EP4181838A2

EP4181838A2 - Method for controlling a prosthesis or orthosis

Info

Publication number: EP4181838A2
Application number: EP21754925.2A
Authority: EP
Inventors: Martin Seyr; Thomas Hofmann; Dirk Seifert; Philipp Kampas; Dries GLORIEUX
Original assignee: Otto Bock Healthcare Products GmbH
Current assignee: Otto Bock Healthcare Products GmbH
Priority date: 2020-07-20
Filing date: 2021-07-20
Publication date: 2023-05-24
Also published as: JP2023534396A; US20230293320A1; CN116194064A; WO2022018073A3; WO2022018073A2; DE102020004336A1

Abstract

The invention relates to a method for controlling a prosthesis or orthosis of the lower extremity, which prosthesis or orthosis has an upper part (10) and a lower part (20), which lower part is connected to the upper part (10) by means of a knee joint (1) and is mounted for pivoting relative to the upper part (10) about a joint shaft (15); wherein an adjustable resistance device (40) is disposed between the upper part (10) and the lower part (20), by means of which resistance device a flexion resistance (Rf) is changed on the basis of sensor data; wherein an axial force (FA) acting on the lower part is sensed by at least one sensor (54) and is used as the basis for a change of the flexion resistance (Rf); wherein, in the case of decreasing axial force (FA) and/or an approximately vertical position of a leg tendon (70) and/or of an extended knee joint (1), the flexion resistance (Rf) is reduced; and wherein the flexion resistance (Rf) is increased again if, within a temporally defined interval, no knee flexion is detected and/or the knee joint (1) and/or the leg tendon (70) and/or the axial force (FA) fall below or exceed specific limit values.

Description

Method for controlling a prosthesis or orthosis

The invention relates to a method for controlling a prosthesis or orthosis of the lower extremity with an upper part and a lower part which is connected to the upper part via a knee joint and which is pivotably mounted about a joint axis relative to the upper part, with the upper part and the lower part being an adjustable resistance device is arranged, via which a flexion resistance is changed on the basis of sensor data, with an axial force acting on the lower part being detected by at least one sensor and used as the basis for a change in the flexion resistance.

Artificial knee joints are used in prostheses and orthoses, as well as in exoskeletons as a special case of orthoses. An artificial knee joint has an upper part and a lower part, which are mounted so that they can pivot relative to one another about a joint axis, the knee axis. In the simplest case, the knee joint is designed as a single-axis knee joint, in which, for example, a bolt or two bearing points arranged on a pivot axis form a single knee axis. Artificial knee joints are also known which do not form a fixed axis of rotation between the upper part and the lower part, but instead have either sliding or rolling surfaces or a large number of linkages connected to one another in an articulated manner. In order to be able to influence the movement properties of the knee joints and to obtain a movement behavior of the orthosis or prosthesis or the exoskeleton that approximates the natural gait behavior, resistance devices are provided between the upper part and the lower part, via which the respective Wi resistance can be changed. Purely passive resistance devices are passive dampers, for example hydraulic dampers, pneumatic dampers or dampers that change the movement resistance on the basis of magnetorheological effects. Active resistance devices, such as motors, also exist or other drives that can be operated as a generator or energy store via a corresponding connection.

The respective knee joints, ie the prosthetic joints or orthotic knee joints, are fixed to the patient with the respective connection means. In the case of knee joint prostheses, the fixation is usually carried out via a thigh shaft which accommodates a limb stump. Alternative types of fixation are also possible, for example through osseointegrated connection means or through straps and other devices. In the case of orthoses and exoskeletons, the upper and lower parts are fixed directly to the thigh and lower leg. The fastening devices provided for there are, for example, belts, cuffs, shells or frame structures. Orthoses can also have foot parts for putting on a foot or shoe. The foot parts can be articulated on the lower part.

