DE29920434U1 - Foot for a prosthetic leg - Google Patents

Description

The invention relates to a foot for a leg prosthesis with a hindfoot spring, a forefoot spring connected to the hindfoot spring and a connecting element connected to the hindfoot spring.

Such a foot is known from DE 298 23 435 Ul. This known foot or foot insert consists of a forefoot or base spring that extends over almost the entire length of the foot insert, as well as a C-shaped rear foot spring arranged in the heel area, which absorbs the prosthesis load with its upper C-leg and rests on the forefoot spring with its lower C-leg. An adaptation device or restraint is provided between the upper C-leg and a bearing block connected to the forefoot spring.

Heiligenbreite 7, OT Angerstein Tel.: 0 5503/91 D-37176 Nörten-Hardenberg . Jf

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.50 0J. .. J .. .

Klausheider Straße 31 Tel: 0 5254/66 06 ß-33 \06 Paderborn _m Fax: 0 5254/66 06

The disadvantage of the known foot is that the adaptation device is relatively complex, complicated, bulky and expensive due to the use of a pneumatic cylinder and a special air pump.

The object of the present invention is therefore to improve the known foot so that it can be manufactured more easily and cost-effectively and still has good movement behavior.

This object is achieved according to the invention in conjunction with the preamble of claim 1 in that the rear foot spring is designed as an e-shaped spiral spring, the upper free end of which, facing away from the forefoot spring, is folded inwards and connected to a lower part of the connecting element.

Because the rear foot spring is designed as an E-shaped spiral spring, it can be kept relatively long with a comparatively low height. The length of the rear foot spring can have a positive effect on the soft response of the foot. Since the height of the foot shortens when the rear foot spring is loaded, it also has a shock-absorbing effect. The adaptation device or restraint can be completely dispensed with by designing the rear foot spring as a spiral spring. This means that the foot can be designed in a simpler and more cost-effective way. The elimination of the restraint and the design of the spiral spring also enable a certain rotation of the lower leg in relation to the foot.

According to a preferred embodiment of the invention, the lower part of the connecting element is freely movable through an opening in the external spring coil.

The opening in the outer spring coil allows the lower part to be attached to the upper free end of the rear foot spring relatively easily. The outer coil allows the lower part of the connecting element to pass through the opening without any restrictions on movement. It is basically possible to guide the lower part past the outer coil. The lower part can also be connected to the free part of the spiral spring that is folded inwards using a special connecting part.

According to a further preferred embodiment of the invention, the spiral spring has two adjacent leaf spring elements which are connected to one another at the upper free end.

By connecting the two leaf spring elements at the upper free end, the inner second leaf spring element is sufficiently fixed in position and a relative movement of the leaf spring elements in their longitudinal direction is enabled. This allows favorable suspension properties to be achieved.

According to a further preferred embodiment of the invention, a friction-influencing layer is arranged between the leaf spring elements. The friction can be influenced by an additional layer.

According to a further preferred embodiment of the invention, the outer first leaf spring element has a friction-reducing coating, for example made of a PTFE material, on its inner surface facing the inner second leaf spring element.

The friction-reducing coating between the two leaf spring elements promotes the relative movement between the leaf spring elements caused by different paths during rolling up or down.

According to a further preferred embodiment of the invention, the movement of the adjacent leaf spring elements relative to one another can be influenced by a first adjustment. The two leaf spring elements, which cover different distances when rolling up and down due to their different sizes, can be limited or released in the difference in their movement by the first adjustment. For example, the first adjustment can consist of a clamping device that influences the relative movement of the leaf spring elements. This adjustment option can influence the stiffness of the rear foot spring and thus the entire characteristics of the foot.

According to a further preferred embodiment of the invention, a rear foot stop is arranged in front of the rear foot spring or spiral spring inwards towards the heel. This rear foot stop is designed to be elastically springy and can be adjusted by a second adjustment.

The rear foot stop can be used to increase stability and also to change the movement of the foot in terms of shock absorption as well as the movement of the foot during heel strike.

According to a further preferred embodiment of the invention, a forefoot stop is arranged in front of the rear foot spring or spiral spring, outwards towards the forefoot spring. The forefoot stop is arranged on the forefoot spring and is adjustable by a third adjustment. The forefoot stop also serves to increase stability and the third adjustment can also be used to make the behavior of the foot in the rolling and pushing-off phase either softer or harder.

