Patent Description:
Several types of prosthetic ankle-foot devices are known in the art, which can be divided into three big categories: conventional feet (CF), energy storing and returning feet (ESR), and bionic feet (BIO).

Conventional feet, which were developed first, have no concentrated-type degree of freedom, and cannot therefore make physiological movements; their main function is to damp the forces generated by the impact of the foot on the ground and transfer them to the tibia.

Energy storing and returning feet may be either of the single-joint type, typically having one degree of freedom corresponding to the ankle (talocrural) joint, or of the multijoint type, wherein the prosthesis can move about different articulation axes, more or less corresponding to physiological movements. Bionic feet can be divided into two types, i.e. stabilizing (also referred to as "quasi-active") bionic feet and propulsive (also referred to as "active") bionic feet. In the former, the active components (usually consisting of motors) perform the function of adjusting some of the prosthesis' features, e.g. ankle rigidity or foot angle, in order to adapt to different sloping grounds. In the latter, the active components perform the function of supplying power to the joints (in particular, the talocrural one), thus causing the prosthesis to move according to a given control logic.

At present, most commercial prosthetic devices fall within the energy storing and returning feet (ESR) category, since only a few stabilizing bionic prostheses and just one propulsive bionic prosthesis is currently available on the market. Typical commercial prostheses include a main element corresponding to the ankle-foot assembly and made of deformable material, e.g. carbon-fiber sheet, which allows relative movement between the foot and the leg due to the deformability of the material.

Most prostheses currently undergoing research and development have just one degree of freedom, typically associated with the ankle joint (i.e. the talocrural joint), since the foot is usually considered as a secondary, non-functional element.

It is therefore apparent that such prosthetic devices do not permit the achievement of a mechanical behaviour of the prosthesis that is comparable to that of the biologic ankle-foot system, which has been optimized by genetic evolution and therefore represents an optimal trade-off between different functionalities such as, for example, adaptability to different grounds (thanks to the large number of joints), propulsive capability (due to the presence of muscles), and energetic efficiency (due to the presence of elastic elements capable of storing and releasing energy).

It must also be pointed out that people who have suffered amputation and wearers of lower-limb prosthetic devices establish compensation mechanisms which result in gait asymmetry and which may lead to the onset of secondary disorders (osteoarthritis, osteoporosis, and the like) and/or to higher metabolic energy consumption, inevitably resulting in increased fatigue.

<CIT> discloses a foot prosthesis comprising a heel and a foot tip capable of bearing on the ground and an ankle support wherein it further comprises at least one damping element configured to be distant from said ground.

<CIT> relates to a passive prosthetic device made up of several parts. In fact, the device described in document <CIT> comprises a phalanx portion, a metatarsal portion that is movably coupled to the phalanx portion, an ankle portion that is movably connected to the phalanx portion, and a calcaneus portion that is movably coupled to the ankle portion, wherein each coupling between the parts of the device is effected by means of a torsion spring.

Although in document <CIT> the foot is considered as a functional element, also the prosthetic device described in such document suffers from a few drawbacks.

In particular, such drawbacks are due to the fact that the phalanx portion and the metatarsal portion made in accordance with the teachings of document <CIT> consist of solid, rigid bodies that do not allow the prosthetic device to achieve adequate adaptability to different grounds, especially when such grounds are rough and/or unstable.

Moreover, the coupling of the parts of the device by means of torsion springs does not ensure an adequate mechanical connection between the forefoot joint and the plantar arch, which is a peculiar characteristic of the biologic ankle-foot complex.

In this frame, it is the main object of the present invention to provide a prosthetic ankle-foot device, in particular of the biomimetic type, which is so conceived as to overcome the drawbacks of the prior art.

In particular, it is one object of the present invention to provide a prosthetic ankle-foot device so realized as to permit the achievement of a mechanical behaviour which is comparable to that of the biologic ankle-foot system.

It is another object of the present invention to provide a prosthetic ankle-foot device which offers adequate adaptability to different grounds and high energetic efficiency, being realized to provide optimal energy storage and release.