DE 102013 011 080 A1 relates to a method for controlling an orthopedic technical joint device of a lower extremity with an upper part and a lower part articulated thereon, between which a conversion device is arranged, via which mechanical work is performed during pivoting of the upper part relative to the lower part is converted from the relative movement and stored in at least one energy store. The stored energy is fed back to the joint device with a time delay in order to support the pivoting of the upper part and lower part in the course of the movement. The relative movement is supported in a controlled manner. In addition to the conversion device, a separate damper in the form of a flydraulic damper or pneumatic damper can be provided, which is adjustable so that the damper device can influence the resistance while walking both in the flexion direction and in the extension direction.

An artificial knee joint has a knee angle of 180° in the constructively maximum achievable extension; hyperextension, which corresponds to an angle on the posterior side of more than 180°, is generally not provided for. Pivoting the lower part posteriorly relative to the upper part is referred to as knee flexion, pivoting anteriorly or forwards in the direction as extension.

Control of a passive prosthetic knee joint with adjustable damping of the flexion resistance is known from DE 10 2006 021 802 A1. The adjustment is made to climbing stairs, with a low-torque lifting of the prosthetic foot being detected and the flexion damping in the lifting phase being lowered to below a level that is suitable for walking on a level surface.

The flexion damping can be increased depending on the change in the knee angle and depending on the axial force acting on the lower leg.

There are also control procedures for walking alternately on a level surface, which allow the flexion resistance to be adjusted depending on the respective walking situation. Special situations that make it necessary to bend the knee joint are problematic, for example starting from a standing position, especially with the prosthesis or orthosis in front.

The object of the present invention is therefore to provide a method with which artificial knee joints can be used more comfortably for a user.

According to the invention, this object is achieved by a method having the features of the main claim. Advantageous refinements and developments of the invention are disclosed in the dependent claims, the description and the figures.

The method for controlling a prosthesis or orthosis of the lower extremity with an upper part and a lower part which is connected to the upper part via a knee joint and which is mounted pivotably about a joint axis relative to the upper part, with an adjustable resistance device being arranged between the upper part and the lower part is about which, based on sensor data, a flexion resistance is changed, with an axial force acting on the lower part being recorded by at least one sensor and used as a basis for changing the flexion resistance, provides that with a decreasing axial force and/or with a leg tendon and/or an extended leg being in a near-vertical position Knee joints kes the flexion resistance is reduced, the flexion resistance being raised again if no knee flexion is detected within a timed interval and/or the knee joint and/or the leg tendon and/or the axial force exceed certain limit values. The above conditions are no longer met, for example, when the knee joint is largely or completely unloaded in the axial direction. The axial force is detected, for example, by an axial force sensor, which is arranged on the prosthesis or orthosis, in particular on the lower part of a component attached to the lower part. If a forward rotation of the joint axis is detected, which can occur, for example, during a rolling movement over the foot or by bending the lower leg around an ankle joint axis, the flexion resistance is reduced. The forward rotation of the joint axis and thus also of the entire knee joint means that the joint axis and thus also a proximal end of the lower part pivots around a distal pivot point, with the distal pivot point being either a joint axis on an ankle joint or a wandering point on the sole area can be. The flexion resistance is also reduced if, alternatively or additionally, a vertical position of a leg tendon is detected. The leg tendon is defined in particular as a connecting line between two defined points on the upper part and the lower part or a component adjoining the lower part. A preferred embodiment provides that the leg tendon is defined as the connecting line between a point proximal to the joint axis on the upper part and a point distal to the joint axis on the lower part, eg hip pivot point and foot point. When using a prosthetic knee joint, the hip pivot point is determined by an orthopedic technician anyway and determines the segment length of the thigh or upper part, which is defined as the distance between the joint axis or knee axis and the hip pivot point. The segment length of the lower part is defined by the distance between the knee axis and a foot point. ned. For example, the middle of the foot, the instantaneous center of a rolling movement, the end point of the plumb line of the lower leg at the sole level of the foot part, the prosthetic foot or on the floor can be defined as the foot point; other points close to the ground are also suitable for defining a foot point. Since orthoses or exoskeletons do not require a foot part to support an existing natural foot, the distance from the floor to the joint axis can also be used. The position and/or the length of the leg tendon provide reliable information about the orientation of the leg and the progress of the movement. The leg tendon can be calculated or estimated using absolute angle sensors in conjunction with the known segment lengths, an absolute angle sensor and a knee angle sensor. A positive hamstring angle is when the hamstring is tilted posteriorly in the sagittal plane. This is the case when, for example, the foot or the ankle joint axis is located in front of the knee or the knee joint axis as seen in the forward walking direction. A negative hamstring angle is when the hamstring is tilted forward, such as when the knee joint and hip joint are in front of the knee joint axis. With a positive hamstring angle, increasing distance of the hamstring from the perpendicular is counted positively as an increase or enlargement. . With a negative hamstring angle, increasing distance of the hamstring from perpendicular is counted negatively as a decrease or reduction.

