EP1121085B1 - Splint for mobilising lower limb - Google Patents

Abstract

The invention concerns the medical field, in particular a splint characterised in that the footrest is mounted on the tibial cradle via at least a slide (11) with interposed elastic return means (34) constantly tending to return the footrest into a least extended position relative to the tibial cradle. The invention is useful for the passive mobilisation of a lower limb.

Description

The present invention relates to the medical field and relates to materials used for orthopedic or rehabilitation treatments functional of the lower limbs.

PRIOR ART:

For the above purposes, the proposed material is generally made up in the form of a splint comprising a base or base supporting a structure articulated composed of a crural segment or cradle connected by an articulation to a leg segment or cradle most often equipped, like the crural cradle, with a hammock for receiving and supporting the corresponding part of the lower limb mobilize.

Such splints, called articulated as opposed to fixed splints, do not allowing the immobilization in determined posture of a lower limb, are intended to allow mobilization in flexion-extension at least for two of the joints of a lower limb, namely the hip joint and the knee.

For this purpose, it is generally planned to mount the end of the cradle leg on a carriage which is movable along a longitudinal axis of the base or the base. By such an arrangement, it becomes possible to control the sliding alternative of the trolley either directly by the physical action of the lower limb, or indirectly through a motor acting independently.

This last type of material is generally called a splint of passive mobilization, since it is responsible for causing flexion and extension of the lower limb without the muscular systems of the latter are responsible for such a movement.

Such splints called passive mobilization have brought a great advances in rehabilitation methods and should be seen as giving generally satisfied.

However, the putting into practice of such materials made it possible to note a non-optimal flexion-extension functionality in certain applications or applications in action.

Indeed, according to the types of materials and / or the implementation of use, it is frequent to note that the axis of articulation of the crural segment on the base or the base is not located in exact coincidence with the anatomical axis of the joint hip. It is frequent to note a shift of plan compared to that support of the base, but also a shift in the same plane.

Such a non-coincidence has a consequence which is that the effective length of the crural segment between its articulation on the base and the axis articulation with the leg segment, appears longer than that of the bone segment of the limb to be rehabilitated and, more particularly, the length of the femur between the coxo-femoral axis and the knee.

The consequence of such non-identity is that from a situation of bending, for example of the order of 90 ° and in which it could be considered that the knee joint and the joint between the crural and leg segments are substantially coincidentally, any displacement in extension results in an offset between the trajectories in arcs of a circle described by these points of articulation.

This results in an absence of support between the foot and the footrest and rehabilitative conditions which, due to this consequence, are no longer optimal and induce disorders and constraints which are not favorable to obtaining the desired result.

The problem therefore arises of being able to propose a solution that overcomes this difficulty so that by construction it can be remedied disadvantage, in order to be able to properly mobilize a lower limb without bring about induced fatigue which negatively offsets the results rehabilitation provided by the commissioning of such a splint.

The object of the invention is to propose a constructive solution which allows precisely to solve the problem thus posed.

The means according to the invention are particularly designed to respond, in addition to the above problem, there is a second requirement frequently imposed on the personnel responsible for the commissioning of such splints and who is that of the need to be able or to have to adjust the length of the leg segment according to the length of the corresponding bone segment of the limb to be rehabilitated.

The object of the invention, by the means used to regulate the previous problem, opens a possibility of automatic adjustment of such length.

The object of the invention is also designed to take into account a observation frequently made in the field of rehabilitation, when the functional rehabilitation treatment, following a major trauma, leaves the lower limb in a passive level of work involving no voluntary muscular effort, mainly in the thigh muscles.

In such a case and if the rehabilitation treatment is to take place during a relatively long time, it is common to find a significant loss of muscular possibilities of the quadriceps group which must then be considered for re-education by other means to restore the patient's voluntary contraction reflex, as well as previous muscle power.

The object of the invention is precisely to choose technical means which, if necessary, can be implemented to provide a first type of response to such a finding, without claiming to be a substitute for effective and efficient means of functional rehabilitation of the quadriceps muscles.

An additional object of the invention is therefore to propose means techniques capable of offering several rehabilitative functionalities that can be considered independently or simultaneously.

FR-A-2 085 118 shows a splint for mobilizing the leg. There is a footrest which is brought back to a position of less extension by straps without using behind the scenes.

