WO1999042071A1

WO1999042071A1 - Joint extension assist hinge mechanism

Info

Publication number: WO1999042071A1
Application number: PCT/AU1998/000100
Authority: WO
Inventors: Robert Timothy Bakes
Original assignee: Orthotic Consultants Asia Pacific Pty. Limited
Priority date: 1996-08-14
Filing date: 1998-02-18
Publication date: 1999-08-26
Also published as: AUPO161896A0

Abstract

A method of mobilising bodily joints comprising positioning a joint extension assistance hinge apparatus (1) on each side of an anatomical joint, such apparatus comprising an upper geared arm (2) which is adapted to be connected to the limb above the joint and a geared lever arm (3), the two arms being co-planar and pivotally connected at the joint end (4) to a lower arm (5) positioned underneath said upper geared arm (2) and geared lever arm (3), so that for every one degree of movement of the upper arm (2), the geared lever arm (3) moves twice the amount and said lower arm (5) being adapted to be connected to a limb below the joint, and means whereby the lever arm (3) can be connected to the upper arm (2) in such a way as to apply tension thereto.

Description

JOINT EXTENSION ASSIST HINGE MECHANISM

This invention relates to a joint extension assist hinge

mechanism which aids in the treatment associated with either the

manipulation or reconstruction of bodily joints and the method

employed in use of such apparatus

Reconstruction surgery is quite often carried out on body joints,

such as elbows and knees. If one considers a knee where ligaments have become detached from the bones, following surgery, physiotherapy is usually necessary to restore joint function.

Physiotherapy includes stretching exercises to improve flexion (that is, movement of connected parts of the body towards each other) and extension (that is, movement which is opposite to that

of flexion) .

In some instances reconstructive surgery of body joints such as

elbows and knees may not achieve the desired result in that the

arm or leg is unable to attain either full extension or full

flexion, or both. It would in such instances be desirable to have

the use of an apparatus which would promote and assist joint 2 extension or flexion, such apparatus being able to sustain a

continuously applied, adjustable force.

Further to this, it has been found that, when a patient rests

after a course of physiotherapy the gain in mobility of a joint

is often lost.

It is an object of the invention to overcome this disadvantage

as well as those associated with limits in the range of extension

and flexion of a limb joint.

The invention in its broadest sense comprises a method of

mobilising bodily joints comprising positioning a joint extension assistance hinge apparatus ( 1 ) on each side of an anatomical joint, such apparatus comprising an upper geared arm(2) which is

adapted to be connected to the limb above the joint and a geared

lever arm(3), the two arms being co-planar and pivotally

connected at the joint end(4) to a lower arm(5) positioned

underneath said upper geared arm(2) and geared lever arm(3), so

that for every one degree of movement of the upper arm(2), the

geared lever arm(3) moves twice the amount, and said lower arm(5)

being adapted to be connected to a limb below the joint, and 3 means whereby the lever arm(3) can be connected to the upper

arm(2) in such a way as to apply tension thereto.

In order that the invention shall be more readily understood, we

shall describe one particular form of a joint extension assist

hinge mechanism with reference to the accompanying drawings, in which:

Fig 1. shows a plan view of a joint extension assist hinge

mechanism.

Fig 2. shows a side elevation of a joint extension assist

hinge mechanism.

Because of the gearing(6) between the upper arm(2) and the lever

arm(3), any pressure applied to the lever arm(3) is multiplied

when acting on the upper arm.

It may be preferred that the lower arm comprises a back plate(7)

including a motion limiting mechanism(8) , and said geared lever

arm at its non-joint end has an aperture(9), whereby a tensor(lθ)

can run from said aperture to a corresponding position on the

upper arm. 4 In order that the invention may be more readily understood, we

shall describe a preferred embodiment of the invention.

The invention essentially consists of a joint extension assist

apparatus(l) which may be positioned on each side of an

anatomical joint, such apparatus comprising a lower arm(5), which

is adapted to be connected to a limb below the joint, and to which is pivotally fastened at the joint end(4), an upper geared

arm(2) which is adapted to be connected to the limb above the

joint. This arm has a gear(6) formed at its joint end(4). The joint end(4) of the geared lever arm(3) and joint end(4) of the upper geared arm(2) abut one another and each have geared teeth(ll) on their respective ends allowing a variety of angles to be attained when the two respective arms are moved by manual

means .