The flexion resistance is also reduced if an extended knee joint is detected as an alternative or in addition. The reduction in flexion resistance is maintained and reversed for only a timed range, wherein the increase in flexion resistance may be increased to the same or a different flexion resistance level. The flexion resistance is increased in particular if no knee flexion is detected within the timed interval. Alternatively or additionally, the flexion resistance is increased when the knee joint and/or the leg tendon is no longer in an approximately vertical position and/or the knee joint is no longer largely or completely relieved in the axial direction. Even with a complete relief of the knee joint, when no more ground reaction force acts in the longitudinal extension of the lower part in the direction of the articulation axis Ge, the flexion resistance is increased if at least one of the other criteria is met in order to raise the flexion resistance again. With the method, it is possible, for example, to achieve easier bending of the knee joint when starting from a standing position. When the prosthesis or orthosis is relieved, for example when the body weight is shifted to the contralateral side, the flexion resistance is automatically reduced in order to be able to flex without flexion resistance and thus with a significantly reduced flexion resistance. This makes it possible to move the knee joint slightly forward despite contact with the floor, without the orthosis or prosthesis having to be completely lifted off the floor by a compensatory movement in the hip and pelvis. The foot or prosthetic foot can roll forward until the flexion in the knee joint reduces the effective length of the prosthesis or orthosis to such an extent that it can swing forward without ground contact. With the procedure, the knee joint remains secured in the stance phase in the event of an axial load, giving the patient increased stability and greater confidence in the prosthesis or orthosis. At the same time, sufficient dynamics are provided within the knee joint, which enables a sufficiently comfortable initiation of a swing phase even in special situations.

A development of the invention provides that the flexion resistance is reduced when starting from a standing position, in particular only when starting from a standing position. The standing situation can be recognized or detected, for example, by measuring the axial force over time. If there is a constant or almost constant axial force for a defined period of time, it can be assumed that the user of the prosthesis or orthosis is not moving but is standing. Usually, users of orthoses or prostheses stand with both legs standing with about half your body weight on the prosthesis or orthosis, possibly with a little less weight. This weight range can be specified as a limit value. If the measured axial force is within this limit value range over a certain time horizon, this can be regarded as a prerequisite for the procedure described above to be initiated. The same can be done by monitoring a flexion angle. If the knee joint is not flexed for a certain period of time and is in an extended position, this alone or in conjunction with the axial force monitoring can serve as an indication that the user of the orthosis or prosthesis is standing upright. Standing can be distinguished from locomotion or walking and/or a gait cycle with one or more IMUs.

The flexion resistance can be reduced as a function of the decrease in the axial force. In particular, a degressive reduction in the flexion resistance to a target value is advantageous. With an initially slight reduction in the axial force, there is a comparatively large reduction in the flexion resistance, so that, starting from locking by maximum hydraulic resistance with a comparatively small decrease in the axial force, flexion against a flexion resistance is fundamentally possible. With an increasing decrease in the axial force, the reduction will then be less pronounced.

Flexion resistance can be reduced to a level below stance phase damping, particularly to a level below stance phase damping when walking on a level surface.

A reduction in flexion resistance may occur as a function of axial force, leg chord angle, and/or base solid angle, any or all of which may be considered when calculating and determining how flexion resistance reduction is to occur. In addition to a pure switching of the flexion resistance when reaching or exceeding If the specified limit values are exceeded or fallen below, smooth transitions and resistance changes can be set and initiated depending on changing parameters.

