ITBG20090020A1 - PROSTHETIC FOOT TO WALK - Google Patents

Description

â € œ Prosthetic foot for walking

DESCRIPTION

The present invention relates to a prosthetic foot to be walked.

In particular, the present invention refers to a prosthetic foot dedicated to lower limb amputees with medium-low mobility.

To meet the needs of amputee patients since the 1980s, energy-returning prosthetic feet have been launched on the market which, thanks to the use of composite materials, such as carbon fiber, are able to store energy in the first phase. support, during the so-called loading, and to return it in the second phase of the support on the ground, called the response phase, before the flight phase.

The purpose of the invention is to create a prosthetic foot mainly dedicated to people with medium-low mobility, with greater attention to stability and comfort during the support phase on the ground.

A further purpose of the invention is to create a prosthetic foot that allows you to return energy, during the moments of resting on the ground, in a more gradual and constant way to meet the needs, especially of elderly people, having a much slower average walking speed than that of younger people. Furthermore, the foot allows an effective plantarflexion, guaranteeing an elastic and active energetic contribution, in the final phase of the support on the ground, when the prosthetic foot is loaded in correspondence with the â € œvirtual toesâ € and during which the elderly subject searches for the energy contribution in the prosthetic foot in order to minimize muscle fatigue.

The technical task, as well as these and other purposes, according to the present invention are achieved by making a prosthetic foot according to the attached claims.

Advantageously, the prosthetic foot according to the invention must be resistant in compliance with the ISO 10328 standard, but at the same time flexible so as to allow the application and management of the load in a fluid and natural walk.

The characteristics and advantages of the present invention will become evident from the following detailed description of a practical embodiment thereof, illustrated by way of non-limiting example in the accompanying drawings, in which:

figure 1 shows a side view of the complete prosthetic foot;

Figure 2 shows an exploded side view according to the invention;

figure 3 shows an isometric view of the complete prosthetic foot;

Figure 4 shows an exploded isometric view according to the invention.

With reference to the aforementioned figures, a prosthetic foot indicated as a whole with the reference number 1 is shown.

In the embodiment shown in the figures, it is noted that the prosthetic foot 1 comprises a sheet of composite material 1 a and an ankle joint 1 b, consisting of an upper part 2 ending in a pyramidal shape, in titanium, aluminum, or its alloy, through which the applied load is transferred from the prosthesis to the prosthetic foot 1 and from a lower part 3 constrained to the upper part by means of a pin 6 and to the lamina by mechanical fixing.

The upper part 2 is free to rotate around the pin 6.

A torsional spring 4 is housed inside the ankle joint; a damper 5 is fixed at the rear end of the upper part 2 of the ankle joint 1 b; the ankle joint 1 b is covered with an aesthetic cover 8.

Lamina 1a consists of a curvilinear section 9 with concavity towards the top (in the configuration of normal use of the foot) and representative of the calcaneus, a humped curvilinear section 10 which represents the plantar arch with its Vsup vertex , a straight section 11 that connects section 10 with the final section 12 defining the forefoot which has a concavity towards the top and may or may not have a flex.

The Vsup vertex passes in correspondence with an axis 13 parallel to the median axis 14 of the pyramidal end of the ankle joint, along which the weight of the user is discharged and moved forward by 30 ± 10 mm, in practice this median axis 14 is the load line. It is possible to vary the position of the load axis, passing through the center of the pyramid of the ankle joint, with respect to the tip of the foot between 70% and Î “80%.

The torsional spring 4 guarantees dorsiflexion and plantar-flexion of the ankle during walking. The particular orientation and position of the spring allows the user to load it from the first instant of the Initial Contact phase up to the Mid Stance phase, when the load line is perpendicular to the ground. Once loaded, the spring releases the elastic energy accumulated, when it exceeds the moment of the Mid Stance, in which the tibia is perpendicular to the ground, until the last moment of the Toe Off phase, offering a torsional moment to the ankle which guarantees a gradual contact with the ground and helps the patient in the propulsive phase. The spring works in synergy with the lamina of composite material, both of which store elastic energy with different principles: torsion in the first case, elastic deformation in the second. Both components charge and release energy during the contact of the prosthetic foot to the ground.

The torsional spring is of different type according to the weight of the user and his mobility and its torsional stiffness can be adjusted according to the user's needs. The torsional stiffness can be adjusted by known techniques.

The torsional spring is made of carbon steel or light alloys.

In the rear end of the upper part 2 of the ankle joint 1 b, near the median axis 14 along which the user's weight is discharged, a damper 5 is linked with a mechanical fixing, which has the function of optimizing comfort during contact with the ground. If the foot is loaded too much and / or the torsional spring is loaded too much, the upper part 2 rests on the lower part not directly but on the damper 5.

The ankle joint 1 b is bound to the lamina 1a in correspondence with the rectilinear portion of the same by means of two holes which guarantee the fixing by means of a fixing with screws and bolts. There may be a spacer (not shown) between the lower part 3 of the ankle joint and the lamina 1a.

