Prosthetic knee joint

Abstract

The invention relates to a prosthetic knee joint having a lower joint part, an upper joint part and a hydraulic system, the hydraulic system having at least one switching valve, wherein the hydraulic system has an extension chamber, a flexion chamber and at least one piston, by the movement of which the volume of the extension chamber and / or the volume of the flexion chamber can be changed, the switching valve has a valve housing and a switching element which is movably supported in the valve housing, the switching element can be brought into a first position and a second position inside the valve housing and the interior of the valve housing is divided into a first chamber and a second chamber, the switching element is preloaded by at least one preloading element which is arranged in the switching valve, the prosthetic knee joint has at least one spring element which exerts a counterforce on the switching element, the counterforce being oriented opposite to the preloading, wherein at least one fluid connection between the first chamber and the second chamber is arranged inside the valve housing and / or the switching element.

Description

Technical Field

[0001] This invention relates to a prosthetic knee joint having a subarticular portion, a supraclavicular portion, and a hydraulic system. The hydraulic system has at least one switching valve, wherein the hydraulic system has an extension chamber, a flexion chamber, and at least one piston, the volume of the extension chamber and / or the flexion chamber being changeable by movement of the piston. The switching valve has a valve housing and a switching element movably supported within the valve housing. The switching element is capable of being moved to a first position and a second position within the valve housing and dividing the internal space of the valve housing into a first chamber and a second chamber. The switching element is preloaded by at least one preload element arranged in the switching valve. The prosthetic knee joint has at least one spring element that applies a reaction force to the switching element, the reaction force being oriented opposite to the preload. Background Technology

[0002] This type of prosthetic knee joint is known by DE 10 2018 111441A1.

[0003] Prosthetic knee joints have long been known in the art. These joints are crucial components of prostheses and should mimic the function of the human knee as realistically as possible. The human knee allows movement in some situations and locks that movement in others. This is important to provide the required stability as consistently as possible. The multifaceted flexibility of the human knee presents a challenge for prosthetic knees. To enable movement at different speeds and with different damping, prosthetic knees are typically equipped with hydraulic systems. Hydraulic prosthetic knees usually have at least two hydraulic chambers, namely an extension chamber and a flexion chamber, which are fluidly connected to each other. At least one connecting line exists for this purpose. Pistons are arranged in both chambers, allowing movement within the chambers and thus changing the volume of the respective chamber. The piston can be configured as a single piston. In this case, the two chambers are arranged on opposite sides of the piston, which is preferably configured as a rotary piston. This allows the volume of one chamber to decrease while the volume of the other chamber increases accordingly. Alternatively, the two pistons can be arranged in separate cylinders, each defining a chamber within its respective cylinder.

[0004] The upper part of the joint is supported in a swinging manner relative to the lower part of the joint around the swing axis.

[0005] Flexion refers to the bending of the knee, that is, the movement of the upper part of the joint relative to the lower part of the joint along a first direction called the flexion direction. During this movement, hydraulic fluid, such as hydraulic oil, flows from the flexion cavity to the extension cavity. The opposite movement, called extension, is the extension of the knee joint. Here, hydraulic fluid flows from the extension cavity to the flexion cavity. The extension cavity is the cavity where pressure increases during extension, and the flexion cavity is the cavity where pressure increases during flexion.

[0006] The speed at which hydraulic fluid flows from one chamber to another is crucial to the speed of joint movement, i.e., the movement of the upper part of the joint relative to the lower part. This speed is also related to the flow cross-section of the connecting pipes. A device is known from DE 69312 771T1 that can be used to control the hydraulic system in a thigh prosthesis.

[0007] Different speeds are advantageous at different stages of the walking cycle, thus the switching valve is integrated into the prosthetic knee joint. This allows switching, for example, between two different connecting lines with different flow cross-sections and thus different flow resistances. The switching valve has a valve housing in which a switching element is located. The switching element is configured, for example, as a movable piston or spool valve. The switching element is a component that, by moving to a first or second position, can change the flow cross-section or flow velocity within the hydraulic system and / or open or close hydraulic lines or fluid communication devices. The valve housing is a component of the prosthetic knee joint in which the switching element can move to the first and second positions. The valve housing can be configured as a separate component. Alternatively, other components of the prosthetic knee joint, such as the subarticular or supraclavicular portion, can also constitute the valve housing. For this purpose, cavities or orifices exist in the respective components, in which the switching element moves.