In the event of a decrease in the axial force, starting from a starting value, for example an axial load while standing relaxed on both legs, to a level above a limit value, for example above 10% of body weight, and a determined leg tendon angle above a limit value, in particular above 5°, in a development of the invention there is no reduction in the flexion resistance. If the leg tendon is displaced posteriorly, e.g., pivoting backwards or posteriorly by an angle of 5° or more, there will be no reduction in flexion resistance unless a sufficiently large reduction in axial force has occurred. The hip or the hip joint is shifted behind the foot or the distal reference point for determining the leg tendon. With a sufficiently large decrease in the axial force and a corresponding backward rotation of the leg tendon, it can be concluded that a patient wants to sit down, for which purpose an increased flexion resistance is advantageous in order to provide increased safety against collapsing of the knee joint. If a reduced backward rotation of the leg tendon is detected, the flexion resistance is reduced accordingly. If there is no backward rotation of the leg tendon, a full reduction of the flexion resistance is possible.

A variant of the invention provides that when the axial force decreases to a level below a limit value, for example to a level below 10% of the body weight and a determined leg chord angle outside of a defined angular range around the vertical, e.g. with a positive leg chord angle of more than 30° or with a negative leg tendon angle less than -10°, there is no reduction in flexion resistance. Such a situation can occur, for example, when walking backwards or when crossing an obstacle with a large forward step. A complete reduction in flexion resistance can occur with a positive chord angle of up to 20°, with increased flexion resistance as the chord angle increases. Alternatively, from a negative leg tendon angle of less than -10°, the flexion resistance can be completely reduced. The flexion resistance, on the other hand, can be increased with a smaller leg tendon angle.

A variant of the invention provides that when the axial force decreases to a level below a limit value, for example below 10% of the body weight of the user of the orthosis or prosthesis, and a determined angle of inclination of the lower part is within a defined angular range around the vertical , i.e. the so-called roll angle is in a defined area close to the vertical, there is no reduction in flexion resistance, especially if the positive roll angle is less than 15° and the negative roll angle is greater than -5°.

A complete reduction in flexion resistance can occur at a positive base cant angle of 20° or more, with the flexion resistance being increased at a smaller cant angle. Alternatively, it is provided that the flexion resistance decreases completely from a negative angle of inclination of -10° and the flexion resistance is increased or not reduced at a larger negative angle of inclination, ie when the lower part is inclined in the direction of the vertical.

The flexion resistance can be increased when an extension movement takes place in the knee joint, which can be detected via a knee angle sensor. This can also be done by evaluating IMU data. The flexion resistance is also increased when a gait cycle is detected, for example via recurring load patterns or movement patterns such as regular flexion angles in the knee joint or in the ankle joint. Likewise, the flexion resistance can be increased with an increase in the axial force. ok

Flexion resistance cannot be reduced if rearward base tilt is detected. In particular, the method serves to make it easier to start running, walk backwards, climb over an obstacle and place a foot or an orthosis on the next lower stair nosing or stair step when walking down the stairs. In the cases mentioned, the reduction in flexion resistance, which is intended to make it easier to start from a standing position, is not carried out to the same extent or is reduced. This not only makes the sequence of movements easier for the cases mentioned, but also ensures adequate safety for the user in these cases.

In particular, the method is used to control a prosthesis or orthosis of the lower extremity with an upper part and a lower part which is connected to the upper part via a knee joint and which is pivotably mounted about a joint axis relative to the upper part, with a adjustable resistance device is arranged, via which a flexion resistance is changed on the basis of sensor data, with an axial force acting on the lower part being detected by at least one sensor and used as the basis for a change in the flexion resistance, for starting from a standing position in which the resistance to flexion is reduced from an initial value with a decreasing axial force, particularly when the flexion angle does not exceed a limit value. In particular, the limit value can be set to a value not greater than 10°. The method is used in particular to adjust the flexion resistance when the user is not in a gait cycle and wants to perform a movement other than walking on a plane. A reduction in damping or a decrease in resistance does not take place or is aborted if it is recognized that the user is changing into a gait cycle, a knee extension is taking place or the axial load in the direction of the joint axis increases again.

