PROSTHETICS FITTING

Description

[0001] The invention relates to a prosthetic device for a lower extremity, comprising a prosthetic knee joint with an upper part on which a proximal prosthetic component is arranged, with a lower part pivotally connected to the upper part about a knee joint axis, and with a distal prosthetic component to which a prosthetic foot can be secured. The proximal prosthetic component can be designed, in particular, as a prosthetic socket that is or can be attached to the prosthetic knee joint via a first connection arranged or formed on the upper part.

[0002] Prosthetic knee joints replace natural knee joints and enable the pivoting of a lower leg component, which primarily consists of a lower leg tube and an attached prosthetic foot, relative to the thigh or a part of the thigh. Prosthetic knee joints are typically attached to a femoral stump. For this purpose, a so-called prosthetic socket is connected to a proximal first connection on the prosthetic knee joint. The prosthetic socket accommodates the femoral stump and secures the remaining prosthesis to the patient. The prosthetic socket can be designed as a rigid socket that is held to the stump or patient by straps, a vacuum system, or a so-called liner system. In principle, other prosthetic socket designs are also possible.

[0003] The simplest form of a prosthetic knee joint is a uniaxial prosthetic knee joint, which allows free pivoting around a single axis. Polycentric prosthetic knee joints also exist, allowing complex, relative pivoting movements from the upper part to the lower part. Prosthetic knee joints can be equipped with damping devices, adjustable end stops, drives, brakes, or locking devices to adapt to the requirements during use.

[0004] In non-motorized prosthetic knee joints, stance phase flexion is influenced by damping devices or spring devices.

[0005] EP 0 439 028 A1 discloses a polycentric prosthetic knee joint in which a polycentric assembly can be pivoted around a pivot axis against a spring or damper force, allowing for yielding under heel load at the beginning of the stance phase of walking. To achieve this, the entire polycentric assembly is relocated without altering the polycentric assembly itself.

[0006] JP 2009-232999 A relates to a prosthetic knee joint with an upper and lower part, which are hinged together around a pivot axis. A resistance device is supported on an eccentric, which pivots together with the upper part around the pivot axis. As the pivot angle increases, the resistance device is displaced in an increasingly linear manner. The displacement speed of the resistance device can be varied via the contour of the eccentric.

[0007] US 6 808 540 B1 relates to a polycentric knee joint with an upper part and a pivotally mounted lower part. A hydraulic damper and a spring element are arranged within the lower part. A compressive force is exerted on a control cam via a roller coupled to the spring element via the hydraulic cylinder. When the prosthetic knee joint is flexed, the control cam shifts, and resistance is provided by the hydraulic damper in conjunction with the elastic element. As the upper part pivots, increasingly greater resistance to flexion is provided.

[0008] Flexion against damping and spring resistance during the stance phase is comparatively small and independent of walking speed. When walking on level ground, the human knee joint undergoes increasing knee flexion after heel contact with increasing walking speed. Conventional prosthetic knee joints cannot replicate this effect because the hip extension moment increases significantly with increasing walking speed, counteracting the inflexion effect.

[0009] The object of the present invention is therefore to provide a prosthetic device with which walking is possible with less effort.

[0010] According to the invention, this object is achieved with a prosthetic device having the features of the main claim. Advantageous embodiments of the invention are disclosed in the subclaims, the description, and the figures.

[0011] The prosthetic device according to the invention for a lower extremity with a prosthetic knee joint with an upper part on which a proximal prosthetic component is arranged, a lower part which is pivotally connected to the upper part about a knee joint axis, and a distal prosthetic component to which a prosthetic foot can be fixed, provides that the distal prosthetic component is displaceably mounted in the direction of the knee joint axis by an axial force acting in the longitudinal extent of the distal prosthetic component and a force transmission device is assigned to the knee joint, which converts a displacement of the distal prosthetic component in the direction of the knee joint axis and thus a change in length of the distal prosthetic component into a flexion moment about the knee joint axis in the stance phase.The longitudinal mobility of the distal prosthetic component makes it possible to convert an axial force acting in the longitudinal direction of this distal prosthetic component into a flexion moment acting around the knee joint axis. For this purpose, a force transmission device is assigned to both the knee joint and the distal prosthetic component and coupled to both components, so that the compressive force, for example, during a heel strike, is converted into flexion support. The conversion can occur directly, for example, via a mechanical force transmission device, which can be designed as a cable pull, connecting rod, or curved track, or via a hydraulic force transmission device, which offers advantages in terms of force transmission.Both mechanical and hydraulic force transmission devices can be equipped with a gear mechanism, a deflection device, or a transmission element to enable force transmission or displacement transmission. This allows for redirection of force directions, lengthening or shortening of displacement for the application of a flexion moment, and force changes or limitations, which would not be possible without a device located between the distal component and the knee joint.

