ANKLE MOBILIZATION DEVICE

Description

ANKLE MOBILIZATION DEVICE DESCRIPTION TECHNICAL FIELD OF THE INVENTION The present invention relates to a device for assisted mobilization and selective functional recovery of the tibiotarsal joint and, therefore, the ankle. More specifically, the device of the present invention aims to accelerate the recovery of tibiotarsal joint function in subjects undergoing total or partial ankle replacement surgery, as well as in subjects who have suffered severe ankle trauma. To this end, the device of the present invention acts solely on the tibiotarsal joint without involving the midfoot joint complex, thus improving and accelerating the recovery of lost function. STATE OF THE ART The ankle joint, also called the tibiotarsal joint, is formed by the distal portions of the tibia and fibula and the talus, which is located within the tibiofibular fossa, as well as the concavity formed at the ends of the tibia and fibula. The talus, together with the calcaneus, forms the hindfoot, the most proximal part of the foot, followed by the midfoot, which includes the other tarsal bones (navicular, cuboid, and the three cuneiforms), and the forefoot, which includes the metatarsals and phalanges of the toes. One of the most common conditions affecting this joint is osteoarthritis, a degenerative disease caused by aging, trauma, and rheumatic conditions. It causes the cartilage covering all bone surfaces to wear away, causing joint stiffness and swelling, as well as pain and limited movement.Today, ankle replacement is one of the most commonly used techniques, where possible, for this condition. Following this surgery, treatment is necessary. -1P6436IT00 by: ALMA MATER STUDIORUM - UNIVERSITY OF BOLOGNA UNIVERSITY OF FLORENCE RIZZOLI ORTHOPAEDIC INSTITUTE provides functional rehabilitation and passive mobilization of the ankle joint area, performed by professionals such as physiotherapists and rehabilitation specialists. However, the use of motorized devices capable of mobilizing the ankle according to specific protocols is becoming increasingly widespread in rehabilitation practice. The growing use of such devices is driven by the potential unavailability of specialized therapists and the inevitable operator-dependent variability in the final rehabilitation outcome. Furthermore, physiotherapists prefer not to intervene manually, as they have no measure of the range of motion they impose on the ankle during treatment and are therefore unable to ensure that the imposed movements remain within certain ranges defined by the clinician in the case of post-traumatic rehabilitation, or determined by the mechanics of the implanted prosthesis (e.g., the physiotherapist's foot).g. Range Of Motion (ROM) in the case of post-surgical rehabilitation. In this context, ankle rehabilitation using motorized devices is particularly challenging due to some unique characteristics of the ankle joint compared to large joints such as the shoulder, elbow, hip, and knee. While the latter can be considered isolated, i.e., relatively distant from other joint complexes, the movements of the foot-ankle complex (e.g., dorsiflexion and plantarflexion) are produced by the biomechanical synergy of the ankle, subtalar joints, and the Chopart and Lisfranc joint complexes, all adjacent to the tibiotalar-fibular joint. Because of this synergy, it becomes difficult to mobilize the ankle joint without also mobilizing all the other joints involved in foot movement. Consequently, selective rehabilitation of this joint becomes difficult. If the movement is dispersed across multiple joint planes, effective ankle mobilization is reduced, and thus the effectiveness of the treatment. Documents US9603768, KR10-2019-0092918, CN109498367, RU2658760, in particular, describe devices intended to rotate the foot relative to the tibia by using a rotary motor with a rigid transmission, possibly -2P6436IT00 by: ALMA MATER STUDIORUM - UNIVERSITY OF BOLOGNA UNIVERSITY OF FLORENCE RIZZOLI ORTHOPAEDIC INSTITUTE considering the possibility of making the actuation axis coincide with that of the ankle joint using an additional motor (CN109498367). Documents CN105476819, CN108542703, CN107803820, while considering the movement of the joint axis, do not take into account the compensatory motions of the midfoot. In all the cases cited, and in general for all prior art devices of which we are aware, since no restrictions are foreseen on the mobilization of the hindfoot and midfoot, several joints in addition to the ankle are mobilized, causing the latter joint to absorb only part of the imposed ROM.This makes it impossible to accurately assess the range of motion imparted to the ankle during the rehabilitation