An exemplary embodiment of the invention is explained in more detail below with reference to the attached figures. Show it: FIG. 1 shows a schematic representation of a prosthetic leg;

Figure 2 - an illustration of leg tendons;

Figure 3 - a course of axial force, resistance and knee angle when walking down stairs;

FIGS. 4 to 6 - flexion resistance curves over leg tendon angle and roll angle; such as

Figure 7 - an illustration of an orthosis.

Figure 1 shows a schematic representation of an artificial knee joint 1 in egg ner application on a prosthetic leg. As an alternative to being used on a prosthetic leg, an appropriately designed artificial knee joint 1 can also be used in an orthosis or an exoskeleton. Instead of replacing a natural joint, the respective artificial knee joint 1 is then arranged medially and/or laterally on the natural joint. In the exemplary embodiment shown, the artificial knee joint 1 is in the form of a prosthetic knee joint with an upper part 10 with an anterior or in the direction of walking or in front of the side 11 and a posterior side 12 that lies opposite the anterior side 11 . A lower part 20 is pivotably mounted about a pivot axis 15 on the upper part 10 . The base 20 also has an anterior side 21 or front side and a posterior side 22 or rear side. In the exemplary embodiment shown, the knee joint 1 is designed as a monocentric knee joint; in principle, it is also possible to control a polycentric knee joint accordingly. At the distal end of the lower part 20, a foot part 30 is arranged, which can be connected either as a rigid foot part 30 with an immovable foot joint or with a pivot axis 35 with the lower part in order to enable a movement sequence approximated to the natural movement sequence. The knee angle KA is measured between the posterior side 12 of the upper part 10 and the posterior side 22 of the lower part 20 . The knee angle KA can be measured directly via a knee angle sensor 25 which can be arranged in the area of the pivot axis 15 . The knee angle sensor 25 can be coupled to a moment sensor or have one in order to detect a knee moment about the joint axis 15 . An inertial angle sensor or IMU 51 is arranged on the upper part 10, which measures the spatial position of the upper part 10, for example in relation to a constant force direction, for example the gravitational force G, which points vertically downwards. An inertial angle sensor or an IMU 53 is also arranged on the lower part 20 in order to determine the spatial position of the lower part during use of the prosthetic leg.

In addition to the inertial angle sensor 53, an acceleration sensor and/or lateral force sensor 53 can be arranged on the lower part 20 or the foot part 30. A force sensor or torque sensor 54 on the lower part 20 or foot part 30 can be used to determine an axial force FA acting on the lower part 20 or an ankle moment acting around the ankle joint axis 35 .

A resistance device 40 is arranged between the upper part 10 and the lower part 20 in order to influence a pivoting movement of the lower part 20 relative to the upper part 10 . The resistance device 40 can be designed as a passive damper, as a drive or as a so-called semi-active actuator, with which it is possible to store kinetic energy and at a later point in time to release it again in order to slow down or support movements. The resistance device 40 can be designed as a linear or rotary resistance device. The resistance device 40 is connected to a control device 60, for example wired or via a wireless connection, which in turn is coupled to at least one of the sensors 25, 51, 52, 53, 54. The control device 60 electronically processes the signals transmitted by the sensors with processors, processing units or computers. She has one electrical power supply and at least one storage unit in which programs and data are stored and in which a working memory is available for processing data. After processing the sensor data, an activation or deactivation command is output, with which the resistance device 40 is activated or deactivated. By activating an actuator in the resistance device 40, for example, a valve can be opened or closed or a magnetic field can be generated in order to change a damping behavior.

A prosthesis socket is fastened to the upper part 10 of the prosthetic knee joint 1 and serves to accommodate a thigh stump. The prosthetic leg is connected to the hip joint 16 via the thigh stump, and a hip angle HA is measured on the anterior side of the upper part 10, which is between a vertical line through the hip joint 16 and the longitudinal extent of the upper part 10 and the connecting line between the hip joint 16 and the knee joint axis 15 is applied to the anterior side 11. If the thigh stump is raised and the hip joint 16 is flexed, the hip angle HA is reduced, for example when sitting down. Conversely, the hip angle HA increases with an extension, for example when standing up or similar movement sequences.