[0012] The distal prosthetic component is preferably designed to be telescopic or displaceably mounted on the lower part in order to be able to provide a change in length in the event of an impact or load in the axial direction of the distal component, which is then converted into a flexion moment about the knee joint axis.

[0013] The distal prosthetic component can be preloaded against displacement by a spring element to ensure no or only a slight change in length during the swing phase or during static loading, for example, when standing. The dimensioning of the spring element can ensure that a flexion moment about the knee joint axis is only exerted under certain loading situations. The spring preload can be adjustable, in particular motor-adjustable, to allow adaptation to the respective usage situations or to the specific wishes of the prosthetic user even during use of the prosthetic device. The spring preload can also be set so high that an effective change in length is not possible.It is also possible that a locking device is assigned to the distal prosthetic component in order to prevent longitudinal displacement and thus the ability to change the length and the application of a flexion moment.

[0014] The spring element can provide progressive resistance to axial displacement of the distal prosthetic component, thereby limiting the maximum flexion moment.

[0015] The knee joint can be assigned an energy storage device for storing flexion energy. The energy storage device can store energy during the flexion process and feed it back into the joint to support an extension movement. In this way, flexion support can be provided by the force transmission device against a spring or an energy storage device, whereby the energy storage device can offer progressive resistance to flexion. This flexion energy is stored in the energy storage device and can be fed back into the joint to support an extension movement. This is particularly useful during stance phase extension in order to facilitate the extension movement after flexing the prosthetic knee joint immediately after the heel strike and to avoid having to perform it exclusively via the hip muscles.

[0016] In a further development of the invention, the energy storage device is designed as a spring element, in particular as a spring element with a spring stiffness that changes over the knee angle. The spring element can, for example, be designed as a buckling spring that acts in the extension direction. Particularly during stance phase flexion, the distance between the force vector of the ground reaction force and the knee joint axis increases. The spring element or extension spring exhibits increasing compliance with an increasing flexion angle, i.e., with a decreasing knee angle.This ensures that the impact impulse during a heel strike causes the spring element to compress or deform, and with increasing flexion of the knee joint, a decreasing restoring force is provided in order to provide a decreasing or at least not increasing flexion moment due to the increasing distance between the force vector of the ground reaction force and the knee joint axis. At a large flexion angle, the degressive spring characteristic of the spring element achieves greater compliance with regard to knee flexion. If, during walking in the stance phase, the resulting vector of the ground reaction force is shifted back towards the knee axis and in front of the knee axis in the walking direction, the knee joint extends and the extension is supported by the relaxing spring. The more extended the knee is, the greater the supporting effect of the spring element.By appropriately tuning the spring element, it is possible to achieve shock absorption during walking through knee flexion, rather than through an axial damping device, without the desired energy dissipation through the conversion of kinetic energy into heat. The spring characteristic curve of the spring element can initially increase and then decrease again above a certain degree of deformation.

[0017] The energy storage device can be associated with an activation and / or deactivation device. This makes it possible to provide a return element and extension support for different movement situations and to exclude them for other movement situations.

[0018] In a further development of the invention, it is provided that the knee joint is assigned at least one damper for damping the pivoting movement about the knee joint axis. Alternatively or additionally, it is provided that at least one damper is assigned to dampen the displacement movement of the distal prosthetic component in the direction of the joint axis. The damping with the damper makes it possible to provide conventional stance phase and / or swing phase damping in addition to flexion support when an axial force occurs. This makes it possible to influence the prosthetic device with regard to its extension or flexion behavior even during the swing phase. A damper for influencing the displacement movement enables adaptation of the behavior of the flexion support and the manner and extent of the application of the flexion moment.

