PROSTHESIS FOR ABOVE-HIGH AMPUTS

Description

Domaine technique de l'invention

[0001] The present invention relates to the field of knee prostheses for femoral amputees, and more particularly to fully mechanical knee prostheses, that is to say without any sensor and / or electronic control system. État de la technique

[0002] To better simulate the joint of a healthy knee, recent developments have focused on equipping prostheses with sophisticated embedded electronic systems for determining and controlling the flexion of the tibial component relative to the femoral component, based on position and acceleration data obtained using various sensors. A drawback of this type of solution is the need for particularly efficient processors to handle the sensor data and implement relatively complex algorithms designed to ensure the wearer's stability while reproducing the most natural leg movement possible.On the one hand, this type of solution proves particularly expensive to ensure a consistently short response time for the system; on the other hand, it consumes a significant amount of energy and requires frequent replacement or recharging of the batteries that power it; finally, an electronic failure could prove catastrophic for the wearer of the prosthesis.

[0003] The applicant's patent document EP2015711 consists of an example of such a solution equipped with electronic means, using a sensor placed at the level of the foot and an angular sensor at the level of the knee joint, as well as a processor to process the sensor data.

[0004] US patent document 2003 / 125814 relates to another articulated prosthesis solution using a piston whose resistance properties at the joint between the femoral and tibial part are determined by the results of the analysis of a sensor.

[0005] Since the late 1960s, however, other types of prostheses have become known, which are entirely mechanical, meaning they require no sensors or electronic systems, and therefore no electrical power supply. These prostheses, which primarily use a piston, preferably hydraulic, simulating the muscle group associated with them, particularly the quadriceps, are often called "swing and stance" prostheses because they operate alternately in a weight-bearing mode – "stance," where resistance to flexion is high – and an oscillating mode – "swing," where joint resistance is reduced and the leg can thus bend more easily, for example, when taking a step, following the push-off phase of one leg and bringing it forward. As explained in the scientific article: Mauch - Stance Control for AK Prosthesis, Bulletin of Prosthetics Research / Fall 1968 , Apart from the user's deliberate locking of the prosthesis in weight-bearing mode to prevent imbalance, several control mechanisms automatically manage its alternating activation during normal gait. These include "heel control," based on heel strike detection, with a default non-weight-bearing mode; "toe control," based on foot flexion and / or pressure detection on the forefoot, with a default weight-bearing mode; and "weight control," which detects the application of compressive force on the prosthesis and whose operation is relatively similar to that of "heel control." However, none of these mechanisms has proven suitable for tasks such as descending stairs, making their use rather impractical.

[0006] To address this issue and improve user comfort in as many real-life situations as possible, including descending stairs, an alternative system, known as "hyperextension control," has been proposed. This control mechanism is load-bearing by default when weight is applied to the prosthesis, corresponding to heel strike, but activates the swing phase when the leg is fully extended, that is, when the tibial component is substantially aligned with the femoral component of the prosthesis. In other words, a release mechanism allowing easier leg flexion is theoretically only possible at the end of the push-off phase, and never at any other time.A re-extension of the leg is also permitted, to perform the usual oscillation of the tibial part of the leg, when a step is taken, from a slightly bent position at the moment when the foot is no longer in contact with the ground, thanks to the action of a valve which is only intended to close when a weight is applied to the prosthesis, and is therefore in an open position at that moment.

[0007] One drawback of this type of prosthesis described above is that there is a risk of unlocking the weight-bearing mode during an involuntary extension of the leg, which could then cause it to fall.

[0008] Therefore, there is a need for a solution free from these known limitations.

[0009] Patent document US6159248 also relates to a prosthesis for a transfemoral amputee containing a knee joint equipped with a locking system that allows switching from a weight-bearing mode to an oscillating mode when the heel is lifted off the ground. No shock-absorbing system is provided, however, but simply a locking / unlocking mechanism to activate the oscillating phase. Summary of l'invention

[0010] One aim of the present invention is to provide a prosthesis with improved reliability, while maintaining reduced manufacturing and labor costs.

[0011] According to the invention, these goals are achieved through the articulated linkage device for femoral amputee prosthesis according to claim 1, and in particular the characteristics of the characterizing part thereof, i.e. a fully mechanical locking system, arranged to allow the activation of the second mode of operation - where the resistance value corresponds to a second minimum value, as opposed to the modular one, easily adaptable to most existing pistons intended for "swing and stance" (SNS) type prostheses, without requiring structural modifications or significant additional arrangements on the prosthesis.

