US3069692A - Artificial leg - Google Patents

Description

Dec. 25, 19.62 c. E. REGNELL 1 3,069,592

ARTIFICIAL LEG Filed July 13. 1959 2 Sheets-Sheet 1 kam -55 NVENTO BY I f M W [all fl/Wfm,

Dec. 25, 1962 Filed July 13, 1959 2 Sheets-Sheet 2 INVENTOR CHRL ERIK KEGNELL BY United states atent Ufitice 3,969,692 Patented Dec. 25, 1962 3,069,692 ARTIFICIAL LEG Carl Erik Regnell, Vaxjo, Sweden, assignor to Karl Axel Olof Friberg, Oskarshamn, Sweden Fiied July 13, 1959, Ser. No. 826,676 Claims priority, application Sweden Aug. 27, 1958 11 Claims. (Cl. 3-1.2)

This invention relates to artificial legs and more specifically of the kind to be attached to a femural stump. The artificial leg comprises a thigh and a hollow shank journalled to said thigh by means of a knee joint shaft, said shank including an hydraulic unit decelerating the motion of the knee joint, an artificial foot attached to said shank, said hydraulic unit comprising two coaxially arranged cylinders filled with liquid and communicating with each other through a channel, piston means adapted to press liquid from one of said cylinders to the other and vice versa during gait, said piston means arranged on a piston rod, the upper end of said piston rod hinged to said thigh at some distance from said knee joint shaft.

The primary object of the invention is to obtain a control of the swing phase of the shank of an artificial leg of this kind during gait in such a way that the shank is not swung abnormally high reawards and that the swinging movement forwards of the shank is decelerated and further that the performance of a noisy shock just before the complete stretching or extension of the prosthesis is prevented.

The essential feature of the invention resides in the arrangement of a movable slide in the connection channel between said cylinders for decreasing the liquid passage through said channel at sudden pressure impulses in the cylinders on either side of said channel. The device is adapted to function in dependence of the speed of gait of the amputee who uses the artificial leg and as a lower limit could be mentioned the value of 50 steps per minute, preferably however at 65 steps per minute. When put into function the decelerating effect of the device will increase in correspondence to the increase in the gait speed. In such a way the artificial leg is moved with the same cadence as the natural leg and the gait resembles that of a person with two natural legs.

The invention is intended to be applied especially to such artificial legs in which the hydraulic decelerating unit comprises two coaxially arranged cylinders on either side of a valve housing and two pistons parting the said cylinders each in two cylinder chambers, the upper and the lower of these four cylinder chambers interconnected with an axial bore in a piston rod carrying the said pistons and the two intermediate cylinder chambers interconnected with a channel, said piston rod hinged to the thigh, at some distance from the knee joint. The channel is formed in a valve housing between said cylinders, whereas a valve is arranged in said channel, said valve via movable means connected with the artificial foot, said valve being closed by means of a spring when the artificial foot is exposed to a load so as to lock the knee joint, said valve being instantly opened when said load is removed.

According to a further feature of the invention, the device is so constructed as to render possible an adjustment of the swinging of the shank if desired, eg for very fast, active walkers, in such a way that said swinging is made more slow at the beginning of the swing phase.

The invention will now be elucidated with reference to the accompanying drawings. In the drawings:

FIGI is a perspective view in a partial longitudinal section of an artificial leg according to the invention,

FIG. 2 shows on an enlarged scale a longitudinal section through the valve housing of the prosthesis, said housing provided with a device for the control of the swing phase,

FIG. 3 shows a longitudinal section through the control device according to a somewhat modified embodiment of the invention,

FIG. 4 is a cross section through the valve slide of the control device on the line IVIV in FIG. 3,

FIG. 5 shows ina longitudinal section similar to that of FIG. 2 a modified embodiment of the valve housing, and

FIG. 6 is a side elevation in a partial longitudinal sec tion of the hydraulic unit according to a modified embodiment of the invention.