[0019] The at least one damper is preferably adjustable in order to be able to adapt to the respective user behavior or to the needs of the respective patient. The damper device for damping the pivoting movement about the knee joint axis can be coupled to the damper device for damping the displacement movement. It is also possible for the damper for damping the pivoting movement to be coupled to a fluid reservoir in the distal prosthetic component in such a way that, upon displacement of the distal prosthetic component in the direction of the knee joint axis, a hydraulic fluid is directed into an extension chamber or flexion chamber, depending on which movement is to be supported or counteracted.The supply line can be assigned a switching valve that directs the hydraulic fluid compressed by the displacement movement either into the extension chamber or the flexion chamber, depending on the gait situation or the desired behavior of the prosthetic device.

[0020] A switchable stop or brake can be assigned to the knee joint, which locks or brakes flexion around the knee joint axis. The stop can be activated or deactivated depending on the respective movement phase. If a sensor device detects that the prosthetic device is in the stance phase, for example via a force sensor in a prosthetic foot, a stop is activated that limits maximum flexion. Appropriate measures can be implemented via a brake, which decelerates a flexion movement once a certain knee angle is reached. If the patient is in the swing phase with the supported leg, which is also determined via a force sensor in the sole of the foot or another axial force sensor, the flexion stop or flexion brake is deactivated or released so that swing phase flexion can take place unhindered or without braking.Only at a much later point in time, when a maximum flexion angle of approximately 60° is reached, can such a flexion stop or brake be activated to prevent excessive flexion during the swing phase.

[0021] A further development of the invention provides that at least one sensor, in particular for detecting the axial force, the axial force curve, the angular position, the spatial position or the accelerations of at least one component of the prosthetic device, is coupled to a control device which activates or deactivates a drive of the stop or the brake.

[0022] Exemplary embodiments of the invention are explained in more detail below with reference to the accompanying figures. They show: Figure 1- a schematic representation of a prosthetic device; Figure 2- a schematic representation of a prosthetic device with power transmission device; Figures 3 - 5- variants of the Figure 2; and Figure 6- different knee angles; Figure 7- a variant of the Figure 2 with energy storage; Figure 8- a variant of the Figure 2 with sensors; Figure 9: support-- knee angle curves at different extension angles; and Figure 10: representations of spring characteristics.

[0023] In the Figure 1A schematic representation of a prosthetic device for a lower extremity in the form of a prosthetic leg is shown, which has a prosthetic knee joint with an upper part 10 on which a first, proximal connection 11 in the form of a pyramid adapter is arranged. A proximal prosthetic component 12 in the form of a prosthetic socket for receiving a femoral stump can be arranged on the proximal first connection 11. The femoral socket can be secured to the patient's stump using suction technology or other securing mechanisms. A knee joint axis 30 is formed on the upper part 10, around which a lower part 20 of the prosthetic knee joint is pivotally attached.In the illustrated embodiment, the lower part 20 is designed as a receiving frame in which a hydraulic damping device is arranged, the damping properties of which are adjustable during walking. Distal to the lower part 20 is a distal prosthetic component 22 in the form of a lower leg tube, wherein the lower leg tube also has receiving devices for attaching a prosthetic foot 50 to the distal prosthetic component 22.

[0024] Prosthetic devices for a lower extremity with a prosthetic knee joint generally have this design if a modular design is present, i.e., the prosthetic shaft 12 is manufactured separately from the prosthetic knee joint and can be attached to it via a connection 11. It is also possible for the proximal prosthetic component 12 to be designed to receive a prosthetic stump directly with the upper part 10, so that in addition to the formation of a pivot axis 30 between the upper part 10 and the lower part 20, the receiving function for the stump is simultaneously realized. Furthermore, it is also possible for the prosthetic foot 50, instead of a separate prosthetic foot, to be designed directly on the distal prosthetic component 22 or the lower leg tube.However, a modular design has the advantage that the prosthetic device can be manufactured more cost-effectively and that one type of component can be used for several different users.

