Ankle ergometer

Abstract

Disclosed is an ankle ergometer for measuring a force exerted on a user's ankle joint by muscles involved in ankle mobility, including: a first splint-type portion receiving the lower limb when the user's knee is extended, and including a lower limb immobilizer with the leg in extension, and a second portion including: a) a main body attached to the first portion, b) a counter-supporting unit secured to the main body, c) a rigid plate forming a supporting surface for the lower surface of the foot, the rigid plate being substantially static relative to the counter-supporting unit, d) a force sensor between the plate and the counter-supporting unit, the plate not being secured to the main body so the sensor measures the force exerted on the supporting surface of the plate by the ankle mobility muscles, the force being transmitted from the plate to the counter-supporting unit.

Claims

1. An ergometer (100) for measuring a force exerted on the joint of the ankle (C) of a lower limb of a user (U) by flexor muscles involved in the mobility of said ankle (C), configured to be used in a sitting position of the user (U), said ergometer (100) including: a first portion (10) comprising a splint able to receive said lower limb when the knee of said user (U) is in extension, and comprising a set of straps (11) configured for immobilizing said lower limb with the knee in extension and limiting flexion of the knee, and, a second portion (20) comprising: a) a main body (21) attached to the first portion (10), b) a counter-supporting plate (22) secured to said main body (21), c) a rigid plate (23) forming a supporting surface for the lower surface of the foot of the user when said lower limb is immobilized with the set of straps (11), said rigid plate (23) being substantially static relative to said counter-supporting plate (22), d) a force sensor (24) inserted between said plate (23) and said counter-supporting plate (22), e) a rolling or sliding track (30) comprising a plank (31) having a plurality of beads (32) distributed uniformly over said plank (31), and f) a rolling or sliding member (40) comprising a planar contact surface (41), directly or indirectly attached to the main body (21), said rolling or sliding member (40) being able to cooperate with said track (30) in order to limit the friction between said main body (21) and said track (30), said plate (23) being indirectly secured to said main body (21), said ergometer (100) being configured so that said force sensor (24) is able to measure the force exerted on the supporting surface of the plate (23) by the flexor muscles of the foot of the user involved in the mobility of said ankle (C), said force being transmitted from the plate (23) to the counter-supporting plate (22) with limited interference by the muscles participating in the flexion of the knee, whose flexion is limited due to its immobilization by said first portion (10).

2. The ergometer (100) according to claim 1, wherein the force sensor (24) is a 3D sensor for measuring a force exerted during plantar flexion and/or dorsal flexion of the foot of the user (U).

3. The ergometer (100) according to claim 2, wherein said force sensor (24) is a force moment sensor, able to measure the forces and the force moments in three dimensions.

4. The ergometer (100) according to claim 1, wherein said plate (23) comprises at its lateral edges stiffening elements (23a, 23b), each one comprising a plate which extends perpendicularly relative to said plate (23).

5. The ergometer (100) according to claim 1, wherein the second portion (20) comprises a shoe (25) for receiving the foot of the user (U), said shoe (25) being attached on the plate (23) so as to maintain said foot of the user (U) secured with said plate (23).

6. The ergometer (100) according to claim 1, further including first adjustment means (50), configured for adjusting the angular position of the second portion (20) relative to the first portion (10).

7. The ergometer (100) according to claim 6, wherein the first adjustment means (50) comprise: a pair of retractable nuts (51) positioned on the first portion (10), and a plurality of adjustment holes (52) made on the main body (21) of the second portion (20), said nuts (51) being able to be introduced into the adjustment holes (52) for the adjustment and the locking of the angular position of the second portion (20) relative to the first portion (10).

8. The ergometer (100) according to claim 1, further including second adjustment means (60), configured for adjusting the position of the first portion (10) relative to the second portion (20).

9. The ergometer (100) according to claim 1, including a computer processing unit including a processor able to receive and treat measurement signals from said sensor (24) in order to determine the force exerted by the flexor muscles of the foot of the user.

10. A method for conducting force tests on a patient in order to evaluate the capability of the patient of maintaining an orthostatic posture, the method comprising providing the ergometer of claim 1, and having the patient use the ergometer to evaluate said capability.