session, as well as to evaluate the actual state of the ankle in terms of ROM recovered during the rehabilitation period, casting doubt on the effectiveness of the treatment itself. PURPOSES AND SUMMARY OF THE INVENTION The aim of the present invention is, therefore, to provide a device for ankle mobilization that allows the joint to be mobilized selectively, excluding the other joints of the foot from the movement, thus improving the effectiveness of the rehabilitation treatment. This purpose is achieved by a device comprising: - a frame; - a calcaneal support configured to accommodate a user's ankle, said ankle being equipped with a dorsiflexion / plantarflexion rotation axis; - a restraint system for a leg of the user of the device, configured to prevent and / or reduce movements of the leg; - actuation means comprising a motor and a joint configured to couple the motor to the heel support. The joint has at least one translational degree of freedom in the direction of the actuation axis and no torsional degrees of freedom, so as to compensate for misalignments. -3P6436IT00 by: ALMA MATER STUDIORUM - UNIVERSITY OF BOLOGNA UNIVERSITY OF FLORENCE RIZZOLI ORTHOPAEDIC INSTITUTE between the actuation axis and the rotation axis (x). The joint is also equipped with two further translational degrees of freedom in the transverse directions and two rotational degrees of freedom in flexion. The heel support, on the other hand, includes: - a rigid casing; and - a deformable filling positioned inside the rigid casing and capable of being shaped to the shape of the user's heel. The joint, through which the motor rotates exclusively the calcaneal support and, therefore, the ankle joint, can be either a flexible joint or a constant-velocity joint. Both can absorb any misalignment between the motor axis and that of the ankle joint. Rigidly aligning the two axes would be complex, and possibly harmful, due to the difficulty of identifying the ankle joint's instantaneous rotation axis, which in any case does not remain fixed during its movement. Both the flexible joint and the constant-velocity joint, if properly selected, can compensate for this difference, ensuring the transmission of the drive torque to the ankle joint without forcing it into incorrect movements, limiting losses and thus improving the effectiveness of the treatment. The particular structure of the calcaneal support, which, as mentioned above, is divided into a rigid external part and a deformable internal filling that can be customized for the patient, allows it to compensate for the differences in shape between the foot and the rigid external part, thus allowing it to grip and adhere solely to this part of the foot (heel), thus being integral with it and transmitting the movement, in turn transmitted by the joint, directly to it, without loss of torque. A second aim of the present invention is, moreover, to ensure the safety of the mobilization treatment. This aim is achieved by the present invention thanks to the presence of the elastic joint, as well as the constant-velocity joint, since any misalignment, poorly or uncompensated, between the axis of the actuation system and that of the ankle joint could constitute a risk for the -4P6436IT00 by: ALMA MATER STUDIORUM - UNIVERSITY OF BOLOGNA UNIVERSITY OF FLORENCE RIZZOLI ORTHOPAEDIC INSTITUTE safety. A third purpose of the present invention is to ensure stability in the heel socket. This third purpose is achieved through the particular shape of the heel support itself, as it adheres to the heel thanks to the deformable filling that compensates for the differences between the rigid external part and the foot. A fourth aim of the present invention is to provide a device for ankle mobilization that ensures high levels of comfort. This aim is achieved by the present invention thanks to the presence of a deformable filling in the heel support. This filling, being soft and customizable to the patient's foot, provides an extremely comfortable interface with the limb. Last but not least, the present invention aims to improve the accuracy of ankle recovery monitoring. This goal is achieved by this device, which allows for exclusive mobilization of the ankle joint without involving the midfoot and forefoot. This allows for more precise measurement of the actual ROM imposed on the ankle and, thus, more accurate monitoring of functional recovery. These and further characteristics of the present invention will be made clearer by reading the detailed description that follows, relating to some preferred ways of realizing the present invention, to be considered as an example, and not a limitation, of the more general concepts claimed. BRIEF DESCRIPTION OF