WO1994022411A1

WO1994022411A1 - Movement system for the upper talocalcanean joint

Info

Publication number: WO1994022411A1
Application number: PCT/EP1994/000740
Authority: WO
Inventors: Jochen Staubesand; Josef Anton Grotenhuis; Bernd Holz
Original assignee: Medireha Gmbh
Priority date: 1993-03-31
Filing date: 1994-03-10
Publication date: 1994-10-13
Also published as: DE59402761D1; EP0691837A1; EP0691837B1; ATE152904T1

Abstract

The device is intended for the movement of the upper talocalcanean joint. It comprises two pedal shafts (1a, 1b) fitted horizontally in a bearing (6a, 6b) and extending coaxially to left and right on which a left and right pedal (2a, 2b) are radially secured integrally in rotation and driven by a gear motor (3) in such a way that the rotary movement of the motor shaft (4) is converted into an alternating contrarotatory oscillating movement of the left and right pedals (2a, 2b) between to terminal positions within a restricted angular region. In addition there are means (5; 8; 9; 10) which limit the torque transmitted from the motor shaft (4) to the pedal shaft (1a; 1b) on the forced stoppage of a pedal (2a, 2b) resulting from the reaching of an end position in the range of movement of a talocalcanean joint to a selectable maximum value, the force/travel diagram of the means (5; 8; 9; 10) preferably having a torque limitation characteristic which is substantially flat when the selected salient point is exceeded.

Description

Movement device for the upper ankle

The invention relates to a device for moving the upper ankle, according to the preamble of claim 1.

Devices of the type mentioned are used for passive and active joint mobilization. Most of these are devices that were designed without taking into account the special features of the upper ankle.

The situation in the upper ankle is a very special one. At their distal ends, the tibia and fibula extend to the clearly visible and palpable ankles (malleolus lateralis et medialis). The role (trochlea) of the anklebone (talus) moves in this Malleolen fork. It is therefore a hinge joint that allows both extension (dorsiflexion) and flexion (plantar flexion) of the foot against the lower leg and vice versa about an axis running across the inner and outer ankle and referred to as the upper ankle joint (articulatio talocruralis) becomes.

Due to the close contact of the Malleolen fork with the ankle bone roller, other types of movement are not possible, apart from certain wobbling movements that occur with increasing Plantar flexion becomes larger, because in this position the rear, narrower section of the ankle bone lies in the malleolar fork.

From the basic position, in which the foot is at a right angle to the lower leg, a movement amplitude of a total of 70 ° - 80 ° is possible, whereby it must be taken into account that the movement deflection considerable individual, e.g. training-related fluctuations, and becomes significantly smaller with increasing age and with joint-stiffening processes. The upper ankle is enclosed in a capsule that is relatively thin and limp at the front and back, while it is reinforced on both sides by strong ligaments. Upper ankle movements that occur when walking, running, jumping, etc. take place, additionally affect the venous return flow.

It is generally known that the return of blood from the leg veins to the heart is promoted by so-called "muscle and joint pumps". As a result of the upright posture of the person and the associated hydrostatic pressure load, the veins of the lower extremities are given a special position. The energy transmitted from the heart via the arteries is sufficient initially, but not permanently, to ensure the flow in the venous vascular region of the legs. The main contraction of the leg muscles is the driving force behind the venous return flow. They lead to compression of the veins, the flap valves of which ensure that the blood can not eat peripherally, but only centrally - i.e. towards the heart. But also the movement in the joints, from the toes to the feet, the knees to the hip joints, leads to dilatation and compression of the veins. This significantly supports the effect of the muscle pump. It is particularly important to note that active and passive movements in the joints promote blood flow. This makes it possible to make the articulated pumps effective even with anesthesia, loss of consciousness, paralysis or fixation by gypsum and other bandages with muscle-inactive patients with the help of "outside" forces.

The upper ankle is of particular importance. In its environment there are dense skin vein networks and, in addition, numerous blood vessels in the fat body between the Achilles tendon and Malleolenkabel, which - like a sponge - are filled distally with every movement in the articulatio talocruralis or squeezed outwards.