[0008] The switching element can be brought to a first position and a second position relative to the valve housing. If the switching element is in the first position, the valve is in a first state, which, for example, opens the first connecting line. In a preferred configuration, the connecting line has high flow resistance, thus strongly damping the movement of the knee joint. This allows only slow and loaded movement of the upper part of the joint relative to the lower part, which is advantageous, for example, when walking while standing, when sitting, and when walking down stairs or downhill.

[0009] Conversely, if the switching element is brought to the second position relative to the valve housing, the switching valve is in a second state, in which an additional path for the hydraulic fluid is opened. This path can be, for example, a second connecting line. Preferably, the damping of knee joint movement in this state of the valve is less than, for example, achievable, in that the second connecting line has less flow resistance than the first connecting line. The second state is advantageous, for example, during the swinging phase of stepping, because the knee is not under load during this phase and large damping is unphysiological in this case.

[0010] The switching element of this type of prosthetic knee joint divides the internal space of the valve housing into a first chamber and a second chamber. The switching element is preferably located entirely within the valve housing and, more preferably, is completely surrounded by the corresponding hydraulic fluid.

[0011] In order to move the switching element from a first position to a second position and switch the switching valve in the aforementioned manner, an operating mechanism is preferably provided, by which force can be applied to the switching element. The switching element is preloaded by at least one preloaded element, for example in the form of a spring, particularly a helical spring. The preload is preferably oriented toward the first position of the switching element, which causes greater damping.

[0012] The first position of the switching element relative to the valve housing can be related to several parameters. This first position may also be related to: preload parameters; hydraulic pressure generated in the hydraulic system; possible flow paths selected by the hydraulic fluid through the system, particularly from one chamber to another; the typical dimensions of the prosthesis, particularly the prosthetic knee; and the type of prosthetic knee, to name just a few. However, accurate determination of the first position of the switching element relative to the valve housing is crucial because it determines the required movement path that must be taken to move the switching element from the first position to the second position. The first position also determines how quickly the switching valve responds and, for example, when it is switched from the first state to the second state during a stepping cycle, in which the switching element is in the first position. Unfortunately, the preload element is located inside the valve and thus primarily within the hydraulic system and typically within the hydraulic fluid, making it almost impossible or completely unreachable. The remaining parameters are typically only obtained during knee assembly and cannot be, or only poorly, predetermined. Therefore, setting the first position of the switching element relative to the valve housing is either impossible or extremely costly.

[0013] The prosthetic knee joint also includes a spring element, which is similarly configured to apply force, i.e., a reaction force, to the switching element. This can be achieved directly, for example, by mechanical contact between the spring element and the switching element, or indirectly, by the spring element transmitting force to the intermediate member and from there directly or indirectly to the switching element. If no additional force is applied to the spring element from the outside, thereby reinforcing the reaction force, the preload force is greater than the reaction force, and the switching element is in a first position. In the first position, the flow resistance against the hydraulic fluid flowing through the hydraulic system, and particularly through the switching valve, is greater than in the second position of the switching element. The standard valve setting ensures this large resistance in such a way that it resists the oscillation of the upper joint portion relative to the lower joint portion.

[0014] If an external force is applied to the spring element, this force amplifies the reaction force, which can overcome the preload force and move the switching element from the first position to the second position. If the external force is reduced or completely canceled at a later point in time, the reaction force also decreases, becoming less than the preload force. The preload force then moves the switching element back to the first position. The faster this occurs, the greater the resultant force caused by the preload force and the reaction force. Summary of the Invention

[0015] Therefore, the objective of this invention is to improve the prosthetic knee joint in such a way that a first position suitable for controlling the knee joint can be easily reached.