THE DRAWINGS The following description refers to the attached figures, in which: - Figure 1 is a perspective view of a device according to the present invention together with a schematic representation of the limb whose ankle is to be mobilized; - Figure 2 is a perspective view of a detail of the device of the present invention consisting of the frame; -5P6436IT00 by: ALMA MATER STUDIORUM - UNIVERSITY OF BOLOGNA UNIVERSITY OF FLORENCE RIZZOLI ORTHOPAEDIC INSTITUTE - Figure 3a is a perspective view of a detail of a first embodiment of a device according to the present invention consisting of the actuation means; - Figure 3b is a cross-section of a detail of a first embodiment of a device according to the present invention consisting of the actuation means; - Figure 3c is a perspective view of a detail of a first embodiment of a device according to the present invention consisting of the joint, as well as the means for the rigid transmission of motion from the joint to the heel support; - Figure 4a is a perspective view of a detail of a second embodiment of a device according to the present invention consisting of the joint, as well as the means for the rigid transmission of motion from the joint to the heel support; - Figure 4b is a front view of a detail of a second embodiment according to the present invention consisting of the joint, as well as the means for the rigid transmission of motion from the joint to the heel support; - Figure 5 is a perspective view of a detail of the present invention relating to the heel support; - Figure 6 is a perspective view of a detail of a first embodiment of the present invention together with a schematic representation of the foot whose ankle is to be mobilized, said detail relating to the assembly consisting of the calcaneal support and the joint, as well as the means for the rigid transmission of motion from the joint to the calcaneal support; - Figure 7 is an exploded view of the joint of a first embodiment of the device according to the present invention, together with a schematic representation of the foot whose ankle is to be mobilized, the foot being positioned in the heel support; - Figure 8 is an exploded view of the joint of a second embodiment of the device according to the present invention, together with a schematic representation of the foot whose ankle is to be mobilized, the foot being positioned in the -6P6436IT00 by: ALMA MATER STUDIORUM - UNIVERSITY OF BOLOGNA UNIVERSITY OF FLORENCE RIZZOLI ORTHOPAEDIC INSTITUTE heel support; and - Figure 9 is an exploded view of a detail of a first embodiment of the present invention together with a schematic representation of the foot whose ankle is to be mobilized, said detail relating to the assembly consisting of the calcaneal support from the joint, as well as the means for the rigid transmission of motion from the joint to the calcaneal support. DETAILED DESCRIPTION OF THE INVENTION With reference to Figures 1, 2, 3a, 3b, 3c, 5, 6, 7 and 9, a first embodiment of the device (100) of the present invention comprises: - a frame (10, 107, 11, 12, 12', 13, 16) comprising a retention system (13, 16) of a leg of the user of the device (100), configured to prevent and / or reduce movements of the leg (200); - a heel support (31', 31, 32, 33, 34, 35, 36', 36, 37) configured to accommodate a user's ankle, said ankle being equipped with a dorsiflexion / plantarflexion rotation axis (x); - actuation means (21, 22, 23, 24', 24, 25, 26) comprising a motor (25) configured to generate rotation around an actuation axis and an elastic joint (26) placed between the motor (25) and the heel support (31', 31, 32,33,34,35,36', 36, 37); - means of coupling / uncoupling (15,27,28,29,30) of the actuation means (21,22,23,24', 24, 25,26) to the frame (10,10', 11,12,12', 13,16); and - means of fixing the leg (200) to the frame (10,10', 11,12,12', 13, 16) consisting of Velcro strips. The frame (10,10', 11,12,12', 13,16), in turn, includes: - a base (11) which may include the electronic components necessary for the operation and control of the device (100); - a first pair of rods (10, 107) that can be tilted with respect to the base -7P6436IT00 by: ALMA MATER STUDIORUM - UNIVERSITY OF BOLOGNA UNIVERSITY OF FLORENCE RIZZOLI ORTHOPAEDIC INSTITUTE (the); - a second pair of rods (12,12') configured for height adjustment of the support structure (13), the rods (12, 12') of said second pair being hinged to the rods (10, 107) of the first pair and the base (11) comprising a guide (11, 11') for each rod (12,12') of the second pair (12,12'), each guide (11, 11') being configured for sliding one end of a rod (12,12') of the second pair. The adjustment of the height of the support structure as well