FR2630643A1 - System for locking a simple knee joint in extension - Google Patents

Abstract

The locking system comprises a bolt pin 15 arranged perpendicular to the axis 7 of articulation of a body 1 on a clevis 6 which receives and immobilises a lower leg segment tube 10; the pin 15 receives a locking index 27 which normally bears vertically on the face 28 of a stop triangle 29 fixed by screws 30, 31 onto the clevis 6; a screw 46 takes up the play of the index 27 against the bearing face 28; an operating lever 17 makes it possible to pivot the pin 15, the said lever being held normally in abutment by an elastic return means; elastomer bearings damp the return of the articulation in extension.

Description

Locking system in extension of a single knee joint.

The invention relates to a locking system in extension of a single knee joint.

 Locking systems are already known in knee joint extension. These systems use a vertical locking index which immobilizes the lower leg segment in the extension of the thigh axis. The operating device is arranged at the rear and on the lower part of the knee joint.

 The disadvantage presented by these systems is as follows: the unlocking control device is disposed on the fixed lower part of the joint, at the front or at the rear. As a result, the control cable, hooked to the unlocking lever, crosses the covering of the fixed part in which it moves when the upper part of the joint bends, which tears little by little. little foam coating covering the joint.

 The purpose of the locking system according to the invention is to overcome this drawback.

This object is achieved according to a preferred embodiment of the invention by means of a retractable lock by pivoting, in normal support on a stop, disposed laterally relative to the knee, being mounted symmetrically either to the right or to the left along the leg to equip, controlled manually, either by a small lever with elastic return, directly on the knee, or by means of a cable return at the hip.

 The advantages of the locking system according to the invention are as follows: - lateral arrangement of the unlocking control at the front of the upper part of the joint preventing the cable from tearing the foam covering covering the knee, the following cable all bending movements - great flexibility of the pivoting unlocking means; - symmetrical mounting of the same parts for the right and left positions; - manual operating lever fitted with a ball or cable to ensure unlocking; - lightness of the assembly made of light alloy.

 The invention is described in the following text with reference to the accompanying drawings given by way of nonlimiting examples, in which: - fig.1 shows the articulation according to the invention seen in elevation; - Fig.2 shows the joint seen in section in elevation along A of Fig.3; - Fig.3 shows the articulation in section seen from above along B of Fig.1; - Fig.4 shows the articulation in section in elevation along C of Fig.6; - Fig.5 shows the joint in rear view; - Fig.6 shows the sectional joint in top view along D of Fig.2; - Fig.7 shows the joint in top view.

 As shown in fig.1 and 5, the joint according to the invention comprises: - a body 1 on top of which is fixed a thigh support 2 by means of a screw 3 screwed into a nut plate 4 engaged in a groove 5; - A yoke 6 on which the body 1 is articulated by means of an axis 7 immobilized on the body 1 by a needle screw - 8; the lower part of the yoke has a bore 9, arranged vertically, in which is immobilized a tube 10, constituting the lower leg segment, by means of a screw 11, causing a tightening by elastic deformation of the tubular part of the clevis split in 12, by screwing in a boss 13; - the articulation locking system, shown in section along A in fig.3, consisting of a locking pin 15, pivoting in a blind bore 16 of the body 1 arranged perpendicular to the articulation axis 7, under the action of a lever 17 (fig.4) crossing the axis 15, resiliently biased in abutment on the bottom 18 of a clearance 19.20 (fig.1.6) by means of a return spring 21 .

The spring is hooked on a screw 22 passing through a clearance 23, 24, and engaged in a hole 25 in the end of the operating lever 17; said lever 17 is provided with a second hole 26 intended to receive an operating cable hanging on the hip. The lock pin 15 is provided with an index finger 27 fitted hard into a hole, from its internal end, oriented vertically downwards when the lever 17 is in abutment on the bottom 18 of the clearance 19,20.

This index is in normal support against the edge 28 of a stop triangle 29 fixed by screws 30, 31 on a machined surface 32 of the yoke 6; the lateral edges of this stop triangle 29 are chamfered at 33.34 to ensure the lateral release of the index 27, along the axis 35, when the lever 17 is operated upwards, along arrow 36, at this moment the index is completely free and the joint is unlocked allowing its flexion.

