WO2003026539A1

WO2003026539A1 - Fixing device for finger prosthesis

Info

Publication number: WO2003026539A1
Application number: PCT/SE2002/001514
Authority: WO
Inventors: Stellan Brimalm
Original assignee: Bergomed Ab
Priority date: 2001-08-27
Filing date: 2002-08-26
Publication date: 2003-04-03
Also published as: SE0102837D0

Abstract

Fixing device (1) for fixing of a finger prosthesis (2) of substantially natural size e.g. to a metacarpus prosthesis (3) intended to replace at least partly a human hand. The finger prosthesis (2) at the fixing device (1) has a first joint (4) intended to allow a bending of the finger prostehsis (2) from a forward direction (R) in an exension of the extended finger prosthesis, in a bend direction (I) in towards a palm (5) and back to the extended position. The fixing device (1) has a second joint (6) intended to allow pivoting in a direction substantially orthogonal to the forward direction (R).

Description

TITLE

Fixing device for finger prosthesis,

DESCRIPTION

TECHNICAL FIELD

The present invention concerns a device for fixing a finger prosthesis to another prosthesis part e.g. a metacarpus prosthesis. The finger prosthesis and metacarpus prosthesis are intended to replace corresponding lost body parts.

BACKGROUND OF THE INVENTION AND PROBLEM

When a hand or metacarpus and fingers are lost or amputated, they can be replaced by a corresponding prosthesis. This means a loss of a functioning body part with a realistic appearance, movement pattern and force absorption capacity.

The prosthesis to replace the lost body parts must be easy to repair and also have a Cost-effective construction.

To give a finger prosthesis or hand prosthesis a reatistic appearance, a prosthesis cover is used which is normally made of a substantially elastic material. The cover has a friction which depends amongst others on the material from which it is made. The cover must also resemble the human skin and protect the structural parts from dirt. For repair or service, the cover is removed from the prosthesis finger and then replaced, which is difficult for many users in particular for users with both hands amputated.

OBJECT OF THE INVENTION AND SOLUTION TO THE PROBLEM

The object of the invention is to solve one or more of the above problems.

This is achieved with a device according to claim 1. By arranging at a finger prosthesis of substantially natural size a fixing device for fastening the finger prosthesis to another prosthesis part e.g. a metacarpus prosthesis, which part is intended to replace at least part of the human hand, where the finger prosthesis at the fixing device has a first joint designed to allow a bending of the finger prosthesis from a forward direction in an extension of the extended finger, in a bending direction towards a palm and back to the extended position, and by providing the fixing device with another joint designed to allow pivoting in a direction substantially orthogonal to a forward direction in the extension of an extended finger prosthesis, and a spring element arranged supporting between the finger prosthesis and the prosthesis part, the prosthesis fingers can be substantially held in a predetermined position. Thus the prostheses have an e.g. lateral flexibility which facilitates for example the application and removal of the prosthesis cover.

The prosthesis fingers can also be moved from this position by means of an external force so that e.g. several prosthesis fingers arranged next to each other can give good support to each other.

DESCRIPTION OF THE DRAWINGS

The invention will be described below in an embodiment example with reference to figures as follows:

Rg. 1 shows a diagrammatic cross-section view of a fixing device according to the invention in a view from the side in a preferred embodiment,

Fig. 2 shows a diagrammatic sketch of a finger prosthesis with a fixing device according to the invention at a metacarpus prosthesis in a view from above,

Fig. 3 shows a diagrammatic sketch according to figure 2 with the prosthesis fingers in a laterally blocked position,

Fig. 4 shows a diagrammatic cross-section sketch of a fixing device according to the invention in a view from the side in an alternative embodiment,

Fig. 5 shows a partial enlargement of a fixing in figure 4, Rg. 6 shows a diagrammatic cross-section View of a fixing device according to the invention in a view from above in an alternative embodiment.