11. The ergometer (100) according to claim 2, wherein said plate (23) comprises at its lateral edges stiffening elements (23a, 23b), each one comprising a plate which extends perpendicularly relative to said plate (23).

12. The ergometer (100) according to claim 3, wherein said plate (23) comprises at its lateral edges stiffening elements (23a, 23b), each one comprising a plate which extends perpendicularly relative to said plate (23).

Description

SHORT DESCRIPTION OF THE APPENDED FIGURES

(1) Other features and advantages of the present invention will become apparent from the description above, with reference to the appended FIGS. 4 to 6 which illustrate an embodiment thereof without any limitation and wherein:

(2) FIG. 1 schematically illustrates a foot in plantar flexion P1 and in dorsiflexion P2.

(3) FIG. 2 shows a first prior art ergometer.

(4) FIG. 3 shows a second prior art ergometer.

(5) FIG. 4 schematically illustrates a lateral view of an ergometer according to an exemplary embodiment;

(6) FIG. 5 schematically illustrates a front view of an ergometer according to FIG. 4;

(7) FIG. 6 schematically illustrates a lateral view of an ergometer according to FIG. 4 with a rolling or sliding member and track.

DETAILED DESCRIPTION OF DIFFERENT EXEMPLARY APPLICATIONS

(8) An ergometer according to an exemplary embodiment of the present invention will now be described in the following by referring jointly to FIGS. 4 to 6.

(9) As a reminder, during the isometric contraction of the muscles of the ankle towards the extension, it is noted on most ergometers of the state of the art that the user uses the support of his/her back or of his/her shoulders for pushing on the pedal of the ergometer, which involves a participation of other muscles on other joints inducing an overestimation of the evaluation of the forces (or force moments) developed on the joint of the ankle.

(10) It is also observed that the ergometers of the ankle type which position the user in the sitting position, with the knee bent to 90 in order to limit the participation of the joint of the knee, reducing the forces of the gastrocnemius muscles.

(11) Now, it is important to evaluate the forces developed by these gastrocnemius muscles on the ankle.

(12) It is therefore preferable to conduct the tests with the knee in extension for taking into account these forces.

(13) One of the objects of the present invention is therefore to design an ergometer able to measure, in the position with the stretched leg (i.e. knee in extension), the maximum force developed by the flexor muscles and/or by the extensor muscles of the ankle; i.e. the muscles allowing stabilization of the ankle in the sagittal plane (plantar flexion and dorsiflexion).

(14) This is made possible in the example which follows with an ergometer 100 of the ankle type like one illustrated in FIG. 4.

(15) In the example described here, the ergometer 100 comprises a first portion 10 of the splint type.

(16) In this example, this first portion 10 is a Zimmer splint: said splint is able to receive the lower limb of the user U when the knee of the user is in extension as illustrated in FIG. 6.

(17) Of course, one skilled in the art will understand here that other types of splint may be used like for example a gutter-shaped splint receiving the thigh and the leg. Other types of splint may further be contemplated.

(18) This splint consists of two rigid and longilinear rods 12 which extend along the leg of the user U.

(19) These rods 12 are adjustable and comprise adjustment means 60 in height for adjusting the height of the splint according to the size of the user.

(20) In this example and as illustrated in FIG. 4, these adjustment means 60 consist in a slider mechanism 62 allowing sliding of the rods 12 for adjusting the height and a set of screws 61 allowing blocking in position of the rods, once the height is adjusted.

(21) It is therefore sufficient for the user U to position his/her leg in the splint after having adjusted beforehand the height of the splint if required.

(22) As illustrated in FIG. 6, the splint comprises immobilization means 11, for example a set of straps, for immobilizing the lower limb of the user U when the knee is in extension.

(23) One skilled in the art will understand here that it is possible to contemplate means other than the straps for immobilizing the lower limb.

(24) Once in position, the user U with the knee in extension may tighten the straps for immobilizing his/her lower limb.

(25) In the example described here, the ergometer 100 comprises a second portion 20, also called a 3D force platform.

(26) In this example, this second portion 20 comprises a main body 21 attached to the first portion 10. This main body 21 encompasses the foot of the user U.