[0012] According to a preferred embodiment, the secure switching device is also adjustable, in order to adapt as best as possible to the gait of the prosthesis wearer and thus to maximize the reliability of stability when the heel strikes the ground. Brève description des dessins

[0013] Other advantageous features will become clearer from the following description of a particular embodiment of the invention given by way of non-limiting example and represented by the accompanying drawings, in which: there figure 1 illustrates a prosthesis known from prior art; the figure 2 illustrates the detail of the piston valve control mechanism of such a prosthesis, according to the prior art; the figure 3 illustrates a schematic diagram showing the different possible configurations for the prosthesis; the figure 4A illustrates a schematic view of a prosthesis according to the invention, in a first operating position, in wearer mode. figure 4B illustrates a schematic view of a prosthesis according to the invention, in a second operating position, still in wearer mode. figure 4C illustrates a schematic view of a prosthesis according to the invention, in a fourth operating position, still in wearer mode. figure 4D illustrates a schematic view of a prosthesis according to the invention, in a fifth operating position, in which the weight-bearing mode has been switched to oscillation mode. figure 5 is a cross-sectional view of a modified pendulum for switching between the support mode and the oscillation mode of the prosthesis according to a first preferred embodiment of the invention. figure 6 is a cross-sectional view of a modified pendulum for switching between the support mode and the oscillation mode of the prosthesis according to a second preferred embodiment of the invention. figure 7 is an illustration of a modified pendulum for switching between the support mode and the oscillation mode of the prosthesis according to a third preferred embodiment of the invention. Description détaillée

[0014] There figure 1 is a profile view of a "Swing and Stance" type prosthesis, which will be referred to hereafter simply as an "SNS" prosthesis.

[0015] The prosthesis 1 classically comprises a femoral part 101, terminating the thigh, and intended to be fitted onto the amputee's residual limb, as well as a tibial part 102 replacing the amputee's leg, and a foot part 104 replacing the amputee's foot, in order to provide support on a surface 5, typically the ground. To ensure an articulated connection between the femoral part 101 and the tibial part 102 of the prosthesis, the intermediate knee part 103 that connects them includes an articulated linkage device 2 simulating this joint by providing a limited degree of rotational freedom between a first position P0 of hyperextension, in which the femoral part 101 and the tibial part 102 extend substantially in line with each other, and a second position P1 of maximum flexion, illustrated later in the diagram. figure 3 in which the femoral part 101 and the tibial part 102 form a predefined maximum angle of flexion. The articulated joint device 2 is also arranged asymmetrically, just like a healthy knee, and flexion is only possible in a single given direction of rotation.

[0016] Prosthesis 1 shown on the figure 1 also potentially includes an ankle-type joint 105 between the foot part 104 and the tibial part 102; however, the articulated linkage device 2 according to the present invention, described below, does not require such a joint at the foot and would also work with a prosthesis 1 which would lack it.

[0017] The articulated linkage device 2 of the prosthesis also includes a shock-absorbing mechanism 200, here in the form of a piston, intended to oppose a predetermined and variable resistance to the prosthesis 1, in order to replace the thigh and leg of the amputee in the most realistic way possible, while systematically ensuring stability to the wearer of the prosthesis each time a weight is applied to it.For this purpose, the piston is capable of being switched between a first operating mode M1, selected by default, in which the resistance value is fixed at a first maximum value (Vmax), which therefore corresponds to the so-called "carrier" mode and, a second operating mode M2, in which the resistance value is fixed at a second minimum value (Vmin), and which therefore corresponds to the so-called "oscillation" mode, which is only supposed to be actuable in the first hyperextension position P0, in which the prosthesis is represented on the . figure 1 In this figure, the prosthesis 1 is shown resting on the front part of the foot 104, that is, just before this foot leaves the ground when a step is taken. The prosthesis 1 is thus slightly inclined forward, and the angle formed between the tibial part 102 of the prosthesis 1 and the vertical forms a first predetermined oriented angle X1 greater than or equal to 0 in the direction of walking S, which corresponds to the sum of the second predetermined oriented angle X2 formed between the piston and the vertical and the angle between the piston and the tibial part Θ, usually a few degrees, at most 5 to 10 degrees.

