GB2279261A

GB2279261A - Orthotic joint

Info

Publication number: GB2279261A
Application number: GB9410336A
Authority: GB
Inventors: Mark Justin Freeman
Original assignee: Hugh Steeper Ltd
Current assignee: Hugh Steeper Ltd
Priority date: 1993-05-26
Filing date: 1994-05-24
Publication date: 1995-01-04
Anticipated expiration: 2014-05-24
Also published as: GB9310837D0; GB9410336D0; GB2279261B

Abstract

The joint, which may be an ankle joint (Figure 1), knee joint (Figure 4), elbow joint or wrist joint, comprises a first orthosis (12) and a second orthosis (14) pivotally connected together by crossing links (20, 22), at least one of the crossing links (20, 22) being provided with an adjustable stop (48, 50) for limiting relative pivotal movement of the two orthoses with respect to each other. The same basic design of joint can be used for knee-bracing applications or for limb fracture bracing, the knee joint being lockable into its extended position. <IMAGE>

Description

Orthotic Joint This invention relates to orthotic joints, such as ankle joints, knee joints, elbow joints and wrist joints.

It is already known for a shin orthosis to be pivotally connected to a foot orthosis, the connection generally being in the form of a single-pivot joint. This gives rise to high stress concentrations at the interface between the two orthoses.

The aim of the present invention is to provide an orthotic joint which is an improvement over the orthoses assembly described above, and according to the invention an orthotic joint comprises a first orthosis and a second orthosis which are pivotally connected together by crossing links. Preferably, at least one of the crossing links is provided with an adjustable stop for limiting relative pivotal movement of the two orthoses with respect to each other.

Examples of an orthotic ankle joint and an orthotic knee joint in accordance with the invention are shown in the accompanying drawings, in which Figure 1 is a diagrammatic side view of an orthotic ankle joint with the foot orthosis horizontal and the shin orthosis vertical; Figure 2 is a side view of the orthotic ankle joint shown in Figure 1 but with the foot orthosis dropped so as to be at an angle to the horizontal; Figure 3 is a view similar to Figures 1 and 2 of the same orthotic ankle joint but with the foot orthosis raised; and Figures 4 and 5 are views similar to Figures 1-3 of an orthotic knee joint.

The orthotic ankle joint 10 shown in Figures 1-3 comprises a shin orthosis 12 and a foot orthosis 14 which are pivotally connected together at their opposed faces 16 and 18 respectively by two crossing links 20 and 22.

The crossing link 20 is pivotally connected at 24 to a part 26 of a mounting plate which is connected to the shin orthosis 12 at 28. Similarly, the crossing link 22 is pivotally connected at 30 to another part 32 of the mounting plate which is connected to the shin orthosis 12 at 34. The other end of the crossing link 20 is pivotally connected at 36 to a part 38 of a second mounting plate which is connected to the foot orthosis 14 at 40. Likewise, the other end of the crossing link 22 is pivotally connected at 42 to a part 44 of the second mounting plate which is connected to the foot orthosis 14 at 46. The first mounting plate is additionally connected to the shin orthosis 12 at 52, while the second mounting plate is additionally connected to the foot orthosis 14 at 54.

The geometry of the linkage is such that, during flexion of the foot orthosis as shown in either Figure 2 or Figure 3, the ankle joint provides for relative movement between the shin/foot orthoses about an approximately single axis of rotation.

In order to limit relative pivotal movement of the two orthoses with respect to each other, one or other of the two crossing links 20, 22 (in this case link 22) is provided with adjustable stops 48 and 50. These are positioned at or near the ends of the link 22 and are adjustable so as to control the angle of plantar-flexion (Figure 2) and dorsi-flexion (Figure 3) of the ankle joint. The two stops 48 and 50 each comprise a number of distal stop faces machined on a cam which abuts the other crossing link, i.e., the link 20. In this way, the ankle joint can be completely immobilised and the amount of flexion increased in predefined steps. In the particular ankle joint shown in the drawings, the plantar-flexion and dorsi-flexion can be increased or decreased in increments of 50 independently of each other.