(27) As illustrated in FIG. 5, this second portion 20 comprises a counter-supporting element 22.

(28) This counter-supporting element 22 consists in a plate secured to the main body 21.

(29) Those skilled in the art will understand here that the counter-supporting element 22 and the main body 21 may form a single and same single piece part, for example obtained by molding.

(30) In the example described here, and as illustrated in FIG. 5, the second portion 20 also comprises another rigid plate 23 which forms a supporting surface for the lower surface of the foot of the user U when the lower limb is immobilized by the splint with the immobilization means 11.

(31) In the example described here and illustrated in FIG. 5, this plate 23 is substantially parallel to the counter-supporting element 22.

(32) In this example, the plate 23 is fixed relatively to the counter-supporting element 22.

(33) Thus, this plate 23 is static; i.e. it does not move and does not deform, from a macroscopic point of view, relatively to the counter-supporting element 22, even when the foot of the user exerts a force on said plate 23.

(34) In order to further limit any deformation, the plate 23 has on its lateral edges stiffening elements 23a and 23b (see FIG. 5).

(35) Between this plate 23 and the counter-supporting element 22, a force sensor 24 is inserted.

(36) The layout of such a force sensor 24 inserted between the counter-supporting element 22 and the plate 23 is characteristic of the present invention.

(37) Indeed, when the user U exerts a force on the plate 23 via his/her foot, this force is transmitted from the plate 23 to the counter-supporting element 22.

(38) The force sensor 24 positioned between both elements 22 and 23 may then measure this transmitted force.

(39) In this example, the sensor 24 is a 3D force sensor which contains a force-torque sensor of the type SH100D1002A2-2 from Sensix.

(40) Such a force sensor 24 gives the possibility of measuring the forces during plantar flexion and during dorsal flexion.

(41) It is provided that the foot of the user U be accommodated in a shoe 25 securely attached on the supporting surface of the plate 23.

(42) In a complementary way, it is also possible to provide a set of straps 26 such as for example: two re-positionable self-adhesive attachment strips for maintaining the foot of the user U in position, other complementary re-positionable self-adhesive attachment strips attached on the force platform for blocking the movement of the ankle, one passing at the rear of the heel, the other one passing on the front of the joint of the ankle.

(43) It is further possible to provide another re-positionable self-adhesive attachment strip placed at the dorsal face of the metatarsophalangeal joint in order to block any movement of the forefoot.

(44) Once the set of these immobilization elements are positioned, the foot of the user U is secured to the supporting surface of the plate 23: in this configuration, the foot of the user U is firmly maintained in place with a shoe 25 attached to the plate 23, this plate 23 being itself attached on the force platform.

(45) As illustrated in FIG. 6, the ergometer 100 according to the present invention is therefore used in the sitting position (or in the lying position), the lower limb of the user U being placed in the splint with the knee in extension and the foot fixed in the shoe 25 being securely attached to the platform of the ergometer 100.

(46) Preferably, the axis of rotation of the ankle is aligned with the axis of the ergometer.

(47) The leg is in extension at the joint of the knee and the joint of the ankle is in a neutral position: the longitudinal axis of the foot forms an angle of 90 with that of the leg in the sagittal plane, as this may be during the maintaining of the orthostatic position.

(48) It is however possible to adjust the angular tilt of the joint of the ankle.

(49) This is made possible by means of angular adjustment 50 which give the possibility of adjusting the angle formed by the axis of the foot P and that of the leg J.

(50) As illustrated in FIGS. 4 and 5, these adjustment means 50 consist in a set of retractable nuts 51 positioned at the lower portion of the rods 12, the rods being attached to the main body 21 through a pivot.

(51) The main body 21 has adjustment holes 52 for introducing said nuts 51.

(52) By selecting the adjustment hole 52, it is possible for the user U to adjust the tilt of his/her foot relatively to the axis of his/her leg.

(53) In the example described here, the ergometer is used in an open chain.

(54) According to this configuration, the heel of the boot (i.e. the heel of the second portion) comprises a rolling member 40.

(55) In this example, the member 40 is formed by a plank 41 directly attached or indirectly attached to the heel of the boot (i.e. to the rear of the main body 21).