as the adjustment of the inclination of the same by means of the second (12,12') and the first pair (10, 10') of rods, respectively, allow the use of the device (100) both in the lying position and in the sitting position and allow the patient himself to be able to easily modify the usage configuration independently every time he intends to carry out a rehabilitation session, thus guaranteeing the possibility of using the device (100) even at home. The retention system (13,16) is hinged to the frame (10,10', 11,12,12', 13,16), and comprises: a support structure (13) having a variable inclination by means of a knob (14) positioned in correspondence with a joint connecting the support structure (13) with a rod of the first pair (10, 10') and a mobile element (16) shaped to wrap around the user's thigh. Once seated, or lying down, the patient must rest the tibia on the support structure (13), fixing it to it by means of the means for fixing the leg (200) to the frame (10,10', 11,12,12', 13, 16) and, that is, by means of Velcro straps not shown in the figures.The use of these bands is important to avoid compromising the effectiveness of the means of implementation (21,22, 23, 24', 24, 25, 26) and, more generally, of the device (100) which must rotate the foot (300) around the axis (x) of the ankle joint, without the tibia moving, nor tending to lift from the support structure (13). The mobile element (16) shaped to wrap around the user's thigh further prevents the movement of the tibia and its movement away from the support structure (13) during the treatment, thus ensuring greater stability in the motion. -8P6436IT00 by: ALMA MATER STUDIORUM - UNIVERSITY OF BOLOGNA UNIVERSITY OF FLORENCE RIZZOLI ORTHOPAEDIC INSTITUTE The calcaneal support (3Γ, 31, 32,33,34,35,36', 36, 37), in turn, includes: - a rigid casing (31', 31) divided into two components (31', 31) placed at a variable distance depending on the size of the user's foot (300), said two components (31', 31) being brought closer / further apart by means of a screw / nut system (36', 36); - a deformable filling (32) coupled with a silicone insole (33) positioned inside the rigid casing (31', 31) and such that it can be shaped based on the shape of the user's heel; and - Velcro straps (34) configured to wrap the foot (300) dorsally. Furthermore, to ensure correct alignment between the parts, pins or dowels can be added in the plantar area. Furthermore, the rigid casing (31', 31) can be designed so that, in the case of anterior prosthesis implantation, a wound located in the dorsal area of ​​the foot and anterior area of ​​the ankle is left free. For this purpose, the front flaps of the casing (31', 31) are designed so as not to cover these areas. Rather than having a casing (31', 31) for each new patient, this is made in sizes and the difference in shape compared to the foot (300) that wears it is filled by the deformable filling (32) made, for example, of expanded polyurethane, memory foam, or consisting of an inflatable chamber. To increase the adhesion between the parts, as mentioned above, a silicone insole (33) can also be used.Once the filling (32) has been formed and the two components (31') and (31) of the rigid casing (31', 31) have been tightened sufficiently, the Velcro strap (34) can be closed between the loops (38, 38') so that the heel support (31', 31, 32,33,34,35,36', 36, 37) is completely integral with the foot (300). An important advantage associated with the deformable and customized filling (32) concerns its possibility of adapting even when the foot, with the passage of time from the operation, begins to deflate. If the differences in shape can no longer be filled, it will be sufficient to use a new filling (32), rather than a new heel support (31', 31, 32,33,34,35, 36', 36, 37) in its entirety. The elastic joint (26) is equipped with at least one degree of translational freedom in the direction -9P6436IT00 by: ALMA MATER STUDIORUM - UNIVERSITY OF BOLOGNA UNIVERSITY OF FLORENCE RIZZOLI ORTHOPAEDIC INSTITUTE of the actuation axis, and no degree of freedom in torsion, so as to compensate for misalignments between the actuation axis and the rotation axis (x). In addition to the elastic joint (26) and the motor (25), the actuation means (21,22,23,24', 24, 25,26) include: - an engine position adjustment system (22,24', 24); - a first housing (21) configured to house the motor position adjustment system (22,24', 24); - a second housing (23) configured to house the motor (25); - means for the rigid transmission of motion (27) to the calcaneal support (31', 31, 32, 33, 34, 35, 36', 36, 37), said means for the rigid transmission of motion (27) being interposed between the joint (26) and the