All adjustment options together make it possible to adapt the foot to all expected levels of activity based on forefoot and rearfoot springs dimensioned based on scaled standard data.

Further preferred embodiments are described in the subclaims.

Further details of the invention will become apparent from the following detailed description and the accompanying drawings, in which preferred embodiments of the invention are illustrated by way of example.

The drawings show:

Figure 1: a side view of a foot for a leg prosthesis and

Figure 2: a plan view of the foot of Figure 1.

A foot 1 for a leg prosthesis essentially consists of a rear foot spring 2, a forefoot spring 3 and a connecting element 4.

The rear foot spring 2 is designed as an e-shaped spiral spring 5 and is arranged in the heel area 6 of the foot 1. The spiral spring 5 is folded inwards at its upper free end 8 facing away from the sole 7 of the foot 1, so that the upper free end 8 is directed towards the tip of the foot 9 of the foot 1 and runs approximately parallel to the sole 7. The lower free end 10 opposite the upper free end 8 runs approximately parallel to the sole 7 and is, however, directed away from the tip of the foot 9. The spiral spring 5 consists of an outer first leaf spring element 11 and a parallel inner leaf spring element.

12. The first leaf spring element 11 has an inner surface

13, which is adjacent to an outer surface 14 of the second leaf spring element 12. The inner surface 13 of the first leaf spring element 11 has a Teflon or PTFE coating (29). In the area of the upper free end 8, the two leaf spring elements 11, 12 are firmly connected to one another.

The connecting element 4 has a pyramid-shaped connecting piece 15 towards a leg prosthesis (not shown). At its end facing away from the connecting piece 15, the connecting element 4 has a lower part 16. The lower part 16 penetrates an opening 17 of an external spring coil 18 of the spiral spring 5 adjacent to the upper end 8. The opening 17 is oval and extends over both leaf spring elements 11, 12. The connecting element 4 sits with its lower part 16 on the upper free end 8 of the spiral spring 5 or rear foot spring 2 and is firmly connected to it. The length of the rear foot spring 2 in the unrolled state can be, for example, three times its overall height.

The forefoot spring 3, which runs approximately parallel to the sole of the foot 7, is firmly connected in its rear region 19 facing away from the tip of the foot 9 to the lower end 10 of the spiral spring 5 or the outer leaf spring element 11.

The movement of the adjacent leaf spring elements 11, 12 relative to one another can be influenced by a first adjustment 20. The first adjustment 20 is designed as a clamping device arranged between the upper end 8 and the lower end 10.

A rear foot stop 22 is arranged in front of the spiral spring 5 inwards towards the heel 21.

The rear foot stop 22 is made of an elastically springy material and is adjustable by a second adjustment 23. The rear foot stop 22 can be moved in a vertical direction from the sole of the foot 7 using hexagon socket screws 24, so-called Allen screws.

A forefoot stop 25 is arranged in front of the spiral spring 5 towards the tip of the foot 9 or towards the forefoot spring 3.

The forefoot stop 25 is arranged on the forefoot spring 3 and is adjustable by a third adjustment 2 6. The forefoot stop 25 can also be moved in the vertical direction using hexagon socket screws 27. The forefoot stop 25 is made of an elastically springy material.

The foot exhibits the following movement behavior:
Heel strike:

When the heel strikes, the load vector is far behind the foot 1 and the spiral spring 5 rolls up. This causes the immediate lowering of the forefoot 28. This movement is carried out by the rear foot spring 2 or spiral spring 5 relatively gently compared to the force of the forefoot spring 3. This movement is limited by the rear foot stop 22.

SME phase:

When the ball of the foot is struck, the load vector moves again over the foot 1 and the spiral spring 5 moves back to its zero position while releasing energy. The release of energy promotes the physiological knee flexion in the rolling phase. This movement takes place with full contact with the ground and gives the patient stability.

Roll-off phase:

In this phase, the load vector continues to move over the foot 1 in a frontal direction. The angle between the lower leg and the forefoot 2 8 becomes increasingly smaller. The spiral spring 5 unrolls and reaches the forefoot stop 25 arranged on the forefoot spring 3. The forefoot stop 25 also tensions the forefoot spring 3.

Repulsion phase:

The patient lifts the foot 1 and is actively supported in the further step process by the relaxing spiral spring 5 and the forefoot spring 3.

