Polycentric prosthetic or orthotic knee with kinematically active braking system

Abstract

The invention relates to a polycentric prosthetic or orthotic knee (1) comprising: - an upper articulation element (2); - a lower articulation element (3) connected to a prosthetic foot (4) with a heel (5); - a shock absorber (6) articulated on the one hand to the upper articulation element (2) about a first pivot axis (7) and, on the other hand, to the lower articulation element (3) about a second pivot axis (8), and comprising a control member (11) which, depending on the phase of walking, adjusts the resistance of the shock absorber as the upper articulation element (2) rotates with respect to the lower articulation element (3); - at least one rear connecting rod (14) articulated, on the one hand, around the upper articulation element (2) and, on the other hand, to the lower articulation element (3) about a third pivot axis (16); - at least one front connecting rod (15) articulated, on the one hand, to the upper articulation element (2) about a fourth pivot axis (17) and, on the other hand, to the lower articulation element (3) about a fifth pivot axis (18); so as to define a deformable parallelogram designed such that, as the knee flexes, the rear connecting rod (14) can adopt two different pivoted positions depending on the phase of walking, namely: - a braking position, pivoted in a first direction, actuating the control member (11) directly or indirectly so as to brake the flexing of the knee (1); - a free-flexing position, pivoted in a second direction opposite to the first direction, actuating the control member (11) directly or indirectly so as to allow the knee (1) to flex freely.

Description

Description Title of the invention: Polycentric prosthetic or orthotic knee with kinematically activated braking system technical field

[0001] The present invention relates to the field of prostheses and orthoses, in particular prosthetic or orthotic knee joints.

[0002] The invention relates more specifically to a multiaxial, or commonly called polycentric, prosthetic or orthotic knee, equipped with an advanced braking system, notably activated by the kinematics of knee movement. Previous art

[0003] Current prosthetic or orthotic knees with braking systems are mainly of two types: those which are braked by default and which require deactivation of the brake for the swing phase, resulting in a more complex mechanical system, and those which mechanically activate the brake during heel support, and which therefore have the disadvantage of having to keep the effort on the knee in flexion for the brake to remain active.

[0004] In a manner known from prior art, prosthetic or orthotic knees that actively mechanically brake during heel support include, for example: - a superior articulation element; - a lower joint element connected to a prosthetic foot with a heel; - a shock absorber, generally hydraulic, articulated on one side to the upper articulation element around a first pivot axis and, on the other side to the lower articulation element around a second pivot axis, and comprising a braking system with a control valve adjusting, according to the phase of travel, the resistance of the shock absorber during the rotation of the upper articulation element relative to the lower articulation element.

[0005] Furthermore, connecting rod systems defining a deformable parallelogram, also called polycentric systems, four-axis systems, or four-bar systems, are widely used in prosthetic and orthotic knee joints to provide motion kinematics adapted to user needs. These systems can be divided into two main categories: those that comply with Grashoff's rule and those that do not.

[0006] According to Grashoff's law, a four-bar articulated system allows continuous movement if the sum of the longest and shortest bars is less than or equal to the sum of the other two bars.

[0007] Systems that do not comply with this rule, called "double rocker" in English, are characterized by the absence of continuous movement for either of the two connecting rods, resulting in blocking positions.

[0008] In the field of prosthetics and orthotics, some knees utilize Grashoff mechanisms, allowing for continuous and fluid movement. Others, such as knees using a non-Grashoff mechanism, can be designed to offer stable positions in extension and flexion, but these are less common.

[0009] Thus, there is no polycentric prosthetic or orthotic knee, that is, one whose knee flexion axis is not fixed and moves according to the phase of walking, and which combines the properties of a non-Grashoff mechanism with an improved braking mechanism, capable of providing stable positions and increased control during walking and other activities.