PRESENTATION OF THE INVENTION:

To achieve the above objectives, the mobilization splint of a member lower, of the type comprising a base carrying an articulated structure composed a crural segment or cradle articulated at one end of the base and a cradle or leg segment linked to the crural cradle by an axis of articulation orthogonal to the direction of a rail defined by the base for guiding the cradle, a means motorization interposed between the base and the articulated structure to move the leg segment relative to the rail according to an alternative rectilinear displacement and a footrest adapted at the end of the leg segment or cradle opposite the cradle crural, is characterized in that, according to the invention, said footrest is mounted on the cradle leg through at least one slide with interposition of a elastic return means always tending to return the footrest to a position lesser extension relative to the cradle.

Various other characteristics appear from the description given below in reference to the accompanying drawings which show, by way of nonlimiting examples, forms of realization and implementation of the object of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS:

Fig. 1 is a schematic perspective of a lower limb mobilization splint.

Fig. 2 is an explanatory diagram highlighting the fundamental problem that the object of the invention aims to solve.

Fig. 3 is a partial sectional elevation showing, on a larger scale, a detail of constructive embodiment of the splint according to FIG. 1.

Fig. 4 is a sectional elevation, on a larger scale, illustrating an alternative embodiment.

Fig. 5 is a partial sectional elevation, partially cut away, showing, on a still larger scale, another embodiment of the means according to the invention.

Fig. 1 shows a so-called passive mobilization splint of a lower limb which can be either a right limb or a left limb, since the illustrated splint reveals a symmetrical construction.

BEST WAY TO IMPLEMENT THE INVENTION:

The splint comprises a base or base 1 which is intended to rest on a support surface, such as 2, of any suitable nature and advantageously constituted by the mattress of bedding.

The base or base 1 comprises a proximal part 3 with which it supports an articulated structure 4 composed of a segment or crural cradle 5 connected by a hinge 6 to the proximal part 3 . The crural segment 5 is composed of two longitudinal members or the like 7 possibly connected together by a spacer and able to be fitted with a flexible element for supporting the thigh of a lower limb, for example, a hammock 8 in any appropriate material.

The structure 4 is also composed of a leg segment 9 which is articulated in the extension of the crural segment 5 by means of trunnions or pivots 10 which define between them a pivot axis x-x ' which is orthogonal to the general direction of the base or base 1 .

The leg segment 9 is constituted by two longitudinal members or the like 11 possibly connected by a transverse spacer 12 and also capable of being fitted with a flexible support mattress, such as a hammock 13 .

The end portion of the leg segment 9 opposite the pins 10 carries a footrest 14 formed by a support 15 optionally adjustable in orientation along an axis y-y ' substantially parallel to the axis x-x' . The support 15 carries a sole 16 which can be adjusted in orientation in the double direction of the arrow f ₁ by means of any suitable means known in the art involving, for example, a pivot and a tightening button. The plate carries a sole 17 possibly adjustable in the double direction of the arrow f ₂ and, preferably, made in the form of an open shell to allow the establishment and support of the foot of the lower limb to be rehabilitated.

Finally, the structure 4 is carried at the level of the leg segment 9 by a carriage 18 supported by a guide track 19 materialized by the base or the base 1 in a rectilinear direction which is orthogonal to the axis x-x ' .

The structure 4 is associated with motorization means, such as those designated by the general reference 20 , to act on the structure so as to control a movement of the carriage 18 in alternating rectilinear travel on the track 19 to drive the structure 4 from of a complete extension in a flexion movement and vice versa, as is known to those skilled in the art. It should be considered that the motorization means 20 , which can be controlled from a remote control unit 21, can be adapted on one of the pivots 10 or even be placed in relation to the carriage 18 by involving then an appropriate transmission.

The choice of such means of motorization is not directly a matter of the invention and are accessible to those skilled in the art.

A mobilization splint of the above type generally, or at least, frequently occurs during its installation, a situation of the type illustrated in FIG. 2 , in which by sliding, inadvertence or impossibility of positioning, the articulation 6 between the crural segment and the base 1 is not in coincidence with the coxo-femoral articulation 22 of the member 23 to be rehabilitated.