[0018] A major objective of the present invention is to allow switching from the first operating mode M1 to the second operating mode M2 ​​of such a prosthesis 1 only in a situation corresponding to that schematically illustrated by the figure 1 that is to say, in a situation where the prosthesis 1 is indeed in hyperextension, but where the leg is also slightly inclined forward in the direction of walking S, in order to preemptively avoid any premature triggering of the oscillation mode, particularly during heel strike or during a backward imbalance of the prosthesis wearer. The sequence of a step with a prosthesis 1 equipped with the articulated linkage device 2 according to the invention is described by the series of figures 4A,4B,4C,4D .

[0019] There figure 2 illustrates a standard switching system 20 implemented in the piston of a prosthesis 1 SNS for switching from the support mode to the oscillation mode, i.e. from the first operating mode M1, chosen by default, to the second operating mode M2. The piston includes, pivotally mounted on its axis 21A disposed on the axis AA of the piston, a pendulum 21 which acts as a non-return valve for the valve 23 during the oscillation mode, in which the piston is represented in this figure, thanks to the stop portion 210 which cooperates on the stem 230 of the valve 23.When the prosthesis is in the first hyperextension position P0, a force F is exerted by a protruding portion on the edge of the piston and tilts the counterweight 22, mounted pivoting around its axis 22A offset from the axis AA of the piston, which releases the pendulum 21 previously held and by default in a locked position, allowing the closure of the valve 23, guaranteeing maximum resistance.The position of the pendulum 21, suspended vertically but now not blocked by the counterweight 22, is such that the resistance of the damping mechanism 200 formed by the piston is switched to a minimum value Vmin, because despite the hydraulic pressure H exerted on the valve 23 in the direction of the arrows directed from bottom to top due to the weight exerted on the prosthesis, the latter can no longer close and the passage of fluid at the level of the orifices usually blocked by the valve 230 in carrier mode reduces by that much the resistance exerted by the damping mechanism 200.

[0020] There figure 3 This diagram schematically illustrates the different parts of a prosthesis and the various relative angles between the femoral part 101 and the tibial part 102 of the prosthesis around the knee part 103 designed to replace this joint. As can be seen in this figure, in the first hyperextension position P0, the angle between the tibial part 102 and the femoral part 103 is a straight angle, that is, approximately 180 degrees. In practice, depending on the model, the angle between these two parts may deviate slightly from this, preferably being a few degrees greater than this straight angle in the hyperextension position so that the wearer of the prosthesis 1 can easily see that it is in a pivotal position allowing the release of the weight-bearing mode, that is, enabling the switch to the oscillation mode.

[0021] There figure 3 The diagram also schematically shows the second flexed position P1 of the prosthesis, here at a maximum flexion angle of approximately 90 degrees; however, this angle can be adjusted as needed. A third intermediate position P2 can also be observed, which deviates slightly, by a few degrees, from the first extension position. The angular difference α between these two positions, that is, the first hyperextension position P0 and the third intermediate position P2, is usually only a few degrees at most, and this angular travel corresponds to the additional advancement of the piston once a resistance threshold due to a spring, typically a Belleville spring, has been overcome, thus allowing the force F to be exerted. figure 2 on the peripheral part of the counterweight 22 to make it tilt and release the pendulum 21. In other words, the magnitude of the force F must exceed a predetermined threshold inherent in this spring, which also provides a "click" effect allowing the user to determine whether the second operating mode M2 ​​of oscillation is activatable or not.

[0022] In what follows, we will refer to the series of Figs 4A-4D which illustrate different positions and configurations of a prosthesis 1 modified according to a preferred embodiment of the invention when a step is taken. Although these steps are intended to approximate as closely as possible what theoretically occurs with a healthy knee, it will nevertheless be noted that the sequence is slightly modified, since it is necessary to manage a switching step between the different resistance modes, whereas the quadriceps muscle group allows this resistance to be managed continuously. Furthermore, since all references relating to the various constituent elements of the prosthesis 1 illustrated schematically are identical, they will not be repeated in detail for each of these figures.

[0023] There figure 4A This shows the first step taken during a gait, that is, when the heel of the foot is placed on the ground. In this configuration, the tibial part 102 forms an oriented angle of -x° with respect to the vertical, and only the rear of the foot part 104 rests on the ground, while the femoral part 101 is not yet fully aligned with the tibial part 102 at the joint formed by the knee part 103. The prosthesis 1 is then typically in the third intermediate position P3, in which the second operating mode M2 ​​of oscillation is not yet activable.

