG. 5 plots the time versus the percent opening between chambers. As can be appreciated, the aim is for the valve to never fully close 100% and remain open throughout a walking gait.
[0070] As mentioned in the Summary section, an ankle joint needs to respond to a walking gait and a standing steady state. The steady state occurs when the body is standing still as illustrated in FIG. 6. The ground reaction force tends to dorsiflex the ankle. However, upon acquiring the standing position, the cam 138 exerts close to or the maximum lift on the occlusion 150. That is, where the angle of rotation is at or near zero and the rate of rotation is also approximately zero, the occlusion 150 will close the channel, thus locking the ankle at that position. FIG. 7 represents the steady state or the closed-valve state of the ankle. The horizontal axis is the degree of rotation, where negative is plantarflexion and positive is dorsiflexion, and the vertical axis is the rate of change of rotation. The ellipse in FIG. 7 represents the conditions where the valve is closed. When standing at a neutral position (where theta is near zero), and the velocity of the joint is also near zero, then, the valve will close to provide full support of the ground reaction force induced moment. When passing through the neutral position during walking, the rate of rotation of the joint is great enough to avoid closing the valve. That is, when walking, the rate of rotation is never small enough to allow the valve to fully close due to the delay of the damping device.
[0071] Referring to FIG. 10, one embodiment of a joint 100 is illustrated. The joint 100 includes a hydraulic case 308, a valve 304, a receiver 302, and a cam assembly 306. The joint includes an aperture for receiving a pivot axle.
[0072] FIGS. 11 and 12 more clearly show the major parts of the joint 100 and their placement on the joint 100. The valve 304 can be the valve disclosed in U.S. application Ser. No. 14/213,293, filed on Mar. 14, 2014. The hydraulic case 308 with pistons and channels can be similar to the ankle joint body 104 with pistons and channels described in U.S. Patent Application Publication No. 2013/0173022, with the modifications noted herein. Both applications are incorporated herein expressly by reference.
[0073] The modifications to the hydraulic system described in U.S. Patent Application Publication No. 2013/0173022 include the removal of electronics that activate the hydraulic system and modifications to allow placement of the cam assembly 306 described herein. The joint described herein, can have electronic sensors, such as accelerometers and angle sensors, for example.
[0074] Referring to FIG. 13 the cam assembly is shown. The cam 310 is connected to a pivoting axle, for example, that pivots about the axis of rotation 330. The cam has a clamp 334 to connect to the pivoting axle. The cam includes a cam surface 312 that lies generally on a plane perpendicular to the line of rotation. The cam surface has a nose 336 that reaches a maximum lift. The cam assembly has a cam follower comprising a roller ball 314, a spring 317, a sleeve 316 and a plunger 318. The ball 314 is held m the sleeve 316. The ball 314 contacts the spring 317, which in turn contacts one end of the plunger 318. The opposite end of the plunger has a pin 332, generically referred to an “occlusion” here. The pin 332 fits into the aperture 338 on the valve 304 shown in FIG. 12. The depth of the pin within the aperture 338 of the valve will determine not only the direction of flow, but, also the resistance to flow. As the ball 314 rides over the cam surface, the depth of the pin 332 can be influenced based on the characteristics of the spring 315. The plunger 318 forward movement into the valve is also counteracted by a spring 322, and damping device 324 dampens the forward movement of the plunger. The plunger is connected to a lever arm 320 at location 340 as shown on FIG. 11 or 12. The opposite end of the lever arm is connected to a damping device. The damping device is then connected via the pin 328 to a hole 342 in the hydraulic case 308.
[0075] Referring to FIGS. 11 and 12, the damping assembly 306 fits into the hydraulic case 308 within the cavity 360. The plunger 318 is enclosed in a shroud 344. The pin 332 projects through a plate 346, such that the pin is aligned with the aperture 338 of the valve 304. The hydraulic case 308 has ports 348 and 350, each one respectively leading to a chamber 356 and 358. The ports 348 and 350 are bi-directional to allow hydraulic fluid both into and out of the chambers and the valve 304.
[0076] In FIG. 11, the ball 314 of the cam follower fits into the hole 352 of the ball receptacle 354. The ball 314 projects out of the ball receptacle 354 to ride on the cam surface. The receptacle 314 contains a spring 317 therein, and the spring 317 rests against one end of the plunger 318.
[0077] Via the mechanism described, the direct motion of the ball 314 is decoupled to the valve open/closure by the spring 317. The spring 317 is part of the decoupling action. Because of the damping element resisting the first spring 317, the system will not respond instantaneously. This allows the valve to stay open during walking even though the cam follower passes a high position.