Referring now to FIG. 1, it is obvious that the thigh attachment 1, i.e., the knee joint, is connected to an hydraulic knee locking unit 3 by means of a lever extending forwards from said thigh attachment 1 for rendering possible a swing movement of the shank. relative to the thigh attachment within an angular range of at least The hydraulic unit 3 is connected to an artificial foot 4 which may be articulated in relation to the shank 38 (shown only partially in FIG. 1) and further is movable vertically in relation to said shank as the artificial foot is hinged to a guide rod 5 which is axially movable in the lower end portion 6 of the unit.

The hydraulic unit 3 for locking the knee joint is arranged in the shank 38. Said unit 3 comprises two coaxially over each other arranged cylinders 7 and 8 filled with liquid, and in each one of said cylinders there is arranged a piston 9 and 10. These pistons are fixed to a common piston rod 11 extending through a bushing 12 in a valve housing 13, situated between the cylinders 7 and 8, and up to the shaft 2.

There is a channel 16, 17 arranged in the valve housing 13 which channel constitutes the connection between the cylinder chambers 14 and 15 and in the channel 16, 17 there is a valve 18 the valve disk 19 of which by means of a valve lifter 20 can be removed from its seat 22 against the action of a helical spring 21 thereby creating a connection between said cylinder chambers 14 and 15. The valve lifter 20 is turnable in the valve housing 13 and is at its outer end provided with a valve arm 23 which by means of a rod '24 ishinged to a disk 25 at the upper end of the guide rod 5. In the position of the lifter 20 shown in FIG. 1, the disk 25 rests on a surface 26 of the portion 6.

In an oblong cylinder space 27 in the channel 16, 17 is axially movable a slide 28 having conical end portions 29,, 30. In the outer end of the cylinder space 27 which is closed by a screw 31, there is screwed a nut 33 having a flow opening 32 for the liquid. A spring 34 is inserted between the nut 33 and one end of the slide 28 and there is a similar spring 35 inserted between the opposite end of the slide 28 and the inner end of the cylinder space 27. The channel 16 terminates in a space 36 outside the nut 33. The slide 28 is in its mantel surface provided with by-pass grooves 37 for the liquid.

When the artificial leg is swung from the position according to 'FIG. 1 and rearwards (i.e. to the left accord} ing to the drawing) liquid is pressed from the cylinder chamber 15 around the valve body 19, through the channel 17 and into the cylinder space 27, further through the by-pass groove 37, the flow opening 32 in the nut 33 and through the channel 16 into the cylinder chamber 14. If the swing movement is performed rapidly, the slide 28 will, due to the pressure impulse occurring when liquid flows rapidly through the channel 17 and into the cylinder space 27, be moved against the action of the spring 34 with its end more or less into the flow opening 32 in the nut 33 and diminish the flow area of this opening, the swing of the shank thereby being decelerated. In the same way, the movement of the shank is decelerated when swung inopposite direction, liquid then being pressed from the cylinder chamber 14 through the channel 16 and the flow opening 32 into the cylinder space 27, further through the by-pass grooves 37 and the channel 17 in the valve body 19 into the cylinder chamber 15. When the shank 38 is swung rapidly in the direction in question, i.e. forwards (to the right according to FIG. 1) the slide 28 is forced by the pressure impulse to the left according to FIG. 2 and with its conical end 29 it is pressed against the action of the spring 35 more or less into the channel 17 thereby diminishing the flow opening of the same which gives as a result a deceleration of the swing of the shank.

A certain adjustment of the deceleration could be obtained by tightening and loosening the nut 33, whereby the distance between the conical end 30 of the slide 28 and the flow opening 32 of the nut 33 is adjusted and also the tension of the springs 34, 35.

The cross section of the by-pass grooves 37 and also of the channels 16, 17 and of the flow passage 32 is to be chosen in such a way that there is obtained the deceleration of the shank necessary for a normal gait. Any notable movement of the slide 28 should thus occur only at a rapid gait when the deceleration of the swing movement' of the shank described here above is necessary.

