PROSTHETIC FOOT INSERT

Abstract

The invention relates to a prosthetic foot insert comprising: a proximal connection device (10) for fastening to a lower-leg tube or lower-leg shank; at least one base element (20), which is coupled or connected to the connection device (10) and has a forefoot region (21); the base element (20) has a heel region (22) or is connected to a heel region (22), which is formed from a first material and extends from the forefoot region (21) in the posterior direction: wherein the forefront region (21) is formed from a second material, which has a lower modulus of elasticity than the first material and projects forwards beyond the anterior end of the heel region (22).

Claims

1. A prosthetic foot insert, comprising: a proximal connection device for fastening to a lower leg tube or a lower leg socket; at least one base element is coupled or connected to the connection device; and a forefoot region, wherein the at least one base element has a heel region or is connected to the heel region, wherein the heel region is formed from a first material and extends from the forefoot region in a posterior direction, wherein the forefoot region is formed from a second material which has a lower modulus of elasticity than the first material and projects forward beyond an anterior end of the heel region.

2. The prosthetic foot insert as claimed in claim 1, wherein the at least one base element is configured as a guide element, a base spring, or a downwardly inclined forefoot spring.

3. The prosthetic foot insert as claimed in claim 1 further comprising a reception pocket for a spring component formed on the at least one base element from the first material.

4. The prosthetic foot insert as claimed in claim 1 wherein the forefoot region is overmolded, injection-molded, formed by a two-component injection-molding method, or formed by an additive production method on the at least one base element, or wherein the forefoot region is materially fastened on the at least one base element.

5. The prosthetic foot insert as claimed in claim 1 wherein the first material is a polyamide, a thermoplastic copolyester elastomer, or a polyether ether ketone, and wherein the second material is a thermoplastic polyamide elastomer, a thermoplastic copolyester elastomer, a thermoplastic olefin (TPO) elastomer, a thermoplastic styrene (TPS) block copolymer, or a urethane-based thermoplastic (TPU) elastomer.

6. The prosthetic foot insert as claimed in claim 1 wherein the first material has a modulus of elasticity greater than the second material by a factor of 2 to 10 than the second material.

7. The prosthetic foot insert as claimed in claim 1 wherein the forefoot region comprises a hallux section, a lateral toe section, and a recess between the hallux section and the lateral toe section.

8. The prosthetic foot insert as claimed in claim 1 wherein the forefoot region protrudes medially and/or laterally beyond the first material of the at least one base element.

9. The prosthetic foot insert as claimed in claim 1 further comprising a ledge which extends locally or fully over a width of the at least one base element, wherein the ledge is formed or arranged on a lower side of the at least one base element.

10. The prosthetic foot insert as claimed in claim 9, wherein the ledge is formed on the at least one base element or by the forefoot region.

11. The prosthetic foot insert as claimed in claim 9 wherein the ledge has a round or rounded cross section provided with a curvature that decreases in an anterior direction.

12. The prosthetic foot insert as claimed in claim 9 wherein the ledge forms a rolling edge which bears on ground over a width of the ledge in a terminal stance phase.

13. The prosthetic foot insert as claimed in claim 1 wherein the forefoot region comprises an edge and upwardly directed bulges on a lower side.

14. The prosthetic foot insert as claimed in claim 1 further comprising stabilizing struts formed in the forefoot region.

Description

[0022] Exemplary embodiments of a prosthetic foot insert are explained in more detail below with the aid of the appended figures, in which:

[0023] FIG. 1shows a perspective view of a prosthetic foot insert;

[0024] FIG. 2shows a representation of a base element with separate material sections;

[0025] FIG. 3shows a plan view of the base element;

[0026] FIG. 4shows a view of the base element from below;

[0027] FIG. 5shows a detail representation in side view; and

[0028] FIG. 6shows a side view in the dorsally flexed state.

[0029] FIG. 1 shows a side view of a prosthetic foot insert 1 having a connection device 10 for fastening to a proximal prosthetic component (not represented), for example a lower leg tube or a lower leg socket. The connection device 10 has a pyramid adapter 11, which is fastened or formed on a holder 12. The holder 12 is in particular formed from a dimensionally stable material, for example a light metal, and in the exemplary embodiment is provided with a cladding. Arranged on the front end region of the holder 12 as seen in the walking direction, there is a bearing block 14 which can be tilted about a rotation axle 13 and is connected to a forefoot spring 6. By means of the bearing block 14, it is possible for the holder 12 to be displaced relative to the forefoot spring 6 during loading, which may be necessary in the event of deformations during the loading. The rear end of the holder 12 is supported by means of two heel cushions 8, 7 on the rear end of a base element 20, which in the exemplary embodiment represented is configured as a guide element with little spring action. Alternatively, the base element 20 is configured as a base spring. The rear end of the forefoot spring 6 is arranged between the two heel cushions 7, 8. The forefoot spring 6 either may be held in a clamping fashion between the two heel cushions 7, 8 or is fastened on at least one of the heel cushions 7, 8, for example fastened with a form-fit or force-fit or adhesively bonded.