[0078] However, when standing at the location of the high dwell, the damping element yields (in time) to the first spring 317 and the valve closes shutting off hydraulic fluid transfer. The amount of time this takes is tunable by the rate coefficient of the damping element.
[0079] FIG. 14 is a second embodiment of the prosthetic hydraulic joint shown in FIG. 3, however, the joint of FIG. 4 includes a hydraulic fluid path 402 with a one-way valve 402 connecting the first hydraulic chamber 430 to the second hydraulic chamber 428.
[0080] FIG. 15 is a schematic illustration of a non-electronic mechanism 500 for controlling the flow responsive to both a position of the prosthetic joint and a rate of change of position of the joint and the mechanism is arranged such that a dwell at a particular joint location or locations will occlude fluid flow. A specific mechanism has already been described in connection with FIGS. 10-13 above. However, the mechanisms are not thereby limited. FIG. 15 is representative of a non-electronic mechanism using a cam surface 502 in contact with a cam follower 504. The cam surface can be dictated, in part, by the gait characteristics of the particular user. The cam follower 504 is in contact with a first spring 506, which in turn is in contact with a damping element 508 and a second spring 510. The mechanism operates a valve 512 to control the hydraulic flow between a first chamber and second chamber of the prosthetic joint, such as the joints that are illustrated in either FIG. 3 or FIG. 14. As can be appreciated, the cam follower 504 generally being at the location of the high dwell 514 of the cam surface 502 is configured to coincide when a person with the joint is standing. Given sufficient time at the high dwell location, the damping element 508 yields to the first spring 506 and the valve 512 closes shutting off hydraulic fluid transfer. The amount of time this takes is tunable by the rate coefficient of the damping element 508.
[0081] FIG. 16 is a schematic illustration of a non-electronic mechanism 600 for controlling the flow responsive to both a position of the joint and a rate of change of position of the joint and wherein the mechanism is arranged such that a dwell at a particular joint location or locations will occlude fluid flow. A specific mechanism has already been described in connection with FIGS. 10-13 above. However, the mechanisms are not thereby limited. FIG. 16 is representative of a non-electronic mechanism using a first magnet 602 moving in proximity to a second magnet 604. The first magnet 602 moves back and forth along the direction indicated by the arrow. The second magnet 604 moves perpendicular to the motion of the first magnet. As can be appreciated, when the north (or south) pole of the first magnet is aligned in closest proximity to the north (or south) pole of the second magnet, the greatest repulsion force will be realized. In other configurations, the attraction force may also be used. The second magnet 604 is in contact with a damping element 608 and a spring 610. The mechanism operates a valve 612 to control the hydraulic flow between a first chamber and second chamber of the prosthetic joint, such as the joints that are illustrated in either FIG. 3 or FIG. 14. As can be appreciated, the magnets generally being at the greatest repulsion force (or attraction force) is configured to coincide when a person with the joint is standing. Given sufficient time at the greatest repulsion (or attraction force), the damping element 608 yields to the spring 610 and the valve 612 closes shutting off hydraulic fluid transfer. The amount of time this takes is tunable by the rate coefficient of the damping element 608.
[0082] While a preferred embodiment of the invention has been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.
[0083] FIG. 17 shows a prosthetic foot with an ankle joint pursuant to an embodiment of this invention. The first connector 702 and the second connector 704 are connected to each other pivoting via a joint 706. An only diagrammatically illustrated prosthesis foot 708 is also placed on the second connector 704. It has a heel area 710 and a toe area 712 which can also be called forefoot or forefoot area.
[0084] In the second connector 704, there is the first chamber 714 and the second chamber 716. In these, there is the first piston 718, on which there is a first cam plunger 720 and a second piston 722 with a second cam plunger 724. A cam plunger can also be called a follower.
[0085] The two chambers 714, 716 are connected to each other via a fluid connection 726.
[0086] The fluid connection 26 can be occluded by means of a closure 728. This has a pin 730, which is placed on a carrier element 732.
[0087] The carrier element 732 is placed in a hollow 734 in which there is a third cam plunger 736 in the lower part in FIG. 17. It abuts to the lower cam 738, which is part of the first connector 702. If the first connector 702 is now pivoted relative to the second connector 704 so that the lower cam 738 is moved up, the third cam plunger 736 is moved up, which compresses the spring 740 and exerts a force upwards onto the carrier element 732. Above the carrier element 732, there is another spring 742 and a dampening element 744 that ensures that the carrier element 732 and the pin 730 aligned on it are moved up with a time delay. The individual phases of a gait cycle and the standing phase are explained in more detail in the further FIGURES.
[0088] Between the first chamber 714 and the second chamber 716, there is a one-way connection 746, in which a check valve 748 is placed.