It is a further object of the present invention to provide a prosthetic ankle-foot device so designed as to minimize the establishment of compensation mechanisms by a person wearing said device and to avoid any gait asymmetry, thus preventing the onset of secondary disorders and/ or a higher consumption of metabolic energy which would result in increased fatigue.

It is another object of the present invention to provide a prosthetic ankle-foot device so realized as to make it possible to assess the effect of a single factor or parameter on a specific functionality of the prosthetic device.

It is yet another object of the present invention to provide a prosthetic ankle-foot device that is not too expensive to manufacture and difficult to set up.

Further objects, features and advantages of the present invention will become apparent in the light of the following detailed description and the annexed drawings, which are supplied by way of non-limiting explanatory example, wherein:.

Referring now to the annexed drawings, reference numeral <NUM> designates as a whole a prosthetic ankle-foot device, in particular of the biomimetic type, according to the present invention.

In accordance with the present invention, the device <NUM> comprises a tibia element <NUM>, a talus element <NUM> movably connected to the tibia element <NUM> through a first talocrural joint A1 comprising a first hinge joint, and a calcaneus element <NUM> movably connected to the talus element <NUM> through a second subtalar joint A2 comprising a second hinge joint.

In addition, the device <NUM> comprises a medial metatarsal element <NUM> movably connected to the calcaneus element <NUM> through a third medial midtarsal joint A3, said third joint A3 comprising a third hinge joint, and a lateral metatarsal element <NUM> movably connected to the calcaneus element <NUM> through a fourth lateral midtarsal joint A4, said fourth joint A4 comprising a fourth hinge joint. The device <NUM> according to the present invention further comprises a medial phalanx element <NUM> movably connected to the medial metatarsal element <NUM> through a fifth medial metatarsophalangeal joint A5, said fifth joint A5 comprising a fifth hinge joint, and a lateral phalanx element <NUM> movably connected to the lateral metatarsal element <NUM> through a sixth lateral metatarsophalangeal joint A6, said sixth joint A6 comprising a sixth hinge joint. It should be noted that said hinge joints are preferably implemented as respective hinges, in particular cylindrical hinges.

The device <NUM> according to the present invention further comprises an elastic actuation element (designated as a whole by reference numeral <NUM> in the annexed drawings) comprising an upper part movably connected to the tibia element <NUM> and a lower part movably connected to the calcaneus element <NUM>. In a preferred embodiment, the tibia element <NUM> has a fork-like shape and comprises a first arm <NUM> and a second arm <NUM> substantially parallel to each other. In accordance with the present invention, the first talocrural joint A1 lies on a first axis X1 and the second subtalar joint A2 lies on a second axis X2, wherein said first axis X1 and second axis X2 (shown in <FIG>) form an oblique ankle dual axis, in particular having biomimetic orientation and position; as a consequence, said oblique dual axis turns out to be similar to the biologic ankle complex, i.e. similar to the physiological talocrural joint and subtalar joint.

In particular, the talocrural axis is inclined relative to the midlateral axis by approximately <NUM>° in the frontal (or coronal) anatomical plane and by approximately <NUM>° in the horizontal (or transversal) plane; as to the subtalar axis, it is inclined relative to the sagittal axis by approximately <NUM>° in the sagittal plane and by approximately <NUM>° in the horizontal plane.

Like its biological counterpart, the first talocrural joint A1 is responsible for the physiological dorsiflexion and plantarflexion movements, i.e. the flexion and extension movements of the ankle; the rigidity of the first talocrural joint A1 is given by the presence of the actuation element <NUM>, and the range of movement of said first talocrural joint A1 is such as to allow different gait types according to a physiological biomechanical pattern, including, without being limited to, walking on flat ground, walking uphill and downhill, and climbing and descending stairs.

