Orthopaedic joint device

Abstract

The invention relates to an orthopaedic joint device comprising: a first part and a second part which are mounted on one another so as to be pivotable about a joint axis; a hydraulic resistance device which opposes resistance to an extension movement and / or a flexion movement of the first part relative to the second part; and a piston which is longitudinally displaceably and rotationally fixedly mounted in a cylinder arranged on the first part, wherein the piston is mounted on a thread which is rotationally fixedly mounted on the first or second part.

Description

[0001] Orthopaedic joint device

[0002] The invention relates to an orthopaedic joint device having a first part and a second part, which are pivotally mounted on one another about a joint axis, with a hydraulic resistance device which opposes an extension movement and / or a flexion movement of the first part relative to the second part, wherein the resistance device has a piston which is mounted in a cylinder arranged on the first part so as to be longitudinally displaceable and non-rotatable.

[0003] Orthopedic joint devices are used in prostheses, orthoses, or exoskeletons. Prostheses replace limbs that are no longer present or are attached to an existing limb or the torso. Prostheses can have a prosthetic joint to pivot two prosthetic components relative to each other. Orthoses are applied to limbs and are designed, among other things, as cross-joint orthoses that are attached to a proximal joint part and a distal joint part of the limb, for example, to the thigh and lower leg. Attachment is achieved using conventional fastening devices such as straps, shells, or the like. Exoskeletons are also attached to the user's body. Orthoses and exoskeletons serve to limit, guide, and / or influence movements.This can be achieved through lateral guidance, by limiting pivot angles, or by providing resistance devices and / or drives on an orthosis or exoskeleton to influence the pivoting movement or pivotability. The same applies to prostheses, where the resistance device is used to influence the pivoting movement or pivotability and is arranged between an upper and lower part of the prosthesis. Resistance devices are often hydraulically designed, for example, as linear hydraulics or rotary hydraulics.

[0004] DE 10 2007 015560 A1 discloses a prosthetic joint or orthotic joint with at least two joint parts that are pivotably mounted relative to one another about a joint axis. A pivoting piston is rotatably mounted on a medial joint part and is guided in a displacement chamber containing a fluid. The pivoting piston divides the displacement chamber into two sub-chambers, which are hydraulically connected to one another via a connecting channel at least over a selected pivot angle range of the pivoting element. At least one contour is formed between the pivoting piston and a displacement chamber wall. This contour determines the flow cross-section and is fluidically connected to the connecting channel and the displacement chamber over a selected pivot angle.Depending on the angular position of the swivel element, different free flow cross-sections are provided for the passage of the fluid and thus a different swivel resistance.

[0005] DE 102017 124 337 A1 relates to an orthopedic joint for a prosthesis comprising an upper part, a lower part pivotably mounted thereon about a pivot axis, and a rotary hydraulic system comprising a housing with a chamber and a pivoting piston pivotably mounted therein. The pivoting piston divides the chamber into a flexion chamber and an extension chamber, which are hydraulically connected to each other via at least one channel. A preloading device supports a pivoting movement of the upper part relative to the lower part and is directly coupled to the pivoting piston via a support.

[0006] EP 3 568 570 B1 discloses an actuator for exerting a controllable force between a first and a second attachment point. The actuator comprises an actuator body and a piston assembly, with a motion screw assembly connecting the actuator body to the piston assembly. The actuator body includes a cylinder bore for receiving a working fluid, with a piston mounted for linear displacement within the cylinder bore. A piston rod extends from the piston to a piston rod end located outside the actuator body and attached to the second attachment point. The actuator body is attached to the first attachment point. The motion screw assembly includes a motion screw that is rotatably and non-displaceably mounted within the actuator body. A motion screw nut is attached to the piston assembly and coupled to a motor to drive the motion screw assembly.The motor drives the actuator screw. The fluid connection between two hydraulic chambers is adjustable via a throttle.

[0007] Conventional rotary hydraulics with a swivel piston have the design challenge that sealing is more difficult than with linear hydraulics. Furthermore, due to the necessary swivel axis, the contact surface of the swivel element is smaller than that of a linear hydraulic system with the same external dimensions.

[0008] The object of the present invention is to provide an orthopaedic joint device which can transmit high forces in a small installation space and which can also be permanently locked.