calcaneal support (31', 31, 32,33,34,35,36', 36, 37) of the foot (300); and - a shaft (28) for transmitting motion from the joint (26) to the means for rigid motion transmission (27). The motor position adjustment system (22, 24', 24') comprises, in turn, a rod (22) configured to translate in a first direction, the first direction lying on a sagittal plane and being parallel to a longitudinal axis of the leg (200) and in a second direction, the second direction being coplanar with the first direction perpendicular to said longitudinal axis. Inside the first housing (21) are positioned a first guide (24') configured for the sliding of the rod (22) in the first direction and a second guide (24) configured for the sliding of the rod (22) in the second direction. The two guides (24', 24), mounted at 90°, allow continuous adjustment of the motor position, on the sagittal plane (yz) by means of two knobs (51,51'). It thus becomes possible to bring the axis of the motor (25) as closely aligned as possible with that (x) of the ankle joint.In any case, the elastic joint (26) allows the transmission of the torque even if the axis of the motor (25) and the axis (x) of the ankle joint are misaligned with each other. The coupling / uncoupling means (15,27,28,29,30) of the actuation means (21,22,23,24', 24, 25, 26), include a seat (15) for coupling / uncoupling (15) via a component with a double T profile. The same seat (15) is located on both the right and left side. -10P6436IT00 by: ALMA MATER STUDIORUM - UNIVERSITY OF BOLOGNA UNIVERSITY OF FLORENCE RIZZOLI ORTHOPAEDIC INSTITUTE left, (not visible in the figures), so that a single device can be used for rehabilitation treatments of both the right and left foot, simply by moving the actuation means (21, 22, 23, 24', 24, 25, 26), on the appropriate side of the frame (10, 107,11,12,12', 13,16) positioning the leg (200) relating to the foot (300) to be treated, in the retention system (13,16). The coupling / uncoupling means (15,27,28,29,30) of the actuation means (21,22,23,24', 24, 25, 26), also comprise magnets (30) configured to prevent axial sliding of the shaft (28), said magnets (30) being inserted in a special support (29) and being configured to prevent axial sliding of the shaft (28). The means for the rigid transmission of motion (27) can also be coupled to the calcaneal support (31', 31, 32, 33, 34, 35, 36', 36, 37) by means of an interface component (35), equipped with a slot (35') which allows the movement of the calcaneal support (31', 31, 32,33,34,35,36', 36, 37). The component (35) can be housed in one of the two seats created on the sides of the two parts of the rigid casing, depending on the foot (300) to be treated, adjusted by means of the knob (37) and fixed. With reference to Figures 1, 2, 4a, 4b, 3c, 5, 8, a second embodiment of the device of the present invention comprises all the components of the first embodiment of the present invention with the sole exception of the elastic joint, which in the second embodiment is replaced by a constant velocity joint (40,41,42,43,44,40', 41', 42'). The second embodiment of the device of the present invention therefore comprises: - a frame (10, 10', 11, 12, 12', 13, 16) comprising a retention system (13, 16) of a leg of the user of the device (100), configured to prevent and / or reduce movements of the leg (200); - a heel support (31', 31, 32, 33, 34, 35, 36', 36, 37) configured to accommodate a user's ankle, said ankle being equipped with a dorsiflexion / plantarflexion rotation axis (x); -11P6436IT00 by: ALMA MATER STUDIORUM - UNIVERSITY OF BOLOGNA UNIVERSITY OF FLORENCE RIZZOLI ORTHOPAEDIC INSTITUTE - actuation means (21, 22, 23, 24', 24, 25, 26) comprising a motor (25) configured to generate rotation around an actuation axis and a constant velocity joint (40,41,42,43,44,40', 41', 42') placed between the motor (25) and the heel support (31', 31, 32,33, 34, 35,36', 36, 37); - means of coupling / uncoupling (15,27,28,29,30) of the actuation means (21,22,23,24', 24, 25,26) to the frame (10,10', 11,12,12', 13,16); and - means of fixing the leg (200) to the frame (10,10', 11,12,12', 13, 16) consisting of Velcro strips. The constant velocity joint (40,41,42,43,44,40', 41', 42') comprises, in turn, a first universal joint (40, 41, 42), a second universal joint (40', 41', 42') and a prismatic joint (43,44) interposed between the first (40,41,42) and the second universal joint (40', 41', 42'), the first universal joint (40, 41, 42) being connected to the engine (25) and the second universal joint (40', 41', 42') being connected to the coupling / uncoupling means (15,27,28,29,30) of the actuation means (21,22,23,24', 24, 25, to the frame (10,10', 11, 12,12', 13,16).If