[0016] The objective of this invention is achieved by a prosthetic knee joint according to the invention, characterized by at least one fluid communication device between a first cavity and a second cavity arranged within the valve housing and / or the switching element. If a force is now applied, for example, from the outside to the spring element, resisting the preload force of the preload element, the spring element is preferably tensioned, particularly preferably compressed, and thereby loaded with potential energy. The spring element then applies a force to the switching element. This can be achieved directly, for example, by having the end of the spring element rest against the switching element, or indirectly, by having the spring element first transmit its force to one or more other components of the prosthetic knee joint, which then continue to transmit the force directly or indirectly to the switching element.

[0017] If the switching element is to avoid this force, it must move against the preloading force of the preloading element. This causes one of the two chambers inside the valve housing to shrink and the other to expand. That is, the switching element must allow at least a portion of the hydraulic fluid to leave the shrinking chamber. Simultaneously, the hydraulic fluid must flow into the expanding chamber. For this purpose, at least one fluid communication device exists between the first and second chambers, located inside the valve housing according to the invention. The cross-section of the at least one fluid communication device is crucial for the amount of hydraulic fluid flowing from the shrinking chamber into the expanding chamber through it. The fluid communication device, also known as a bypass, is arranged inside the valve housing without requiring additional structural space, which is typically measured as narrow in prosthetic knee joints. Preferably, there are multiple, for example, at least three fluid communication devices. The fluid communication devices can be constructed identically. These devices, for example, have the same length and / or the same cross-section, and / or the same cross-sectional area, preferably less than 1 mm. 2 Particularly preferred is less than 0.5 mm 2 And more preferably less than 0.385mm 2Preferably, the fluid communication device produces the same flow resistance. For this purpose, the same length, the same cross-section, or the same cross-sectional area is not necessary, but rather advantageous. The fluid communication device can also be constructed differently and, for example, not produce the same flow resistance.

[0018] If the valve is to be switched, a force must be applied to the switching element to move it from a first position to a second position, or vice versa. The movement of the switching element within the valve housing is damped according to the invention by dividing the internal space of the valve housing into two chambers filled with hydraulic fluid. To enable the movement of the switching element, fluid must be directed from one chamber to the other. This is independent of the valve's switching state, i.e., the position of the switching element, and can be achieved solely through a fluid communication device. The cross-section of this connection determines how quickly the switching element can respond to externally applied force impacts.

[0019] The reaction, which is damped, may prevent brief force shocks that should not normally cause a change in the valve's switching state from lasting for a sufficient period of time to deliver a sufficient amount of fluid between the two chambers inside the valve housing and to switch the valve.

[0020] In a preferred configuration, multiple fluid communication devices are configured to function in different positions of the switching element. For this purpose, multiple recesses, such as grooves, channels, or channels, are preferably arranged in the inner wall of the valve housing, and these recesses preferably contact the switching element. The recesses are preferably of different lengths. This allows, on the one hand, the recesses to be closed by the switching element moving from a first position to a second position. On the other hand, the fluid communication device can also be opened by the moving switching element.

[0021] The recess in the inner wall of the valve housing thus forms a fluid communication device between the first and second chambers. One end of the recess must be located in the region of the inner wall defining the boundary of the first chamber, and the other end must be located in the region of the inner wall defining the boundary of the second chamber. When the switching element moves from the first position to the second position or vice versa, one chamber expands and the other chamber shrinks. This also changes the portion of the inner wall defining the boundary between the first and second chambers.

[0022] Preferably, at least one fluid communication device extends through the switching element. Particularly preferably, the at least one fluid communication device is an orifice arranged in a plane of the switching element perpendicular to the direction of movement of the switching element. Preferably, there are multiple fluid communication devices constructed identically or differently. Alternatively or supplementarily, a recess is preferably arranged on the outer side of the switching valve.

[0023] Instead, or otherwise, at least one fluid communication device extends through the valve housing. Particularly preferably, the fluid communication device is arranged as a recess, groove, or channel in the wall of the valve housing, which defines the boundary of the internal space of the valve housing. In this configuration, the cross-section of the fluid communication device is also decisive for the amount of fluid that is forced from the narrowed cavity into the expanded cavity by the force applied by the spring element.

