FR2711512A1 - Prosthetic component for the knee joint - Google Patents

Abstract

Prosthetic component for the knee joint, which component is deformable between a block (4) connected to a sleeve for engagement of a thigh stump and a body (9) forming a leg piece and containing a hydraulic shock absorber connected via a piston rod, characterised by a piston rod (27) guided inside the body (9) by a ball-bearing bushing which is held in a sheath centred in the body (9) by a seat serving as a support for a compression spring (32) tending to lift a hood (31) carried by the end of the rod (27) of the piston (28) which is displaceable in a cylinder (29) delimited below the said seat (20), the said cylinder communicating at its top part and at its bottom part via orifices (22, 23) with tubes of a device for controlling the flow rate of fluid.

Description

 The present invention relates to a new prosthetic part for the knee joint.

 The invention relates to prosthetic parts whose articulation is of the connecting rod type, that is to say in which a set of connecting rods delimits a deformable quadrilateral whose pivoting reproduces the movements of the joint of a natural knee. The invention aims to simplify the entire prosthetic part by allowing it to always have an extremely smooth movement, without jerks, without there being any apparent play and the operation of which is completely silent. In addition, the invention creates new means which prevent any risk of the leg being able to slip away, regardless of the angular position occupied by the prosthetic piece relative to the stump of the amputee.

 The invention also makes it possible to ensure easy adjustment of the speed of pivoting of the prosthetic piece, both in the flexion and extension phase, so that the amputee can himself adjust the prosthetic piece as a function of the type of walk he wishes to program, the adjustment being able to be made by a simple maneuver, accessible through clothing.

 According to the invention, the prosthetic part for the knee joint in which a set of connecting rods delimits a deformable quadrilateral between a block connects to a sleeve for fitting a thigh stump and a body forming a leg part and containing a fluid damper connected by a piston rod to a control rod for the movement of the block is characterized in that the piston rod is guided inside the body by a ball bushing held in a sheath central in the body by a bowl serving as a support for a compression spring tending to lift a cap carried by the end of the piston rod displaceable in a cylinder delimited below said bowl, said cylinder communicating at its upper part and at its lower part by orifices with pipes of a device for adjusting the flow of fluid.

 Various other characteristics of the invention will also emerge from the detailed description which follows.

 Embodiments of the object of the invention are shown, by way of nonlimiting examples, in the accompanying drawings.

 Fig. 1 is an expanded view illustrating four phases of walking.

 Fig. 2 is a transverse elevation section, in accordance with the invention and partly schematic, of the prosthetic part for the knee joint.

 Fig. 3 is a side elevation seen substantially along line III-III of FIG. 2.

 Fig. 4 is a sectional elevation similar to FIG. 2 illustrating a different position of the organs of the prosthetic part.

 Fig. 5 is a section seen substantially along the line V-V of FIG. 4.

 Fig. 6 is a partial side elevation of a variant of a link device that includes the prosthetic part of the previous figures.

 Figs. 7 and 8 are sections seen substantially along the line VII-VII of FIG. 2 of a regulator that includes the prosthetic part of the previous figures.

To facilitate understanding of the description which follows, FIG. 1 schematically illustrates characteristic positions of the legs during walking. The illustrated figure shows a natural leg
A drawn in solid lines and an artificial leg B drawn in double lines. For each leg, the walk generally breaks down into a support phase and a pendulum phase. In position Oi, the natural leg A leaves the ground while the foot of the artificial leg B rests on the ground. This corresponds to the start of the pendulum phase of the natural leg A and the start of the support phase of the artificial leg B. The arrows illustrate the current pivoting of the legs A and B.

 In @ , natural leg A is no longer in contact with the ground and is in the knee flexion phase, that is to say at the start of the pendulum phase flexion cycle. The artificial leg B then oscillates around the foot in the support phase. In this position, the knee should not be able to flex. Figure 0 shows the natural leg A during the pendulum phase extension cycle. The knee is still slightly bent but the foot does not yet touch the ground. The artificial leg B is still in support, the foot pivoting only relative to the ground.