the double universal joint (40,41,42,40', 41', 42'), similarly to the elastic joint (26) of the first embodiment, has the function of absorbing any misalignments between the actuation axis and the rotation axis (x) of the ankle, the prismatic joint (43,44), guaranteeing a degree of translational freedom in the direction of the actuation axis, allows the self-regulation of the position of the motor with respect to the connection point, along the axis of the motor itself (25), to the coupling / uncoupling means (15, 27,28,29,30) of the actuation means (21,22,23,24', 24, 25, to the frame (10,10', 11,12, 12', 13,16). More specifically, the homokinetic joint (40, 41, 42, 43, 44, 40', 41', 42') of the second embodiment of the device of the present invention, is structured as described below.After the motor shaft (25) there is the first universal joint (40,41,42) composed of a cross (41) placed between two forks (40,42); the second fork (42) is made integral by forced coupling to a telescopic shaft equipped with a limit switch (43), which transmits the motion to the second universal joint (40', 41', 42'). Similarly to the first embodiment, a suitably formed shaft (28) is forced onto the first fork (40') of the second universal joint (40', 41',. -12P6436IT00 by: ALMA MATER STUDIORUM - UNIVERSITY OF BOLOGNA UNIVERSITY OF FLORENCE RIZZOLI ORTHOPAEDIC INSTITUTE 42'). The support (29) for the magnet (30) and the means for the rigid transmission of motion (27), via shape coupling, to the heel support (31', 31, 32,33,34,35,36', 36, 37) are also fitted onto this. Based on the above, the operation of the device in its various embodiments can be summarized as follows: - dressing of the heel support (31', 31, 32,33,34,35,36', 36, 37), in which the silicone insole (33) and the deformable filling (32) have already been inserted; - adjustment of the two components (31') and (31) of the external rigid casing with the knob (36), causing the filling to deform and adhere correctly to the foot (300), even in the plantar area; - adjustment of the position of the interface component (35) using the knob (37) to make the axis of the actuation system coincide as much as possible with that of the ankle; - height and inclination adjustment of the retention system (13,16) via the rods (12,12') and the knob (14), depending on whether the patient wants to use it in a sitting or lying configuration; - connection of the means of actuation (21,22,23,24', 24, 25,26,40,41,42,43, 44,40', 41', 42') to the frame (10,10', 11,12,12', 13,16); - once the patient is in position, move the actuation axis using the two knobs (51, 51') on the external part of the housing (21) which contains the first guide (24') configured for the sliding of the rod (22) in the first direction and the second guide (24) configured for the sliding of the rod (22) in the second direction, until it coincides with the interface component (35) of the calcaneal support (31', 31, 32,33,34,35, 36', 36, 37); - connection of the actuation means (21,22,23,24', 24, 25,26,40,41,42,43, 44, 40', 41', 42') to the heel support (31', 31, 32, 33, 34, 35, 36', 36, 37) by means of the means for rigid transmission of motion (27) and the interface component (35); -13P6436IT00 by: ALMA MATER STUDIORUM - UNIVERSITY OF BOLOGNA UNIVERSITY OF FLORENCE RIZZOLI ORTHOPAEDIC INSTITUTE - closing of the Velcro band (34) on the heel support (31', 31, 32,33,34, 35,36', 36, 37) and fixing of the tibia to the support structure (13); - closing of the retention system (13,16) for the leg; and - turning on the device (100). Thanks to the procedure described above, the device of the present invention can be used for rehabilitation treatments for functional recovery of the ankle both in the post-operative period (rehabilitation sessions, in fact, begin a few days after surgery to prevent the mechanical parts of the prosthesis from stiffening) and following an injury. Rehabilitation can be both passive and active: in the first case, the joint is mobilized according to predefined kinematic patterns to increase the ankle's range of motion, possibly reaching the maximum range allowed by the implanted prosthesis; in the second case, however, the patient moves the ankle independently and the interaction forces between the parts are measured to modulate the exercise according to the patient's progress.In fact, if appropriately sensorized via encoders and load cells, the device can monitor ankle mobility, measuring the ROM that the patient reaches at each session, and the interaction forces. It can record the rehabilitation sessions performed, and thus allow an appropriate evaluation of the clinical condition of the ankle (even possibly in the pre-operative phase).