During a gait cycle when walking on level ground, the foot portion 30 is first struck with the heel, the initial contact of the heel or a heel portion of the foot portion 30 is called a heel strike. Then there is a plantar flexion until the foot part 30 rests completely on the ground, as a rule, the longitudinal extent of the lower part 10 is behind the vertical, the steering axis 35 runs through the knuckle joint. When walking on level ground, the body's center of gravity is then shifted forward, the lower part 20 pivots forward, the ankle angle AA decreases and the load on the front foot increases. The ground reaction force vector travels forward from the heel to the forefoot. At the end of the stance phase, the toes are released or the so-called toe-off, followed by the swing phase, in which the foot part 30 is shifted behind the center of gravity or the hip joint on the ipsilateral side when walking on a level surface, reducing the knee angle KA, and then after reaching a minimum knee angle KA, to be turned forward in order to then reach heel contact again with a knee joint 1 that is usually maximally stretched. The force application point PF thus migrates from the heel to the forefoot during the stance phase and is shown schematically in FIG.

In FIG. 2, the leg tendons 70 of an ipsilateral, treated leg and a contralateral, untreated leg are defined. The leg tendon goes through the hip pivot point 16 and forms a line to the ankle joint 35. As can be seen from FIG. Height differences DH to be overcome can be estimated and predicted or determined via the course of the change in the length and/or orientation of the leg tendon 70 . The respective control commands are then derived from this. The respective orientation of the ipsilateral leg tendon cpu relative to the gravitational direction G and the contralateral leg tendon cpu _< is entered in each case.

FIG. 3 shows the change in the flexion resistance Rf together with the course of the flexion angle Af and the course of the axial force FA. The gait situation corresponds to starting with the prosthesis at the beginning of a flight of stairs, placing the prosthesis on the next lower step and knee flexion without reduced flexion resistance. At the beginning of the movement, at the left end of the flexion angle course, the knee joint is maximally extended, the knee angle KA is approximately 180°, the flexion angle Δf is therefore 0 or approximately 0. The prosthetic knee joint is subjected to a maximum axial force FA, and the prosthesis user wants this begin with the treated leg or ipsilateral leg and descend the stairs. For this purpose, the axial force FA is first reduced, with a slight time delay, the flexion resistance Rf is also reduced, so that flexion is facilitated and the flexion angle Af can increase. The flexion resistance Rf is reduced to approximately 25% of the initial value. A complete omission of damping or flexion resistance Rf is not scheduled. Even if the prosthetic knee joint is completely unloaded and the axial force FA is eliminated, there is no further reduction in the flexion resistance Rf. The knee joint flexes, the flexion angle Af increases, so that the knee joint and the joint axis can be brought forward by flexing the aft joint. The foot or the prosthetic foot swings over the edge of the step, causing an extension movement and thus a reversal of the course of the flexion angle Af. After reaching a maximum flexion angle and reversing the movement, the flexion resistance Rf is increased very quickly to the initial value and remains at the starting level.

In a further consequence of the movement, up to the contact of the prosthetic foot with the next lower step, which can be recognized by a strong increase in the axial force FA, the flexion resistance Rf remains at the high level, so that a safe stance phase damping after putting on the supplied foot legs is guaranteed. The flexion resistance Rf is reduced again only after the axial force FA has dropped, i.e. when the prosthetic knee joint is relieved again for the purpose of walking on level ground or for further descent of stairs.

FIG. 4 shows the course of a change in the resistance Rf as a function of the axial force Af and the leg chord angle OLC. A positive leg chord angle OLC of a leg chord is when the distal reference point or foot point is taken as the starting point and the hamstring 70 is canted in a posterior direction to the perpendicular or gravitational line G . A schematic representation of the orientation is shown in the left part of FIG. The further the leg tendon 70 is tilted backwards, i.e. the aft joint 16 is in the sagittal plane behind the foot point or the ankle joint, the greater the positive angle of inclination of the leg tendon 70. With a reduced axial load on the prosthetic leg, for example, to a force that than 10% of the total body weight, for example between 40% and 15% of the body weight tes, the resistance Rf is reduced to a maximum in an almost vertical orientation, in the exemplary embodiment shown to 25% of the initial resistance.