[0024] Next, as illustrated in Figure 4B, by bracing against the heel of prosthesis 1, one can move into the first hyperextension position P0 by applying slight pressure to the rear of the thigh stump, in the opposite direction to the direction of travel S, so that switching to the oscillation mode is possible. The angle of the tibial part 102 relative to the ground remains unchanged and still forms an oriented angle of -x° with respect to the vertical. In such a configuration, although the second oscillation operating mode M2 ​​is theoretically activatable due to the hyperextension position P0 in which prosthesis 1 is located, no switching is possible due to the locking system 3 described later in the diagram. figures 5 à 7 .

[0025] Next, as illustrated in the following figure 4C, the prosthesis 1 remains in the first hyperextension position P0, but it is tilted forward in the direction of travel S, while the foot portion 104 is fully in contact with the ground, such that the angle between the tibial portion 102 and the vertical relative to the ground is reduced to approximately 0 degrees. Due to the locking system 3, switching from weight-bearing mode to swinging mode is always inoperative.

[0026] It was only during the last sequence shown on the figure 4D that the switch will be possible. The prosthesis 1 is then still in the first hyperextension position P0, but continues to tilt forward in the direction of travel S, such that now only the toes are in contact with the ground and the angle between the tibial part 102 and the vertical relative to the ground exceeds a positive angle of +x° relative to the vertical. Only from this point is the switch from the first weight-bearing mode, where the resistance of the damping device 200 consisting of the piston is at its maximum (value Vmax), to the second operating mode M2, where the piston resistance is at its minimum (value Vmin), and the tibial part 102 can oscillate backward.

[0027] Thus, the locking device 3 ensures that in the configuration illustrated by the figures 4B et 4C These intermediate stages following heel strike ensure that no malfunction can now occur in terms of the prosthesis switching unexpectedly from one operating mode to another. With previous prostheses, such an issue could arise depending on the wearer's gait and the timing of hyperextension, as no locking or unlocking mechanism was available to provide additional safety. Furthermore, even if the wearer of prosthesis 1 loses their balance backward and the counterweight is involuntarily unlocked while moving into the first hyperextension position (P0), switching to the oscillation mode will not be possible.

[0028] Thus, according to the invention, additional safety is provided compared to existing prostheses, making the possibility of switching from one operating mode to the other conditional on the value of the angle formed by the tibiable part 102 with respect to the vertical. Several variants will be described below, illustrated in particular by the figures 5 à 7 relating to a preferred embodiment for the implementation of the locking device 3 according to the invention, which is incorporated into a piston acting as a damping mechanism 200, and involving a modified pendulum whose center of gravity has been offset relative to the axis of this piston to constitute a modified switching system. Such a variant involves only minimal structural modifications compared to an existing SNS prosthesis and therefore greatly facilitates the implementation of the locking system 3, without requiring the addition of a dedicated system fulfilling the new safety requirement. Furthermore, the ergonomics of the prosthesis are not affected, as no special modifications are required apart from the piston, which also minimizes the constraints in terms of the required volume.

[0029] According to the preferred embodiment illustrated by the figures 5 à 7 , it can be observed that the piston switching device 20 used as a shock-absorbing mechanism 200 includes functional elements similar to those of a standard switching system 20, namely a pendulum cooperating alternately on the one hand with a counterweight in the first operating mode (M1), and on the other hand with the valve in the second operating mode (M2); nevertheless the modification of the structure of these elements gives them different physical properties altering the activation conditions of switching from the carrier mode, which is the default operating mode to the oscillation mode, without however calling into question the need to be in a hyperextension position P0 of the prosthesis to make such switching possible.

[0030] The same physical principle that applies to all these embodiments is to "delay" the action of the pendulum on the valve when a step is taken, so that its non-return valve function is only activated when the tibial part 102 has already tilted in the direction of travel S. Thus, the center of gravity of the pendulum at rest and suspended from the vertical is preferably offset, in various ways, slightly backward, in the opposite direction of travel S', relative to the axis AA of the piston, so that its function can preferably only be activated when a certain predetermined angle of inclination forward, i.e., in the direction of travel S, is exceeded for the tibial part 102. Due to the angular offset between the piston and the tibial part 102, this corresponds in practice to a condition of exceeding another predetermined angle of inclination determined by the relation: x > X 1 = X 2 + Θ ,

[0031] Where x is the current angle of the tibial part 102 of the prosthesis 1 with respect to the ground, X1 a first predetermined oriented angle in the direction of walking and X2 a second predetermined oriented angle in the direction of walking which is deduced directly from the first.