[0009] This invention is achieved with an orthopedic joint device having the features of the main claim. Advantageous embodiments and further developments of the invention are disclosed in the subclaims, the description, and the figures.

[0010] The orthopedic joint device with a first part and a second part, which are pivotally mounted on one another about a joint axis, with a hydraulic resistance device that offers resistance to an extension movement and / or a flexion movement of the first part relative to the second part, with a piston that is mounted in a cylinder arranged on the first part for longitudinal displacement and in a rotationally fixed manner, is characterized in that the piston is mounted on a thread that is mounted in a rotationally fixed manner on the first or second part. The cylinder can have any cross-section and accommodates the piston, so that a displacement of the piston within the cylinder, which has an elongated component or is designed as an elongated component, is possible.The cross-section of the cylinder, and thus also of the piston, does not need to be mirror-symmetrical or rotationally symmetrical, although a round cross-section makes the seal easier to implement. A non-rotationally symmetrical cylinder and piston have the advantage that no separate anti-rotation device is required.

[0011] When fitted, orthopedic joint devices are attached to a human body, so that a component arranged proximally to the joint axis is usually referred to as an upper part, and a component arranged distal to the joint axis is usually referred to as a lower part. The first part can be either the upper part or the lower part, and the second part is then the other part, i.e. the lower part or the upper part. The first and second parts do not move relative to one another in the axial direction during pivoting in the area of ​​the bearing point, apart from normal axial play. The piston is arranged in a cylinder that is arranged or formed on the first part. In addition, the piston is mounted longitudinally displaceably and rotationally fixed within the cylinder and divides the cylinder into two chambers. The anti-twist device can be located in the first part or the second part.The piston, in turn, is mounted on a thread, in particular a movement thread, which is mounted in a rotationally fixed manner on the first or second part. If the first part is pivoted relative to the second part about the joint axis, the thread moves relative to the anti-rotation device, together with the first or second part. Because the piston is mounted on the thread or movement thread and is rotationally fixed and longitudinally displaceable in the cylinder, the piston is not rotated together with the thread, but is displaced longitudinally within the cylinder in one direction or the other, depending on the pivoting direction. The piston does not rotate within the cylinder relative to the cylinder during the displacement movement.This sliding movement provides resistance to movement on the thread, for example by forcing hydraulic fluid through a tight fluid connection, so that the pivoting movement of the first part relative to the second part via the piston is also subject to resistance. Due to the fact that a linear movement of the piston is directly coupled to the rotational movement of the first part relative to the second part via the thread, the resistance device can transmit very high forces, since the entire surface of the piston and the cylinder can be used to transmit force. Furthermore, a longitudinally displaceable, particularly cylindrical piston can easily be completely sealed, so that in a design as a hydraulic resistance device via the piston, no or only minimal leakage is to be expected and the joint device can be completely locked.Furthermore, cylinders and pistons with a circular cross-section are easy to manufacture and capable of sustaining and transmitting very high forces. References to "threads" below refer to all threads, including and especially motion threads. The thread can be external or internal, and a corresponding mating thread can be internal or external, respectively.

[0012] In one embodiment, the piston is mounted coaxially to the joint axis, with the cylinder also arranged coaxially to the joint axis. This results in a compact design of the orthopedic joint device with the resistance device, as the components can be arranged axially one behind the other along the pivot axis. By selecting the thread pitch, the transmission ratio and thus the stroke of the piston can be adjusted or set at a specified pivot angle, allowing the properties of the resistance device to be easily adapted to the desired application.

[0013] In one embodiment, the cylinder is arranged in or formed on a housing, wherein at least one fastening device for one or more orthopedic components is arranged or formed on the housing. The fastening device is designed, for example, to receive a prosthetic socket or a splint or another component of an orthosis or prosthesis. Fastening devices can also be arranged or formed on the second part in order to secure further orthopedic components, for example a prosthetic lower part such as a lower leg tube, a prosthetic wrist joint or a forearm tube. In a design as an orthosis or exoskeleton, a splint or another component for securing the orthosis or exoskeleton to a body part with the option of transmitting forces and moments is provided on this fastening device.The arrangement of both the piston and the cylinder in a housing with fastening devices further enables a very compact design of an orthosis medially or laterally on the limb in the area of ​​the natural joint axis and a prosthesis with a very small construction volume, if necessary also with a medial and lateral arrangement on a common joint axis.