Fig, 7 shows a partial enlargement of a fixing in figure 6,

Rg. S shows in perspective a substantially complete artificial hand prosthesis in a view showing the prosthesis knuckles,

Rg. 9 shows in perspective a substantially complete artificial hand prosthesis in a view showing the prosthesis palm,

Rg. 10 shows a diagrammatic sketch according to figure 2 with the prosthesis fingers in a laterally compressed position,

Fig. 11 shows a diagrammatic sketch according to figure 2 with the prosthesis fingers with a motor for sideways pivoting.

DESCRIPTION OF EMBODIMENT EXAMPLE

A fixing device for fastening a finger prosthesis is generally referred to as 1 and the finger prosthesis as 2. The device 1 is arranged at a rear part of the prosthesis 2 and is designed to attach the prosthesis finger bendably and pϊvotably to another prosthesis part 3 e,g, a metacarpus prosthesis 3. The prosthesis parts 2, 3 substantially have natural size and are designed to simulate the corresponding human body parts in appearance, size and movement pattern. At the fixing device 1 is a first joint 4 about which the prosthesis finger 2 is designed to be able to bend repeatedly from a forwards direction ( ) in the extension of the extended fingers, in a bend direction I towards the palm 5 and back to the extended position of the finger prosthesis 2. A second joint 6 is also arranged at the fixing element and is intended to allow a pivoting in direction S substantially orthogonal to the forward direction R. The joint 6 comprises an at least partially spherical body 9 which is connected to the finger prosthesis 2 by means of a rod 8. Body 9 is placed in a position between two clamping elements 10a, 10b, which each have a partially spherical concave surface corresponding to the shape of body 9 so that body 9 can be clamped between the two concave surfaces, The clamping is achieved e.g. by clamping screws (not shown) or a similar device. The damping elements hold the body 9 in position while the body is pivoted and thus allow the finger prosthesis 2 to pivot. Pivoting takes place in directions substantially orthogonal to the forward direction R up to 30° from the forward direction R and preferably up to 15°. This pivoting can also be described as an angle change in any direction about the fixing of the finger prosthesis 2 from a straight position. A spring element 7 exemplified in figure l by an 0-rϊng is arranged about the rod 8 and clamped against the rod 8 by a recess 11 though which runs the rod- Thus the rod 8 is centred in the middle of the recess 11 and on pivoting of the finger prosthesis 2 about the second joint 6, on subsequent release of the finger prosthesis 2 causes a return to a position for the rod 8 in the middle of recess 11 and hence also a return of finger prosthesis 2 to a predetermined position substantially in the forward direction F. To simulate a relaxed position for a human finger, the predetermined position of finger prosthesis 2 can constitute a position for the finger prosthesis 2 slightly different from the forward direction F and the bent direction I. To prevent turning of the finger prosthesis about its longitudinal axis the fixing device can be provided with a stop preferably arranged at the rod 8 or body 9 and produced as a projection (not shown) intended at maximum turn to stop against the other prosthesis 3.

When several finger prostheses 2, 2a, 2b, 2c are arranged next to each other according to figs. 2, 3 and 8 - 10, this means that finger prostheses 2, 2a, 2b, 2c on pivoting can be brought into contact with each other and thus cooperate to absorb e.g. force F from the side as shown in figure 10. The capacity to absorb force F from the side depends amongst others on the combined factors firstly of the fixed individual capacity of finger prostheses 2, 2a, 2b, 2c to resist an angle change and secondly their individual capacity to resist a position change in direction F due to the shear forces occurring between the finger prostheses 2, 2a, 2b, 2c on side loading at the contact point between the finger prostheses 2, 2a, 2b, 2c,

When a prosthesis cover (not shown) is to be applied to finger prostheses 2, 2a, 2b, 2c and/or the entire prosthesis hand, see figures 8, 9, the process is facilitated in that the prostheses 2, 2a, 2b, 2c can pivot at joint 6 and preferably can be blocked from each other sideways s, see figure 3.