 Fig.3 shows the arrangement of the index 27 resting on the face 28 of the stop triangle. The index 27 moves in the direction of the arrow 37, escapes the corner of the triangle Z9 and moves in the direction of the arrow 38 during the tilting of the body 1 and remains released however that the lever 17 has returned to bear on the bottom 18 of the clearance 19.20 under the action of the return spring 21. When the articulation returns normally in extension, the index 27 meets the corresponding chamfer 33 (fi.4) and automatically returns to abutment on the face 28 of the stop triangle under the effect of the return spring 21.

 To allow the lever to be placed on the right or on the left, depending on the leg to be fitted, provision has been made to be able to mount the lever 17 to the right or to the left, as well as the return spring 21 thanks to the symmetrical clearances 23, 24 and 19, 20 and the symmetrical holes 40,41 to reverse the position of the triangle 29 Ifig.3), the latter having chamfers 42 on its two faces to receive the screws 30,31, in one direction or the other. When the stop triangle is arranged symmetrically with respect to its position in fig.3, the index 27 emerges on the other side.

 In fig. 6, the arrangement of the locking system and the light 43 for passage of the index have been shown, the latter being put in place from below.

 In fig.4 we see the edges 44 and 45 of the symmetrical passage clearance of the index 27 to allow it to be unlocked in both directions. To compensate for the wear of the locking index 27, due to the friction on the surface 28 of the stop triangle 29, a screw 46 was used, screwed into a thread located on the throat side of the bore 16, in the extension of the axis XX 'of pivoting of the bolt axis 15. This screw pushes the index finger 27 against the face 28 by pressing on the end of the axis 15. This screw can be blocked either by a drop of glue, or by a lock nut.

 To avoid abrupt contact of the body on the clevis 6, two damping stops 50 (fig. 1) are provided, each pushed by a screw 51, 52 (fig. 5) coming to bear against the edge 53 of the clearance of passage of the blanks 54 of the yoke 6.

Fig.7 shows the joint in top view and in particular the position of the nut 4 for fixing the thigh support 2.

 To reduce the weight of the prosthesis, the body 1 and the yoke 6 are made of light alloy. Two bearing rings 55, 56 are mounted on the body 1 to reduce wear (fig. 5).

Claims (6)

CLAIMS: 1 - Locking system in simple knee joint extension comprising a body articulated on a clevis, a locking means in extension, a means of adjusting the de-locking position, a means of fixing a thigh support, means for centering and immobilizing a tube constituting the lower leg segment, characterized in that said system consists of a pivoting latch (15) disposed laterally on the upper part (1) of the joint, at the front of the tilting body, and in that it includes a clearance adjustment means acting on the bolt axis (15), and in that the locking control parts are designed to be mounted on the right or to the left. 2 - System according to claim 1, characterized in that the locking means is constituted by a bolt axis (15) disposed perpendicular to the articulation axis (7) of the knee, in a blind bore (16) of the body (1), and in that a locking index (27) is fitted into the internal end of the axis (15) and projects outside of said axis so as to abut vertically on the corresponding face (28) a stop triangle (29) in the normally locked position. 3 - System according to claims 1 and 2, characterized in that the bolt axis (15) is operated by means of a pivoting lever (17) fitted into a hole drilled in the axis (15) moving in a clearance (19,20) of the body (1), normally held in abutment on the bottom (18) of the clearance under the action of a return spring (21). 4 - system according to claims 1 and 2, characterized in that the backlash of the index (27) against the face (28) of its stop is obtained by means of a screw (46) screwed into a thread of the body 1 along the axis XX 'of the lock (15), acting longitudinally to push the axis (15). 5 - System according to claim 1, characterized in that adjustable stops (50), arranged in the walls of the yoke (6), under the hinge axis (7), provide damping of the return in extension of the articulation by relying on the clearance (53) of the walls opposite the yoke (6).  6 - System according to claims 1,2 and 3, characterized in that the body (1) has clearances <l9, -20) symmetrical for the passage of the lever 17 and symmetrical clearances (44,45) for the passage of the index on the right and on the left, as well as symmetrical fasteners (22a, 22b) of the return spring, and in that the yoke (6) is designed to receive the stop triangle (29) symmetrically on the right or left and in that the stop triangle (29) is designed to be mounted symmetrically on the right or on the left, and in that it comprises a face (39) at an angle and two chamfers (34,34) for clearing the passage of the index (27).