[0014] The piston divides the cylinder into an extension chamber and a flexion chamber, which are fluidly connected to each other. In particular, the resistance device is designed as a hydraulic resistance device, so that a hydraulic fluid is transported from the extension chamber through channels or lines into the flexion chamber and back when a pivoting movement of the first part relative to the second part occurs, thereby displacing the piston within the cylinder in one direction or the other. Due to the flow resistance on the path from the extension chamber to the flexion chamber and back, the resistance to a pivoting movement of the first part relative to the second part is provided.

[0015] In order to be able to adjust the resistances in the pivoting movement, for example to set different resistances in the extension direction and flexion direction and / or to provide an adapted resistance during the movement depending on sensor data or on certain angular positions, at least one adjustable throttle and / or at least one switchable or adjustable valve is arranged in the fluidic connection between the flexion chamber and the extension chamber, via which an adjustment and setting of the respectively desired resistance is possible.

[0016] A further development of the joint device provides that the fluidic connection opens at an end face of the first part so that a connection to the second part can be easily established and, moreover, the entire stroke of the piston can be fully utilized.

[0017] In order to compensate for leaks or different displacement volumes of the piston or volume changes due to temperature differences, in one embodiment, a compensation volume is formed or arranged in the first part, in which the medium displaced by the piston, in particular a hydraulic fluid, is stored. The compensation volume is fluidically connected to the cylinder and can be provided with a force storage device, for example, a pneumatic element, to force the medium or hydraulic fluid into the cylinder.

[0018] In one embodiment, a non-rotationally symmetrical pin is arranged in the cylinder, which protrudes into a corresponding recess in the piston and thereby ensures that the piston is secured against rotation relative to the cylinder. In one embodiment, a positive-locking element is arranged or formed on the piston, in particular on the inside of the piston, which engages with a corresponding counter-element on the first part, thus creating a functional surface that prevents the piston from rotating together with the thread on the second part, while still being arranged for longitudinal displacement in the cylinder.

[0019] The piston has a thread corresponding to the thread as a counter-thread, which in one embodiment is designed as an insert that is subsequently inserted into the piston and secured thereto. Manufacturing a separate threaded insert is easier than with a one-piece design. Furthermore, the mechanical properties of the threaded insert can be adapted to the loads because the piston for pressure transmission does not necessarily have to have the same material properties as the thread or counter-thread.

[0020] In one embodiment, the thread is also arranged coaxially to the joint axis on the second part. In one embodiment, the thread provides that the pitch angle is greater than 1°, in particular greater than 5°.

[0021] Instead of a thread pairing between the piston and the thread of the first or second part as a pure gear thread, the thread principle can also be designed as a recirculating ball screw.

[0022] Exemplary embodiments of the invention are explained in more detail below with reference to the figures. Like reference numerals denote like components. They show: Figure 1 - a perspective view of an orthopedic joint device;

[0023] Figure 2 - in an exploded view of Figure 1 in section;

[0024] Figure 3 - an exploded perspective view from a first perspective;

[0025] Figure 4 - an exploded view according to Figure 3 from a second perspective;

[0026] Figure 5 - a detailed view of the piston and thread;

[0027] Figure 6 - a detailed view of the thread;

[0028] Figure 7 - a detailed view of a multi-part piston before joining;

[0029] Figure 8 - a detailed view of a bearing cap with insert;

[0030] Figure 9 - a sectional view of the bearing cap, thread and piston;

[0031] Figure 10 - a side view of the first part with housing;

[0032] Figure 11 - a perspective, cut-out view of the first part;

[0033] Figure 12 - a detailed view of the housing;

[0034] Figure 13 - a detailed view of the housing in oblique plan view;

[0035] Figures 14 and 15 - a variant of the resistance device;

[0036] Figure 16 - a variant of the resistance device with double piston;

