WO2003094807A1

WO2003094807A1 - A prosthetic limb

Info

Publication number: WO2003094807A1
Application number: PCT/ZA2003/000062
Authority: WO
Inventors: Philip Bailey Askeland; Tobias Johannes De Villiers De Vos; Louise Kruger
Original assignee: Philip Bailey Askeland; De Vos Tobias Johannes De Vill; Louise Kruger
Priority date: 2002-05-14
Filing date: 2003-05-13
Publication date: 2003-11-20
Also published as: AU2003252186A1

Abstract

A prosthetic limb (20) for use as part of a lower leg, which limb includes a Neidhart unit (10) for connecting a foot part (22) with a connector (24) for connecting the Neidhart unit to a remaining part of a leg (26) of a person such that forces exerted on the foot part relative to the connector is transmitted from the foot part to the connector via the Neidhart unit.

Description

Title: A Prosthetic Limb

Technical field of the invention

This invention relates to a prosthetic limb. More particularly, it relates to a prosthetic limb for use as part of a lower leg.

Background to the invention

The mechanics and movements of a lower leg of a person during a walking or running cycle are complex. Normally, a foot approaches the surface of the ground with the leg above and behind the foot, then the heel makes contact with the surface and the ankle bends to place the foot flat on the surface with the shin muscles resisting and controlling the bending of the ankle to absorb shock, the leg moves forward over the foot, the ankle continues to bend as the leg moves over the foot up to a point where the heel lifts of the surface and the person propels forward by pushing upward and forward on the toes of his or her foot using his or her calf muscles to bend the ankle. It will be appreciated that a prosthetic limb for use as part of the lower leg, which includes the ankle region and which can sufficiently mimic the mechanics of a lower leg of a person during a walking or running cycle will greatly improve the quality of life of a person using such a prosthetic limb. Existing, inexpensive prosthetic limbs for use as part of a lower leg do not have the capacity to mimic the mechanics of a lower leg of a person during a walking or running cycle. Existing, expensive prosthetic limbs for use as part of a lower leg sometimes make use of a resiliently flexible blade, normally of carbon fibre, to mimic the mechanics of a lower leg of a person during a walking or running cycle. Often complicated pneumatic or hydraulic piston type damping means are used.

The applicant is aware that large numbers of victims of landmines in war torn countries are in need of inexpensive prosthetic limbs for use as part of the lower leg, which includes the ankle region and which can sufficiently mimic the mechanics of a lower leg of a person during a walking or running cycle.

General description of the invention

In this specification, the Neidhart unit will be understood to mean a torsion element comprising an elongate shaft trapped within a concentrically orientated elongate sleeve, together with a number of resiliently flexible and/ or deformable elements located intermediate an outside of the shaft and an interior face of the sleeve. The shaft and the sleeve, which are generally of triangular or square cross-section, are generally axially aligned and longitudinally off-set relative to each other by approximately 60° (for triangular cross-section) or 45° (for square cross-section), thus defining either three or four elongate bores intermediate the shaft and the sleeve. The resiliently flexible and/ or deformable elements, which are generally elongate rubber elements, are located in these bores, the arrangement being such that when the shaft is rotated about its longitudinal axis relative to the sleeve the elements are substantially resiliently deformed, thus creating rotational tension or forces on the shaft and sleeve in opposite directions. The tension or forces increase with the amount of rotation of the shaft relative to the sleeve.

According to a first aspect of the invention there is provided a prosthetic limb for use as part of a lower leg, which limb includes a Neidhart unit for connecting a foot part with a connector for connecting the Neidhart unit to a remaining part of a leg of a person such that forces exerted on the foot part relative to the connector is transmitted from the foot part to the connector via the Neidhart unit.

The sleeve of the Neidhart unit may be connectable to the foot part and the shaft of the Neidhart unit may be connectable to the connector, or the shaft of the Neidhart unit may be connectable to the foot part and the sleeve of the Neidhart unit may be connectable to the connector. It will be appreciated that the Neidhart unit functions as an ankle joint and the forces resulting from movement transmitted between the foot part and the connector will be mostly result from rotational movement in a general plane in which the foot part and leg of a person normally moves during a walking or running cycle.