[0030] In order to ensure association of the connection device 10 with the base element 20 in the rear, posterior section of the latter, a strap 9 is passed around the upper side of the holder 12, below the cladding and below the base element 20, and is adjusted in its length so that the heel cushions 7, 8 are prestressed. The forefoot spring 6 is thereby clamped and held between the two heel cushions 7, 8.

[0031] In the region of the front end of the forefoot spring 6, the reception pocket 23 is arranged on the base element 20, for example having a slot into which the front end of the forefoot spring 6 is inserted and optionally secured by a fastening element or by adhesive bonding or welding. The reception pocket 23 forms an abutment, so that the forefoot spring 6 cannot be displaced forward beyond the base element 20. As an alternative to a material connection, the forefoot spring 6 is coupled to the base element 20 in such a way that it can be released without the base element 20, the reception pocket 23 and/or the forefoot spring 6 being destroyed. In this way, it is possible to replace the base element 20 and to customize the prosthetic foot insert 1.

[0032] The base element 20 has a forefoot region 21 at the front end in the walking direction, which is positioned in the walking direction before the first end of the forefoot spring 6 and before the reception pocket 23. Arranged or formed on the rear end of the base element 20 in the walking direction, there is a fastening region 29 which has form-fit elements in order to fasten a rear force transmission element or a ledge thereon and to secure the strap 9 against accidental displacement in the anterior or posterior direction. As an alternative thereto, the respective force transmission element is fixed on the fastening region 29 with a force-fit, for example held in a clamping fashion or by means of a magnetic retainer. As an alternative or in addition, fixing by means of a clip connection, hook and loop fasteners or fastening by means of separate fastening elements such as pins, springs or screws are likewise possible and provided. Formed on the upper side of the fastening region 29, there is a reception device 291 for receiving the lower heel cushion 7, into which the heel cushion 7 can be inserted. The heel cushion 7 is thereby secured against lateral displacement and against displacement in and counter to the walking direction. The strap 9 and the prestress prevent the heel cushions 7, 8 from being able to loosen in the proximal direction.

[0033] On the lower side, approximately at the height of the reception pocket 23, the prosthetic foot insert 1 has a ledge 30 so that a substantially linear force transmission region is formed in the event of forefoot loading. The load transmission during the loading of the forefoot region 21 takes place relatively far to the front as seen in the walking direction, approximately at the height of the metatarsophalangeal joints in the case of a natural foot, so that the maximum lever length for bending moment transmission into the prosthetic foot insert 1 is achieved. By the substantially linear force transmission region, it is possible to absorb and release a very high energy density so that a high dynamic range may be achieved during walking. Because of the force transmission region positioned far to the front and the linear contact with a small contact area, increased flexibility is provided when standing. The ledge 30 ends approximately at the height of the natural metatarsophalangeal joint, which in purely technical terms would be sufficient to ensure the essential functions of walking for the prosthetic foot insert 1. The overall visual impression as well as the psychological effect of a foot shorter by from 20 to 25% is disadvantageous, however, and corresponding devices for fixing the prosthetic foot insert 1 in a prosthetic cosmetic need to be found and arranged.

[0034] The base element 20 has a base spring or guide element has a heel region 22, which extends from the reception pocket 23 to a rear, posterior end. The material of the heel region 22 has a relatively high modulus of elasticity in order to absorb the forces incurred at the moment after a heel strike, during the rolling phase and during increasing forefoot loading, or in order to ensure stable and precise guiding of the movement of the heel cushions 7, 8. During a normal step, for example on the flat, after the heel contact and the planting of the entire foot, the essential force transmission takes place at the rear end of the heel region 22 and on the lower ledge 30, and possibly a region adjacent thereto rearward in the walking direction. In a similar way to a natural foot, the heel region 22 has an upwardly directed curvature in the central foot region, so that no ground contact or only slight round contact exists during the stance phase in the region below the articulation axle 13. The forefoot region 21, which consists of a softer material than the material of the heel region 22, extends forward beyond the heel region 22. In other words, the material of the forefoot region 21 has a lower modulus of elasticity than the material of the heel region 22. The material of the heel region 22 is for example a polyamide, although fiber reinforced materials or materials with comparable mechanical properties may alternatively be used. Materials which may be used for a 2-component injection-molding method are advantageous since the possibility of injection-molding the forefoot region 21 then exists. The forefoot region 21 may also be connected durably and nondestructively releasably to the material of the heel region 22 in other ways. It is likewise possible for the base element 20 to be produced in the scope of an additive manufacturing method.

[0035] Particularly in situations or states in which a very pronounced dorsiflexion of the forefoot region 21 occurs, for example when walking uphill, when ascending ramps or when kneeling, making the forefoot region 21 from a soft material has substantial advantages. Although, besides shaping which is approximated to the natural foot shape, the softer material of the forefoot region 21, for example a TPU having a modulus of elasticity of between 5% and 50% of the modulus of elasticity of the first material, offers only a lower resistance against bending, it does increase the contact area and ensure stability against sideways tilting in the medial direction or lateral direction. In particular, the yielding of the forefoot region 21 in a configuration with a recess 26 between a hallux section 24 and a lateral toe section 25 prevents the prosthetic foot having to be planted on the tip of the hallux section 24 and tilting about a point contact.