[0010] A monoaxial or monocentric prosthetic knee, meaning that the flexion movement is performed around a single, fixed axis, is known from the prior art and is therefore not relevant to the present invention. This type of prosthesis is described in document US20050234562. Description of the invention

[0011] One of the aims of the invention is to overcome the disadvantages of the prior art, in particular by proposing a polycentric prosthetic or orthotic knee which combines a multiaxial system with a kinematically activated braking system.

[0012] Another objective of the invention is to provide such a knee that is capable of providing stable positions and increased control during walking and other activities.

[0013] To this end, a polycentric prosthetic or orthotic knee has been developed, meaning that the axis of knee flexion is not fixed and moves according to the phase of walking, the knee comprising: - a superior articulation element; - a lower joint element connected to a prosthetic foot with a heel; - a shock absorber articulated on one side to the upper articulation element around a first pivot axis and, on the other side to the lower articulation element around a second pivot axis, and comprising a control device adjusting, according to the phase of walking, the resistance of the shock absorber during the rotation of the upper articulation element relative to the lower articulation element; - at least one rear connecting rod articulated, on the one hand, around the upper articulation element and, on the other hand, to the lower articulation element around a third pivot axis; - at least one front connecting rod articulated, on the one hand, to the upper articulation element around a fourth pivot axis and, on the other hand, to the lower articulation element around a fifth pivot axis; so as to define a deformable parallelogram between the upper articulation element, the front connecting rod, the lower articulation element, and the rear connecting rod; the deformable parallelogram constituting the polycentric system of the knee.

[0014] According to the invention, the deformable parallelogram is designed so that, during knee flexion, the rear connecting rod can adopt two different pivoted positions depending on the phase of walking, namely: - a braking position, pivoted in a first direction, directly or indirectly actuating the control organ to brake the flexion of the knee; - a free flexion position, pivoted in a second direction opposite to the first direction, directly or indirectly actuating the control organ to release the flexion of the knee.

[0015] In other words, the control unit allows the state of the shock absorber to be modified according to the configuration of the polycentric system constituted by the deformable parallelogram.

[0016] The invention allows for precise adjustment of knee flexion resistance according to the phase of walking, through kinematic activation of the braking system.

[0017] The main advantage of this design is to allow smooth and automatic control of knee flexion, thus reducing user effort while ensuring optimal safety during the different phases of walking.

[0018] In other words, the invention allows for two possible flexion movements, with one that pivots the rear connecting rod in a first direction to switch the control member into a position or state of knee braking, particularly during the heel support phase, and the other that pivots the rear connecting rod in a second direction to switch the control member into a position or state of brake release, particularly during the pendulum phase.

[0019] The shock absorber can be of any type, for example controlled by a microprocessor, and the control element can be a switch or an angle sensor, which, depending on the direction of pivoting of the rear connecting rod, can be activated / switched / actuated to control the shock absorber to brake or release the brake.

[0020] According to one particular embodiment, the shock absorber is hydraulic and the control unit is a valve which can be driven by an electric motor, for example a proportional valve, driven according to the direction of rotation of the rear connecting rod to activate, deactivate or vary the resistance of the brake.

[0021] Preferably, this valve is rotary and positioned, for example, around the second pivot axis, and comprises a first part, such as a rotor linked to the lower articulation element, and a second part, such as a stator linked to the hydraulic damper, the rotor being able to adopt, depending on the position of the rear connecting rod: - a closed position of the rotary valve to brake the flexion of the knee; - an open position of the rotary valve to release knee flexion.

[0022] In this way, the rotary valve is controlled mechanically and achieved by the kinematics of knee flexion movement.

[0023] Thus, in this embodiment, during controlled or pendulum bending, the movement of the rear connecting rod displaces the lower articulation element relative to to the hydraulic damper. In this embodiment, it is this displacement which generates at the lower axis of rotation of the hydraulic damper a rotational movement of the internal part of the valve relative to the external part, to open or close the hydraulic circuit of the rotation resistance control valve.

[0024] This mechanism ensures smooth and controlled movement.