[0037] Figures 17 to 23 - variants of pistons; and

[0038] Figures 24 to 30 - Variants of the anti-twist device. Figure 1 shows a perspective view of an orthopedic joint device in an assembled state. The orthopedic joint device has a first part 10 and a second part 20, which are pivotally mounted on one another about a joint axis 15. In the illustrated embodiment, the first part 10 is an upper part, and the second part 20 is a lower part of the orthopedic joint device. Both the first part 10 and the second part 20 have fastening devices 80 for additional orthopedic components. If the orthopedic joint device is designed as an orthotic joint, the fastening devices 80 are designed as so-called splint boxes, so that orthotic splints can be attached to them for application to limbs.In principle, other designs of fastening devices for rails to a joint device are also suitable and are provided as an alternative to rail boxes. In the case of a prosthetic joint device, the fastening devices 80 are designed, for example, to receive a prosthetic shaft on the first, proximal part 10 and to receive a distal prosthetic component, for example a lower leg tube or a forearm tube, on the second, distal part 20. The first part 10 forms a housing 70 in which a cylinder is arranged as a component of a resistance device 30. The resistance device 30 is located between the first part 10 and the second part 20 and is designed as a hydraulic resistance device 30 in order to influence a pivoting movement of the first part 10 relative to the second part 20 about the pivot axis 15.

[0039] Figure 2 shows a sectional exploded view of the structure of the orthopedic joint device of Figure 1. The first part 10 has the fastening device 80 molded onto the housing 70 and forms the cylinder 50 within it. The cylinder 50 is machined from the material of the housing 70; alternatively, a cylinder is inserted into a corresponding housing and secured thereto. The fastening device 80 is also formed integrally with the housing 70, but can also be manufactured as a separate component and then fixed to the housing 70. Within the housing 70, a fluid connection 32 is formed as a hydraulic channel in a wall of the housing 70. The fluid connection 32 enables the transport of hydraulic fluid from an extension chamber to a flexion chamber.Also visible is the piston 40, which, like the cylinder 70, has a circular outer contour and is movably mounted within the cylinder 50. A thread 44 is formed inside the piston 40, which engages with a thread 60 on a pin in the assembled state. The thread 60 on the pin is mounted in a rotationally fixed manner on the second part 20 in a bearing housing 55 and is fixed thereto by the bearing pin 21. The bearing housing 55 with the thread 60 as an external thread on the pin, the piston 40 with the corresponding internal thread 44, and the cylinder 50, together with the fluidic connection and the valves or throttles therein, form the resistance device 30. Internal teeth are formed on the pin with the thread 60 as an external thread, which will be explained later and via which the pin is rotationally fixedly connected to the second part 20 by the bearing pin 21.The bearing housing 55 is screwed onto the housing 50 and secured to the housing 70 in a rotationally fixed manner. A flange with positive locking elements 28 is arranged or formed on the inside of the bearing housing 55 on the outside, which engage with corresponding positive locking elements of the piston 40 and thus ensure that the piston 40 is secured against rotation within the cylinder 50 and the bearing housing 55.

[0040] Figures 3 and 4 show the individual components of the orthopedic joint device in exploded views from different perspectives. The bearing pin 21 has a projection with external teeth 26, which correspond to the internal teeth 61 of the thread 60 on the pin. The second part 20 has a through-bore for the bearing pin 21, thereby enabling the rotationally fixed attachment of the thread 60 to the second part 20. The bearing housing 55 has an internal thread 54, which corresponds to an external thread 14 on the first part 10 on one end face of the housing 70. The two threads 54, 14 make it possible to secure the bearing housing 55 for assembly to the first part 10. The second part 20 can be interlaced around the pivot axis 15 together with the bearing pin 21 and the thread 60 on the pin.

[0041] On the outside of the flange within the bearing housing 55, four form-locking elements 28 are formed, which secure the piston 40 against rotation and at the same time enable longitudinal mobility in the axial direction in the joint axis 15. For this purpose, corresponding form-locking elements 48 are formed on the inside of the piston 40 on the piston wall, which, in the fully assembled state, engage with the form-locking elements 28 on the outside of the flange. An internal thread 44 is arranged or formed within the piston 40; this internal thread is manufactured on the inside of an insert and engages with the thread 60 on the pin. The rotationally fixed fixing of the thread 60 to the second part 20 is achieved, for example, by a screw (not shown), which is inserted through the bearing pin 21 into the pin and screwed thereto.The external toothing 26 then engages the internal toothing 61, and the bearing pin 21 is clamped to the second part 20 via the screw. The bearing housing 55 is rotatably mounted on a shoulder on the thread 60.