[0036] FIG. 2 shows the base element 20 in the manner of an exploded representation, in which the different material regions, which are fastened to one another nondestructively releasably, are shown separated from one another. The heel region 22 adjoins the reception pocket 23 and the ledge 30 arranged underneath. The reception pocket 23 and the ledge 30 are formed from the same material as is used for the heel region 22. Because of the high modulus of elasticity of the material, a high deformation resistance is ensured. The heel region 22 does not need to extend as far as the rear end of the base element 22, although it does in an advantageous configuration. The fastening region 29 may be overmolded on the rear, posterior end of the base element 20. It is also possible for the rear part of the base element 20 to have a different stiffness or a different modulus of elasticity than the anterior or central region. The material thickness of the base element 20 may be different over the longitudinal extent of the latter. The forefoot region 21 is represented separated from the heel region 22 of the base element 20. The forefoot region 21 has a material section extending in the walking direction behind the reception pocket 23, or behind the ledge 30, which is used to protect the lower side of the hard or stiff guide of the heel region 22. FIG. 2 furthermore shows that the softer material of the forefoot region 21 is arranged medially and laterally with respect to the heel region 22, so as to achieve broadening of the contact area and improved stability in the mediolateral direction. Furthermore, this lateral broadening better replicates the natural foot shape.

[0037] On the upper side of the forefoot region 2, the material is curved in order to replicate the spatial appearance of a natural toe or the toes. The upper side of the reception pocket 23 is covered at least partially by the softer material of the forefoot region 21 formed integrally with the heel region 22 adjacent in the posterior direction.

[0038] FIG. 3 shows the finished base element 20 in a plan view. The relatively narrow, rectilinearly configured heel region 22 is arranged between the fastening region 29 and the forefoot region 21. A slight broadening in the front region in the direction of the reception pocket 23 increases the tilting stability. The broadening in the fastening region 29 with the reception 291 may also be seen as a cup or border for fixing the lower cushion element 7 in five directions.

[0039] FIG. 4 shows the base element 20 according to FIG. 3 from the lower side. Besides the fastening region 29 on the rear end of the heel region 22 with a corresponding oblique or rounded lower contour to facilitate rolling and the groove to receive the strap 9, the overmolding of the forefoot region 21 on the front region of the base element 20 may be seen. The forefoot region 21 has a circumferential edge 26 on the lower side, substantially running in a plane, from which the bulges 27 extend upward in order to form the upper-side contour or shape in the toe section 25, or the hallux section 24. Stabilizing struts 28 are overmolded inside the bulges 27 in order to achieve a desired stability inside these regions. Likewise visible on the lower side is the ledge 30, which extends over the entire width of the heel region 22 and is also covered on the lower side by the softer material of the forefoot region 21.

[0040] FIG. 5 shows a lateral detail view of the front region of the base element 20 with the heel region 22 and the reception pocket 23 formed integrally with the heel region 22, and the overmolded ledge 30 ledge likewise formed integrally with the heel region 22. In this exemplary embodiment, neither the reception pocket 23 nor the ledge 30 is fully encapsulated with the soft second material of the forefoot region 21. On the reception pocket 23, the rear region in the walking direction is left free, and the side faces on the ledge 30 are not coated with the softer material. The forefoot region 21 protrudes forward in the anterior direction beyond the anterior end of the reception pocket 23 and of the ledge 30. The reception pocket 23 and the ledge 30 form the anterior front end of the heel region 22.

[0041] FIG. 6 shows the base element 20 according to FIG. 5 in a position such as is reached for example at the end of the rolling phase, when walking uphill or in a kneeling position. The forefoot region 21 is dorsally flexed and provides a flat contact for the prosthetic foot insert 1. When the ledge 30, which has a rounded, forwardly flattened contour, is likewise resting on the ground, there is linear contact in the region of the ledge 30 and an adjacent flat contact, which is provided by the softer material of the forefoot region 21.

[0042] By the front end overmolded, injection-molded around or on, or integrally produced by the forefoot region 21 from a relatively soft material, a visually large foot length with a correspondingly good aesthetic effect is achieved, the forefoot region 21 being flexible and generating a wide contact area of the prosthetic foot when the prosthesis wearer kneels. Such a contact area is generated by additional medial and/or lateral overmoldings or regions of the softer material next to the reception pocket 23 and optionally next to the ledge 30. Despite the visually appealing large effective foot lengths, an excessive effective foot length is avoided in particular walking situations and positions. By the forefoot region 21, a function approximated to the natural foot function may be achieved without great design outlay. Furthermore, noise during the movement is prevented and the risk of mechanical failure is reduced.

[0043] The heel region 22 is used as the major functional component for receiving the mechanical loads and is formed, for example, as a polyamide with a shear stress of 50 MPa. The forefoot region with the softer material, for example a technical polyurethane, may for example have a shear stress of 5 MPa.