 In position g, the natural leg rests on the ground; it is the end of the pendulum phase and the beginning of the support phase, while the artificial leg B ceases to be in support and begins the pendulum phase for which the knee must begin to bend as soon as said artificial leg B ceases to be in compression as it was during the support phase.

 To allow the execution of the support and pendulum phases of the artificial leg B, the prosthetic part of the invention is provided for subjects whose amputation is practiced, either at the knee joint, or at- above this joint.

 As the drawing illustrates, in particular fig. 2, the prosthetic part comprises a plate 1 mounted so as to be able to rotate around its median axis 2 which appears more particularly in FIG. 4 although this illustrates a position which can only rarely be reached. The plate 1 is supported by bearings 3, preferably ball bearings, forming both rolling bearing and thrust bearing. The bearings are supported in a block 4 which includes a spring locking pin 5 to immobilize the plate 1 relative to the block 4 in a position suitable for a sleeve 6 for wrapping the base of the stump.

 The plate 1 is made to be as thin as possible and to make little or no projection relative to the joint C2.

 The locking finger 5 is adjustable by means of a button 7 to vary the angulation of the prosthetic piece relative to the stump.

 The block 4 above is articulated in a substantially horizontal plane around an axis C2 which extends between the branches 8a, 8b (fig. 2 and 5) of a yoke 8 articulated on an axis C4 supported by the body 9 of the prosthetic part. The block 4 supports, moreover, an axis C1 connected by a link 10 to an axis C3 also carried by the body 9.

The sets of connecting rods described above delimit a deformable quadrilateral ensuring a complex pivoting of the plate 1 relative to the body 9 of the prosthetic part so that the curve followed by the plate 1 during the deformation of the quadrilateral corresponds substantially to the pivoting movement and sliding of the natural knee joint.

 The body 9 is constituted by a rigid tubular element inside which is fixed a jacket 11 constituting a cylinder for a piston 12 and which is extended downwards by a sleeve 13 which is for example screwed as illustrated in FIG. 4. A seal 14 is provided between the sleeve 13 and the jacket 11 to form the bottom 15 of the cylinder which the jacket 11 delimits.

 The sleeve 13 is used to install a leg piece 16, for example tubular, (fig. 2), at the end of which is mounted a prosthetic piece of ankle and foot 17. A stop screw 18 or other similar member is provided to ensure the locking of the leg part 16 and its adjustment in angulation.

 Fig. 4 clearly shows that the jacket 11 has in the vicinity of its upper part a shoulder 19 for centering a bowl 20 mounted in leaktight manner for example by screwing with the interposition of a seal 21. The bowl 20 forms the upper part of a cylinder 29 which communicates through a high orifice 22 and a low orifice 23 with an adjustment device 24 (FIGS. 2 and 7, 8) which is described in detail in the following.

 The bowl 20 delimits a sleeve 25 in which is disposed a ball bushing 26 or the like for axial guidance without play of a piston rod 27 to which is fixed a piston 28 movable inside the cylinder 29 delimited by the jacket 11.

In a known manner, the piston 28 is provided with seals 30. The piston rod 27 is engaged in a cap 31 serving as a stop for a compression spring 32 bearing against the top of the bowl 20 and guided by the sheath 25. A deformable membrane 33 is disposed between the internal wall of the body 9 and the cap 31 to isolate the ball bushing 26 from any contamination which may come from the set of connecting rods described in the above and so that this ball bushing can possibly be lubricated and be protected in any case as well as the piston rod. The cap 31 is articulated on an axis C5 mounts at the foot of a connecting rod 34 whose head is articulated on an axis
C6 carried by one end of the block 4. The compression spring 32 tends to push up the cover 31 to bring it into the position illustrated in FIG. 2, which has the effect of bringing the piston 12 to the upper part of the cylinder 29 and tends to keep the block 4 in the position for which the sleeve 6 for holding the stump is substantially vertical. In this position, the block 4 bears against a stop 35 constituted by a cross-member connecting two arms of the connecting rod 10.

 A flexible lining 36 (fig. 2) is provided opposite the stop 35 under the block 4 to avoid any impact noise during the operation of the prosthetic part.