[0025] According to a particular form of implementation: - in the braking position, the third pivot axis is located in front (i.e., on the front connecting rod side) of a hydraulic shock absorber axis that extends between the first pivot axis and the second pivot axis, - in the free flex position, the third pivot axis is located behind (i.e. on the rear connecting rod side) the axis of the hydraulic shock absorber.

[0026] This configuration allows for precise control of knee movement, providing a smooth transition between braking and relaxation phases. The technical effect is a significant improvement in stability and safety during daily activities, reducing the risk of involuntary shifts into a relaxed position.

[0027] Preferably, the deformable parallelogram is designed so that a heel support allows the instantaneous center of rotation of the knee (CIR) to be moved in front of a ground reaction force line, also called the load line, or "GRF" from the English expression "Ground Reaction Force", so as to cause the rear link and the lower articulation element to pivot into the braking position, and that the initiation of the pendulum phase with the knee in full extension and the toes on the ground allows the CIR to be moved in front of the ground reaction force line so as to cause the rear link to pivot into the release position.

[0028] This feature allows for automatic engagement of braking or release in response to the user's natural movements, thus optimizing the device's efficiency while walking.

[0029] According to a preferred embodiment, the control valve rotor is positioned inside the stator, thus minimizing space requirements and optimizing the The mechanism is protected from external elements. This compact and protected design increases the durability and reliability of the prosthesis.

[0030] Finally, the knee according to the invention preferably comprises two parallel front connecting rods and two parallel rear connecting rods, thus reinforcing the stability and robustness of the joint. This design improves the distribution of forces and ensures more uniform and secure operation of the prosthetic or orthotic knee.

[0031] In summary, the invention proposes a prosthetic or orthotic knee joint with an innovative flexion control system, combining natural stable positions, automatic response to walking phases, and increased durability, thus offering an advanced solution for users of prostheses and orthoses. Brief description of the drawings

[0032] [Fig.1] is a perspective view of the prosthetic or orthotic knee according to the invention.

[0033] [Fig.2] is a side view of the knee in Figure 1.

[0034] [Fig.3] is a view similar to that of figure 2, with the rear connecting rod pivoted into a braking position.

[0035] [Fig.4] is a view similar to that of figure 3, in longitudinal section.

[0036] [Fig.5] illustrates in detail the longitudinal section of the control valve in the closed position.

[0037] [Fig.6] is a view similar to that of figure 2, with the rear connecting rod pivoted into a relaxed position.

[0038] [Fig.7] is a view similar to that of figure 6, in longitudinal section.

[0039] [Fig.8] illustrates in detail the longitudinal section of the control valve in the open position.

[0040] [Fig.9] illustrates the phase of walking flat with the knee according to the invention

[0041] [Fig.10] illustrates the phase of walking downhill.

[0042] [Fig.11] illustrates the phase of walking down stairs. Detailed description of the invention

[0043] With reference to figures 1 to 11, the present invention relates to a polycentric prosthetic or orthotic knee (1), designed to offer precise and kinematic (mechanical or electronic) control of flexural resistance, particularly during heel support, descent of stairs or slopes, and the pendulum phase.

[0044] The knee (1) comprises an upper joint element (2) and a lower joint element (3) connected to a prosthetic foot (4) with a toe and a heel (5). In a known manner, a shock absorber (6) is articulated between these two joint elements (2, 3), around a first pivot axis (7) on the upper joint element (2) and a second pivot axis (8) on the lower joint element (3).

[0045] The shock absorber (6) is for example hydraulic and includes a piston (9) which can move inside a hydraulic cylinder (10), by compressing or extending the piston (9).

[0046] When the upper joint element (2) and the lower joint element (3) pivot relative to each other, particularly for the flexion of the knee (1) as such, the piston (9) moves inside the cylinder (10), displacing the hydraulic fluid between two chambers of the cylinder.

[0047] The movement of the piston (9) in the cylinder (10) causes the hydraulic fluid to move through the hydraulic damper (6). The resistance to this fluid movement is controlled by a control element (11), thus adjusting the resistance to knee flexion (1).