[0042] A groove is formed on the outside of the piston 40, which serves to accommodate a sealing ring or a piston ring. Channels are incorporated within the housing 10 around the cylinder, forming the fluid connection 32 so that hydraulic fluid can flow from one chamber to the other chamber upon displacement of the piston due to rotation of the second part 20 relative to the first part.

[0043] Figure 5 shows the assignment and basic structure of the piston 40 in conjunction with the thread 60. Outside the internal toothing 61, a shoulder without the thread 60 is formed. The thread 60, with a pitch of more than 1°, engages the internal thread 44 within the piston 40 in the assembled state. Between the inside of the piston wall and the thread 44, a space is formed between the piston wall 40 and the closed outer wall of the internal thread 44. In this space, form-locking elements 48 are formed as flats or strips or guides, which engage with the corresponding form-locking elements on the flange of the bearing housing 55 and extend essentially in the axial direction.

[0044] Figure 6 shows the thread 60 in detail with a closed top. Figure 7 shows the multi-part construction of the piston 40. The piston 40, with the piston wall and the form-locking elements 48 formed therein, has a recess or through-bore at its front end into which the insert 42 is inserted and fixed to the piston 40. The insert 42 is designed as a sleeve with an open end and a closed end with a shoulder. The closed end forms part of the piston crown. The thread 44 corresponding to the thread 60 is formed within the open end. The insert 42 can be made of a material that differs from the remaining material of the piston 40 in order to provide a suitable material pairing with the thread 60. The separate production of the insert 42 facilitates the design and manufacture of the piston 40.

[0045] Figure 8 shows the structure of the bearing housing 55 with the internal thread 54, which is configured to correspond to the external thread 14 on the housing 70. A separate flange is inserted within the bearing housing 55. It has notches or flattened portions on its outer surface that serve as positive-locking elements 28 for receiving the corresponding projections as positive-locking elements 48 of the piston 40. The flange has a through-bore or recess so that the thread 60 can be inserted and guided through it.

[0046] Figure 9 shows a sectional view of the arrangement of the bearing housing 55 with the internal thread 54 and the flange 58. The thread 60, with its smooth shoulder and internal toothing, is passed through the opening within the bearing housing 55 and secured, for example, by screwing it to the bearing pin 21. The piston 40 with the thread 44 within the insert 42 is placed onto the form-locking elements 28 of the flange before the thread 60 is screwed to the second part (not shown) and the rotationally fixed locking device. If the second part 20 is then pivoted relative to the bearing housing 55 and the first part 10, the piston 40 moves in one or the other axial direction depending on the pivoting direction.

[0047] Figure 10 shows a side view of the first part 10 with the fastening device 80 for securing proximal orthopedic components such as splints or prosthetic shafts. The cylinder 55 is formed within the housing 70, and the external thread 14 for securing the bearing housing 55 is formed on the outside of the housing 70. Flow channels are incorporated into the end face of the housing 70 as part of the fluidic connection 32. For this purpose, pockets are formed within the cylinder 50 at the level of the end face in order to connect the bores formed within the wall of the housing 70 or the cylinder wall with radially outwardly extending bores or flow channels at the closed end of the cylinder 50 in order to establish a fluidic connection between the chambers.

[0048] Figure 11 shows the first part 10 in a perspective, partially sectioned view. In addition to the cylinder 50 and the external thread 14, the channels are shown as a fluid connection 32 and associated valves or throttles. An adjustable throttle 34 and a switchable or adjustable valve 36 are arranged within the fluid connection 32 and enable the hydraulic flow from an extension chamber to a flexion chamber to be influenced. The openings of the fluid connection 32 into the respective end regions of the cylinder 50 are not visible in the figure. In addition, a compensation volume 90 is formed in the housing 70, which is also connected to the fluid connection 32 between the chambers in order to compensate for volume fluctuations or different displacement volumes.