The limb may include a foot part.

The limb may include a connector for connecting the Neidhart unit to a lower leg of a person.

The foot part may have a tread and may define a hole for snugly receiving the sleeve, the sleeve of the Neidhart unit being snugly received therein such that the axis of the shaft of the Neidhart unit is generally transverse to a general plane in which the foot part and leg of a person normally moves during a walking or running cycle. The shaft of the Neidhart unit may be connected to the connector.

The connector may include a u-shaped member and the shaft of the Neidhart unit being connected to and extending between the free ends of the u-shaped member. The connector may further include a connection means for connecting the connector to a remaining part of a leg of a person.

A removable tread member may provide the tread. The tread member may be of a resiliently deformable rubber material.

The foot part may be of a plastics material and may be moulded into a shape, which resembles of a foot of a person.

Detailed description of the invention

The invention is now described by way of example with reference to the accompanying diagrammatic drawings. In the drawings:

Figure 1 shows a three dimensional view of an example of a Neidhart unit; Figure 2 shows a stage of a walking cycle with a prosthetic limb, in accordance with the invention, during which stage a rear part of a tread of a foot part of the limb makes contact with the ground;

Figure 3 shows a further stage of a walking cycle with a prosthetic limb, during which stage a rear part of a tread of a foot part of the limb makes contact with the ground;

Figure 4 shows a stage of the walking cycle with the prosthetic limb, during which stage the tread of the foot part is flat on the ground;

Figure 5 shows a further stage of the walking cycle with the prosthetic limb, during which stage the tread of the foot part is flat on the ground; and Figure 6 shows a stage of the walking cycle with the prosthetic limb, during which stage a front part of the tread of the foot part of the limb makes contact with the ground.

Referring now to Figure 1 , an example of a Neidhart unit is generally indicated by reference 10. The Neidhart unit is a torsion element comprising an elongate hollow shaft 12 trapped within a concentrically orientated elongate sleeve 14, together with a number of resiliently deformable elements 16 located intermediate an outside of the shaft 12 and an interior face of the sleeve 14. The shaft 12 and the sleeve 14, which are of square cross-section, are longitudinally off-set relative to each other by approximately 45°, thus defining four elongate bores intermediate the shaft 12 and the sleeve 14. The resiliently deformable elements 16, which are generally elongate rubber elements, are located in these bores, the arrangement being such that when the shaft 12 is rotated about its longitudinal axis relative to the sleeve 14 the elements 16 are substantially resiliently deformed, thus creating rotational tension on the shaft 12 and sleeve 14 in opposite directions. Referring now to figures 1 to 6, the prosthetic limb for use as part of a lower leg, in accordance with the invention, is generally indicated by reference numeral 20.

The prosthetic limb 20 includes a Neidhart unit 10 for connecting a foot part 22 with a connector 24 for connecting the Neidhart unit 10 to a remaining part of a leg 26 of a person such that forces exerted on the foot part 22 relative to the connector 24 is transmitted from the foot part 22 to the connector 24 via the Neidhart unit 10.

The sleeve 14 of the Neidhart unit 10 is connected to the foot part 22 and the shaft 12 of the Neidhart unit 10 connected to the connector 24. The foot part 22 defines a hole 28 wherein the sleeve 14 is snugly received and located. The connector 24 includes a u-shaped member and the shaft 12 of the Neidhart unit 10 being connected to and extends between the free ends 30 of the u-shaped member. The connector 24 further includes a socket 32 defined thereon for receiving for receiving a prosthetic member 34 extending from a fastening member fastened to remaining part 26 of a leg of a person.

The foot part 22 includes a removable tread 36 of a resiliently deformable rubber material.

The foot part 22 is moulded of a plastics material into a shape, which resembles of a foot of a person.