With increasing rearward inclination of the leg tendon 70, with an increase in the leg chord angle OLC in the positive direction, the flexion resistance Rf is reduced less until a limit value, which in the illustrated embodiment is set at a rearward inclination of 5°, no reduction in the flexion resistance Rf is carried out and the flexion resistance Rf is 100%.

FIG. 5 shows a further variant of the reduction in the flexion resistance Rf as a function of the axial load and the leg chord angle ai_c. With an axial load of less than 10% of the body weight, for example between 0% and 10% of the body weight, i.e. with a further reduction in the axial load compared to standing with both legs, relaxed, the flexion damping or the flexion resistance Rf is different than with a small relief as in Figure 4 adapted. If the leg tendon 70 is inclined backwards very far at an angle between 20° and 30°, for example when stepping over a obstacle, no or only a limited reduction in the flexion resistance Rf is carried out. The increase takes place from a leg chord angle ÖLC of 20°, until then the resistance can be reduced to the target value with a reduction in axial force. There is no reduction from an angle of 30°. With a negative leg tendon orientation, i.e. with a forward displacement of the leg tendon 70, a reduction to the target value, in the illustrated embodiment to 40% of the maximum resistance, only takes place from 10°, with a greater forward inclination, a smaller reduction or no reduction at all is permitted , even if an axial load reduction occurs. A negative leg chord angle C(LC is found, for example, when walking backwards. The reduction and increase in the flexion resistance Rf can take place over a certain angular range, as shown in FIG Such type of Anpas solution has been found to be particularly advantageous in the negative angle range, ie with a forward inclination of the lower part 20. FIG. 6 shows a further example of the dependency of the reduction in resistance on further sensor signals depending on the load condition. The reduction in the axial force Af does not follow a level according to FIG. 4, but rather a level according to FIG. 5, so that the reduced axial force Af is no more than 10% of the body weight. The axial force can be reduced to 0% or 5% of the body weight on the treated leg, for example. FIG. 6 shows the roll angle as, which is measured between the lower part 2 and the vertical G, as a further criterion for reducing the flexion resistance. The perpendicular G runs through the pivot axis 35 of the ankle joint between the foot part 30 and the bottom part 20 or through the pivot point at floor level when the foot part 30 is rigidly coupled to the bottom part 20 . A displacement in the posterior direction is a positive roll angle as. In the case of a displacement forward, so that the knee joint lies in front of the vertical G with the joint axis 15, there is a negative roll angle as. If, for example, the negative roll angle is more than minus 10° to the vertical G, the flexion resistance Rf is completely reduced, here too to the level of 40% of the initial resistance. With a smaller forward inclination, i.e. with a smaller negative roll angle as, the flexion resistance Rf remains larger and the reduction is therefore smaller. With a positive roll angle as, a full reduction to the target value of the flexion resistance Rf takes place from an angle of 20°, no reduction takes place up to an angle of 15°.

FIG. 7 shows a schematic representation of an exemplary embodiment of an orthosis with an upper part 10 and a lower part 20 mounted thereon so that it can pivot about a pivot axis 15, with which the method can also be carried out. Characterized a kunstli Ches knee joint 1 is formed between the upper part 10 and the lower part 20, which is arranged laterally to a natural knee joint in the illustrated embodiment. In addition to a one-sided arrangement of upper part 10 and lower part 20 relative to a leg, two upper parts and lower parts can also be arranged medial and lateral to a natural leg. The lower part 20 has at its distal end a foot part 30 which is pivotable about an ankle joint axis 35 to the lower part 20 . The foot part 30 has a footplate on which a foot or shoe can be placed. Fastening devices for fixing to the lower leg or thigh are arranged both on the lower part 20 and on the upper part 30 . Devices for fixing the foot on the foot part 30 can also be arranged on the foot part 30 . The fastening devices can be in the form of buckles, straps, clasps or the like in order to be able to put the orthosis on the user's leg in a detachable manner and remove it again without destroying it. The resistance device 40 is fastened to the upper part 10 and is supported on the lower part 20 and on the upper part 10 and provides an adjustable resistance to pivoting about the pivot axis 15 . The sensors and the control device, which were described above in connection with the exemplary embodiment of the prosthesis, are also present on the orthosis accordingly.