Since hemostasis in the veins (= stasis) is undoubtedly one of the main factors that promote thrombosis, any measure that counteracts stasis is of preventive importance because it reduces the risk of thrombosis-embolism.

Physical thrombosis prophylaxis alone or to support drug therapies is therefore generally indicated in bedridden patients. It is also known that movements in the upper hocks result from the chronic venous insufficiency (eg "open legs") and joint-stiffening processes can favorably influence. The acceleration of the venous return flow in the superficial and deep venous system of the lower extremities caused by these movements is accompanied by an increase in arterial inflow. This also has a positive effect on arterial circulatory disorders in the area of the legs. Initial experiments also indicate that such movements can improve the results of lymphographies by compressing the lymphatic vessels in the vicinity of the ankle.

Since passive movements in the upper ankle are usually only possible to a limited extent by nursing staff or physiotherapists, there is a need for a mechanical device that can largely perform these functions.

Such mechanical devices provided with foot pedals (= foot supports) with an electric or pneumatic drive, the rotating or the linear movement of the drive being converted into a back and forth swiveling of the foot pedal, are known. It is also known that the rotational angle speed can be regulated and the swivel range can be adjusted. In addition, all known devices do not meet the practical requirements of the clinic. They are either too cumbersome, too heavy, too loud, too unwieldy or too prone to failure. Therefore, they are not accepted by patients, nursing staff or procurement offices. Therefore, they have not been able to assert themselves on the market. Another disadvantage of the known devices is that the swiveling range of the pedals or footrests has to be adjusted from patient to patient to the mobility of the foot, because there are large individual variations in the range of motion in the upper ankle.

Clinical measurements have shown differences from 0 to 35 degrees in dorsiflexion and from 27 to 65 degrees in plantar flexion depending on age, gender and the influence of venous diseases and stiffening. Page differences also occur frequently, i.e. that extension and flexion are different on the left and right side.

When adjusting the swivel range to the movement of the foot, errors can be made, or changes can occur during operation due to unintentional adjustment, which can lead to injuries or excessive stress.

For reasons of safety as well as practical handling, there is a demand for a device that is designed in such a way that the swivel range of the foot pedal automatically adjusts to the maximum degree of mobility of a foot, so that the range of motion is restricted due to age or illness no adjustment by the nursing staff is required in the upper ankle. This automatic setting should be done separately for both feet so that an automatic adjustment takes place even if the range of motion in the upper ankle joint of the right and left foot is unequal.

Further requirements regarding safety and practical handling are the following:

The maximum torque that can occur in the device when the pedals are at a standstill as a result of the end of a possible extension or flexion from the reversing movement must be significantly below the pain limit and must not increase when the two foot pedals or one of them is at a standstill. In other words, the selected maximum torque should represent a break point in the almost straight-line characteristic curve in the force / displacement diagram, in the sense that after this break point is exceeded, the characteristic curve continues essentially flat.

From US-A-3 695 255 a foot movement device according to the preamble of claim 1 is known, in which the drive shaft of the motor is connected to the pedal shaft by means of a resiliently contractible connecting linkage. This fulfills the requirement that when a foot pedal is forced to stand still as a result of reaching an end position in the range of motion of the upper ankle, the motor shaft can continue to run. However, the second much more important requirement that when a foot pedal is at a standstill the maximum torque when the motor shaft continues to run must not be met. The coil springs disclosed are conventional type, so that even after reaching an end position in the range of motion of an upper ankle, the characteristic curve of these helical springs continues to rise in a straight line and thus the force acting on the ankle further increases.

Since patients waking up from anesthesia are often very restless, the device should be easy to attach to any bed.

In patients with thick thighs, it is necessary that the foot pedals are axially adjustable so that the feet come apart.

For patients with X- or O-legs, it is desirable that the foot pedals can also be adjusted to the left and to the right in the attachment pivot point.