In a preferred embodiment, the first talocrural joint A1 comprises a first aperture 11A associated with the first arm <NUM> of the tibia element <NUM> and a second aperture 12A associated with the second arm <NUM> of the tibia element <NUM>, wherein said apertures 11A, 12A are coupled to a talocrural pin <NUM> integral with the talus element <NUM>; preferably, each one of said apertures 11B, 12B comprises a bushing, in particular of the self-lubricating type.

As far as the second subtalar joint A2 is concerned, it is responsible, just like the corresponding biological joint, for pronation and supination movements.

The second subtalar joint A2 comprises a hole <NUM> on the talus element <NUM>, which is coupled to a subtalar pin <NUM> integral with the calcaneus element <NUM>; preferably, said hole <NUM> houses at least one bushing, in particular of the self-lubricating type.

Moreover, the second subtalar joint A2 is so realized as to have a rigidity of its own. For this purpose, the second subtalar joint A2 comprises a subtalar pad <NUM> positioned between opposed faces of the talus element <NUM> and of the calcaneus element <NUM>; preferably, said subtalar pad <NUM> is made of elastomeric material, and in such a way as to obtain a rigidity of the second subtalar joint A2 that substantially corresponds to that of the biological counterpart.

The particular construction of the subtalar pad <NUM> makes it possible to specifically design the rigidity curve of the second subtalar joint A2 as needed, even as a non-linear one.

The third medial midtarsal joint A3 and the fourth lateral midtarsal joint A4 are substantially parallel and coaxial to each other, said joints A3, A4 lying on a third axis X3 and a fourth axis X4, respectively, which substantially coincide; for this reason, the third axis X3 and the fourth axis X4 are represented in <FIG> as a single dashed-dotted line.

According to a preferred embodiment, the third medial midtarsal joint A3 comprises a first pin 32A integral with the calcaneus element <NUM>, which articulates with a hole <NUM> that is present on a proximal part of the medial metatarsal element <NUM>, in particular said hole <NUM> being associated with at least one radial bearing or a self-lubricating bushing.

Furthermore, the fourth lateral midtarsal joint A4 comprises a second pin 32B integral with the calcaneus element <NUM>, which articulates with a hole <NUM> that is present on a proximal part of the lateral metatarsal element <NUM>, in particular said hole <NUM> being associated with at least one self-lubricating bushing.

The fifth medial metatarsophalangeal joint A5 and the sixth lateral metatarsophalangeal joint A6 lie on a fifth axis X5 and a sixth axis X6, respectively, which are substantially parallel and not coinciding.

The fifth medial metatarsophalangeal joint A5 consists of a hinge joint comprising a medial metatarsophalangeal pin <NUM> which articulates with at least one first aperture <NUM> that is present on a distal part of the medial metatarsal element <NUM> and with a second aperture <NUM> that is present on an arm <NUM> extending from the medial phalanx element <NUM>.

In its turn, the sixth lateral metatarsophalangeal joint A6 consists of a hinge joint comprising a lateral metatarsophalangeal pin <NUM> which articulates with at least one first aperture <NUM> that is present on a distal part of the lateral metatarsal element <NUM> and with a second aperture <NUM> that is present on an arm <NUM> extending from the lateral phalanx element <NUM>.

It is therefore clear that the tibia element <NUM>, the talus element <NUM> and the calcaneus element <NUM> find a direct biological counterpart in the biological tibia, talus and calcaneus, respectively. As concerns the medial metatarsal element <NUM>, the lateral metatarsal element <NUM>, the medial phalanx element <NUM> and the lateral phalanx element <NUM>, they do not have a direct biological counterpart, since they are "functional" elements. In fact, the medial metatarsal element <NUM> mimics the function of the first and second biological metatarsi, while the lateral metatarsal element <NUM> mimics the third, fourth and fifth biological metatarsi; the same also applies to the medial phalanx element <NUM> and the lateral phalanx element <NUM>. This division into functional groups allows reducing the complexity of the device <NUM> according to the present invention, while at the same time maintaining the main functionalities of the corresponding biological elements. In particular, the structure of the device <NUM> according to the present invention makes it possible to obtain three plantar arches (medial longitudinal, lateral longitudinal and transverse), while at the same time permitting the coupling between the plantar arches (midtarsal joints) and the metatarsophalangeal joints.