[0032] To reflect physical realities, in practice, the first predetermined oriented angle will preferably be between 0° and 5°, and this angle will preferably be adjustable to adapt as precisely as possible to the gait of the prosthesis wearer. However, it will be understood that other angular values ​​are possible without departing from the scope of the present invention.

[0033] In what follows, given that the piston body and many different components of the locking system 3 are identical for the figures 5 , 6 And 7Not all the elements common to these figures will be described in detail for each of them.

[0034] There figure 5 This describes a preferred embodiment for the locking system 3 integrated into a modified switching system 20' of a conventional SNS piston, comprising a modified pendulum 31 of substantially tapered and arched shape, much simpler to machine than the potato-shaped one usually employed for such a pendulum. The modified pendulum 31 is pivotally mounted about a pivot axis 31A offset rearward relative to the axis AA of the piston, i.e., in the opposite direction of travel S', such that its center of gravity is offset accordingly and requires a more pronounced forward inclination of the piston, i.e., in the direction of travel S, in order for it to fulfill its function as a check valve for the valve 23.

[0035] As on the figure 2 As described previously, the piston still acts as a shock-absorbing mechanism 200 which still includes a valve 23 with a rod 230 at its upper end, cooperating with a stop portion 310 arranged on the lower end of the modified pendulum 31, while an internal bearing surface 311 is provided to allow the end of a counterweight, which here takes the form of a straight lever 32 pivoting around its pivot axis 32A arranged on the front of the piston, i.e. in the direction of travel S relative to the axis AA of the latter, to come to rest on a lower portion of the pendulum to lock it in a position where the return of the valve is never prevented.The modified switching mechanism 20' of the shock-absorbing mechanism 200 is shown in a hyperextension position P0 of the prosthesis, i.e., where the change in operating mode is activatable due to the raised position of lever 32 through the action of force F at its other end. This allows the rocking motion of lever 32, illustrated by the arrows, between its rest position and the disengaged position as shown in the figure. figure 5 , a clearance 312 is provided on the internal surface of the modified pendulum 31, so that no additional arrangements are necessary apart from the volume of the piston.

[0036] As can be seen on the figure 5 , the modified pendulum 31 is furthermore arranged at the end of a first articulated arm 33, whose pivot axis 33A is located on the axis AA of the piston, and whose rearward offset position in the opposite direction of travel S' can be adjusted using an adjustment device 4 comprising an adjustment screw 41 arranged along the axis AA and which is connected, at its lower end, to a second articulated arm 36 whose pivot axis 36A is also located on the axis AA of the piston.The relative lengths of the different articulated arms—that is, the length of the first articulated arm 33 and the length of the second articulated arm 36—and the pitch of the adjusting screw 41 are preferably configured such that switching to the second operating mode M2, i.e., the oscillation mode of the prosthesis 1, can only be triggered when the tibial part 102 of the prosthesis is tilted forward in the direction of travel S by a few degrees. The adjustment can be made continuously over a range of minimum tilt angle values ​​that determine the triggering threshold, corresponding to the first predetermined oriented angle X1, which is preferably strictly positive to ensure the desired additional safety condition, and preferably between 0° and 5°.The illustrated preferential adjustment device 4 thus manages the value of the first predefined oriented angle (X1) as the activation threshold for switching to the oscillation mode via the offset of the pivot axis 31A of the modified pendulum 31 relative to the piston axis. According to the illustrated embodiment, the relationship between the offset value relative to the piston axis AA in millimeters and the additional inclination value required to enable switching is not linear; for example, it was found that an offset of the pendulum axis 31A of 2.8 mm set the value of the first predefined oriented angle X1 to +2°, while an offset of the pendulum axis 31A of 3.8 mm set the value of the first predefined oriented angle X1 to +5°.We can therefore assume that the adjustment is finer the closer we set the inclination to the vertical, i.e. at the beginning of the latter when the pivot axis 31A of the pendulum is almost located on the axis of the piston AA, and the granularity decreases as we progress in the setting of the trigger threshold for switching.