The Neidhart unit 10 functions as an ankle joint in conjunction with calf and shin muscles and the forces transmitted from the foot part 22 to the connector 24, and vice versa, will be mostly rotational forces in a general plane in which the foot part 22 and a remaining part 26 of a leg of a person normally moves during a walking or running cycle. In use, the foot part 22 approaches the surface 38 of the ground with the part 26 behind the foot part 22. When a rear part of the tread 36 of the foot part 22 makes contact, as shown in Figure 2, with the surface 38, the shaft 12 rotates relative to the sleeve 14, as shown in Figure 3, and the resiliently deformable elements 16 substantially resiliently deformed, thus creating rotational tension on the shaft 12 and sleeve 14 in opposite directions to absorb the impact shock upon contact, to allow the tread 36 of foot part 22 to be placed flat on the surface 28, as shown in Figure 4 and to assist the remaining part 26 to move over the foot part, as shown in Figure 5. At this point, the resiliently deformable elements 16 are not deformed. The remaining part 26 continues to move over the foot part 22, up to a point where the rear part of the tread 36 lifts of the surface 38, as shown in Figure 6. At this point the resiliently deformable elements 16 are again substantially resiliently deformed, thus creating rotational tension on the shaft 12 and sleeve 14 in opposite directions which propels the limb 20 forward by pushing the remaining part 26 upward and forward.

The applicant believes that the invention provides an inexpensive, easy to maintain prosthetic limb for use as part of the lower leg 26, which will sufficiently mimic the mechanics of a lower leg of a person during a walking or a running cycle and will greatly improve the quality of life of a person using such a prosthetic limb 20. The invention also provides a high degree of mobility to a person using the prosthetic limb 20. Since the shaft 12 is trapped in the sleeve 14 by resiliently deformable members 16, the invention also provide for a sufficient degree of movement of the foot part 22 transverse to the general plane in which the foot part 22 and a remaining part 26 of a leg of a person normally moves during a walking or running cycle. This provides to a person using such a prosthetic limb 20 further comfort walking over uneven terrain.

It shall be understood that the example is provided for illustrating the invention further and to assist a person skilled in the art with understanding the invention and is not meant to be construed as unduly limiting the reasonable scope of the invention.

Claims

1. A prosthetic limb for use as part of a lower leg, which limb includes a Neidhart unit for connecting a foot part with a connector for connecting the Neidhart unit to a remaining part of a leg of a person such that forces exerted on the foot part relative to the connector is transmitted from the foot part to the connector via the Neidhart unit.

2. A prosthetic limb as claimed in claim 1 , wherein the sleeve of the

Neidhart unit is connectable to a foot part and the shaft of the Neidhart unit connectable to a connector for connecting the Neidhart unit to a remaining part of a leg of a person.

3. A prosthetic limb as claimed in claim 1, wherein the shaft of the

Neidhart unit is connectable to a foot part and the sleeve of the Neidhart unit is connectable to a connector for connecting the Neidhart unit to a remaining part of a leg of a person.

4. A prosthetic limb as claimed in any one of claims 1 to 3, which includes a foot part.

5. A prosthetic limb as claimed in Claim 4, wherein the foot part define a hole for snugly receiving and locating the sleeve.

6. A prosthetic limb as claimed in any one of claims 1 to 5, which includes a connector for connecting the Neidhart unit to a lower leg of a person.

7. A prosthetic limb as claimed in Claim 6, wherein the connector includes a u-shaped member and the shaft of the Neidhart unit being connected to and extending between the free ends of the u-shaped member.

8. A prosthetic limb as claimed in any one of claims 6 or 7, wherein the connector includes a connection means for connecting the connector to a remaining part of a leg of a person.

9. A prosthetic limb as claimed in any one of claims 4 to 8, wherein the foot part includes a tread.

10. A prosthetic limb as claimed in claim 9, wherein a removable tread member provides the tread.

11. A prosthetic limb as claimed in claim 10, wherein the tread member is of a resiliently deformable rubber material.

12. A prosthetic limb as claimed in any one of claims 4 to 11, wherein the foot part is of a plastics material and moulded into a shape, which resembles a foot of a person.

13. A prosthetic limb substantially as described herein with reference to the accompanying drawings.