[0024] Instead, or otherwise, at least one fluid communication device extends between the valve body and the switching element.

[0025] Regardless of the configuration and / or number of existing fluid communication devices, the greater the resistance of the flow resistance through at least one fluid communication device to the movement of the switching element, the smaller the total cross-section of all provided fluid communication devices.

[0026] If the switching element is in the first position, the hydraulic system resists the movement of the lower joint portion relative to the upper joint portion with high resistance. This movement is extremely damped in this state. In the second state of the switching valve, the switching element is in the second position, and the movement of the lower joint portion relative to the upper joint portion is weakly damped. The prosthetic knee joint also has at least one spring element that applies a reaction force to the switching element, the reaction force being oriented opposite to the preload.

[0027] Preferably, at least one fluid communication device, preferably all fluid communication devices, cannot have their cross-section altered and / or the corresponding fluid communication devices, preferably all fluid communication devices, cannot be shut down.

[0028] Preferably, at least one spring element is arranged such that the switching element can be brought from a first position to a second position by applying force to at least one spring element for at least a predetermined time period. Particularly preferably, by applying force to the spring element for a time period shorter than the predetermined time period, the switching element cannot be brought from the first position to the second position. This configuration ensures that a brief force impact shorter than the predetermined time period does not cause the switching element to be brought from the first position to the second position. Such force impacts occur, for example, when the wearer of the prosthetic knee falls or hits an object. This typically occurs during the swing phase, that is, when the foot, connected to the wearer's body via the prosthetic knee, is not in contact with the ground. Due to the force impact, at least one spring element is compressed and loaded with energy in the aforementioned manner. The force impact is applied, for example, to a spring pin in a housing in which at least one spring element is arranged. Once the force is no longer applied, the stored energy is thus unloaded and the spring pin moves back to its initial position. The time during which at least one spring element is loaded with mechanical energy in this case is too short for the switching element to move sufficiently to reach the second position. It should be noted that this does not mean the switching element does not move. Movement is perfectly possible; however, this movement does not result in reaching the second position.

[0029] Preferably, a force must be applied to at least one spring element to move the switching element from the first position to the second position. Preferably, there are no other possibilities for moving the switching element.

[0030] To reduce noise, particularly when one component, such as a spring sleeve, collides with another component, such as a spring cover or spring housing, at least one bushing is arranged between the two components that can contact each other in the aforementioned manner. This bushing is preferably made of plastic, particularly thermoplastic. Polyoxymethylene, commonly abbreviated as POM, is suitable, for example.

[0031] Particularly preferably, the prosthetic knee joint can be manufactured or is manufactured according to one of the methods described herein. Particularly preferably, a reaction force applied by at least one spring element is provided. Attached Figure Description

[0032] An embodiment of the present invention will now be described in detail with reference to the accompanying drawings. In the drawings:

[0033] Figure 1 -A schematic cross-sectional view of a prosthetic knee joint according to an embodiment of the present invention.

[0034] Figure 2 –From Figure 1 A magnified partial image,

[0035] Figure 3- Switching elements used for switching valves,

[0036] Figure 4 - Spring box for prosthetic knee joints

[0037] Figures 5 to 7 -Based on Figure 1 A cross-sectional view, and an enlarged partial view showing the switching elements in different positions.

[0038] Figures 8 to 10 - Schematic diagrams of different arrangements of fluid communication devices, and

[0039] Figure 11-1 A schematic diagram of another spring box. Detailed Implementation

[0040] Figure 1 A schematic cross-sectional view of a prosthetic knee joint is shown, the prosthetic knee joint having a subarticular portion 2, a supraclavicular portion 4, and a hydraulic system, with a switching valve 6 located in the hydraulic system. The hydraulic system includes a flexion chamber 8 and an extension chamber 10, which are fluidly connected to each other. When the knee is extended, i.e., straightened, hydraulic fluid flows from the extension chamber 10 to the flexion chamber 8. When the knee is flexed, i.e., bent, hydraulic fluid flows in the opposite direction from the flexion chamber 8 to the extension chamber 10. The two chambers 8, 10 are separated from each other by a piston 12, which is configured as a oscillating piston in the illustrated embodiment. If the piston 12 moves, one of the two chambers 8, 10 expands and the other of the two chambers 10, 8 contracts.