Such a situation also involves a length of crural segment 5 which is different from the length of the femoral articular segment of the limb 23 , so that two types of offsets can occur between axes 6 and 22 , namely an offset N relative to the plane of the base and an offset n in a plane perpendicular to this plane.

This absence of coincidence translates automatically during an extension-flexion movement by trajectories t ₁ and t ₂ which are different for the axis x-x ' and for the knee 24 to which normally this axis x-x' must correspond.

The difference between the trajectories t ₁ and t ₂ can be variable but, in all cases, results in non-optimal functional conditions.

Fig. 2 clearly shows that the offset of the trajectories t ₁ and t ₂ has the consequence that, in the extended position, the knee trajectory t ₂ is located behind the trajectory t ₁ relative to the distal end of the base and that, as a result, the footrest 17 gradually disappears forward relative to the foot which is no longer supported nor, if necessary, supported.

The object of the invention is to propose means which make it possible to compensate for this progressive deviation during the trajectory, so as to restore, over the entire trajectory, a support between the foot and the footrest 17 , whatever the difference between the trajectories t ₁ and t ₂ .

To this end, as illustrated in FIG. 3 , provision is made to mount the support 15 carrying the plate 16 and the footrest 17 , on at least one rod 30 and, preferably, two, which are arranged so that they can slide telescopically inside at at least one and, preferably, of the two longitudinal members 11 , which in this regard are at least partially tubular. Each rod 30 is provided with an end collar 31 and slides in a tubular plug 32 closing the distal end of the beam 11 , so as to constitute a sliding bearing for the rod 30 . The spar 11 delimits a blind bore which defines, with the rod 30 , an annular gap 33 capable of receiving an elastic return member 34 constituting a means always tending to act on the rod 30 , so as to urge it in the direction of the arrow f ₃ to give it a position of least extension relative to the spar 11 . Such a position of lesser extension is, for example but not exclusively, determined by the supply bearing the collar 31 on the bottom of the bore of the beam 11 . The elastic members 34 are advantageously constituted by helical springs placed under compression stress.

The plug 32 can be made in the form of a plain bearing, or even a ball bushing and is fitted on the end of the beam 11 , advantageously removable to facilitate the mounting of the rod 30 , as well as that spring 34 .

By resting on fig. 2 , it can be seen that the adaptation of the splint to the member 23 to be mobilized takes place in a position of initial presetting of flexion, for example at 90 °, in which the existence of a pseudo can be considered coincidence between the axis x-x ' and the axis 24 of the knee. In such a position, the useful length between the axis x -x ' and the axis y-y' is adjusted, for example, by means of the position of the support 15 on the rods 30 , in such a way that it is less than the length of the tibial segment 25 of the lower limb 23 , so that in this position, the footrest 17 is urged in partial extension stroke against the antagonistic action of the spring or springs 34 which are subjected to a stress greater than that which they undergo in the position of least extension, as mentioned above.

During the extension movement requesting the articulated structure in the direction of the arrow f ₄ , the offset between the trajectories t ₁ and t ₂ shows that that t ₂ followed by the knee 24 tends to lag behind that t ₁ followed by the axis x-x ' .

Ordinarily in such a situation, this results in a withdrawal of the foot relative to the footrest 17 , so that the third point of support initially sought is lessened or even eliminated.

On the contrary, according to the invention, the delay taken by the trajectory t ₂ causes a retreat of the foot which is faithfully followed by the footrest 17 urged in the retraction stroke and of lesser extension by the spring or springs 34 whose preload d he origin was accentuated by the adjustment carried out as said previously.

Fig. 4 shows that it may be advantageous to constitute the plug 32 in the form of a smooth or ball bearing, adjustable, for example by thread-tapping, in the direction of the arrow f ₅ relative to the spar 11.

Such an adjustment makes it possible, when it is desirable, to modify the restoring force of the spring 34 and to consider, for example, using the means according to the invention to offer a possibility of active mobilization which would be voluntarily maintained by the patient to cause the footrest 17 to recede against the antagonistic action of the spring or springs 34 , so as to stress the muscular function of the quadriceps.

It should be considered that such a possibility is more fully offered when it is possible to adjust the nominal length of the leg segment 9 by means of the means for fixing and mounting the support 15 on the rods 30 , for example at by means of tightening knobs 35 .