Below the portions 9 and 12 of the lamina 1 a, two bearings, not shown, of elastomeric material are positioned to prevent direct contact between the carbon fiber lamina and the elastic cosmetic covering inside which the prosthetic foot is housed.

The overall length of the lamina 1 a approximates the length of a natural foot; naturally it will be differentiated according to the characteristics of each user and therefore to the size of the prosthetic foot chosen according to its function.

The width of the transversal section of the lamina 1a narrows starting from the section 9 (which defines the heel), towards the hump section 10 (which defines the plant arch) and then widens reaching the maximum value at point 16, which it delimits the sections 11 and 12 of the lower lamina 1a and which is indicative of the virtual fifth metatarsus, corresponding to the maximum width of the forefoot.

The thickness of the foil is preferably constant, even if it depends on the load applied and therefore on the weight of the user and his level of mobility.

Foot sizes vary for 5 classes depending on the shoe size of the user: class I n ° 35-36, class II n ° 37-38, class III n ° 39-40, class IV n ° 41 -42, class V n ° 43-44. Of course, other classes are also possible.

The material with which this prosthetic foot is produced allows the absorption and release of energy: it is a composite material such as carbon fiber, aramid fiber, glass fiber fabric, etc.

The presence of the torsional spring, combined with the elastic deformability of the foil, allows the user to load the prosthetic foot with only the lost force and to return this energy during the pushing phase.

In particular, during the initial contact phase, the loading of the spring and the lowering of the upper part 2 of the joint towards the lamina 1 a and the compression of the damper 5 guarantee acceptance and gradual absorption of the load. The ankle joint 1 b and the lamina 1a perform the function of absorbing the load and also the action of the anterior tibial muscle which guarantees control of the â € œrollingâ € of the foot and therefore a gradual contact with the ground, from the heel to the forefoot, stretch 12 of the lower lamina 1 in. After the spring loading phase, the upper part 2 of the joint resumes its initial position by means of a sort of â € œcatapult effectâ € which regulates the rolling of the foot and allows propulsion.

The material of which the lamina 1a is made is such as to allow a rather slow lowering of the foot, while guaranteeing stability and support to the amputated limb to meet the needs of people with medium-low mobility.

From the moment in which the lamina 1 a comes into contact with the ground, this begins to load, together with the spring, but at the same time offers a high stability in support.

Spring 4, which has begun to load already in the first support phase, extends its loading up to the Mid Stance phase (when the prosthetic foot is totally in contact with the ground) and immediately afterwards begins to return energy favoring the transition from Mid Stance to the Toe Off phase.

The lower lamina 1 a begins to return energy, right from the Initial Contact phase, accompanying the foot up to Mid Stance and from Mid Stance to Toe Off, guaranteeing active support even in the last phase of contact with the ground, when the terminal section of foot 12 (the virtual forefoot) is still resting on the ground, in order to generate the energy necessary for the propulsive thrust, minimizing the muscular fatigue of the amputee.

The morphology of the foil ensures stability even in the static phase with natural supports. In fact, in an orthostatic condition, the weight is discharged on the portion 9 of the lower lamina 1a (which simulates the heel) and on the portion 12 of the same lower lamina 1a (which simulates the forefoot).

The system thus conceived is susceptible of numerous modifications and variations, all of which fall within the scope of the inventive concept; furthermore, all the details can be replaced by technically equivalent elements.

Claims (10)

CLAIMS 1. Prosthetic foot for walking comprising an attachment that can be attached to a tube of an artificial limb, and a lamina, associated with said attachment, which is able to rest on the floor characterized by the fact that said attachment comprises a torsional spring. 2. Prosthetic foot according to claim 1, characterized in that it comprises an initial section defining a heel, an intermediate humped section, and a final section which defines the forefoot. 3. Prosthetic foot according to claim 1, characterized by the fact that said initial section and said final section of said lamina are curvilinear with concavity facing upwards, said lamina also presenting a rectilinear section interposed between said humped section and said section final curvilinear, where the connection between said lamina and said joint at the ankle is made in correspondence with said rectilinear section of said lamina. 4. Prosthetic foot according to claim 1, characterized in that said attachment comprises a mechanical fastening placed in correspondence with the middle of the foot. 5. Prosthetic foot according to claim 2, characterized in that the humped intermediate section has a vertex which passes in correspondence with a parallel axis at a distance of 30 ± 10 mm to that along which the weight of the user is discharged. 6. Prosthetic foot according to claim 1, characterized in that the distance of an axis along which the weight of the user is unloaded can be varied with respect to the tip of the foot between 70% and 80% of the total length of said lamina. 7. Prosthetic foot according to claim 1, characterized in that said torsional spring can have a different torsional stiffness according to the weight and mobility of the user. 8. Prosthetic foot according to claim 1, characterized in that said torsional spring has an adjustable torsional stiffness. 9. Prosthetic foot according to claim 1, characterized in that it comprises a damper placed in proximity to an axis along which the weight of the user is discharged. 10. Prosthetic foot according to claim 1, characterized in that said lamina is associated with said attachment by means of a pin.