In this frame, the first talocrural joint A1 and the second subtalar joint A2 constitute the joints of an ankle complex of the device <NUM> according to the present invention, and have a direct biological counterpart, in that they mimic its position and spatial orientation.

The remaining four joints (i.e. the third medial midtarsal joint A3, the fourth lateral midtarsal joint A4, the fifth medial metatarsophalangeal joint A5 and the sixth lateral metatarsophalangeal joint A6) constitute the joints of the foot of the device <NUM> according to the present invention and do not have a direct biological counterpart, in that they are functional joints. In this frame, the two midtarsal joints A3, A4 mimic the function of the biological midtarsal joint (also referred to as Chopart's joint), which is composed of the calcaneocuboid and talonavicular joints, while the two metatarsophalangeal joints A5, A6 mimic the biological function of the five biological metatarsophalangeal joints. Moreover, said four joints A3, A4, A5, A6 constitute a single functional group, just like in the biological foot, where there is a direct coupling between midtarsal and metatarsophalangeal joints. In particular, the complex formed by the calcaneus element <NUM>, the third medial midtarsal joint A3, the medial metatarsal element <NUM>, the fifth medial metatarsophalangeal joint A5 and the medial phalanx element <NUM> constitutes the medial longitudinal arch. Likewise, the complex formed by the calcaneus element <NUM>, the fourth lateral midtarsal joint A4, the lateral metatarsal element <NUM>, the sixth lateral metatarsophalangeal joint A6 and the lateral phalanx element <NUM> constitutes the lateral longitudinal arch. In addition, the transverse (or transversal, or anterior) arch is formed as a consequence of the presence of the medial longitudinal arch and the lateral longitudinal arch between the heads of the medial metatarsal element <NUM> and of the lateral metatarsal element <NUM>.

As can be seen in the annexed drawings, the actuation element <NUM> preferably comprises a spring <NUM>, in particular a coil spring, connected to an upper body <NUM> which articulates with the tibia element <NUM> through a pivotable fork system allowing two degrees of freedom between said actuation element <NUM> and the tibia element <NUM>.

In this respect, the pivotable fork system according to the present invention comprises a fork-shaped element <NUM> and first connection elements which allow a first relative rotational motion between the actuation element <NUM> and the fork-shaped element <NUM>; note that said first rotational motion constitutes the first degree of freedom between the actuation element <NUM> and the tibia element <NUM>. In the embodiment shown in the annexed drawings, said first connection elements comprise radial bearings 82C associated with the upper body <NUM> of the actuation element <NUM>, which articulates with respective pins 91P associated with the arms <NUM> of the fork-shaped element <NUM>.

Furthermore, the pivotable fork system according to the present invention comprises second connection elements (designated by reference numerals <NUM>, <NUM>, <NUM> and <NUM> in <FIG>), which allow a second relative rotational motion between the actuation element <NUM> and the fork-shaped element <NUM>; note that said second rotational motion constitutes the second degree of freedom between the actuation element <NUM> and the tibia element <NUM>. Preferably, said second connection elements comprise at least one bearing <NUM>, <NUM>, <NUM> mounted to a rod <NUM> of the fork-shaped element <NUM>, which articulates with at least one respective seat (not shown in the annexed drawings) associated with the tibia element <NUM>. In the embodiment shown in <FIG>, one can see that said second connection elements comprise a plurality of bearings, i.e.:.