Claims

Patent Claims:

1. A method for controlling a prosthesis or orthosis of the lower extremity with an upper part (10) and with the upper part (10) via a knee joint (1) connected lower part (20) about a hinge axis (15) relative to the upper part (10) is pivotably mounted, with an adjustable resistance device (40) being arranged between the upper part (10) and the lower part (20), via which a flexion resistance (Rf) is changed on the basis of sensor data, with a flexion resistance (Rf) acting on the lower part Axial force (FA) is detected by at least one sensor (54) and used as the basis for changing the flexion resistance (Rf), characterized in that a. when the axial force (FA) decreases and/or the position of a leg tendon (70) and/or an extended knee joint (1) is approximately vertical, the flexion resistance (Rf) is reduced, b. wherein the flexion resistance (Rf) is increased again if no knee flexion is detected within a timed interval and/or the knee joint (1) and/or the leg tendon (70) and/or the axial force (FA) falls below or exceeds certain limit values .

2. Method according to claim 1, characterized in that the resistance to flexion (Rf) is reduced when starting from a standing position.

3. The method as claimed in claim 1 or 2, characterized in that the flexing resistance (Rf) is reduced as a function of the decrease in the axial force (FA).

4. The method according to claim 1 or 2, characterized in that the flexion resistance (Rf) is reduced to a level below a stance phase resistance.

5. The method according to any one of the preceding claims, characterized in that the flexion resistance (Rf) is reduced as a function of the axial force (FA), the leg chord angle (ÖLC) and/or a solid angle (as) of the lower part (20).

6. The method according to any one of the preceding claims, characterized in that when the axial force (FA) decreases to a level above a limit value and a positive leg chord angle (ÖLC) is determined above a limit value, in particular above 5°, there is no reduction in the flexing resistance (Rf) takes place.

7. The method according to any one of the preceding claims, characterized in that when the axial force (FA) decreases to a level below a limit value and a determined leg chord angle (ÖLC) outside of a defined angular range around the vertical (G), in particular at ei With a positive leg chord angle (ÖLC) greater than 30° and a negative leg chord angle (ÖLC) less than -10°, there is no reduction in flexion resistance (Rf).

8. The method according to claim 7, characterized in that the flexion resistance (Rf) is reduced completely at a positive leg chord angle (ÖLC) of up to 20° and the flexion resistance (Rf) is increased at a larger leg chord angle (ÖLC) or that From a negative leg tendon angle (ÖLC) of -10° there is a complete reduction in the flexion resistance (Rf) and the flexion resistance (Rf) is increased with a smaller leg tendon angle (ÖLC).

9. The method according to any one of the preceding claims, characterized in that when the axial force (FA) decreases to a level below a limit value, in particular below 10% of the patient's body weight, and a determined angle of inclination (as) of the lower part ( 20) relative to that vertical (G) within a defined angular range around the vertical (G), in particular within a range between a positive angle of inclination (as) less than 15° and a negative angle of inclination (as) greater than -5° no reduction in flexion resistance (Rf) takes place.

10. The method according to any one of the preceding claims, characterized in that a complete reduction in the flexion resistance (Rf) at egg nem positive angle of inclination (as) of the lower part (20) of 20 ° or more he follows and the flexion resistance (Rf) at a smaller angle of inclination (as) is increased or that from a negative angle of inclination (as) of the lower part (20) of -10° there is a complete reduction in the flexion resistance (Rf) and the flexion resistance (Rf) at a larger negative angle of inclination (as) is enlarged.

11. Method according to one of the preceding claims, characterized in that the flexion resistance (Rf) is increased when an extension movement takes place, a gait cycle is detected and/or an increase in the axial force (FA) is detected.

12. The method according to any one of the preceding claims, characterized in that the flexion resistance is not reduced if a backward inclination of the lower part (20) is detected.