From the basic position, in which the foot is at a right angle to the lower leg, the device according to the invention provides a lifting (dorsiflexion) of 20 ° and a lowering (plantar flexion) of 40 ^* , ie a swivel range of 60 ° in total. If the patient's right foot (starting from said basic position) allows a dorsiflexion of 6 ° and the left foot allows a plantar flexion of 32 °, then the right foot pedal stops at "6 ° lifting" and the left pedal swivels until "32 ° Lower "further. At a standstill, the right foot with the specified maximum torque remains as pressure on the sole of the foot, and the left foot with the same maximum torque loaded as a train on the instep. The motor shaft that continues rotates the pedals by reversing the crank movement. When the individual end position of the plantar flexion is reached (e.g. 28 °), the right pedal stops, while the left pedal stops when the individual end position of the dorsiflexion (e.g. 10 °) is reached. In both cases, a tensile or compressive load on the instep and sole is guaranteed with the specified maximum torque. According to the invention, this maximum value can never be exceeded.

Furthermore, the device should be convertible in a few simple steps for a single leg, either for the left or the right. This applies e.g. for accident injuries with leg surgery and for some orthopedic surgery on one leg. In this case, the foot pedal that is not in use must not swivel, and therefore it is best not to be present.

The invention has for its object to provide a device for moving the upper ankle, which overcomes the disadvantages described and in particular the pivoting range of the two foot pedals automatically the possible, possibly limited by illness or age and often also left and right different, movement adjusts the circumference of the patient's feet. The invention achieves the stated object with a device which has the features of claim 1. Further advantageous embodiments of the invention are characterized in the dependent claims.

The advantage of the device according to the invention is, above all, that when a foot pedal is forced to stand still due to reaching an end position in the range of motion of a foot, the torque on the stationary foot pedal shaft reaches a predetermined maximum value and remains almost constant while the motor shaft continues to run, so that the foot In its possible end position, both in the plantar flexion and in the dorsiflexion, the predetermined, almost constant torque remains applied, irrespective of the angle at which a foot pedal comes to a standstill in the swivel range.

An embodiment of the invention, which also explains the principle of operation, is shown in the drawing and is described in more detail below.

1 shows a longitudinal section through the device according to the invention;

2 shows a cross section through the device according to the invention; 3 shows a front view of the device according to the invention;

4 shows a side view of the device according to the invention;

FIG. 5 shows a push rod designed as a hollow rod of the device according to FIG. 1;

FIG. 6 shows a schematic illustration of the mode of operation of the hollow rod according to FIG. 5;

FIG. 7 shows a diagram with the characteristic curve of the disc springs contained in the push rod according to FIG. 5;

8 shows a schematic partial illustration of a variant of the push rod for the device according to the invention;

9 shows a schematic partial illustration of a second variant of the push rod for the device according to the invention; and

10 shows a schematic partial illustration of a third variant of the push rod for the device according to the invention. The device shown in FIGS. 1 to 4 for moving the upper ankle comprises within a housing 7 two foot pedal shafts la, lb lying horizontally in a bearing 6a, 6b, coaxially extending left and right, on each of which radially a left and right foot pedal 2a, 2b are mounted in a rotationally fixed manner.

As shown in FIG. 3, each foot pedal 2a, 2b can be axially displaced on an angled rail 23a, 23b in a slot 24a, 24b, so that the foot pedals 2a, 2b can be adjusted further apart axially in patients with obese thighs. At any point in said slot 24a, 24b, each pedal 2a, 2b can also be pivoted to the left or right at the pivot point of rotation, as indicated by arrow 25, by about 10 ° to adapt the device to patients with X or O legs. The foot pedals 2a, 2b are fixed by means of an eccentric tensioning lever 29.

