GB2080115A

GB2080115A - Shin member and foot assembly for artificial leg

Info

Publication number: GB2080115A
Application number: GB8023309A
Authority: GB
Original assignee: Vessa Ltd
Current assignee: Vessa Ltd
Priority date: 1980-07-16
Filing date: 1980-07-16
Publication date: 1982-02-03
Also published as: GB2080115B

Abstract

In assembly of a shin member and a foot for an artificial leg, a disc 46 having teeth 47, 48 formed about the circumference of its upper and lower faces at different angular spacings locates between an attachment member 38 of the shin and an ankle base 42 forming part of a foot to allow for variation in the angular position of the foot relative to the shin in very small rotational increments. <IMAGE>

Description

SPECIFICATION Shin member and foot assembly for artificial leg The present invention relates to an assembly of a shin member and a foot for an artificial leg, wherein there is provision for variation of the angular position of the foot relative to the leg in very small rotational increments with secure locking.

The present invention provides an assembly of a shin member and foot for an artificial leg having a disc sandwiched between them, a first set of circumferentially spaced teeth on the upper face of the disc locating in sockets in the shin member and a second set of circumferentially spaced teeth on the lower face of the disc locating in sockets in the foot, and means securing the foot to the shin member against movement longitudinally apart whereby the foot is located in a fixed predetermined angular position relative to the shin member.

Preferably the foot is secured to the shin member by a bolt which passes through a hole in the disc and locates in an internally threaded anchorage point at the base of the shin member. The angular spacing of the teeth of the first and second sets is preferably slightly different in order to obtain a differential effect. The foot preferably comprises a keel member of rigid material moulded into a body of cellular plastics material, an ankle base member above the keel member and fixed to the shin member and transverse pivot means interconnecting the keel member and the ankle base member.

An embodiment of the invention will now be described by way of example only, with reference to the accompanying drawings, in which Figure 1 is a side view in vertical section of the lower portion of a shin member being a foot secured thereto; Figure 2 is an enlarged underneath view of an ankle attachment member which forms part of the shin member shown in Fig. 1; Figure 3 is an enlarged plan view of an ankle base forming part of the foot shown in Fig. 1; and Figures 4a, 4b and 4c are respectively top, side and underneath views on an enlarged scale of a locating disc which fits between the ankle base and the ankle adaptor.

In Fig. 1, there is shown a shin member 12 which is of endoskeletal type and includes a shin tube 36 to which is secured an upstanding boss 37 forming part of an ankle attachment member 38 of glass filled thermoplastics material. The member 38 has a generally planar lower face in which there is a centrally positioned vertically directed internally threaded metal insert 39. A cosmesis 40 in low-density elastomer surrounds shin tube 36 and the sides of attachment member 38.

The shin member 12 is fitted with a uniaxial foot 14 made up of a body 25 of a low density micro-cellular elastomeric material in which is moulded a relatively rigid keel 41 of glass-reinforced plastics material. An angle base 42 also of glass-reinforced plastics material is secured at its upper face to the angle attachment member 38 and at its lower face is pivoted to the keel 41 about a transverse ankle pivot 43 which is held within a tee-bolt 43a with intermediate bearing bushes.

An instep buffer 44 and a heel buffer 44a both of natural or synthetic rubber are located respectively between anterior and posterior portions of the ankle base 42 and the keel 41 to provide the appropriate degree of resistance to flexion of the foot 14 relative to the shin member 12 from a normal position which they define. The ankle base 42 is secured to the ankle attachment member 38 against movement longitudinally apart by means of a bolt 24 which is engaged in the threaded insert 39 and angular location of the foot 14 relative to the shin member 12 is achieved by means of a disc 46 having rows of circumferentially spaced teeth 47, 48 on its upper and lower faces which locate in respective sockets in attachment member 38 and an ankle base 42 as described in more detail below.The ankle base may be selected from a range of standardised injection-moulded angle bases each having different lower face angles so that variation in heel height can be accommodated. The full range of ankle bases can be produced in a single mould, pads defining the desired angle for the lower face of the angle base being inserted into the mould before the moulding operation is carried out.

The ankle attachment member of Fig. 2 is formed with a plurality of recesses 60 disposed about the circumference of a circle to receive the teeth 47 of the disc 46. It will be noted that the ankle attachment member has eighteen recesses at equal angular spacings of 20 and the top face of the disc 46 has six teeth at angular spacings of 20 . The ankle base 42 is formed with sixteen sockets 61 disposed at equal angular spacings of 22.5 and the disc 46 is formed on its lower face with eight teeth 48 at angular spacings of 45". This differential spacing of the teeth on the upper and lower faces of the disc 46 enbles the angular position of the disc 46 relative to the ankle adaptor 38 and the angular position of the ankle base 42 relative to the disc to be combined so that the foot 14 assumes any one of a large range of closely spaced angular positions relative to the anterior-posterior plane of the leg. The disc 46 is firmly held in position by the bolt 24 and the insert 39, and engagement of the teeth 47, 48 in their respective sockets 60 and 61 positively locates the foot 14 at a desired toeout angle. The teeth provide a relatively large bearing surface well spaced from the bolt 48 and therefore in a good position to resist turning forces on the foot 14.

Claims

1. An assembly of a shin member and foot for an artificial leg having a disc sandwiched between them, a first set of circumferentially spaced teeth on the upper face of the disc locating in sockets in the shin member and a second set of circumferentially spaced teeth on the lower face of the disc locating in sockets in the foot, and means securing the foot to the shin member against movement longitudinally apart whereby the foot is located in a fixed predetermined angular position relative to the shin member.

2. An assembly according to Claim 1, wherein the foot is secured to the shin member by a bolt which passes through a hole in the disc and locates in an internally threaded anchorage point at the base of the shin member.

3. An assembly according to Claim 1 or 2, wherein the angular spacing of the teeth of said first and second sets is slightly different.

4. An assembly according to any preceding claim, wherein the foot comprises a keel member of rigid material moulded into a body of cellular plastics material, an ankle base member above the keel member and fixed to the shin member and transverse pivot means interconnecting the keel member and the ankle base member.

5. An assembly of a shin member and a foot for an artificial leg provided with a disc having upper and lower toothed faces to give angular adjustment of the foot in small rotational increments with secure locking, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.