Said second connection elements comprise also a locking element <NUM> which is coupled to the rod <NUM> of the fork-shaped element <NUM> to tighten the bearings <NUM>, <NUM>, <NUM> against the tibia element <NUM>; when observing <FIG>, it can be noticed that said locking element <NUM> may consist of a castellated nut, possibly associated with a cotter pin (not shown) to prevent it from turning about said rod <NUM>. The lower part of the actuation element <NUM> articulates with the calcaneus element <NUM> through a terminal <NUM> that allows two degrees of freedom between said actuation element <NUM> and calcaneus element <NUM>. In the embodiment shown in the annexed drawings, said terminal <NUM> articulates with a fork <NUM> of the calcaneus element <NUM> and comprises a ball joint <NUM> associated with anti-torsion elements; in particular, said anti-torsion elements comprise lateral faces of the ball joint <NUM> provided with elements tangent to the inner faces of said fork <NUM>. Such an embodiment permits locking exclusively an undesired third degree of freedom of the ball joint <NUM>, i.e. the degree of freedom corresponding to torsion of the actuation element <NUM>.

In accordance with a preferred embodiment, the device <NUM> comprises a motor <NUM>, in particular of the electric type, associated with the upper body <NUM> of said actuation element <NUM>, possibly through the interposition of a reducer <NUM>.

It is clear that, due to the provision of the motor <NUM>, the prosthetic device <NUM> of the present invention becomes active, since it can produce net positive power. In this context, the assembly made up of the actuation element <NUM> and the motor <NUM> reproduces the positioning (i.e. the origin and the insertion) of the biological soleus muscle, which is a biarticular muscle because it acts simultaneously upon both the talocrural joint and the subtalar joint. It should be noted that the particular implementation shown in the annexed drawings permits minimizing the peak power required from the motor <NUM> in order to cause the device <NUM> to make the walking gesture.

Furthermore, the assembly made up of the actuation element <NUM> and the motor <NUM> reproduces the functionalities of the whole set of biological plantarflexor and dorsiflexor muscles; however, unlike biological muscles, this assembly can operate in a desmodromic manner both when pulling (plantarflexion) and when pushing (dorsiflexion), and can produce all the power of the complex of plantarflexor (mainly soleus, medial and lateral gastrocnemius) and dorsiflexor (mainly anterior tibial) muscles.

It should be noted that, in accordance with the teachings of the present invention, the actuation element <NUM> is positioned in series with the motor <NUM>, just like the tendon is in series with the active element (muscle) in the biological counterpart.

In accordance with a preferred embodiment, the rigidity of the actuation element <NUM>, in particular the spring <NUM>, must be such as to provide a trade-off among: minimization of the peak power of the electric motor during the walking cycle, minimization of the energy consumed by the electric motor during the walking cycle, and possibility of using the prosthesis with a locked motor (motor turned off). It has been observed, in fact, that the optimal rigidity of the active actuation system including the motor <NUM> (minimization of peak power and energy consumption) corresponds, with due approximation, to the optimal rigidity that would be necessary if the device <NUM> did not include the motor <NUM> and were, as a consequence, totally passive (linear regression of the torque vs. ankle angle curve). Note that such optimal rigidity also corresponds, with due approximation, to the physiological rigidity of the Achilles tendon (tendon of the plantarflexor muscles).

The prosthetic device <NUM> according to the present invention can therefore be made to operate correctly also in "passive mode", by preventing the rotation of the electric motor <NUM> or by building the device <NUM> without associating the motor <NUM> with the actuation element <NUM>.

From the above description it clearly emerges that the kinematic mechanism formed by the tibia element <NUM>, the talus element <NUM>, the calcaneus element <NUM>, the actuation element <NUM> and the fork-shaped element <NUM>, possibly also including the motor <NUM>, constitutes a closed-chain spatial kinematic mechanism, as opposed to a planar kinematic mechanism like those of prior-art devices.

In this context, the pivotable fork system with two degrees of freedom that connects the upper part of the actuation element <NUM> to the tibia element <NUM> and the ball joint reduced to a double cylindrical joint that connects the lower part of the actuation element <NUM> to the calcaneus element <NUM> perform a dual function. Firstly, such an embodiment ensures a smooth actuation of a system with two degrees of freedom, made up of the first talocrural joint A1 and the second subtalar joint A2 coupled together; it is thus possible to actuate said system with two degrees of freedom between the tibia element <NUM> and the calcaneus element <NUM> (as in the biological ankle-foot complex), instead of actuating one degree of freedom at a time with planar mechanisms. Secondly, such an embodiment makes it possible (even though if the mechanism is a spatial kinematic mechanism) to obtain the previously described desmodromic system, i.e. a system capable of both pulling and pushing.