[0049] Figure 12 shows a detailed view of the housing 70 in a sectional view. The housing 70 is a component of the first part 10 and has the external thread 14 at the right end shown. Within the wall of the cylinder 50, the fluidic connection 32 is incorporated by a flow channel that extends parallel to the direction of leftward displacement of the piston within the cylinder 50. Radial bores or recesses at the upper and lower ends of the cylinder 50 allow the inflow and outflow of the fluid displaced by the piston (not shown) and thus establish the fluidic connection between an extension chamber and a flexion chamber, which are separated by the piston.Figure 13 shows a detailed individual illustration of the fluidic connection 32 with an adjustable throttle 34, which can also be designed as a control valve or switching valve. Cutouts or milled recesses are formed on the end face of the housing 70 with the cylinder 50 in order to provide a radial flow channel on the end face facing the second part 20. An axially extending bore within the housing wall leads to the closed side of the housing; the fluidic connection to the end opposite the end face is established via a radial bore or recess. The bore can also be continuous and then closed from the outside with a plug.

[0050] Figure 14 shows a variant of the orthopedic joint device. The first part 10 is shown without a fastening device and is only indicated schematically. The piston 40 is mounted within the cylinder 50 for longitudinal displacement and rotation. Instead of rotationally fixed mounting by the form-locking elements arranged on the inside of the piston wall, a non-rotationally symmetrical pin protrudes from the closed side of the cylinder 50 in the axial direction into the cylinder and is received by a corresponding recess 46 within the piston 40. This recess 46, as a pocket in the piston 40, can be seen in Figure 15, which is a sectional view of Figure 14. The piston 40 forms a flexion chamber 52 and an extension chamber 54 in the cylinder 50, which, however, has only a minimal size due to the maximally enlarged flexion chamber 52.

[0051] All components of the resistance device 30, in particular the thread 60, the thread 44 on the inside of the piston 40, the piston 40, and the cylinder 50, are arranged coaxially with the joint axis 15. The valves or throttles can be adjustable and / or adjustable, for example, depending on an angular position, loads, sensor values, or the like. The orthopedic joint device enables high force transmission at high resistances due to the rotationally symmetrical design of the outside of the piston 40 and the cylinder 50. An almost completely tight locking of the joint device with a closed fluidic connection 32 can be achieved due to the low leakage. High forces can be transmitted due to the large effective hydraulic area.The ratio of the pivot angle about the joint axis 15 to the piston stroke can be adjusted by appropriately selecting the pitch angle of the thread 60 and the associated thread 44. The greater the pitch angle, the greater the displacement for a given pivot angle and the greater the adjustment travel of the piston 40 and thus the displaced quantity of hydraulic fluid. The pitch angle can be 1° or more, for example 5°. Unless the piston and cylinder are rotationally symmetrical, the piston and cylinder are already designed to be rotationally secure and movable relative to one another due to their outer contour or corresponding inner contour. Any sealing difficulties that may arise can be compensated for by eliminating a separate anti-rotation device.

[0052] Figure 16 shows a further variant of the orthopedic joint device, in which the resistance device is equipped with two pistons 40 that are rigidly coupled to one another as a double piston. The coupling is effected via a threaded rod with the counter thread 44 as an external thread, which is mounted in a thread 60 designed as an internal thread. The thread 60 is arranged or formed on the second part 20, for example as a threaded insert, and is rotatable relative to the first part 10. The housing with the cylinder 50 is arranged or formed in the first part 10, wherein the housing 50 can also be designed in several parts in order to form a plurality of cylinders 50 therein.The cylinders 50 are arranged on both sides next to the second part 20, and the pistons 40, which are displaceably mounted therein, are held in a rotationally fixed manner on the first part 10 via form-locking elements 48, which act as an anti-twist device. The displacement in one direction or the other occurs according to the pivoting movement of the second part 20 relative to the first part 10. On the outside, for example in a corresponding groove, seals 41 are provided in the piston 40, thereby enabling an effective separation between an extension chamber and a flexion chamber. The flow resistance in the fluidic connection (not shown) between the extension chambers and the flexion chambers influences the pivoting movement of the first part 10 relative to the second part 20. Figure 17 shows a variant of the arrangement of the functional surfaces of the piston 40 in a sectional view.Located within the piston 40 is the thread 44 or counter-thread, which engages with the thread (not shown) of the second part to effect longitudinal displacement. The sealing surface 41 is located on the piston circumference, and an anti-rotation device via at least one form-locking element 48 is arranged on a shoulder with a larger outer diameter.