[0041] Hydraulic fluid also flows through switching valve 6 along the path from extension chamber 10 to buckling chamber 8 and / or vice versa. Switching valve 6 has switching element 14, which can be brought to a first position and a second position.

[0042] Figure 2 It shows the source Figure 1 A magnified partial view shows the switching valve 6 more specifically. In the illustrated embodiment, the switching element 14 is entirely submerged in hydraulic fluid and movably supported within the valve housing 16. For this purpose, a force and / or torque is applied to an external member 18, which compresses the spring element 20. The spring element is housed in a spring box, which will be discussed in detail later. The spring box has a spring pin 22, which is moved by the force applied by the pre-compressed spring element 20. The spring pin 22 transmits this force to a deflection lever 24, which is oscillatingly arranged about a deflection axis 26. The arm 28 of the deflection lever 24 rests against a valve pin 30, pushing the valve pin upward and thereby moving the switching element 14. This moves the switching element 14 from a first position to a second position.

[0043] The switching element 14 is preloaded by the preload element 32. In the illustrated embodiment, the preload element 32 is configured as a compression spring and presses the switching element 14 downwards. That is, the preload force of the preload element 14 further resists the force applied by the spring pin 22. Depending on which of the two forces is greater, the switching element 14 moves to either a first position or a second position.

[0044] Figure 3 A cross-sectional view of the switching element 14 is shown. In the assembled state, the valve pin 30 rests against the lower side 34 of the switching element. In the illustrated embodiment, the switching element 14 has a recess 36 at the opposite end, in which a preload element 32 rests in the assembled state. A fluid communication device 38 extends through the switching element 14, and the volume above the switching element 14 is fluidly connected to the volume below the switching element 14 via the fluid communication device. If the switching element 14 is to move within the valve housing 16, hydraulic fluid flows through the fluid communication device 38.

[0045] Figure 4 A spring housing is shown, in which a spring element 20 is located. In the illustrated embodiment, the spring element 20 is also configured as a compression spring. The compression spring is located within a spring housing 40, and a spring sleeve 42 is located within the spring housing, the spring sleeve being movable relative to the spring housing 40. A spring pin 22 is arranged on the spring sleeve 42. The spring sleeve 42 is movably arranged relative to the spring housing 40, which has a spring housing cover 46 through which the spring pin 22 passes.

[0046] Figure 5 A view of a spring box with a leftward-moving spring pin 22 is shown. The spring pin 22 is in its basic state and the spring 20 is not compressed. This causes the deflection lever 24 to swing about the deflection axis 26, thereby causing the arm 28 to move the valve pin 30 and thus the switching element 14 upward. This causes the switching element 14 to release the opening 44, thereby reducing the resistance to the flow of hydraulic fluid between the two chambers 8, 10.

[0047] exist Figure 6 In this case, spring element 20 is unloaded and no force is applied, or only a small force is applied. The force applied by preload element 32 is greater, thus pressing switching element 14 downward. As a result, opening 44 is closed and hydraulic fluid is prevented from flowing through opening 44.

[0048] Figure 7 It shows the source Figure 5 and 6 The arrangement in which the spring element 20 is compressed. This is achieved, for example, by a force acting from the outside on the spring element 20 and / or the spring housing 40. The spring housing 40 is connected to the spring element 20 and / or the spring housing 40. Figure 6 The view is shifted to the left, so that the spring pin 22 no longer protrudes from the spring housing to such an extent. Note here that... Figure 7 The spring pin 22 in the view shown is from Figure 6 The view is different from that of other components of the prosthetic knee joint. Specifically, the deflection lever 24 does not swing, and thus the switching element 14 does not move. The force acting on the spring element 20 is therefore applied for a very short period. When the force is applied only briefly and then immediately and strongly reduced or canceled, the spring element 20 is unloaded, and the switching element 14 does not move. This mitigates the brief force impact without causing the valve to open.