As soon as the prosthesis with its foot abuts against the ground, the guide rod with the disk and the rod 24 is moved upwards while provoking a turning of the lifter 20 in a counterclockwise direction according to FIG. 2 whereas the spring 21 closes the valve 18, and there will not any longer be any connection between the cylinder chamber 15 and the cylinder chamber 14. It is then possible for the amputee to rest on the artificial leg Without any risk for the same to collapse.

*In FIG. 3 there is shown an embodiment which differs from the embodiment disclosed in FIG. 2 only thereby that there is at the inner end of the cylinder space 27 arranged a nut 40 having a flow opening 39 resembling the nut 33 at the outer end of said cylinder space 27. Such an arrangement provides for an even better precision of the device as then the flow openings 32 and 39 of the two nuts 33 and 40 as well as the conical ends 29 and could be easily ground.

In FIG. 5 there is shown an embodiment of an artificial leg to be used by a person having a rather long and strong femural stump, as some of those persons do not need or do not want to have a valve controlled by the foot as they themselves can control the knee joint and lock it by pressing rearwards the lower end of the thigh thereby preventing the prosthesis from collapsing. InFIGS. 2

and 5 corresponding parts have been given corresponding reference letters and these parts will therefor not be described once again. In the cylinder space 27 there is according to FIG. 5 arranged a nipple 41 having a flow channel 42 which constitutes a continuation of the channel 17 from the cylinder chamber 15. The nipple 41 fits into the cylinder space 27 with practically no play and forms an abutment for one end of the spring which with its opposite end surrounds one of the conical ends 29 of the slide 28. In the opposite end of the cylinder space 27 there is arranged a spring 34 clamping in the same manner as the spring 35 the conical end 30 of the slide 28 and a nipple 43 with its outermost coils. The slide 28 differs in this embodiment from the one shown in FIG. 2 in that it has no by-pass grooves but has a flange 44 having a diameter which is smaller than the diameter of the cylinder space 27 by an amount such that there is provided a clearance between said flange 44 and the wall of the cylinder space 27 having about the same area as the flow opening 42. The nipple 43 is pressed against the inner end of a screw 45 closing the opening of the cylinder space 27 and being provided at its inner end with a flow channel 46 corresponding to the flow opening in the nipple 43. The screw 45 can be loosened or tightened by means of a hexagon key inserted in a hexagon notch 47 in said screw head.

When at the swinging of the artificial leg pressure arises for instance in the cylinder chamber 14, liquid is forced through the channels 16 and 46. If the pressure arises suddenly, as the case is at a quick walking, the jet of liquid from the orifice in the nipple 43 will press the slide 28 in the direction towards the nipple 41 at the inner end of the cylinder space 27. Thereby, the stream of liquid is diminished not only by the conical end 29 which is moved more or less towards the orifice in the nipple 41 but there is also a decelerating effect obtained by the coils of the spring 35 which are pressed closer to each other while preventing liquid from passing through the spaces between them. As obvious, also in this case the swing phase control according to the invention involves the same advantages as in the embodiment where the artificial leg was provided with a valve controlled by its foot.

In FIG. 6 there is shown an hydraulic device in a view corresponding to the view shown in FIG. 1 and in these two figures corresponding parts have been given same reference letters. The action of the device is principally the same as that of the device according to FIG. 1 but as there is no valve controlled by the foot the liquid in this hydraulic unit is streaming as described in connection with the valve housing shown in FIG. 5. In the device according to FIG. 6 there is, however included an attachment plate 4 8 having a turning rod 49 which plate is to be fixed to the thigh of the prosthesis. In the bed for the turning rod 49 there is arranged a guide rod 50 with a handle which turning rod 49 is connected to a Bowden-wire 51 or the like. By swinging the turning rod 49 with the handle a valve 52 is moved from an opened to a closed position or vice versa under intermediary of a valve arm 53. This valve 52 serves for closing the channel between the cylinder chambers 14 and 15 so as to lock the knee joint when the amputee intends to be standing for a while and he does not want to have to think of locking the knee joint himself by pressing the lower end of the thigh rearwards. The plate 48 is to be placed in such a way that the rod 49 can be easily reached by the amputee for instance through the pocket so as to render it possible to manipulate the rod 50 as inappreciably as possible.