The motion and thus the attainable positions of the geared upper

arm(2) are limited by means of a motion limiting mechanism(8)

comprising limiting screws(12) or other similar devices which may

be positioned along a semi-circular narrow aperture(13) at the

far end of the lower arm, the limiting screws (12) controlling the

degree of motion of the upper arm(2) so that for every one degree 5 of movement of the upper arm(2), the geared lever arm(3) moves

twice the amount.

On attaining the required position by manual movement of the

arms, a cover plate(14) made of either metal, plastic or other

appropriate material is positioned over the two geared arms so

as to enable the geared arms to remain in a desired position.

The geared lever arm(3) and the geared upper arm(2) are

preferably made of a either a metal or metal alloy as is the lower arm(5) though it may also be possible for the lower arm(5) to be made of a suitable plastic.

At the near end of the geared lever arm(3) is an aperture(9) of

fixed diameter which enables a tensor(10) to run from the said

aperture to a corresponding position on the upper arm(2), the

tension of the strap or like on the geared lever arm(3) providing

an extension or flexion movement about the axis of the anatomical

joint.

The tension of the tensor(10) on the geared lever arm(3) provides

an extension or flexion moment about the point corresponding to

the anatomical axis so that for every one degree of movement of 6 the geared upper arm(2), the geared lever arm(3) moves twice the

amount.

It is envisaged that other embodiments of the invention will

exhibit any number of and any combination of the features of the

previously described two embodiments .

Whilst we have described herein one specific embodiment of the invention it is to be understood that variations and

modifications in this can be made without departing from the spirit and scope thereof.

Claims

The Claims defining the invention are as follows:

1. A method of mobilising bodily joints comprising positioning

a joint extension assistance hinge apparatus on each side

of an anatomical joint, such apparatus comprising an upper

geared arm which is adapted to be connected to the limb

above the joint and a geared lever arm, the two arms being co-planar and pivotally connected at a joint end to a lower

arm positioned underneath said upper geared arm and geared lever arm, so that for every one degree of movement of the upper arm, the geared lever arm moves twice the amount, and said lower arm being adapted to be connected to a limb

below the joint, and means whereby the lever arm can be

connected to the upper arm in such a way as to apply

tension thereto.

2. A method as claimed in Claim 1 wherein the lower arm is

adapted to be connected to the limb below the joint and to

which is pivotally fastened at the joint end, a geared

lever arm which is adapted to be connected to the limb

above the joint. 8

3. A method as claimed in Claims 1 or 2 wherein the joint end

of the geared lever arm and the joint end of the upper

geared arm abutt one another and each possessing geared

teeth on their respective ends.

4. A method as claimed in any preceding claim wherein the two

upper arms are adjusted by manual means before attachment to an anatomical joint so that a required inital angle

between the two arms can be selected.

5. A method as claimed in claim 5 wherein the motion and thus the attainable positions of the geared upper arm are limited by means of a motion limiting mechanism.

6. A method as claimed in claim 6 wherein the motion limiting mechanism comprises a limiting screw or other similar

device which is positioned along a semi-circular narrow

aperture situated at the far end of the lower arm, the

limiting screw controlling the degree of motion of the

upper arm. 9

7. A method as claimed in claim 7 wherein for every one degree

of movement of the upper arm, the geared lever arm moves

twice the amount.

8. A method as claimed in any preceding claim wherein the

geared lever arm, at its near end comprises an aperture of

fixed diameter which enables a tensor to run from the said

aperture to a corresponding position on the upper arm, the

tension of the tensor on the geared lever arm providing an extension or flexion movement about the axis of the

anatomical joint.

9. A method as claimed in claim 8 wherein the tension of the tensor on the geared lever arm provides an extension or

flexion moment about the point corresponding to the

anatomical axis so that for every one degree of movement of

the geared upperarm, the geared lever arm moves twice the

amount .

10. An appartus as utilised in any of the preceding claims such

apparatus being positioned on each side of an anatomical

joint, and comprising an upper geared arm which is adapted

to be connected to the limb above the joint and a geared 10 lever arm, the two arms being co-planar and pivotally

connected at the joint end to a lower arm positioned

underneath said upper geared arm and geared lever arm, so

that for every one degree of movement of the upper arm, the

geared lever arm moves twice the amount, and said lower arm

being adapted to be connected to a limb below the joint,

and means whereby the lever arm can be connected to the

upper arm in such a way as to apply tension thereto.

11. An apparatus as claimed in claim 10 wherein the geared upper arm is made of either a metal or metal alloy as is

the lower arm though it may also be possible for the lower arm to be made of a suitable plastic.

12. A method as substantially herein before described with

reference to the accompanying drawing.

13. An apparatus as herein before described with reference to

the accompanying drawing.