The above-mentioned, angled rails 23a, 23b - in the form of angle plates - are each provided on the housing side with an adapter 27a, 27b with integrated index bolts 26. The shafts la, lb mounted within the housing 7 are also provided with an adapter plate 21a, 21b at the housing outlet and can be connected to one another by means of a knurled screw 28 with the adapters 27a, 27b of the angle rails 23a, 23b in three positions defined by the above-mentioned index bolts. so that two further zero positions can be set in addition to the main zero position (hatched positions in FIG. 4). The motor shaft 4 is driven by means of a geared motor 3 controlled by the power pack 34 via the clutch 31 and the bevel gear 32. On the eccentric disk 33a or 33b, which is connected to the motor shaft 4 in a manner fixed against relative rotation, a push rod 51a or 51b designed as a hollow rod is fastened via a mandrel 35a or 35b. The push rod 51a or 51b engages at its other end - again eccentrically - on the mandrel 22a or 22b of an adapter plate 21a, 21b connected to the foot pedal shaft la or lb in a rotationally fixed manner.

In this way, an alternating, counter-rotating pivoting movement of the left and right foot pedals 2a, 2b is implemented between two end positions within a limited angular range. 2, the push rod 51b is in the top dead center position, which corresponds to the plantar flexion of approximately 40 °. On the right in the figure, the push rod 51a is in the bottom dead center position, which corresponds to the dorsiflexion of approximately 20 °.

As shown in FIG. 5, two disk spring assemblies 52, 58 with opposing spring travel are arranged in the push rod 51a, which are preloaded in the characteristic curve shortly before the break point. The plate spring assembly 58 is arranged in the chamber 57 for the compression stage and the plate spring assembly 52 is arranged in the chamber 53 for the rebound stage. The plate spring assembly 58 is connected to the pressure anchor 56, the plate spring assembly 52 with the tie rod 54. Tie rods 54 and 56 both have a bearing eye 55 at their free end, into which the mandrels 22a and 35a can engage.

In Fig. 6 the structure and operation of the push rod 51a is described in more detail.

In the middle picture of FIG. 6, the push rod is in the rest position for forces within the range of 0-220 Newtons. This value corresponds to a disengagement torque of approx. 5 Nm. The plate spring assembly 52 is mounted on the sleeve 62 with an end plate 65. The tie rod 54 is slidably disposed within the sleeve 62 and abuts the ring 64 with its disk 61. The plate spring assembly 58 is mounted on the hollow pressure anchor 56 with washer 63 and also abuts the ring 64.

The upper picture in FIG. 6 shows how, in the case of expansion with a tensile force of 220 N or greater, the plate spring assembly 52 through the tie rod 54 slidably arranged in the sleeve 62, by means of its firmly connected disk 61, which abuts the sleeve 62, is compressed. Since the tie rod 54 is slidably mounted within the hollow tie rod 56, no forces are exerted on the plate spring assembly 58. The expansion of the push rod 51a is 8 mm in the dimensions provided.

The lower picture in FIG. 6 shows how, in the case of compression with a compressive force of 220 N or greater, the plate spring assembly 58 is firmly connected to the tie rod 56 Disk 63 is compressed while the plate spring assembly 52 remains unloaded. The compression of the push rod 51a is also 8 mm given the dimensions provided.

The characteristic curve of the plate springs used in the plate spring assemblies 52, 58 according to the invention is shown diagrammatically in FIG. 7. The disc spring stroke s is given on the abscissa in millimeters, the force F is given in Newtons on the ordinate. The unshaded area represents the preload area, the hatched area the working area of the disc spring. As can be seen from the diagram, the thickly drawn characteristic curve of the disc spring is preloaded just before its break point. The essentially constant maximum torque when the foot pedal shaft la; lb is forced to stand still lies on the essentially flat characteristic curve after the break point.

Instead of the embodiment explained in FIGS. 1-7, in which cup springs are used to limit the torque, other means 5, 8, 9 can also be used for this purpose.

For example, other mechanical springs can also be used which have a comparable characteristic curve, for example special coiled spiral springs with a strongly degressive characteristic curve, rubber spring elements, etc. However, other mechanical spring elements require a considerably larger installation space than plate spring sets. This is because different springs have to be put together in a system that the Sequence of the respective straight-line characteristics of the force / displacement diagram of the individual springs has kinks, which lead to a flattening of the total system.

In particular, it must be emphasized that with springs which have an essentially rectilinear characteristic, it is not possible to maintain an almost constant torque over the entire swivel range when forced to stand still. Commercially available cylindrical compression springs with a constant spring rate c in N / mm are therefore not usable for the solution according to the invention.