In the embodiment of FIG. 6 there is arranged a pin 56 projecting upwards from the bottom 54 of the outer, lower cylinder chamber 55 of the cylinder 8, i.e. the cylinder chamber situated on the outside of the piston 10, said pin 56, the upper end of which preferably is conical, projects into the cylinder chamber 55 and is arranged in such a way that it enters into the downwards widening mouth of a central bore 57 in said piston rod 11 in the lower end position of the latter. When the shank is swung forwards, the piston rod 11 with the pistons 9 and 10 is pressed downwards, liquid then streaming from the lower cylinder chamber 55 upwards through the central bore 57 in the rod 11 until the mouth of a bore is put over the pin 56 which, as the mouth widens conically in the direction downwards, continuously closes said month more and more until it, before the lower end of the pistons rod 11 strikes against the bottom 54 of the cylinder chamber 55, completely or almost completely closes said mouth and prevents further movement downwards of said rod 11. The pin 56 thus provides fora smooth and effective stopping of the movement downwards of the rod 11 and thus also of the swing forwards of the shank whereby is prevented a noisy shock when the rod 11 reaches the bottom 54 and also is ensured a longer life of the knee joint. By using a suitable steel material in the pin 56 the latter will be exposed to practically no wearing especially as oil will be used as hydrualic medium.

The pin 56 could of course be used with the same ad vantage in the embodiment shown in FIG. 1. Practical tests have proved that the pin 56 renders impossible even a voluntary damage of the knee joint by hard swinging of the shank.

The shown and described embodiments are to be regarded only as examples and the different details of the prosthesis could be constructively changed in many Ways within the scope of the invention. There could thus be arranged a further valve in a special, narrow conduit between the cylinder chambers 14 and 15 to be opened by the amputee when walking down stairs or on uneven ground so as to create a connection between said cylinder chambers when the channel 16, 17 between them is closed due to load on the foot. This regards of course only the embodiment according to FIGS. 1 and 2.

What I claim is:

1. An artificial leg to be attached to a femural stump and comprising a thigh and a hollow shank journalled to said thigh by means of a knee joint shaft, said shank including an hydraulic unit decelerating the motion of the knee joint, an artificial foot attached to said shank, said hydraulic unit comprising two coaxially arranged cylinders filled with liquid and communicating with each other through a channel, piston means adapted to press liquid from one of said cylinders to the other and vice versa during gait, said piston means arranged on a piston rod, the upper end of said piston rod hinged to said thigh at some distance from said knee joint shaft, a valve housing arranged between said cylinders, said channel arranged in said housing with the ends opening into said cylinders and a valve arranged in said channel, movable means connecting said valve with the artificial foot, a spring arranged to close said valve in order to lock the knee when said artificial foot is exposed to load and to open said valve when there is no load, a slide arranged in said channel between the ends thereof and having a cross sectional area slightly less than the cross sectional area of said channel for partially obstructing flow through said channel, and resilient means in said channel bearing on said slide urging it into position in said channel intermediate the ends of said channel, said slide being movable from an intermediate position in either direction against said resilient means at pressure impulses in either of said cylinders for decreasing the cross sectional area of the flow path in said channel for decreasing the passage of liquid through said channel, said slide provided with conical end portions, said channel having reduced cross sectional areas on both sides of said slide into which said conical end sections move depending on the liquid pressure.