(56) This plank 41 is itself placed on a rolling track 30 formed here by another plank 31. In this example, this plank 31 has on its contact surface with the plank 41 roller beads 32.

(57) The relative displacement of the plank 41 on the beads 32 gives the possibility of making negligible any friction between the ergometer 100 and the support.

(58) It will be understood here that other means are possible for avoiding such friction, like for example the presence of a roller on the heel of the boot.

(59) In the described example, a cable 24a connecting the force sensor 24 of the ergometer to a computer processing unit (not shown here) is provided for carrying out the acquisitions.

(60) The signals of forces measured by the sensor 24 are then sent through this cable 24a to the processing unit.

(61) Alternatively, it may be provided that these signals are sent through wireless communication means.

(62) These signals are then directly recorded by a processing piece of computing software of the type LABVIEW SIGNAL EXPRESS or MATLAB, with for example a sampling frequency of 100 Hz.

(63) In the example described here, this processing unit includes a processor which may be configured for conducting isometric maximum force tests or for carrying out adapted exercises for rehabilitation.

(64) For example, such a processor may be configured for requesting to the user to achieve explosive contractions (rapid rises with force) and then contractions carried out gradually over 5 seconds up to the maximum intensity (ramp condition: here it is for example possible to use a metronome beating at 60 bpm so that the subject achieves a regular rise in force over 5 seconds).

(65) The processing unit may be connected to a display module (not shown here) for a representation of these objects to attain and viewing in real time the forces provided by the muscles, for example in the form of a graph representing in real time the measured force and the goal to be reached.

(66) This display module thus gives the possibility to the user of controlling the efforts to be provided for example when this is an exercise where the target forces determined beforehand have to be attained.

(67) The ergometer 100 according to the present invention thus appears like an apparatus for evaluating a goal giving the possibility, by means of the presence of a 3D force sensor 24 inserted between a supporting plate 23 which is free and a plate 22 used as a counter-support, the accurate and reliable measurement of the forces exerted on the joint of the ankle by the peri-articular muscles.

(68) Such an ergometer 100 thus appears like a reliable, accurate measurement apparatus and affordable financially; it is moreover easy to transport, which provides the possibility of bringing the measurement instrument to the user (for example as far as his/her bed), and not the opposite as this is generally the case with existing ergometers.

(69) It may therefore be easily transported, which is very appreciable if the intention is for example to test patients, and notably elderly persons or persons suffering from chronic instability of the ankle, who remain difficult to displace.

(70) In the same way, it is possible to transport it into centers or rooms or sports fields for sportsmen in order to be used during training or physical preparation.

(71) Moreover, in addition to the advantages above, it is possible to conduct measurements simultaneously on the two lower limbs by using two ergometers. This is referred to as a bilateral test.

(72) Indeed it is known that the sum of the maximum forces simultaneously exerted by each of the muscles of both lower limbs during bilateral contraction is smaller than the sum of the maximum forces exerted during one-side contractions produced by these same muscles.

(73) This is known under the term of bilateral deficiency.

(74) The simultaneous use of two ergometers 100 according to the invention for a bilateral test shows this bilateral deficiency, when the ergometers are used in a closed chain configuration; i.e. by being supported against an abutment.

(75) However, in the open chain configuration, such a bilateral deficiency is not again found.

(76) The closed chain configuration gives the possibility, during one-sided contractions of using the postural adjustments for pushing more strongly, which is not possible in an open chain configuration.

(77) During a bilateral thrust in an open chain, the postural adjustments are not possible and the force measured by each ergometer 100 only corresponds to the force developed by the plantar flexor or dorsal flexor muscles of the ankle.

(78) Thus, these bilateral tests with two ergometers 100 used simultaneously give the possibility of showing that no bilateral deficiency actually exists, but there rather exists a unilateral facilitation in a closed chain. In other words, whether this is in a one-sided or two-sided condition, the force developed at each ankle remains identical, which confirms the absence of a bilateral deficiency.

(79) It should be observed that this detailed description deals with a particular exemplary embodiment of the present invention, but by no means this description has any limiting nature for the object of the invention; quite on the contrary, it has the goal of removing any possible uncertainty or any poor interpretation of the claims which follow.