[0089] FIGS. 18 to 24 show an enlarged section of the device shown in FIG. 17 in different states. Each shows the lower cam 738 in different positions and the third cam plunger 736. FIG. 18 once again serves the precise designation of the different construction elements. The lower cam 738 is borne pivoting around the joint 706 and abuts to the third cam plunger 736. Between it and the carrier element 732, there is the spring 740 in the hollow 734. The upper part of this hollow is separated from the lower part in which the spring 740 is located by a sealing ring 750. This upper part is filled with a fluid that can flow through a fluid connection 752 into a dampening chamber 754 that is closed off to the bottom by a dampening piston 756. At its end, further springs 758 and a thrust rod 760 are placed.
[0090] The volume of the dampening chamber 754 and the upper part of the hollow 734 can be set by a volume adjustment screw 762. A flow rate 764 between the connection 752 and the dampening chamber 754 can be set by a throttle screw 766. It can be appreciated that, in contrast to FIG. 17, the dampening element 744 has been removed since it is now formed by the dampening chamber 754 and the dampening piston 756 with the springs 758. The pin 730 can further be moved upwards to close the fluid connection 726.
[0091] FIGS. 19 to 21 show the situations in different phases of the gait cycle. FIG. 19 shows the situation right after putting down the foot at approx. 10° plantarflexion. The pin 730 has not closed the fluid connection 726, so that fluid from the first chamber 714 can flow into the second chamber 716 and vice versa.
[0092] FIG. 20 shows the middle standing phase. It can be appreciated that the lower cam 738 has been pivoted relative to the second connector 704. Thus, an upward force has been applied to the third cam plunger 736, upon which it has moved from the position illustrated in a dashed line to the new position. Thus, the spring 740 is compressed and pushes the carrier element 732 upwards against the springs 742. At the same time, fluid is routed through the fluid connection 752 past the throttle screw 766 into the dampening chamber 754, which pushes the dampening piston 756 down. The resulting dampening leads to a time delay between the movement of the third cam plunger 736 and the carrier element 732 with the pin 730 on it.
[0093] FIG. 21 shows the situation in dorsiflexion. The lower cam 738 has been pivoted further, so that the third cam plunger 736 continues to be subject to an upwards force, moving it upwards and further compressing the spring 740. In this strong deflection, the thrust rod 760 is also applied to the lower cam 738 and is also pushed up by its movement. Thus, the dampening piston 756 is also pushed up, and thus moves the fluid in the dampening chamber 754 past the backpressure valve 768 and through the fluid connection 752. Thus, a pressure is applied on the carrier element 732 from above, because of which it moves downwards against the pressure of the spring 740 and thus also moves down the pin 730. Therefore, the pin 730 cannot close the fluid connection 726 during a step.
[0094] This is different when standing. FIG. 22 corresponds to FIG. 19 and shows the situation at approximately 10° plantarflexion. The pin 730 does not close the fluid connection 726. The lower cam 738 is in contact with the third cam plunger 736.
[0095] FIG. 23 corresponds to FIG. 20 and shows how the pivoting of the lower cam 738 moves the third cam plunger 736 upwards and thus pushes fluid into the dampening chamber 754 via the spring 740 around the carrier element 732. At the same time, the pin 730 is pushed up, but does not close the fluid connection 726 yet.
[0096] Since the wearer of the prosthesis remains in this state, the spring 740 can relax further. This is shown in FIG. 24, the lower cam 738 has not moved relative to the second connector 704 and thus also to the third cam plunger 736. By relieving the spring 740, however, the carrier element 732 is moved up and pushes further fluid through the fluid connection 752 into the dampening chamber 754. The thrust rod 760 is not yet in contact with the lower cam 738.
[0097] The pin 730 was moved in this situation so that it closes the fluid connection 726, so that, as shown in FIG. 17, no further fluid can flow from the second chamber 716 into the first chamber 714. Further movement of the foot in the direction of a dorsiflexion thus is not possible.
[0098] To release this lock and this closure and to put the ankle joint from the mode “standing” to the mode “walking”, the wearer of the prosthesis must apply a clockwise torque on the first connector 702 or a counterclockwise torque on the second connector 704 in the embodiment shown. This moves the upper cam 770 down and pushes the first piston 718 down via the first cam plunger 720, so that the volume of the first chamber 714 is reduced. Fluid enters the second chamber 716 through the backpressure valve 748 without having to pass the fluid connection 726. The pivoting of the first connector 702 relative to the second connector 704, which corresponds to a pivoting of the lower cam 738 downwards in FIG. 18, permits springs 740 and 742 to relieve, which moves the carrier element 732 and the pin 730 down, so that the fluid connection 726 is released again.