2. An artificial leg to be attached to a femural stump and comprising a thigh and a hollow shank journalled to said thigh by means of a knee joint shaft, said shank including an hydraulic unit decelerating the motion of the knee joint, an artificial foot attached to said shank, said hydraulic unit comprising two coaxially arranged cylinders filled with liquid, and further comprising a wall between said two cylinders, said wall having a channel therethrough with the ends of said channel opening into said cylinders, said cylinder-s being in communication with each other through said channel, piston means adapted to press liquid from one of said cylinders to the other and vice versa during gait, said piston means arranged on a piston rod, the upper end of said piston rod hinged to said thigh at some distance from said knee joint shaft, a slide arranged in said channel between the ends thereof and having a cross sectional area slightly less than the cross sectional area of said channel for partially obstructing fiow through said channel, and resilient means in said channel bearing on said slide urging it into position in said channel intermediate the ends of said channel, said slide being movable from an intermediate position in either direction against said resilient means at pressure impulses in either of said cylinders for decreasing the cross sectional area of the flow path in said channel for decreasing the passage of liquid through said channel, said slide provided with conical end portions, said channel having reduced cross sectional areas on both sides of said slide into which said conical end portions move in dependence 4. An artificial leg as claimed in claim 2 in which the diameter of said slide is slightly less than the diameter of channel. 7

5. An artificial leg to be attached to a femural stump and comprising a thigh and a hollow shank journalled to said thigh by means of a knee joint shaft, said shank including an hydraulic unit decelerating the motion of the knee joint, an artificial foot attached to said shank, said hydraulic unit comprising two coaxially arranged cylinders filled with liquid, and further comprising a wall between said two cylinders, said wall having a channel therethrough with the ends of said channel opening into said cylinders, said cylinders being in communication with each other through said channel, piston means adapted to press liquid from one of said cylinders to the other and vice versa during gait, said piston means arranged on a piston rod, the upper end of said piston rod hinged to said thigh at some distance from said knee joint shaft, a slide arranged in said channel between the ends thereof and having a cross sectional area slightly less than the cross sectional area of said channel for partially obstructing flow through said channel, and resilient means in said channel bearing on said slide urging it into position in said channel intermediate the ends of said channel, said slide being movable from an intermediate position in either direction against said resilient means at pressure impulses in either of said'cylinders for decreasing the cross sectional area of the fiow path in said channel for decreasing the passage of liquid through said channel, said slide provided with conical end portions, said channel having reduced cross sectional areas on both sides of said slide into which said conical end portions move in dependence of the liquid pressure, at least one of said passage openings being in a nut, said wall having a cylindrical chamber therein for said slide, said chamber being part of said channel and said nut threaded into said chamher.

'6. An artificial leg to be attached to a femural stump and comprising a thigh and a hollow shank journalled to said thigh by means of a knee joint shaft, said shank including an hydraulic unit decelerating the motion of the knee joint, an artificial foot attached to said shank, said hydraulic unit comprising two coaxially arranged cylinders filled with liquid and piston means adapted to press liquid from one of said cylinders to the other and vice versa during gait, said piston means comprising two pistons dividing the said cylinders each in two cylinder chambers,

a piston rod carrying said two pistons and having an axial bore interconnecting the upper and'the lower of these four cylinder chambers and said hydraulic unit having a channel interconnecting the two intermediate cylinder chambers, the upper end of said piston rod hinged to said thigh at some distance from said knee joint shaft, a slide arranged in said channel between the ends thereof and having a cross sectional area slightly less than the cross sectional area of said channel for partially obstructing flow through said channel, and resilient means in said channel bearing on said slide urging it into position in said channel intermediate the ends of said channel, said slide being movable from an intermediate position in either direction against said resilient means at pressure impulses in either of said cylinders for decreasing the cross sectional area of the flow path in said channel for decreasing the passage of liquid through said. channel, said slide provided with conical end portions, said channel hav ing reduced cross sectional areas on both sides of said slide into which said conical end sections move depending on the liquid pressure and a damper means in one of said cylinders for preventing the performance of a sudden I shock at the full extension of the artificial leg, said damper means comprising a pin projecting axially upwards fro-m the'bottom of the lowermost cylinder chamber, said pin being arranged to almost fully close the lower end of said bore at the end of the downward movement of said piston rod at the gait.