The two interface mounting plates, one secured to the shin orthosis 12 and the other secured to the foot orthosis 14, distribute the associated loads over a large area. In addition, stops 48 and 50 incorporate flanges which, together, form a slot for the link 20 to run in, thus preventing the two crossing links 20 and 22 from becoming separated under torsional loads.

The orthotic ankle joint shown in Fogires 1-3 has significant advantages over existing designs. Among these advantages are the following 1. The stop faces on the two stops 48 and 50 are positioned much further away from the centre of rotation of the ankle joint than in single-pivot designs, which means that the forces acting on the stop faces are greatly reduced.

2. Adjustments of the stops for plantar-flexion and dorsi flexion movement can be made by a clinician while the patient is wearing the shin/foot orthoses. Existing designs, in contrast, require the removal of the orthoses from the patient and subsequent dismantling by skilled technical staff to remove and replace stop components.

3. The mechanism illustrated in the drawings distributes the associated loads over a wide area, whereas single-pivot joints have high stress concentrations at the interface between the two orthoses.

4. The joint shown in the drawings has a very low profile, and most of the mechanism operates in the same width as the shin/foot orthoses material. This makes the joint especially suitable for wearing with shoes.

5. The casts required to manufacture the shin/foot orthoses do not require any pre-moulding modifications, whereas existing joints call for special work to be done on them so that the joint can be fitted after moulding. The invention therefore allows the mechanism to be fitted retrospectively to existing shin/foot orthoses.

6. The joint is made up essentially of only four common parts, which makes it inexpensive to manufacture. In addition, it does not require any additional stop faces to be supplied.

7. The design of the joint makes it much more resistant to twisting loads than in a single-pivot design.

The invention is also applicable to other forms of orthotic joints - for example, knee joints, elbow joints and wrist joints. It is especially suitable when used as a knee joint, and this is illustrated in Figures 4 and 5 of the drawings. The reference numerals in these Figures show parts which correspond (using the same reference numerals) to various parts in the ankle joint illustrated in Figures 1-3. This means that the same basic design of joint can be used for knee-bracing applications or for limb fracture bracing, the knee joint being lockable into its extended position. As the condition of the patient improves, the limb can be allowed to flex to increasing angles by simple adjustment to the stops until a full recovery is made. Alternatively, the joint can be held in any one of a number of fixed angles by positioning the appropriate stop faces, thereby preventing any movement in the mechanism.

Claims

1. An orthotic joint, especially an ankle joint, knee joint, elbow joint or wrist joint, comprising a first orthosis and a second orthosis which are pivotally connected together by crossing links.

2. An orthotic joint according to claim 1, in which at least one of the crossing links is provided with an adjustable stop for limiting relative pivotal movement of the two orthoses with respect to each other.

3. An orthotic joint according to claim 1 or claim 2, in which the crossing links are pivotally connected to respective parts of a mounting plate which is connected to the two orthoses.

4. An orthotic joint according to claim 3, in which the crossing links are pivotally connected to a second mounting plate which, like the first mounting plate, is connected to at least one of the two orthoses.

5. An orthotic joint according to any preceding claim, in which relative movement between the two orthoses takes place about an approximately single axis of rotation.

6. An orthotic joint according to any preceding claim, in which the adjustable stop, or each such stop, is positioned at or near an end of its respective link.

7. An orthotic joint according to any preceding claim, in which the stop, or each stop, comprises a number of distal stop faces on a cam which abuts the other crossing link.

8. An orthotic joint according to any preceding claim, in which the stop, or each stop, is provided with a flange which partially forms a slot for at least one of the links to run in, thereby preventing the two crossing links from becoming separated under torsional loads.

9. An ankle joint according to claim 1 substantially as described herein with reference to Figures 1-3 of the accompanying drawings.

10. A knee joint according to claim 1 substantially as described herein with reference to Figure 4 and Figure 5 of the accompanying drawings.