[0037] Furthermore, in order to maintain the stop portion 310 in the blocking position vis-à-vis the stem 230 of the valve 23 even when the trigger threshold allowing switching to the oscillation mode is exceeded, a limit stop 37 is provided to limit the amplitude of the pivoting of the modified pendulum 31 forward, i.e. in the direction of travel S, and thus ensure that it can never return to a position where the return of the valve 23 would no longer be prevented once this inclination threshold has been exceeded; indeed this would then have the consequence of switching the articulated linkage device 2 back into the carrier mode, which is obviously not desirable. Such a limit stop 37 can also be useful in the event of a sudden forward movement which would generate a strong oscillation of the modified pendulum 31 in the direction of travel S and could bring it beyond the desired blocking position preventing the return of the valve 23 of the piston.

[0038] There figure 6 represents a modified switching device 20' according to an implementation variant in which the modified pendulum 31, instead of having a pivot axis 31A offset relative to the axis of the piston AA, as in the figure 5 In order to shift the center of gravity of the pendulum rearward—that is, in the opposite direction of its movement S'—it now includes an unbalanced weight, i.e., a weighted portion 35. While the technical effect obtained in terms of shifting the pendulum's center of gravity is indeed the same, no dynamic adjustment is possible with this variant as illustrated. Since the geometric shape, the arrangement of the weighted portion 35 on the pendulum, and / or the intrinsic modification of the pendulum's shape, as well as the weight of this weighted portion, can influence this shift, it will be understood that a multitude of variations are possible without departing from the scope of the present invention. To provide a preliminary adjustment, even a static one, and a certain degree of precision in the adjustment, weights of varying sizes can be used, and insertion points can be provided on the modified pendulum 31.

[0039] Furthermore, due to the increased inertia of the modified pendulum 31, a second stop 38 is provided, in addition to the end-of-travel stop 37, but this time to limit the amplitude of oscillation of the modified pendulum 31 backwards, i.e. in the opposite direction to the movement S'. This second stop 38 thus makes it possible to compensate for or minimize the inertial effects of the modified pendulum 31 within the framework of a dynamic modeling, the trigger thresholds for activating the change of operating mode, i.e. the first predetermined oriented angle X1 of inclination of the tibial part being otherwise determined by static balancing considerations.

[0040] There figure 7 relates to another preferred embodiment of the invention, still integrating the locking device 3 into the switching system 20 of an SNS piston, thus forming a modified switching system 20'. According to this variant, the modified pendulum 31 is mounted on a tiltable support 39, the position of which controls the radial offset of the position of its pivot axis 31A relative to the axis of the piston 31, similarly to the variant illustrated in the figure 5 previously described where a system of articulated arms was used for this purpose. To perform the adjustment, an adjustment device 4 with a screw 41, arranged along the axis of the piston AA, is still used, but which is now equipped with a tapered pusher head 42 bearing against an adjustment pin 391 fixed to the support 39. Thus, when the pusher head 42 is moved downwards, the support 39 is inclined backwards, i.e. in the opposite direction of travel S', as is the pivot axis of the modified pendulum 31.

[0041] Furthermore, the locking system 3 is now equipped with a gear mechanism 34 to obtain a reduction ratio between the pivoting of a mobile 343, mounted for rotation on the axis of rotation of the piston AA, and that of the modified pendulum 31, in order to slow its return when it tends to be brought into the position where the valve's return is blocked. As illustrated in the figure 7The modified pendulum 31 is mounted to pivot about its pivot axis 31A, but is rotationally fixed to a part having a first toothed portion 341, which meshes with a second toothed portion 342, which is rotationally fixed to the moving part 343, whose rotation axis 343A is here placed directly on the piston axis. The inertia of the moving part 343 is preferably chosen to be much greater than that of the modified pendulum 31, so that it is the movement of the moving part 343 that causes that of the pendulum, and not the other way around; Furthermore, the gear ratio, for example of 2:1 between the number of teeth of the second toothed portion 342 attached to the mobile 343 and that of the first toothed portion 341 attached to the modified pendulum 31 is chosen to confer a lever effect on the rotation of the modified pendulum 31, slowing down the amplitude of the pivoting of the latter according to the proportions of the gear ratio.By adjusting the gear parameters, we can thus adjust the first predetermined oriented angle X1 desired allowing the activation of the second operating mode M2, i.e. the transition from carrier mode to oscillation mode.