In an alternative embodiment of joint δ, see figs, 3 - 6 and 10, the fixing device 1 comprises an extended spring element e.g. made of a piece of piano wire attached at its ends in the second prosthesis part 3. The spring element 7' runs substantially with its centre through a passage 11 in a projection 9a protruding from finger prosthesis 2. Some distance away from spring element 7' in direction F, finger prosthesis 2 is plvotably fastened to the other prosthesis part (3) by means of a screw 6', When the finger prosthesis 2 pivots about the screw 6', the passage 11 in projection 9' is also moved which means that spring element 7' bends. When the finger prosthesis is released the spring element straightens and returns the finger prosthesis to the predetermined position.

In a further alternative embodiment the joint is integrated in the spring element and comprises a spring rod which is attached at a first end to finger prosthesis 2 and extends from this substantially in the extension of finger prosthesis 2 to a fixing in the other prosthesis 3. On pivoting of finger prosthesis the rod is exposed to a force absorbed by the rod and its fixings, and finger prosthesis 2 pivots back due to a return of the rod to its original position.

In yet another embodiment the projection 9' or ball 9 is connected to a motor 12 Intended to pivot the Finger prosthesis preferably sideways s, which is exemplified in figure 12 when projection 9" is extended and connected to motor 12 designed to draw together or move apart the extended projection 9" so that finger prostheses 2, 2a, 2b, 2c pivot. This increases the gripping capacity as the finger prostheses 2, 2a, 2b, 2c can be moved apart before gripping and thus finger prostheses 2, 2a, 2b, 2c can grip over a larger area.

The invention should not be regarded as limited to the examples described above but can vary within the scope of the claims.

LIST OF REFERENCES

1 fixing device

2 finger prosthesis

2a long finger of prosthesis

2b ring finger of prosthesis

2c little finger of prosthesis

3 metacarpus prosthesis

4 prosthesis finger joint

5 palm

6 other joint

7 spring element O-ring

7' spring elements steel wire

8 rod

9 spherical body

9¹ projection

9" extended projection

10a clamping element

10b lamping element

11 passage

12 motor

R forward direction

S sideways direction

Claims

1. Fixing device (1) for fixing a finger prosthesis (2) of substantially natural size to another prosthesis part (3) e.g. a metacarpus prosthesis, which prosthesis part (3) is intended to replace at least part of a human hand, where the finger prosthesis (2) at the fixing device (1) has a first joint (4) designed to allow bending of the finger prosthesis (2) from a forward direction (R) in an extension of the extended finger prosthesis, in a bending direction (I) in towards a palm (5) and back again to the extended position, characterised in that the fixing device (1) further has a second joint (6) intended to allow pivoting in a direction (S) substantially orthogonal to the forward direction (R).

2. Device according to claim 1, characterised in that the spring element (7) is arranged between the finger prosthesis (1) and the prosthesis part (3) and designed to hold the finger prosthesis (2) substantially In a predetermined position.

3. Device according to claim 1 or 2, characterised in that the second joint (6) has an at least partly spherical body (9) connected with the finger prosthesis (2) and placed In a position between two clamping elements (10a, 10b) of a form complementary to body (9) so that the body £)^ and hence the finger prosthesis (2) are allowed to pivot.

4. Device according to any of the above claims, characterised In that the body (9) and the finger prosthesis (2) are connected by means of a rod (8) which runs through a recess (11) in the prosthesis part (1) and that the spring element (7) is placed between the recess (11) and the rod (8) and intended to centre the rod (8) in the recess (11).

5. Device according to claim 1, characterised in that the pivoting direction (S) is substantially sideways (S).

6. Device according to claim 5, characterised In that the sideways pivoting (S) is greater than the distance from another finger prosthesis (2a) arranged at the side of the prosthesis (2).

. Device according to claim 1 or 2, characterised in that the fixing device (1) comprises an extended spring element (7') attached at both ends to the second prosthesis part (3) and substantially with its centre running through a passage (11) in a projection (9') which protrudes from the prosthesis (2) and is also pivotably fastened to the other prosthesis part

(3).

8. Device according to any of the above claims, characterised in that at the joint (6) is a motor (12) and element to transmit the energy from the motor (6) into the sideways pivoting (S) of the finger prosthesis.