In accordance with the present invention, the device <NUM> comprises:.

The connection between the elastic elements <NUM>, <NUM> and the calcaneus element <NUM>, the medial phalanx element <NUM> and the lateral phalanx element <NUM> is accomplished through suitable fastening means, e.g. respective clamps <NUM>, <NUM>.

Said elastic elements <NUM>, <NUM> perform the task of reproducing the function of the biological plantar aponeurosis, in that they confer rigidity on the (medial and lateral) longitudinal plantar arches and permit the coupling between the midtarsal joints A3, A4 and the metatarsophalangeal joints A5, A6.

In a preferred embodiment, the device <NUM> comprises a first system <NUM>, <NUM> for adjusting the tension of the first elastic element <NUM> and a second system <NUM>, <NUM> for adjusting the tension of the second elastic element <NUM>.

In particular, the first adjustment system comprises a first tensioner <NUM> connected to the first elastic element <NUM> and associated with a first adjustment screw <NUM> for causing the first tensioner <NUM> to slide relative to the calcaneus element <NUM> in order to either increase or decrease the tension of the first elastic element <NUM>.

Furthermore, the second adjustment system comprises a second tensioner <NUM> connected to the second elastic element <NUM> and associated with a second adjustment screw <NUM> for causing the second tensioner <NUM> to slide relative to the calcaneus element <NUM> in order to either increase or decrease the tension of the second elastic element <NUM>.

Said adjustment systems make it possible to calibrate and adjust the rigidity curve of the plantar arches and of the metatarsophalangeal joints A5, A6 on the basis of several factors, such as, for example, the person's weight, the mode of operation of the device <NUM> (walking on flat ground, walking on rough ground, etc.), or according to the user's preferences.

Preferably, the underside of the medial metatarsal element <NUM> comprises a first arm <NUM>, whereon the first elastic element <NUM> rests, and the underside of the lateral metatarsal element <NUM> comprises a second arm <NUM>, whereon the second elastic element <NUM> rests.

Said first arm <NUM> and second arm <NUM> have several purposes, in that they allow:.

In accordance with a preferred embodiment, the medial phalanx element <NUM> comprises a first cam <NUM> (visible in <FIG>), whereon the first elastic element <NUM> rests, and the lateral phalanx element <NUM> comprises a second cam <NUM> (also visible in <FIG>), whereon the second elastic element <NUM> rests, wherein said first cam <NUM> and second cam <NUM> may be so realized as to accurately design the rigidity curve of the fifth medial metatarsophalangeal joint A5 and of the sixth lateral metatarsophalangeal joint A6. In substance, by changing the radius of the cams <NUM>, <NUM> it is possible to modify the torsional rigidity of the respective joints A5, A6.

Preferably, the device <NUM> according to the present invention is so realized as to comprise at least one locking element for each one of the foot joints A3, A4, A5, A6.

In particular, the device <NUM> may comprise:.

The possibility of selectively locking the foot joints A3, A4, A5, A6 allows for accurate and detailed quantification of the influence that each one of them has on the functions of interest of the device <NUM>.

In accordance with a preferred embodiment, the device <NUM> according to the present invention is realized to comprise at least one sensor 10E, 10I, 30P, 40P, 50P, 60P, 70P associated with at least one joint A1, A2, A3, A4, A5, A6 for providing a direct reading of the data concerning such joint.

In particular, the device <NUM> according to the present invention is preferably so realized as to comprise one or more of the following sensors (especially visible in <FIG>):.

The measurements taken by the sensors 10E, 10I, 30P, 40P, 50P, 60P, 70P permit obtaining a direct reading in real time of all six (relative) joint angles, as well as reading the absolute angles with respect to the global reference system of the tibia element <NUM>, e.g. in terms of pitch and roll.