 It is important, during the operation of the prosthetic piece, that the angulation movement between the thigh and the leg, can be interrupted as soon as the leg comprising the prosthetic piece, begins to be in support to eliminate any risk that the leg to shy away.

 Figs. 2, 3 and 4 illustrate an embodiment allowing this result to be obtained.

 The yoke 8 is provided on its underside with elastic rings 37 surrounding tubes 38 which can slide in sockets 39 connected by a web 40. The web 40 is provided at its base with a friction part 41 intended to cooperate with a segment friction 42 carried by a roller 43 connected by means of bearings 44, preferably ball bearings, to the axis C4. The friction segment 42 is preferably flexible so as not to cause noise.

 As shown in fig. 5, when a pressure along arrow F1 is exerted on the yoke 8, this is transmitted by the elastic rings 37 to the web 40 and, consequently, the friction part 41 which then clamps the friction segment 42, this which prevents the rotation of the roller 43 on the axis C4 and consequently stops the pivoting movement in progress. As soon as the pressure ceases, the elastic rings 37 release the friction part 41 from the friction segment 42 by sliding the tubes 38 in the sockets 39. The different parts are then found in the position illustrated, in particular in FIGS. 2 and 5.

Fig. 6 illustrates a variant according to which the axis
C3 is not carried directly by the body 9 but is articulated at the head of connecting rods 45 carried by an axis C7. The connecting rods 45 are pushed by a spring 46 disposed in the body 9 and the base of the connecting rods 10 forms friction surfaces intended to cooperate with a friction segment 47 formed by the body 9. At least the friction segment 47 is advantageously slightly flexible.

 It can be seen from the above that a force exerted along arrow F1, that is to say tending to put the leg in support, has the effect of bringing the connecting rod foot 10 against the friction segment 47, this which prevents any subsequent pivoting of the connecting rod 10 relative to the body 9, that is to say that the same result is obtained as that described above with reference to FIG. 5.

 The complex pivoting movement of the deformable quadrilateral articulation device described in the foregoing must, on the one hand, be damped and, on the other hand, its return to the initial position for which the artificial leg is in its position of maximum elongation at the end of the pendulum phase must be able to be carried out more or less quickly.

 This is obtained by the adjusting device 24 which is constituted by a valve body comprising a tubing 48 communicating with the top port 22 and a tubing 49 communicating with the bottom port 23. The tubing 48 leads to a non-return valve. 50 while the tubing 49 leads to a chamber 51 containing an adjustment needle 52 actuable by a cam wheel or a slider 53 accessible from outside the prosthetic part.

 The tubing 49 also communicates with the chamber of a non-return valve 57 controlling the circulation in a channel 58 communicating by the needles 52 and 55 with the chambers 51 and 54.

 The tubing 48 communicates on its side with a chamber 54 containing an adjustment needle 55 operable by a cam wheel or a slider 56 also accessible from outside the prosthetic part.

 When bending the prosthetic appliance, that is to say to pass from the position illustrated in FIG. 2 towards the extreme position illustrated in FIG. 4, during the pendulum phase of walking, the spring 32 is compressed so that fluid passes through the bottom orifice 23 and is led as illustrated in FIG. 8 in tubing 49.

 The non-return valve 57 forces the fluid to pass through the chamber 51 and then to raise the non-return valve 50 to be brought by the tube 48 to the high orifice 22 as the piston 12 descends. acting on the wheel 53, the position of the needle 52 is adjusted and, consequently, the speed at which the prosthetic part can pivot. Conversely, when the prosthetic part pivots in the direction of extension, the fluid is discharged through the orifice 22 and is led as shown in fig. 7 by the tube 48 to the chamber 54 controlled by the needle 55, luimeme control by the wheel or slider 56.

 Depending on the position of the dial or slider 56, the needle 55 more or less blocks the passage to the channel 58 and the non-return valve 57 so that one also acts on the speed of extension.

 Locking balls 59 or other similar members cooperate with each of the knobs or sliders 53, 56 to keep them in the chosen adjustment position.

 The device described in the foregoing can be produced to operate pneumatically or hydraulically at the discretion of those skilled in the art, similarly needle devices can be replaced by other regulating mechanisms known in the art.