[0025] When walking on level ground, it is usually necessary to apply an increased hip extension moment to increase walking speed, which is represented by the upper circle. This hip extension moment is applied during the stance phase to move the body's center of gravity in front of the respective leg as quickly as possible. However, this hip extension moment during the stance phase simultaneously has a stabilizing effect on the knee joint, i.e., an extension moment acts around the knee joint axis 30. The force effect is indicated by the frontal arrow. In a human knee joint, with increased walking speed and an increased hip extension moment, increased knee flexion or flexion is more or less involuntarily executed during the stance phase via a corresponding muscle movement. An increased walking speed and a concomitant increased hip extension moment thus lead to an increased stance phase flexion angle and an overall "smoother" gait.However, in prosthetic devices, an increased hip extensor moment has a stabilizing and extending effect on the knee joint, so that prosthetic knee joints flex less when walking speed increases. This leads to reduced stance phase flexion and an unphysiological, "harder" gait with increasing walking speed.

[0026] A prosthetic device according to the invention is shown schematically in the Figure 2shown in two states. In the right-hand state, the prosthetic device is in a maximally extended state immediately before touching the ground, in the left-hand illustration it is in a position at the end of the stance phase. Both the upper part 10 and the lower part 20 are shown purely schematically, as is the knee joint axis 30, about which the lower part 20 is pivoted relative to the upper part 10. In addition to a monocentric knee joint, a polycentric knee joint can also be arranged or formed between the upper part 10 and the lower part 20. The upper part 10 according to this embodiment can have an adapter or connecting means 11 in order to be connected to a separately manufactured prosthetic socket or another proximal prosthetic component 12.

[0027] The lower part 20 is also only shown schematically; other shapes of the prosthetic knee joint lower part 20 can be formed.

[0028] Distal to the lower part 20, a distal prosthetic component 22 in the form of a lower leg tube is arranged displaceably in the longitudinal direction of the distal prosthetic component 22. The longitudinal displaceability of the distal prosthetic component 22 relative to the lower part 20 is indicated by the arrow in the direction of the knee joint axis 30. The schematically illustrated prosthetic foot 50 is attached to the distal prosthetic component 22.

[0029] Between the distal prosthetic component 22 and the upper part 10, a force transmission device 40 in the form of a connecting rod is arranged, which is articulated to transmit tensile and compressive forces both to the upper part 10 and to the distal prosthetic component 22. If the distal prosthetic component 22 is now displaced relative to the lower part 20 in the direction of the knee joint axis 30, a compressive force is transmitted from the distal prosthetic component 22 to the upper part 10 via the force transmission device 40.The articulation point of the force transmission device 40 on the upper part 10 is located in the walking direction in front of the knee joint axis 30, so that the compressive force exerted by the prosthetic foot 50 via the distal prosthetic component 22 and the force transmission device 40 on the upper part 10 is converted into a flexion moment, which leads to a flexion or at least to a support of a flexion of the prosthetic knee joint about the knee joint axis 30. The left illustration of the . Figure 2 shows that the distal prosthetic component 20 has already been inserted into the sleeve-like receptacle in the lower part 20, so that a pivoting movement of the upper part 10 relative to the lower part 20 has occurred via the force transmission device 40 in the form of a connecting rod. The curved arrow indicates the flexion moment and the direction of action of the applied compressive force from the force transmission device 40 to the upper part 10.

[0030] In the right representation of the Figure 2In addition, an energy storage device in the form of a spring 25 is arranged between the distal prosthetic component 22 and the lower part 20. The spring 25 can, as shown, be designed as a spiral spring or helical spring or another element that absorbs compressive forces and can be compressed when subjected to an axial load. If the distal prosthetic component 22 is displaced relative to the lower part 20 in the direction of the knee axis 30 during heel strike or during the stance phase, the spring element 25 is preloaded. When the load in the axial direction decreases, for example at the end of the stance phase or in the swing phase, the spring element 25 relaxes and moves the distal component 22 back to its original position away from the knee axis 30.This also supports the extension movement of the lower part 20 relative to the upper part 10, since the pressure force of the compressed spring element 25 is converted into an extension movement of the lower part 20 via the coupling device 40.

[0031] A damper 60 is schematically shown on the rear of the prosthetic device. The damper 60 can also be arranged within the lower part 20 in combination with the spring element 25. The damper 60 makes it possible to influence the axial displacement of the distal prosthetic component 22. The damper 60 is advantageously adjustable in order to influence the displacement behavior during compression and during relaxation of the spring element 25. This change in the behavior of relaxation and / or compression simultaneously influences the flexion support and the extension movement during unloading. The spring element 25 can also be arranged externally outside the lower part 20 in the damper device 60.