[0053] In the variant of Figure 18, the arrangement of thread 44 and form-locking element 48 is exchanged compared to the embodiment of Figure 17, the thread 44 is located on the outside on the shoulder, while the form-locking element 48 is located on the inside on an end face of the piston 40.

[0054] In the variant according to Figure 19, both the thread 44 and the form-locking element 48 are located on the outside on the outer circumference of the piston 40, also here on shoulders which are axially spaced from one another, while the sealing surface 41 of the piston 40 is located on an inside in a protruding wall.

[0055] In the embodiment according to Figure 20, the positive locking element 48 or the anti-rotation device is located on the inside of the piston 40 in a shoulder, the seal 41 is located on the outside on the outer circumference, the thread 44 is arranged or formed on a shoulder with an enlarged outer circumference opposite the sealing surface 41.

[0056] In the embodiment according to Figure 21, the seal 41 is located on the outer circumference of the piston 40, the thread 44 is on the inside of a piston wall, the form-locking element 48 or the form-locking elements are located on a central pin which is opposite the piston crown.

[0057] In the embodiment according to Figure 22, the positions of the thread 44 and the positive locking element 48 are exchanged compared to Figure 21, ie the thread 44 is located on the central pin opposite the piston crown, while the anti-twist device is arranged on the piston wall on the inside.

[0058] In the variant according to Figure 23, the thread 44 is arranged on the outside of the piston, the anti-rotation device or the form-locking element 48 is located on the inside on an inner shoulder, the seal 41 is located in a space which has an enlarged inner circumference compared to the inner shoulder.

[0059] In Figures 24 to 26, an anti-rotation device is implemented via a mating thread. In all embodiments according to Figures 24 to 26, the piston 40 has an internal thread 44 that engages with an external thread 60 of a spindle and displaces the piston 40 in one direction or the other when the spindle rotates with the external thread 60. In order to effect a displacement along the longitudinal extent of the spindle, i.e. a linear displacement, the piston 40 must be prevented from rotating together with the spindle. For this purpose, in Figure 24, a further form-locking element 48 is designed as an internal thread concentric to the internal thread 44. The form-locking element 48 engages a correspondingly designed mating element 28, which is designed as a sleeve with a fixed anchorage. An external thread with a direction of rotation oriented opposite to the internal thread 44 or external thread 60 on the spindle is formed on the mating element 28.

[0060] In Figure 25, the principle of Figure 24 is mirrored on the piston 40. The counter-element 28 is located on the side of the piston 40 opposite the spindle 60. In Figure 26, instead of an internal thread, the positive-locking element 48 is arranged as an external thread on the outside of the piston 40 and is located within the hydraulic fluid as a counter-element 28, which has an internal thread as a counter-thread. The counter-elements 28 are each anchored in a rotationally fixed manner. In Figures 24 and 25, the piston 40 has two internal threads 44, 48 that are oriented in opposite directions, i.e., one is designed as a right-hand thread and the other as a left-hand thread. In the variant according to Figure 26, the piston has a counter-thread 44 as an internal thread and an external thread 48 with opposite orientations, wherein the spindle with the thread 60 can be pivoted in one direction or the other in order to effect a translational movement of the piston 40.The principle of the anti-rotation device according to Figures 24 to 26 is that a counter thread is used that has a different direction of rotation than the thread 60 of the spindle, i.e., a left-hand thread if the spindle has a right-hand thread, and vice versa. The respective spindle with the thread 60 is driven and engages the counter thread 44 of the piston 40. Since the piston 40 cannot be rotated due to the counter thread, it is forced into translation.

[0061] Figures 27 and 28 show further embodiments of the anti-twist device. Figure 27 shows a design similar to Figure 24 in a sectional view in the unassembled state. The piston 40 has two internal threads 44, 48, each oriented in opposite directions. The piston 40 is mounted in a housing (not shown) for translational movement. The counter element 28 is an external thread that is firmly anchored and engages with the form-locking element 48. The form-locking element 48 is designed as a counter thread, for example as a left-hand thread. The spindle with the thread 60 is mounted in the hydraulic housing so as to be rotatable about the spindle axis or pivot axis and is in meshing engagement with the internal thread 44 within the piston 40; the internal thread 44 is designed as a right-hand thread in the illustrated embodiment.