In FIG. 8, the means 8 for torque limitation consists of two hydraulic cylinders 83 connected to one another in the axial direction, with opposite stroke movement of the pistons 85 and lateral hydraulic cylinders 83, each with an accumulator 84. The two pistons 85 are in an end position and the piston rods 86 are each connected to the adapter plates 2la, 21b of the foot pedal shafts 6a, 6b and the eccentric discs 33a, 33b of the motor shaft 4 via the mandrels 22a, 22a and 35a, 35b. The two surfaces h and A _{2 of} the pistons 85 are of the same size. The gas pressure of the accumulators 84 corresponds to the selectable maximum value for the torque to be transmitted.

In FIG. 9, the torque-limiting means 9 consists of two pneumatic cylinders 93 connected to one another in the axial direction and equipped with counter-stroke movement of the pistons 95 and gas-filled displacement 97. The two pistons 95 are in an end position and the piston rods 96 are connected via the mandrels 22a, 22b and 35a, 35b to the adapter plates 21a, 21b of the foot pedal shafts la, lb and the eccentric discs 33a, 33b of the motor shaft 4. The two surfaces A- ^ and A _{2 of} the piston 95 are of equal size. The gas pressure in the displacement 97 corresponds to the selectable maximum value for the torque to be transmitted.

In principle, the torque-limiting means can also consist of suitable electronics. In such a case, it is advisable to provide two motors instead of a single motor, since the range of motion of the two feet should be controlled independently of one another. Preferably two direct drives are provided in the ankle axis itself. Electric motors with position or position detection, in particular stepper motors or servo motors, are suitable as motors. The two motors must be able to communicate with each other (synchronization) in order not to get out of step, i.e. a real 2-axis card is required, which regulates or controls the two motors.

The basic mode of operation for electronic torque limitation can be divided into the following steps:

1. Reference run:

The two motors move to their respective limit switches for reference. This step can be carried out when using an absolute position measuring system (e.g. potentiometer or resolver) omitted. In the case of relative displacement measuring systems (e.g. encoders), this step must be carried out without a patient after switching on the device.

2. Measure:

The electronics (microprocessor) control the amplifiers of the two motors with slow speed and low torque. The individual limit values for the patient's range of motion are recorded via the power increase (current and / or voltage) or the following error of the two motors and stored in the electronics.

3. Start of treatment:

The two motors run at full power within the measured angular range in reversing operation, the synchronization being able to be achieved either via different angular velocities on the left and right side of the foot or through different pause lengths in the reverse positions (programming).

A further embodiment of the invention is described in FIG. 10, in which the means for torque limitation comprise a hydraulic cylinder 10 with a continuous piston rod 103 and a rectifier circuit 104 on the side, consisting of four check valves 105 and a controllable pressure relief valve 106. The continuous piston rod 103 on one side and the housing 107 on the other side are provided with a swivel eye 108 for connection to the Adapter plates 21a, 21b by means of the mandrels 22a and 35a, the set spring pressure of the pressure relief valve 106 corresponding to the selectable maximum value for the transmitted torque.

Claims

1. Device for moving the upper ankle, which comprises two foot pedal shafts (la, lb) lying horizontally in a bearing (6a, 6b), coaxially extending left and right, on each of which a left and right foot pedal (2a, 2b) radially are mounted in a rotationally fixed manner and can be driven by means of a motor (3) in such a way that the rotating movement of the motor shaft (4) is converted into an alternating, counter-rotating pivoting movement of the left and right foot pedals (2a, 2b) between two end positions within a limited angular range , characterized in that means (5; 8; 9; 10) are provided which, when a foot pedal (2a, 2b) is forced to stand still, as a result of reaching an end position in the range of motion of an upper ankle joint which is caused by the motor shaft (4) torque transmitted to the foot pedal shaft (la; lb) cannot exceed a selectable maximum value.