List of reference symbols

1 foot

2 rear foot spring

3 Forefoot spring

4 Connection element

5 Spiral spring

6 Heel area

7 Sole of the foot

8 upper free end

9 Toe

10 lower free end 11 leaf spring element

12 Leaf spring element

13 Interior surface

14 Exterior surface

15 Connector 16 Lower part

17 Breakthrough

18 external spring coil

19 rear area

20 first adjustment 21 heel

22 Rear foot stop

23 second adjustment

24 Hexagon socket screw

25 Forefoot stop

2 6 third adjustment

27 Hexagon socket screw

2 8 Forefoot

29 Coating

Claims (23)

1. Foot for a leg prosthesis with a rear foot spring, a forefoot spring connected to the rear foot spring and a connecting element connected to the rear foot spring, characterized in that the rear foot spring ( 2 ) is designed as an e-shaped spiral spring ( 5 ), the upper free end ( 8 ) of which facing away from the forefoot spring ( 3 ) is folded inwards and connected to a lower part ( 16 ) of the connecting element ( 4 ). 2. Foot according to claim 1, characterized in that the lower part is guided past the outer spring coil ( 18 ) adjacent to the upper free end ( 8 ). 3. Foot according to claim 1, characterized in that the lower part ( 16 ) is passed through the outer spring coil ( 18 ) adjacent to the upper free end ( 8 ). 4. Foot according to claim 3, characterized in that the lower part ( 16 ) is freely movable through an opening ( 17 ) of the outer spring coil ( 18 ). 5. Foot according to claim 4, characterized in that the opening ( 17 ) is oval. 6. Foot according to one of claims 1 to 5, characterized in that the spiral spring ( 5 ) has two adjacent leaf spring elements ( 11 , 12 ) which are connected to one another at the upper free end ( 8 ). 7. Foot according to claim 6, characterized in that a layer influencing the friction is arranged between the leaf spring elements ( 11 , 12 ). 8. Foot according to claim 7, characterized in that the outer first leaf spring element ( 11 ) has a friction-reducing coating on its inner surface ( 13 ) facing the inner second leaf spring ( 12 ). 9. Foot according to claim 7 or 8, characterized in that the inner second leaf spring element ( 12 ) has a friction-reducing coating ( 29 ) on its outer surface ( 14 ) facing the first leaf spring element ( 11 ). 10. Foot according to claim 8 or 9, characterized in that the friction-reducing coating ( 29 ) is made of a PTFE material. 11. Foot according to one of claims 6 to 10, characterized in that the leaf spring elements ( 11 , 12 ) are connected to one another at the lower end ( 10 ) of the spiral spring ( 5 ). 12. Foot according to one of claims 1 to 11, characterized in that the springs ( 2 , 3 ) are made of a carbon material. 13. Foot according to one of claims 1 to 11, characterized in that the springs ( 2 , 3 ) are made of titanium. 14. Foot according to one of claims 6 to 13, characterized in that the movement of the adjacent leaf spring elements ( 11 , 12 ) relative to one another can be influenced by a first adjustment ( 20 ). 15. Foot according to claim 1 or 14, characterized in that a rear foot stop ( 22 ) is arranged in front of the spiral spring ( 5 ) inwards towards the heel ( 21 ). 16. Foot according to claim 15, characterized in that the back stop ( 22 ) is elastically resilient. 17. Foot according to claim 15 or 16, characterized in that the rear foot stop ( 22 ) is adjustable by a second adjustment ( 23 ). 18. Foot according to one of claims 1 to 17, characterized in that a forefoot stop ( 25 ) is arranged in front of the spiral spring ( 5 ) outwards towards the forefoot spring ( 3 ). 19. Foot according to claim 18, characterized in that the forefoot stop ( 25 ) is arranged on the forefoot spring ( 3 ). 20. Foot according to claim 18 or 19, characterized in that the forefoot stop ( 25 ) is adjustable by a third adjustment ( 26 ). 21. Foot according to one of claims 18 to 20, characterized in that the forefoot stop ( 25 ) is elastically springy. 22. Foot according to one of claims 18 to 21, characterized in that the forefoot stop ( 25 ) is adjustable in height by the third adjustment ( 26 ). 23. Foot according to one of claims 15 to 22, characterized in that the rear foot stop ( 22 ) is adjustable in height by the second adjustment ( 23 ).