Fig. 4 shows that in certain cases, it may be advantageous to provide a possibility of adjusting the abutment position with lesser extension, other than by bringing the collar 31 to bear on the bottom of the bore of the spar 11 .

Such a possibility of adjustment, as illustrated in FIG. 4 , can intervene by a nut 36 , for example formed by two half-collars assembled by a deformable hoop 37 elastically forcing the half-collars to occupy a tightened state on the rod 30 in an axial immobilization position in which each half -collar is engaged by a rib 38 in notches 39 of a series presented axially by the rod 30.

An alternative embodiment of such a means is illustrated in FIG. 5 in which the tubular proximal part of the spar 11 has one or more series of holes 40 allowing the engagement of a pin 41 on which the collar 31 comes to bear.

In addition to the two functions capable of being assumed by the means described above, it should be noted that the possibility of telescopic sliding with elastic return imparted to the footrest 17 , provides an adjustment for automatic adaptation to the length of the tibial segment. of the member 23 to be re-educated, without it being absolutely necessary to provide a specific adjustment by the buttons 35 when by default, such a nominal length adjustment is chosen below the length of said segment.

Fig. 1 highlights a simplified variant embodiment of the means according to the invention. According to this variant, each rod 30 - spar 11 assembly is associated with an elastic return means constituted by a spring 34 which is interposed under prior stretching constraint between an anchoring ring 42 carried by the rod 30 , or even the support 15 , and a bar with holes 43 carried by the beam 11 near the journal 10 .

The members 34 can be springs of all suitable types and, in particular, elastic cables of the type of those known commercially under the name of SANDOW. A variant may also consist in replacing the helical springs of FIG. 3 by elastic cables housed inside the rods 30 which are then tubular, and so that one of the ends is integral with said rod, while the other is linked to the tube 11.

Such simpler and less expensive means offer a possibility adaptation to the user's wishes and confer the same characteristics functional than those described above.

INDUSTRIAL APPLICATION:

The object of the invention finds a preferred application for splints of knee rehabilitation

Claims (10)

1. A device for moving a lower limb, the device being of the type comprising a base (1) carrying an articulated structure (4) made up of a crural cradle or segment (5) hinged (6) at one end to the base and a tibial segment or cradle (9) connected to the crural cradle via a hinge axis (x-x') orthogonal to the direction of a rail (19) defined by the base for guiding the tibial cradle, motor means (20) interposed between the base and the articulated structure to move the tibial segment relative to the rail in reciprocating rectilinear displacement, and a foot rest (17) fitted to the end of the tibial cradle or segment opposite the crural cradle,
      wherein said foot rest is mounted on the tibial cradle via at least one slider (11, 30) with resilient return means (34) being interposed urging the foot rest continuously into a position of least extension relative to the tibial cradle.
2. A device according to claim 1, characterised in that the resilient return means is fitted externally.
3. A device according to claim 1, characterised in that the resilient return means is included in the slider.
4. A device according to one of claims 1 to 3, characterised in that the resilient return means is associated with a member (32) for adjusting its return force.
5. A device according to one of claims 1 to 4, characterised in that the resilient return means is associated with a member (36 or 41) for adjusting the abutment position of least extension of the foot rest.
6. A device according to one of claims 3 to 5, characterised in that the resilient return means is constituted by a helical spring (34) fitted concentrically around a rod (30) mounted telescopically in an at least partially tubular length member (11) of the tibial cradle (9), said spring being mounted under stress between a collar (31) of the rod and a tubular plug (32) fitted to the length member so as to form a sliding bearing for the rod.
7. A device according to claim 6, characterised in that the bearing plug is adjustable in axial position relative to the length member so as to constitute the means for adjusting the force of the spring.
8. A device according to claim 5, characterised in that the member for adjusting the abutment position is constituted by an adjustable abutment (36) fitted between the rod and the length member.
9. A device according to claim 8, characterised in that the adjustable abutment is constituted by a pin (41) passing through one of a series of holes (40) formed in the length member so as to constitute a stop for the collar of the rod.
10. A device according to claim 8, characterised in that the adjustable abutment is constituted by an elastically-openable nut (36) fitting on a series of notches or the like (39).

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