[0032] A variant of the power transmission device 40 is shown in Figure 3 The basic structure of the prosthetic device corresponds to that of the Figure 2Instead of a connecting rod, the power transmission device 40 in the embodiment of the Figure 3 designed as a curved track. The force transmission device 40 is designed in the illustrated embodiment as a roller which is arranged at the proximal end of the distal prosthesis component 22. Via the roller 40 or via a sliding body, contact is made with a running surface 14 or a sliding surface 14 on the distal end face of the upper part 10 or on a correspondingly arranged running surface 14 or sliding surface 14. In the right-hand illustration of the Figure 3Two different contours of running surfaces or sliding surfaces 14 are shown, the left contour is straight, the right contour has a curved course. If the distal prosthetic component 22 is displaced in the direction of the knee joint axis 30 relative to the lower part 20, the force transmission device 40 slides or rolls on the sliding or running surface 14. The contact point between the force transmission device 40 and the running surface 14 or sliding surface 14 lies in front of the knee joint axis 30, so that upon impact and relative displacement of the distal prosthetic component 22 in the direction of the knee joint axis 30, a force is exerted on the upper part 10, which leads to a flexion moment about the knee joint axis 30. An already bent position due to the pushing of the distal prosthetic component 22 into the lower part 20 is shown in the left illustration of the Figure 3 shown.

[0033] In the Figure 4Instead of a purely mechanical coupling between the distal prosthetic component 22 and the upper part 10, a hydraulic power transmission device 40 is shown. The distal prosthetic component 22 is mounted for longitudinal displacement within the lower part 20 and can be displaced in the direction of the knee joint axis 30 when subjected to load, for example when stepping while walking. The displacement path is, as in the other exemplary embodiments, limited to a length that is not uncomfortable for a prosthetic user. A typical displacement path of between 1 cm and 3 cm is generally acceptable for a prosthetic wearer. The hydraulic power transmission device 40 has a hydraulic actuator with a housing 41, which is mounted on the lower part 20. A movable hydraulic piston 43 is coupled to a boom on the upper part 10 via a piston rod 42.Via a hydraulic line 44, the hydraulic cylinder 41 is coupled to a compressible pressure chamber 45. In principle, it is also possible for the pressure chamber 45 to have a piston movably mounted therein. Alternatively, the pressure chamber 45 is made of a compressible material, for example, an elastic plastic. The pressure chamber 45 is then designed as a type of buffer that is hydraulically coupled to the hydraulic cylinder via the hydraulic line 44. If a force is exerted on the distal prosthetic component 22, for example upon impact, the pressure chamber 45 compresses and hydraulic fluid is pumped through the hydraulic line 44 into the housing 41. As a result, the hydraulic piston 43 is displaced in the proximal direction toward the prosthetic foot 50.Due to the articulation of the piston rod 42 on an arm on the upper part 10 pointing backward in the walking direction, the retraction of the piston 43 into the housing 45 causes a flexion movement and a bending of the upper part 10 relative to the lower part about the knee joint axis 30. Such a compressed position of both the pressure chamber 45 and a bent position of the prosthetic device is shown in the left illustration. If the prosthetic foot 50 is relieved of load, for example, initiating a swing phase, the hydraulic fluid can be sucked from the cylinder 41 through the line 44 into the pressure chamber 45 by elastic restoring forces, which can be applied by a correspondingly elastic design of the pressure chamber 45, whereby a reversal of movement occurs and extension support is provided.In order to provide extension support at the end of the stance phase or during the swing phase, in the case of a mechanical coupling according to the . Figure 2 and 3 A displacement also occurs against a spring force, so that the distal prosthetic component 22 is displaced within the lower part 20 against a spring. When an axial load in the direction of the knee joint axis 30 is removed, a reversal of movement will occur, which leads to the support of an extension movement. As an alternative to an elastic mounting of the distal prosthetic component 22, the upper part 10 can also be preloaded relative to the lower part 20 against a flexion movement via an elastic element.