Claims

1. Device (100) for ankle mobilization comprising: - a frame (10,10', 11,12,12', 13,16) and a retention system (13,16) of a leg of the user of the device (100), configured to prevent and / or reduce movements of the leg (200); - a heel support (31', 31, 32, 33, 34, 35, 36', 36, 37) configured to accommodate an ankle of a user, said ankle being equipped with a dorsiflexion / plantarflexion rotation axis (x); - actuation means (21,22,23, 24', 24, 25,26, 40,41,42,43,44,40', 41', 42') comprising a motor (25) configured to generate rotation around an actuation axis and a joint (26,40,41,42, 43,44, 40', 41', 42') placed between the motor (25) and the heel support (31', 31, 32,33,34,35,36', 36, 37); characterised in that the heel support (31', 31, 32,33,34,35,36', 36, 37), in turn, comprises: - a rigid casing (31', 31);- a deformable filling (32) positioned inside the rigid casing (31', 31) and such that it can be shaped according to the shape of the user's heel; and by the fact that: - the joint (26, 40, 41, 42, 43, 44, 40', 41', 42') is equipped with at least one degree of translational freedom in the direction of the actuation axis, and no degrees of freedom in torsion, so as to compensate for misalignments between the actuation axis and the rotation axis (x).; 2. Device (100) according to claim 1, wherein the retention system (13,16) comprises: -1P6436IT00 of: ALMA MATER STUDIORUM - UNIVERSITÀ' DI BOLOGNA UNIVERSITÀ'DEGLI STUDI DI FIRENZE ISTITUTO ORTOPEDICO RIZZOLI - a support structure (13) having a variable inclination; and - a mobile element (16) shaped to wrap around one thigh of the user.

3. Device (100) according to claim 1 wherein the joint (26,40,41,42,43, 44,40', 41', 42') is an elastic joint (26).

4. Device (100) according to claim 1 wherein the joint (26, 40,41, 42, 43, 44,40', 41', 42') is a constant velocity joint (40,41,42,43,44,40', 41', 42') comprising a first universal joint (40,41,42), a second universal joint (40', 4Γ, 42') and a prismatic joint (43, 44) interposed between the first (40, 41, 42) and the second universal joint (40', 41', 42').