2. Device according to claim 1, characterized in that the means (5; 8; 9; 10) provided for the non-exceeding of the torque are designed in such a way that their characteristic curve in their force / displacement diagram up to a break point which corresponds to the selected one Corresponds to the maximum value, increases essentially in a straight line and then runs essentially flat.

3. Device according to claim l or 2, characterized in that each foot pedal (2a, 2b) on an angular rail (23a, 23b) in a slot (24a, 24b) is arranged axially displaceably, and at any point in the slot (24a, 24b) can also be swiveled to the left and to the right by approximately 10 ° in the fastening pivot point, and the angle rail (23a, 23b) is provided on the housing side with an adapter (27a, 27b) which can be fastened by means of a knurled screw (28) with an adapter (21a, 21b) of the shafts (la, lb) in such a way that the two adapters can be indexed and connected to one another in three different positions, so that two further zero positions can be set in addition to the vertical zero position.

4. Device according to one of claims 1-3, characterized gekenn¬ characterized in that the means (5; 8; 9; 10) for torque limitation connecting the motor shaft (4) and the foot pedal shaft (la; lb) connecting rod designed as a hollow rod (51a, 51b), in which two spring washers (52, 58) preloaded up to shortly before the kink in the characteristic curve of the force / displacement diagram are arranged with opposing spring travel, the essentially constant maximum torque when the foot pedal shaft is forced to stand still ( la; lb) lies on the, essentially flat characteristic after the break point.

5. Device according to one of claims 1-3, characterized gekenn¬ characterized in that the means (5; 8; 9; 10) for torque limitation two connected in the axial direction, with opposite stroke movement of the piston (85) and laterally with one Accumulator (84) provided hydraulic cylinder (83) such that the two pistons (85) are in an end position and the piston rods (86), via the mandrels (22a) and (35a) with the adapter plates (21a, 21b) Foot pedal shafts (la, lb) or the eccentric discs (33a, 33b) of the motor shaft (4) are connected and the gas pressure of the accumulator (84) corresponds to the selectable maximum value for the torque to be transmitted.

6. Device according to one of claims l - 3, characterized gekenn¬ characterized in that the means (5; 8; 9; 10) for torque limitation two connected in the axial direction, with opposite stroke movement of the pistons (95) and with gas-filled displacement ( 97) equipped pneumatic cylinder (93) in such a way that the two pistons (95) are in an end position and the piston rods (96) via the mandrels (22a) and (35a) with the adapter plates (21a, 21b) of the foot pedal shafts ( la, lb) or the eccentric discs 33a, 33b of the motor shaft 4 are connected and the gas pressure in the displacement (97) corresponds to the selectable maximum value for the torque to be transmitted.

7. Device according to one of claims 1 to 6, characterized gekenn¬ characterized in that the motor (3) is a geared motor.

8. Device according to one of claims 1-3, characterized gekenn¬ characterized in that the means (5; 8; 9; 10) for torque limitation comprise an electronic control for the motor (3), preferably with a microprocessor.

9. The device according to claim 8, characterized in that the motor (3) consists of two individual electric motors.

10. Device according to one of claims 1-3, characterized in that the means (5; 8; 9; 10) for torque limitation a hydraulic cylinder with a continuous piston rod (103) and laterally a rectifier circuit (104) consisting of four check valves ( 105) and an adjustable pressure relief valve (106), so that on the one hand the continuous piston rod (103) and on the other hand the housing (107) is provided with a swivel eye (108) for connection to the adapter plates (21a, 21b) by means of the spikes (22a ) and (35a), and the set spring pressure of the pressure relief valve (106) corresponding to the selectable maximum value for the torque to be transmitted.

11. The device according to one of claims 1-3, characterized gekenn¬ characterized in that the means (5; 8; 9; 10) for torque limitation comprises a compression spring system which is wound such that it has a strongly degressive characteristic of the force / displacement Chart.

12. Device according to one of claims 1-3, characterized gekenn¬ characterized in that the means (5; 8; 9; 10) for torque limitation comprises a system made of rubber or plastic springs, the shape of which is selected such that the system has a strongly degressive characteristic curve of the force / displacement diagram.