[0034] In an alternative embodiment of the embodiment according to Figure 4Instead of arranging the piston rod 42 at the rear on a boom, the piston rod 42 can also be extended from the cylinder 41 by means of an appropriate hydraulic connection, so that the articulation can be frontal, i.e., in the walking direction in front of the knee joint. By hydraulically transmitting the compression movement between the distal prosthetic component 22 and the lower part 20, a force and displacement transmission can be easily achieved, for example, by varying the piston diameter.

[0035] A further embodiment of the invention is described in Figure 5, in which the force transmission device 40 is designed as a cable pull that is arranged on the distal prosthetic component 22, which is displaceably mounted within the lower part 20. In the exemplary embodiment, the force transmission device 40 is equipped with a cable 47 that is attached to a frontal, proximal end of the distal prosthetic component 22. Via a deflection device 46, for example a pulley or a bolt, the cable 47 is guided to a lever on the upper part 10 that projects rearward in the walking direction. If the lower part 20 is displaced relative to the distal prosthetic component 22, the proximal end of the distal prosthetic component 22 moves upward, and the cable 47 is pulled downward by the pulley 46, resulting in flexion and the application of a flexion moment about the knee joint axis 30.

[0036] Figure 6shows schematic knee angle curves over time during walking. The upper curve shows a knee angle curve with a prosthetic device without stance phase dynamics, in which from the heel strike, which is shown on the far left, until shortly before the end of the stance phase, which is represented by the dashed, vertical line in the diagram, there is an almost extended prosthetic knee joint with a knee angle of 180°. The lower knee angle curve shows a contralateral knee, i.e. an unsupported, human knee joint with a corresponding knee angle curve. The middle curve shows an example of stance phase flexion support with the prosthetic knee joint according to the invention, from which it can be seen that an almost natural knee angle curve can be achieved during walking.

[0037] Figure 7shows a further variant of the invention, in which an energy storage device 49 is additionally arranged within the force transmission device 40, which acts on the hydraulic piston 43 within the housing 41. The energy storage device 49 stores flexion energy, i.e. the energy required to apply a flexion moment about the knee joint axis 30. The spring 25 can have a preload that is preferably only large enough to allow the desired knee flexion to be initiated via the coupling device 40 with each heel strike. The energy storage device 49 thus represents less resistance to flexion than a flexion moment applied via the coupling device 40.

[0038] As an alternative to being arranged in the coupling device 40, the energy storage device 49 can be arranged outside the coupling device 40, for example, between the upper part 10 and the lower part 20 as a bending spring or buckling spring. In this embodiment, the energy storage device 50 preferably has a spring stiffness that varies with the knee angle. In particular, with an increasing flexion angle, i.e., with a decreasing knee angle α, the flexion resistance is reduced by the energy storage device 49.

[0039] In the Figure 8A further variant of the invention is shown, in which a switchable or adjustable valve 48 is arranged in the hydraulic line 44 between the extension chamber and the flexion chamber, so that the flow rate from the pressure chamber 45 into the flexion chamber can be influenced. The valve 48 acts as a damper, which influences the displacement movement of the distal prosthetic component 22 relative to the lower part 20. By an adjustable design of the valve 48, for example motorized or manual, adaptation to the respective patient or the respective application is possible. Likewise, the damper 60 can be Figure 2 be designed to be adjustable, for example by changing valve positions in a line from the extension chamber to the flexion chamber.

[0040] In the Figure 8A sensor 70 is also shown, which can be designed to detect the axial force, the axial force curve, or accelerations. Instead of detecting axial forces or axial force curves, the sensor 70 can also be designed to detect spatial positions and / or accelerations of the lower part 20. With a different arrangement of the sensor 70, the corresponding variables for the distal prosthetic component 22 can be detected. A further sensor 70 can be arranged on the lower part 20 or the upper part 10 to detect angular positions of the upper part 10 relative to the lower part 20; in the embodiment shown, the angle sensor 70 is arranged on the lower part 20. The sensors 70 are coupled to a control device 80, which in turn controls a drive for the throttle 48 or the valve 48.

[0041] At the upper end of the housing 41 of the coupling device 40, a switchable brake 90 is arranged, which is coupled to the control device 80. Depending on the achieved flexion as a function of axial forces or during gait, it is possible to activate or deactivate the brake 90. By activating the brake 90, it is also possible to variably or permanently set an extension stop and a maximum flexion angle. For example, if an extension stop is reached at a knee angle of 187°, measured at the rear of the prosthetic device, the brake 90 stops further movement; accordingly, upon reaching a maximum flexion angle, further flexion is stopped by activating the brake 90. Alternatively or additionally, a brake 90 or an adjustable stop can be arranged and configured around the knee joint axis 30.