5. Device (100) according to any of the preceding claims wherein the rigid casing (31', 31) is divided into two components (31', 31) placed at a variable distance depending on the size of the user's foot (300), said two components (31', 31) being able to be brought closer / removed by means of a screw / nut system (36', 36).

6. Device (100) according to any of the preceding claims, wherein the frame (10,10', 11,12,12', 13,16) comprises: - a base (11); - a first pair of rods (10, 106 7) tiltable with respect to the base (11); - a second pair of rods (12,12') configured for height adjustment of the support structure (13), the rods (12, 12') of said second pair being hinged to the rods (10, 10') of the first pair and the base (11) comprising a guide (11, 11') for each rod (12,12') of the second pair (12,12'), each guide (11, 11') being configured for sliding one end of a rod (12,12') of the second pair -2P6436IT00 by: ALMA MATER STUDIORUM - UNIVERSITY OF BOLOGNA UNIVERSITY OF FLORENCE RIZZOLI ORTHOPAEDIC INSTITUTE 7. Device (100) according to any of the preceding claims, comprising means for hooking / unhooking (15, 27, 28, 29, 30) the actuation means (21,22,23,24', 24, 25,26,40,41,42,43,44,40', 41', 42') to the frame (10,10', 11,12,12', 13, 16).

8. Device (100) according to any of the preceding claims wherein the actuation means (21, 22, 23, 24', 24, 25, 26, 40, 41, 42, 43, 44, 40', 41', 42') comprise: - a motor position adjustment system (22,24', 24); - a first housing (21) configured to house the motor position adjustment system (22,24', 24); - a second housing (23) configured to house the motor (25) and the joint (26,40,41,42,43,44,40', 41', 42'); and - means for the rigid transmission of motion (27) to the heel support (31', 31, 32, 33, 34, 35, 36', 36, 37), said means for the rigid transmission of motion (27) being interposed between the joint (26,40,41,42,43,44,40', 41', 42') and the heel support (31', 31, 32,33,34,35,36', 36, 37) of the foot (300); and - a shaft (28) for the transmission of motion from the joint (26) to the means for the rigid transmission of motion (27).

9. Device (100) according to the preceding claim, wherein the motor position adjustment system (22, 24', 24') comprises a rod (22) configured to translate in a first direction, the first direction lying on a sagittal plane and being parallel to a longitudinal axis of the leg (200) and in a second direction, the second direction being coplanar with the first direction perpendicular to said longitudinal axis.

10. Device (100) according to the previous claim wherein inside the -3P6436IT00 of: ALMA MATER STUDIORUM - UNIVERSITÀ' DI BOLOGNA UNIVERSITÀ'DEGLI STUDI DI FIRENZE ISTITUTO ORTOPEDICO RIZZOLI first housing (21) are positioned a first guide (24') configured for the sliding of the rod (22) in the first direction and a second guide (24) configured for the sliding of the rod (22) in the second direction.

11. Device (100) according to any of the preceding claims wherein the coupling / uncoupling means (15,27,28, 29,30) comprise a seat (15) for coupling / uncoupling via a component with a double T profile.

12. Device (100) according to any of the preceding claims wherein the coupling / uncoupling means (15, 27, 28, 29, 30) comprise magnets (30).

13. Device (100) according to the preceding claim, wherein the magnets (30) are, further, configured to prevent axial slippage of the shaft (28).

14. Device (100) according to any of claims 5 to 13, wherein the heel support (31', 31, 32,33,34,35,36', 36, 37) comprises: - a silicone insole (33); - Velcro straps (34) configured to wrap the foot (300) dorsally; - an interface component (35), configured for coupling with the means for rigid motion transmission (27), said interface component (35), being equipped with a slot (35') which allows the heel support (31', 31, 32,33,34, 35,36', 36, 37) to be moved relative to the motor (25).

15. Device (100) according to any of the preceding claims comprising means for fixing the leg (200) to the frame (10,10', 11,12,12', 13,16) consisting of Velcro strips.