[0042] It will be understood from the preceding detailed description that the embodiments are given by way of example only, and are not intended to be exhaustive for determining the scope of protection for the present invention. In particular, although presented in a preferred variant as a module integrable into a conventional SNS piston, the solution according to the invention is also compatible with the development of an integral system, including a new piston. Furthermore, the advantageous features derived from the preferred embodiments described may be considered individually or in combination, particularly with regard to the offset of the pivot axis 31A of the modified pendulum 31, the presence or absence of a weighted portion 35, and that of a gear mechanism 34.

Claims

1.

1. Hinged connecting device (2) for a prosthesis (1) for a femoral amputee, the said prosthesis (1) comprising at least: - a femoral part (101) ending the thigh of the amputee; - a tibial part (102) replacing the leg of the amputee; - an intermediate knee part (103) connecting the femoral part (101) to the tibial part (102); - a foot part (104) replacing the foot of the amputee, with a view to ensure taking support on a support surface (5); the said hinged connecting device (2) being configured to be integrated in the said intermediate knee part (103) in such a manner as to ensure an articulated connection between the said femoral part (101) and the said tibial part (102) of the said prosthesis (1) between: - a first position (P0) of hyperextension, in which the said femoral part (101) and the said tibial part (102) extend substantially in the extension one from the other, and - a second position (P1) of maximal bending, in which femoral part (101) and the said tibial part (102) form a predetermined maximal flexion angle, the hinged connecting device further comprising a damping mechanism (200) intended to counter a predetermined resistance at least during the bending of the said prosthesis (1), by replacing the muscle groups usually used for this purpose, the said damping mechanism (200) being capable of being switched between: - a first operating mode (M1), selected by default, in which the value of the resistance corresponds to a first maximum value (Vmax), and - a second operating mode (M2), able to be actuated only in the first position (P0) of hyperextension, in which the resistance value corresponds to a second minimum value (Vmin); the said hinged connecting device (2) moreover comprises a fully mechanical locking system (3), incorporated into a piston acting as damping mechanism (200), the said locking system (3) being designed to permit the activation of the said second operating mode (M2) only from a certain inclination of the said tibial part (102), corresponding to a first predetermined oriented angle (X1) with respect to the vertical in the direction of walking (S), characterized by the said locking system (3) comprising a modified pendulum (31) of a modified switching system (20'), capable of co-operating alternatively with a counterweight (32) in the first operating mode (M1), and with the valve (23) of the piston in the second operating mode (M2), the said modified pendulum (31) comprises a weighted part (35) shifting the center of gravity of the pendulum in the reverse direction of walking (S') with respect to the axis of the piston (A-A), and / or being connected kinematically to a gearing system (34), and / or having a pivot axis (31A) offset with respect to the axis of the piston (A-A).

2. Hinged connecting device (2) according to claim 1, the said first predetermined oriented angle (X1) being greater than or equal to 0 in the direction of walking (S).

3. Hinged connecting device (2) according to claim 1, wherein the said the modified pendulum (31) is configured in such a way that the resistance of the damping device (200) is locked in the first operating mode (M1) as long as the inclination of the axis of the piston does not exceed a second predetermined oriented angle (X2) with respect to the vertical derived directly from the said first predetermined oriented angle (X1) as a function of the angle (Θ) formed between the said tibial part (102) and the said piston.

4. Hinged connecting device (2) according one of the preceding claims, characterized in that it further contains an adjustment device (4) for adjusting the value of the said first predetermined angle (X1).

5. Hinged connecting device (2) according to claim 4, the said adjustment device (4) acting upon the positioning of the pivot axis (31A) of a modified pendulum (31).

6. Hinged connecting device (2) according to claim 5, the said adjustment device (4) comprising a screw (41) actuating a system of articulated arms, one end of which bears the said pivot axis (31A) of the modified pendulum (31).

7. Hinged connecting device (2) according to one of the claims 1 to 6, wherein the modified pendulum (31) is of substantially arched shape and comprises a clearance (312) on its inner surface in order to permit the pivoting of the counterweight (32) towards and from a support surface (311) when the first operating mode (M1) is switched to the second operating mode (M2).

8. Hinged connecting device (2) according to one of the claims 1 to 7, characterized in that it further contains a stop (37) to limit travel of the modified pendulum (31).

9. Prosthesis (1) comprising the hinged connecting device (2) according to one of the preceding claims.