[0048] The knee (1) according to the invention comprises at least one rear connecting rod (14) and at least one front connecting rod (15), which are respectively articulated to the upper (2) and lower (3) articulation elements, thus creating a deformable parallelogram. This parallelogram is preferably non-Grashoff, that is to say, it has two stable stop positions.

[0049] The rear connecting rod (14) is articulated, on the one hand, around the upper articulation element (2) and in the illustrated example around the first pivot axis (7) and, on the other hand, to the lower articulation element (3) around a third pivot axis (16).

[0050] The front connecting rod (15) is articulated, on the one hand, to the upper articulation element (2) around a fourth pivot axis (17) and, on the other hand, to the lower articulation element (3) around a fifth pivot axis (18).

[0051] To enhance the stability and robustness of the joint, the system includes two parallel front connecting rods (15) and two parallel rear connecting rods (14), ensuring a homogeneous distribution of forces.

[0052] According to one embodiment of the invention, the control member (11) is a rotary valve positioned around the second pivot axis (8).

[0053] The rotary valve includes, in particular, a rotor (12), integral with the lower articulation element (3), and a stator (13), integral with the hydraulic damper (6). The rotor (12) is capable of adopting different positions depending on the position of the rear connecting rod (14) during the walking phase: - a closed valve position, see figures 3 to 5, with the fluid circulation channel (13a) closed to brake the flexion of the knee (1); - an open valve position, see figures 6 to 8, with the fluid circulation channel (13a) open to release knee flexion (1).

[0054] The rotor (12) of the rotary valve is positioned inside the stator (13) to minimize bulk and protect the internal components of the mechanism, thereby increasing the durability and reliability of the prosthetic joint.

[0055] Thus, the resistance to rotation of the upper articulation element (2) relative to the lower articulation element (3) can be adjusted, mechanically and kinematically, according to the different phases of walking, while rotation in the direction of extension remains, for example, free.

[0056] When the knee (1) is in controlled flexion, it remains controlled until it returns fully to extension, which allows one to approach descents of slopes and stairs in complete safety.

[0057] The knee support phase control (1) according to the invention adapts to all users without the need for adjustments. The brake remains engaged even when the load is removed.

[0058] Depending on the phase of travel, the rear connecting rod (14) can adopt: - a braking position, particularly during heel support (5), where it pivots in a first direction, specifically counterclockwise relative to the upper articulation element (2) in the illustrated embodiment, causing the lower articulation element (3) to pivot clockwise relative to the axis (8) of the rotating control valve (11), thus causing the valve (11) to close to brake knee flexion (1), and - a position of relaxation, particularly during the pendulum flexion phase, where it pivots in a second opposite direction, here a clockwise direction, causing the lower articulation element (3) to pivot in a counterclockwise direction relative to the axis (8) of the rotating control valve (11), which causes the valve (11) to open to release the flexion of the knee (1).

[0059] In the braking position, the third pivot axis (16) of the rear connecting rod (14) is located in front of the axis of the hydraulic damper (6), on the side of the front connecting rod (15), causing the rotor (12) to pivot towards the closed position of the valve (11). Conversely, in the release position, the third pivot axis (16) moves behind the axis of the hydraulic damper (6), causing the rotor (12) to pivot towards the open position of the valve (11).

[0060] In practice, the deformable parallelogram of the knee (1) according to the invention is preferably designed so that, when the CIR (19) is moved in front of a line of direction of the ground reaction force (GRF) with a heel support (5), this causes the rear connecting rod (14) and the lower articulation element (3) to pivot into the braking position.

[0061] When the CIR (19) is moved in front of a line of direction of the ground reaction force (GRF), heel (5) raised and in full extension, the engagement of the femur causes the rear connecting rod (14) and the lower articulation element (3) to pivot into the release position, i.e. free flexion.

[0062] The "front" or "back" positions of the CIR (19) are to be interpreted in relation to the anatomical positions, either on the side of the front connecting rod (15) or on the side of the rear connecting rod (14).