 The fact that all of the mechanical parts are disposed above the bowl 20 has the effect that the cylinder 29 contains only the piston 12, which allows that the entire section and the height of the cylinder are taken into account for the determination of the desired amortization effects.

 The invention is not limited to the exemplary embodiments, shown and described in detail, because various modifications can be made thereto without departing from its scope.

Claims (11)

 1 - Prosthetic part for the knee joint in which a set of connecting rods delimits a deformable quadrilateral between a block (4) connected to a sleeve for fitting a thigh stump and a body (9) forming a leg part and containing a fluid damper connected by a piston rod to a rod for controlling the movement of the block, ca ractérisee in that the piston rod (27) is guided inside the body (9) by a ball bushing maintained in a sleeve centered in the body (9) by a cup serving as a support for a compression spring (32) tending to lift a cap (31) carried by the end of the rod (27) of the displaceable piston (28) in a cylinder (29) delimited below said bowl (20), said cylinder communicating at its upper part and at its lower part by orifices (22, 23) with pipes of a device for adjusting the flow rate of fluid.  2 - Prosthetic part according to claim 1, characterized in that the deformable quadrilateral comprises parts (10, 41) of friction and segments (42, 47) cooperating to block the articulation with rods in any angular position depending on '' a pressing pressure exerted on the prosthetic part.  3 - Prosthetic part according to one of claims 1 or 2, characterized by a deformable membrane connecting the cap (31) of the piston rod (27) to the body (9) to isolate said piston rod and the ball bushing ensuring only the guidance of this piston rod.  4 - Prosthetic part according to one of claims 1 to 3, characterized in that the friction segments comprise a flexible part.  5 - Prosthetic part according to one of claims 1 to 4, characterized in that one of the connecting rods of the deformable quadrilateral is articulated between two axes (C2 and C4) por tes respectively by the block connected to the abutment sleeve of stump and to the body (9) and comprises tubes (38) sliding in sockets (39) carrying a web forming a friction part (41) facing a friction segment (42) surrounding the axis (C4), said veil being displaceable against the elastic action of elastic rings (37) interposed between this veil and a yoke (8) forming a part of said connecting rod.  6 - Prosthetic part according to one of claims 1 to 4, characterized in that one of the connecting rods of the deformable quadrilateral is carried by a pivoting connecting rod (45) pushed by a spring (46) holding the foot of the connecting rod (10 ) of the deformable quadrilateral opposite a friction segment (47) so that a pressure force exerted on said deformable quadrilateral brings said foot of the connecting rod (10) against said friction segment (47).  7 - Prosthetic part according to one of claims 1 to 6, characterized in that the top (22) and bottom (23) orifices of the cylinder (29) in which the piston (28) slides, the rod of which is guided in the sleeve with balls (27) communicate respectively with pipes (48, 49) of an adjustment device comprising two adjustment members which can be operated independently from the outside to modify the speed of displacement of the piston (29) during the movement corresponding to the bending and of the movement corresponding to the extension of the prosthetic part.  8 - Prosthetic part according to one of claims 1 to 7, characterized in that the adjustment is ensured by locking knobs or sliders accessible from the outside and controlling adjustment needles.  9 - Prosthetic part according to one of claims 1 to 8, characterized in that the block (4) connected to the connecting rods forming a deformable quadrilateral is provided on its top with a turntable (1) and a locking finger lage (5) to modify the angular position of the stump sleeve (6), the level of the turntable being close to that of the joint formed by an axis (C2) of the block (4).  10 - Prosthetic part according to one of claims 1 to 9, characterized in that the body (9) has inside a jacket (11) delimiting the cylinder (29) and a centering shoulder (19) of the bowl (20 ) forming a sleeve (25) for guiding the ball bushing (26) and centering the compression spring (25) interposed between the bottom of the bowl (20) and the cap (31) connected to the body (9) by the deformable membrane (33).  11 - Prosthetic piece according to one of claims 1 to 10, characterized in that the base of the shirt (11) is provided with a sleeve (13) comprising at least one stop screw (18) for a piece of leg (16) provided with a prosthetic part (17).