'7. An artificial leg as claimed in claim 6 in which the lower end of the bore of said piston rod increases in width in the downward direction where said pin enters said bore.

8. An artificial leg as claimed in claim 6 in which said pin decreases in diameter in the upward direction.

9. An artificial leg to be attached to a femural stump and comprising a thigh and a hollow shank journalled to said thigh by means of a knee joint shaft, said shank in cluding an hydraulic unit decelerating the motion of the knee joint, an artificial foot attached to said shank, said hydraulic unit comprising two coaxially arranged cylinders filled with liquid and communicating with each other through a channel, piston means adapted to press liquid from one of said cylinders to the other and vice versa during gait, said piston means arranged on a piston rod, the upper end of said piston rod hinged to said thigh at some distance from said knee joint shaft, a valve housing arranged between said cylinders, said channel arranged in said housing with the ends opening into said cylinders and a manually operated valve arranged in said channel, a slide arranged in said channel between the ends thereof and having a cross sectional area slightly less than the cross sectional area of said channel for partially obstructing flow through said channel, and resilient means in said channel bearing on said slide urging it into position in said channel intermediate the ends of said channel, said slide being movable from an intermediate position in either direction against said resilient means at pressure impulses in either of said cylinders for decreasing the cross sectional area of the flow path in said channel for decreasingthe passage of liquid through said channel, said slideprovided with conical end portions, said channel having reduced cross sectional areas on both sides of said slide into which said conical end sections move depending on the liquid pressure.

10. An artificial leg to be attached to a femural stump and comprising a thigh and a hollow shank journalled to said thigh by means of a knee joint shaft, said shank including an hydraulic unit decelerating the motion of the knee joint, an artificial foot attached to said shank, said hydraulic unit comprising two coaxially arranged cylinders filled with liquid and communicating with each other through a channel, piston means adapted to press liquid from one of said cylinders to the other and vice versa during gait, said piston means arranged on a piston rod, the upper end of said piston rod hinged to said thigh at 8 some distance from said knee joint shaft, a valve housing arranged between said cylinders, said channel arranged in said housing with the ends opening into said cylinders and a valve arranged in said channel, said valve manually operated by means of a handle connected to said valve by means of a Bowden-wire, a slide arranged in said channel between the ends thereof and having a cross sectional area slightly less than the cross sectional area of said channel for partially obstructing flow through said channel, and resilient means in said channel bearing on said slide urging it into position in said channel intermediate the ends of said channel, said slide being movable from an intermediate position in either direction against said resilient means at pressure impulses in either of said cylinders for decreasing the cross sectional area of the flow path in said channel for decreasing the passage of liquid through said channel, said slide provided with conical end portions, said channel having reduced cross sectional areas on both sides of said slide into which said conical cluding a hydraulic unit decelerating the motion of the knee joint, an artificial foot attached to said shank, said hydraulic unit comprising two coaxially arranged cylinders filled with liquid and further comprising a wall between said two cylinders, said wall having a channel there- I through with the ends of said channel opening into said cylinders, said cylinders being in communication with each other through said channel, piston means adapted to press liquid from one of said cylinders to the other and vice versa during gait, a piston rod on which said piston means are mounted, the upper end of said piston rod hinged to said thigh at some distance from said knee joint shaft, an obstruction member arranged in said channel and obstructing the flow passage through said channel to reduce it to an area which is small compared to the cross sectional area of the channel for automatically increasing the resistance of the oil fiow through the channel at fast walking with the artificial leg, and a damper means comprising a pin projecting axially upwards from the bottom of the lowermost cylinder, said lowermost piston having a bore therein, said pin being arranged to almost fully close the lower end of said bore at the end of the downward movement of said piston at the gait for preventing the performance of a sudden shock at the full extension of the artificial leg.

References titted in the file of this patent UNITED STATES PATENTS

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