[0062] In the embodiment according to Figure 28, which is designed similarly to the principle of Figure 26, there is also a spindle with an external thread 60 that engages with a counter thread 44 within the piston 40. On the side of the piston 40 facing away from the spindle, the counter element 28 is designed as a counter thread that is formed in the hydraulic housing. The housing is mounted in a rotationally fixed manner, with the counter thread 44 in the piston 40 and the external thread 48 on the piston 40 being designed in opposite directions, so that a corresponding translational movement of the piston 40, as indicated by the double arrow, occurs when the spindle with the thread 60 rotates in one direction or the other.

[0063] The principle described in Figures 24 to 28 can be varied in that the external thread 60 is mounted in a rotationally fixed manner and the corresponding counter-element 28 is rotated, which also leads to a translation of the piston 40. The relative rotation of the spindle to the counter-element or piston is essential. Figure 29 shows a schematic sectional view of the piston 40 with the internal thread 44 and the driven spindle or pin with the external thread 60. On the side of the piston 40 in which the counter-thread 44 is introduced, form-locking elements 48 in the form of offset bores are also introduced. The form-locking elements 48 in the form of bores serve as an anti-twist device, into which rods or pins 100 engage as corresponding form-locking elements. The rods or pins 100 are mounted in a rotationally fixed manner and allow a linear movement along the longitudinal extent of the rods or pins 100 or.of the bores. If the spindle with the external thread 60 is rotated relative to the piston 40, an axial displacement of the piston 40 in one direction or the other along the longitudinal extent of the bores will occur due to the thread pitches.

[0064] Figure 30 shows a variant of Figure 29, in which the anti-rotation device with the form-locking elements 48 are arranged as bores and rods and pins 100 on the side of the piston 40 facing away from the spindle 60.

Claims

Patent claims 1. An orthopaedic joint device comprising a first part (10) and a second part (20) which are pivotably mounted on one another about a joint axis (15), comprising a hydraulic resistance device (30) which offers resistance to an extension movement and / or a flexion movement of the first part (10) relative to the second part (20), comprising a piston (40) which is mounted in a cylinder (50) arranged on the first part (10) in a longitudinally displaceable and rotationally fixed manner, characterized in that the piston (40) is mounted on a thread (60) which is rotationally fixedly mounted on the first or second part (20).

2. Orthopaedic joint device according to claim 1, characterized in that the thread (60) is a movement thread.

3. Orthopaedic joint device according to claim 1 or 2, characterized in that the piston (40) is mounted displaceably coaxially to the joint axis (15).

4. Orthopaedic joint device according to one of the preceding claims, characterized in that the cylinder (50) is arranged or formed in a housing (70) on which fastening devices (80) for orthopaedic components are arranged or formed.

5. Orthopaedic joint device according to one of the preceding claims, characterized in that the piston (40) divides the cylinder (50) into an extension chamber (52) and a flexion chamber (54) which are fluidically connected to one another.

6. Orthopaedic joint device according to claim 5, characterized in that at least one adjustable throttle (34) and / or at least one switchable or adjustable valve (36) is arranged in the fluidic connection (32).

7. Orthopaedic joint device according to one of claims 5 or 6, characterized in that the fluidic connection (32) opens at an end face of the first part (10).

8. Orthopaedic joint device according to one of the preceding claims, characterized in that a compensating volume (90) is in fluid communication with the cylinder (50).

9. Orthopaedic joint device according to claim 7, characterized in that the compensating volume (90) is formed or arranged in the first part (10).

10. Orthopaedic joint device according to one of the preceding claims, characterized in that a non-rotationally symmetrical pin (56) is arranged in the cylinder (50), which projects into a corresponding recess (46) in the piston (40).

11. Orthopaedic joint device according to one of the preceding claims, characterized in that at least one form-locking element (48) is arranged or formed on the piston (40), which engages with a corresponding counter-element (28) on the first part (10).

12. Orthopaedic joint device according to one of the preceding claims, characterized in that the piston (40) has an insert (42) in which the thread (44) corresponding to the thread (60) is formed.

13. Orthopaedic joint device according to one of the preceding claims, characterized in that the thread (60) on the second part (20) is formed coaxially to the joint axis (15).

4. Orthopaedic joint device according to one of the preceding claims, characterized in that the thread (60) has a pitch angle (a) greater than 1 °.

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