[0049] Figures 8 to 10 Different possibilities for arranging the fluid communication device 38 are shown. Correspondingly, a valve housing 16 is shown, which has a switching element 14 movably disposed therein. Figure 8 In the middle, the annular fluid communication device 38 is located between the valve housing 16 and the switching element 14. Figure 9 A fluid communication device 38 is shown, which extends through the valve housing 16, and Figure 10 A fluid communication device is shown, which extends through a switching element 14.

[0050] Figure 11 Another configuration of the spring box is shown, having a spring housing cover 46 and a spring sleeve 42, on which a spring pin 22 is arranged. The spring 20 is shown only schematically. A bushing 48 is arranged between the spring housing cover 46 and the spring sleeve 42, and the bushing is preferably made of plastic, such as thermoplastic. The bushing 48 is also located between the lower end of the spring sleeve 42 and the spring housing 40. The two bushings 48 are particularly used to reduce noise.

[0051] List of reference numerals

[0052] 2. Subarticular portion

[0053] 4. Upper part of the joint

[0054] 6. Switching valve

[0055] 8. Flexion cavity

[0056] 10. Expansion cavity

[0057] 12 Pistons

[0058] 14 Switching elements

[0059] 16 valve housing

[0060] 18 External components

[0061] 20 Spring elements

[0062] 22 Spring Pins

[0063] 24. Deflection lever

[0064] 26 Deflection axis

[0065] 28 arms

[0066] 30 Valve pin

[0067] 32 Preloaded Components

[0068] 34 Lower side

[0069] 36 Recessed portion

[0070] 38. Fluid communication device

[0071] 40 Spring housing

[0072] 42 Spring Sleeve

[0073] 44 Opening

[0074] 46 Spring Case Cover

[0075] 48. Bushing.

Claims

1. A prosthetic knee joint having a subarticular portion, a supraclavicular portion, and a hydraulic system, said hydraulic system having at least one switching valve, wherein, The hydraulic system has an extension chamber, a flexion chamber, and at least one piston, the volume of which can be changed by the movement of the piston. The switching valve has a valve housing and a switching element movably supported within the valve housing, the switching element being movable within the valve housing to a first position and a second position, dividing the internal space of the valve housing into a first chamber and a second chamber. The switching element is preloaded by at least one preload element arranged in the switching valve. The prosthetic knee joint has at least one spring element that applies a reaction force to the switching element, the reaction force being oriented opposite to the preload. The feature is that at least one fluid communication device between the first cavity and the second cavity is arranged inside the valve housing and / or the switching element; The extension chamber and the buckling chamber are interconnected via hydraulic lines, wherein a switching valve is arranged in the hydraulic lines such that hydraulic fluid flows through the switching valve when flowing from the extension chamber to the buckling chamber or from the buckling chamber to the extension chamber; and The flow resistance of the hydraulic fluid is greater in the first position of the switching element than in the second position of the switching element.

2. The prosthetic knee joint according to claim 1, characterized in that, At least one fluid communication device extends through the switching element.

3. The prosthetic knee joint according to claim 1, characterized in that, At least one fluid communication device extends through the valve housing.

4. The prosthetic knee joint according to any one of claims 1 to 3, characterized in that, The at least one fluid communication device extends between the valve housing and the switching element.

5. The prosthetic knee joint according to any one of claims 1 to 3, characterized in that, The cross-section of the at least one fluid communication device cannot be changed, and / or the fluid communication device cannot be closed.

6. The prosthetic knee joint according to any one of claims 1 to 3, characterized in that, The at least one spring element is arranged such that the switching element can be brought from the first position to the second position by applying force to the spring element for at least one predetermined time period.

7. The prosthetic knee joint according to claim 6, characterized in that, By applying force to the spring element for a period of time shorter than the predetermined time period, the switching element cannot be moved from the first position to the second position.

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