[0042] Figure 9shows three different knee angle curves over time. The three knee joint curves differ essentially in the area of ​​stance phase flexion. The knee angle curve of curve a corresponds to the usual knee angle curve in a healthy, unsupported leg. Knee angle curve b represents a short flexion phase in which the stance phase flexion is shortened in time and an extended, stretched leg is present very quickly after the heel strike and the first stance phase flexion. Such a knee angle curve can be achieved, for example, by a strong energy storage device via the spring element 49 for storing flexion energy, which provides flexion support. The third knee angle curve c provides for delayed extension in which the knee angle α remains reduced for a longer period of time during stance phase flexion, compared to the knee angle curve a of a healthy leg.Accordingly, to achieve the maximum extension angle in the stance phase, a faster extension is initiated than in a natural joint.

[0043] In Figure 10A representation of two spring core lines is shown that can be used in the prosthetic device. The spring, which is attached to a knee lever, serves to influence the flexion or extension of the lower part 20 relative to the upper part 10. In the illustrated embodiment, this spring initially has an increase in spring stiffness up to a maximum value over the deformation path s, i.e. with a decreasing knee angle α. Subsequently, with further bending or deformation of the spring element, only a lower resistance is provided, resulting in a decreasing spring characteristic curve. This is, for example, a possible knee profile with a spiral spring between the upper part 10 and the lower part 20.An alternative spring core line is a linear spring core line, which provides increasing resistance with increasing deformation; such a spring can be used, for example, as a spring element 25 against axial displacement of the distal prosthetic component 22 relative to the lower part 20.

Claims

1. A prosthetic device for a lower extremity, comprising a prosthetic knee joint having an upper part (10), on which a proximal prosthetic component (12) is arranged, a lower part (20), which is connected to the upper part (10) so to be pivotable about a knee joint axis (30), and a distal prosthetic component (22), on which a prosthetic foot (50) is formed or can be secured, characterized in that the distal prosthetic component (22) is mounted so as to be displaceable in the direction of the knee joint axis (30) by means of an axial force acting in the longitudinal extent of the distal prosthetic component (22), and the knee joint is assigned a force transmission device (40) which, in the stance phase, converts a displacement of the distal prosthetic component (22) in the direction of the knee joint axis (30) into a flexion moment about the knee joint axis (30).

2. The prosthetic device as claimed in claim 1, characterized in that the distal prosthetic component (22) is formed telescopically or mounted displaceably on the lower part (20).

3. The prosthetic device as claimed in claim 1 or 2, characterized in that the force transmission device (40) is in the form of a mechanical or hydraulic force transmission device (40).

4. The prosthetic device as claimed in claim 3 or 4, characterized in that the distal prosthetic component (22) is mounted via a spring element (25) so as to be prestressed against a displacement.

5. The prosthetic device as claimed in claim 4, characterized in that the spring element (25) offers progressive resistance to a displacement.

6. The prosthetic device as claimed in one of the preceding claims, characterized in that the knee joint is assigned an energy storage device (49) for storing flexion energy.

7. The prosthetic device as claimed in claim 6, characterized in that the energy storage device (49) is in the form of a spring element, in particular a spring element having a spring rigidity changing via the knee angle.

8. The prosthetic device as claimed in claim 6 or 7, characterized in that the energy storage device (49) is assigned an activation and deactivation device.

9. The prosthetic device as claimed in one of the preceding claims, characterized in that the knee joint is assigned at least one damper (48, 60) for damping the pivoting movement about the knee joint axis (30) and / or the displacement movement.

10. The prosthetic device as claimed in claim 9, characterized in that the at least one damper (48, 60) is adjustable.

11. The prosthetic device as claimed in one of the preceding claims, characterized in that the knee joint is assigned a throttle (48) or a brake (90) which blocks / brakes a flexion about the knee joint axis (30).

12. The prosthetic device as claimed in claim 11, characterized in that a sensor (70) is coupled to a control device (80) which activates or deactivates a drive of the stop (48) or of the brake (90).