[0063] Thus, the invention allows, during the descent of a slope or stairs, the knee (1) to be kept braked since it does not return to full extension.

[0064] Furthermore, in the phase of the descent of a slope or stairs, in the event of a collision with an obstacle in the pendulum phase, the knee (1) remains braked and, in the phase of the descent of stairs, the fact of putting the foot (4) down with a knee (1) which has not returned to extension is not problematic since the knee (1) is still braked.

[0065] Furthermore, in a standing position with the knee (1) extended and the user leaning forward, the knee (1) remains locked in extension because the center of rotation (CIR) (19) of the knee (1) is located behind the knee joint. In particular, the anterior and posterior connecting rods are parallel when the prosthesis is supported on the forefoot and in hyperextension.

[0066] The invention also allows the user to ride a bike without changing the locking mode of his prosthetic or orthotic knee (1).

[0067] During running (4), flexion is slowed with cushioning during support.

[0068] Furthermore, the non-Grashoff parallelogram of the knee (1) according to the invention is preferably specially designed to offer two stable stop positions: one in maximum knee flexion (1) and the other in maximum extension during forefoot stance. The stop position in maximum flexion corresponds to a rotation of the upper joint element (2) relative to the lower joint element (3) by an angle between 120° and 180°, or even more, ensuring natural locking without the addition of further mechanical stops. This configuration effectively stabilizes the knee (1) in extension during heel strike (5), and in maximum flexion during transfer phases, such as kneeling (1) or standing up.

[0069] Figures 9 to 11 describe the functioning and behavior of the knee (1) according to the invention in different phases of walking.

[0070] Figure 9 illustrates the flat walking phase:

[0071] (A): At heel support (5), the GRF passes behind the CIR (19), causing the rear connecting rod (14) to pivot counterclockwise relative to the axis (7), simultaneously causing the lower articulation element (3) to pivot clockwise, and thus moving the control valve (11) to the closed position. The knee (1) is therefore in controlled flexion.

[0072] (B): When the user moves forward, the GRF moves and passes in front of the CIR (19), which brings the knee (1) back into extension.

[0073] (C): The user continues to move forward, the front and rear connecting rods pivot forward and the CIR (19) moves away towards the ground, to infinity.

[0074] (D): Then the CIR (19) returns from above near the hip joint.

[0075] (E): Then the user brings their leg back into extension, engages their femur, the CIR (19) passes in front of the GRF, the control valve (11) is opened and the brake deactivated, it is possible to flex the knee (1) and initiate the pendulum phase. In this movement, the rear connecting rod (14) pivots clockwise relative to the upper articulation element (2), in the relaxed position.

[0076] (F): Knee flexion phase (1) and toe lifting phase (4).

[0077] Figure 10 illustrates the downhill walking phase:

[0078] (A1): At heel support (5), the GRF passes behind the CIR (19), which causes the rear connecting rod (14) to pivot counterclockwise, simultaneously causing the lower articulation element (3) to pivot clockwise, and thus moving the control valve (11) to the closed position. The knee (1) is therefore in controlled flexion.

[0079] (B1): When the user moves forward, the GRF remains behind the CIR (19), the user descends on his knee (1) in controlled flexion.

[0080] (C1): The user continues to move forward on their knee (1) in controlled flexion, until the toe of the foot (4) lifts off.

[0081] (D1): The user puts weight on their other leg and the knee (1) returns to extension, but remains braked because the knee (1) does not return to full extension.

[0082] (E1): Then the user places the heel (5) on the ground, the knee (1) is still in controlled flexion because the GRF remains behind the CIR (19).

[0083] Figure 11 illustrates the phase of walking down stairs:

[0084] (A2): With heel support (5), the GRF passes behind the CIR (19), the knee (1) is therefore in controlled flexion.

[0085] (B2): When the user moves forward, the GRF remains behind the CIR (19), the user descends on his knee (1) in controlled flexion.

[0086] (C2): The user continues to move forward on their knee (1) in controlled flexion, until they leave walking.