The data thus obtained can be used for different purposes, including the creation of robust (because based on multiple input data) control models for the motor <NUM>, the creation of regression models for estimating all the kinematic and kinetic quantities of the prosthetic device <NUM> (such as ground reaction forces, center of pressure trajectory, etc.), the evaluation of the quality of the gait of the person using the prosthetic device <NUM>, and so forth.

In accordance with a preferred embodiment, the device <NUM> according to the present invention comprises at least one interface element <NUM>, <NUM>, <NUM>, in particular made of rubber or a similar material, for damping the ground impact forces and ensuring optimal grip on the ground.

In particular, said at least one interface element comprises one or more of the following elements:.

It is therefore clear that said interface elements <NUM>, <NUM>, <NUM> are similar to the fat pads found in the biological foot.

The device <NUM> according to the present invention has a volumetric size and a mass which are similar to those of the biological counterpart, so that it can be used by amputated people even inside normal footwear; moreover, the device <NUM> is easily scalable for obtaining different sizes comparable to those of the biological foot. The device <NUM> may be so realized as to comprise a covering, in particular made of silicone-based material, into which said device <NUM> can be fitted.

The device <NUM> according to the present invention further comprises a coupling element <NUM>, in particular of the pyramidal type, which permits connecting the device <NUM> to a tibial pylon (not shown in the annexed drawings); preferably, said coupling element <NUM> is fixed to the top part of the tibia element <NUM>.

The features of the prosthetic ankle-foot device <NUM>, in particular of the biomimetic type, according to the present invention, as well as the advantages thereof, are apparent from the above description.

In fact, the device <NUM> according to the present invention is so realized as to permit the achievement of a mechanical behaviour which is comparable to that of the biological ankle-foot system.

Furthermore, due to the provisions of the present invention, the prosthetic ankle-foot device <NUM> offers good adaptability to different grounds and high energetic efficiency, being designed to provide propulsive capability as well as adequate energy storage and release.

The peculiar features of the device <NUM> according to the present invention make it possible to minimize the establishment of compensation mechanisms by a wearer of said device; in particular, the prosthetic ankle-foot device <NUM> prevents gait asymmetry, thus avoiding the onset of secondary disorders and/or a higher consumption of metabolic energy that would result in increased fatigue.

The provision of the prosthetic ankle-foot device <NUM> with sensors 10E, 10I, 30P, 40P, 50P, 60P, 70P makes it possible to accurately quantify the effects of single factors or parameters on a specific function of interest of the device <NUM>.

Claim 1:
Prosthetic ankle-foot device (<NUM>), in particular of the biomimetic type, said device (<NUM>) being characterized in that it comprises:
- a tibia element (<NUM>);
- a talus element (<NUM>) movably connected to the tibia element (<NUM>) through a first talocrural joint (A1) comprising a first hinge joint;
- a calcaneus element (<NUM>) movably connected to the talus element (<NUM>) through a second subtalar joint (A2) comprising a second hinge joint;
- a medial metatarsal element (<NUM>) movably connected to the calcaneus element (<NUM>) through a third medial midtarsal joint (A3), said third joint (A3) comprising a third hinge joint;
characterised by
- a lateral metatarsal element (<NUM>) movably connected to the calcaneus element (<NUM>) through a fourth lateral midtarsal joint (A4), said fourth joint (A4) comprising a fourth hinge joint;
- a medial phalanx element (<NUM>) movably connected to the medial metatarsal element (<NUM>) through a fifth medial metatarsophalangeal joint (A5), said fifth joint (A5) comprising a fifth hinge joint;
- a lateral phalanx element (<NUM>) movably connected to the lateral metatarsal element (<NUM>) through a sixth lateral metatarsophalangeal joint (A6), said sixth joint (A6) comprising a sixth hinge joint;
- an elastic actuation element (<NUM>) comprising an upper part movably connected to the tibia element (<NUM>) and a lower part movably connected to the calcaneus element (<NUM>).