[0087] (D2): The user puts weight on their other leg and the knee (1) returns to extension, but remains braked because the knee (1) does not return to full extension.

[0088] (E2): Then the user places the heel (5) on the ground, the knee (1) is still in controlled flexion because the GRF remains behind the CIR (19).

[0089] It follows from the above that the knee (1) according to the invention ensures precise and responsive control of knee (1) movements, in particular when walking or going down slopes or stairs.

[0090] According to the invention, the brake is actuated mechanically and kinematically depending on the phase of walking, with two different flexion situations, one for the heel support (5) which triggers the brake, and the other for the pendulum flexion phase which releases the brake.

Claims

Demands 1. Polycentric prosthetic or orthotic knee (1) comprising: - a superior articulation element (2); - a lower joint element (3) connected to a prosthetic foot (4) with a heel (5); - a shock absorber (6) articulated on one side to the upper articulation element (2) around a first pivot axis (7) and, on the other side to the lower articulation element (3) around a second pivot axis (8), and comprising a control member (11) adjusting, according to the phase of walking, the resistance of the shock absorber during the rotation of the upper articulation element (2) relative to the lower articulation element (3); - at least one rear connecting rod (14) articulated, on the one hand, around the upper articulation element (2) and, on the other hand, to the lower articulation element (3) around a third pivot axis (16); - at least one front connecting rod (15) articulated, on the one hand, to the upper articulation element (2) about a fourth pivot axis (17) and, on the other hand, to the lower articulation element (3) about a fifth pivot axis (18); so as to define a deformable parallelogram between the upper articulation element (2), the front connecting rod (15), the lower articulation element (3), and the rear connecting rod (14); the deformable parallelogram constituting the polycentric system of the knee; characterized in that the deformable parallelogram is designed so that, during flexion of the knee, the rear connecting rod (14) can adopt two different pivoted positions depending on the phase of gait, of which: - a braking position, pivoted in a first direction, directly or indirectly actuating the control organ (11) to brake the flexion of the knee (1); - a free flexion position, pivoted in a second direction opposite to the first direction, directly or indirectly actuating the control organ (11) to release the flexion of the knee (1).

2. A polycentric prosthetic or orthotic knee (1) according to claim 1, characterized in that the shock absorber is hydraulic and the control member (11) is a rotary valve preferably positioned around the second pivot axis (8), and comprises a rotor (12) linked to the lower articulation element (3) and a stator (13) linked to the hydraulic shock absorber (6), the rotor (12) being able to adopt, depending on the position of the rear connecting rod (14): - a closed position of the rotary valve to brake the flexion of the knee (1); - an opening position of the rotary valve to release knee flexion (1).

3. Polycentric prosthetic or orthotic knee (1) according to any one of the preceding claims, characterized in that: - in the braking position, the third pivot axis (16) is located in front of an axis of the hydraulic shock absorber (6) which extends between the first pivot axis (7) and the second pivot axis (8), - in the free flexing position, the third pivot axis (16) is located behind the axis of the hydraulic shock absorber (6).

4. Polycentric prosthetic or orthotic knee (1) according to any one of the preceding claims, characterized in that the deformable parallelogram is designed so that a heel support (5) allows the instantaneous center of rotation (CIR) of the knee (1) to be moved in front of a ground reaction force line (GRF) so as to cause the rear connecting rod (14) to pivot in the braking position, and that the initiation of the pendulum phase with the knee (1) in full extension and the toes on the ground allows the instantaneous center of rotation (CIR) of the knee (1) to be moved in front of the ground reaction force line (GRF) so as to cause the rear connecting rod (14) to pivot in the release position.

5. Polycentric prosthetic or orthotic knee (1) according to any one of claims 2 to 4, characterized in that the rotor (12) of the control valve (11) is positioned inside the stator (13).

6. Polycentric prosthetic or orthotic knee (1) according to any one of the preceding claims, characterized in that it comprises two parallel front connecting rods (14) and two parallel rear connecting rods (15).

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