GB2136267A

GB2136267A - Sole for leg cast

Info

Publication number: GB2136267A
Application number: GB08304340A
Authority: GB
Inventors: William Anthony Denne
Original assignee: Bayer UK Ltd
Current assignee: Bayer UK Ltd
Priority date: 1983-02-16
Filing date: 1983-02-16
Publication date: 1984-09-19
Also published as: GB8304340D0

Abstract

A leg cast sole has an elongate web (1) for attachment to the lower surface of a leg cast, and a number of ground contacting members (9) depending from the web each in the form of a transversely extending rib of "W- shaped" transverse section, so that each rib provides a pair of ground contacting members spaced one on each side of the longitudinal axis of the sole. The material of the sole is sufficiently flexible that the sole yields under an asymmetric load, so that each projection contacts the ground in use. <IMAGE>

Description

SPECIFICATION Sole for leg cast This invention relates to a sole for a leg cast, and more particularly to a sole which can be applied directly to the curved surface under the foot of a leg cast, while still providing a stable and comfortable support to facilitate walking.

It has been known for many years to provide a heel on the under-surface of the foot of a leg cast to make walking easier for the patient. An example of such a heel is that described in U.S. patent specification No. 3307536.

The optimum point for applying full load to a full leg cast is at the arch of the foot, as this reduces the bending moment at both the ankle and at the knee to a minimum. A walking heel for a plaster cast is therefore usually positioned under the arch of the patient's foot. However, as is well known, the under-surface of the arch of a foot slopes at some 20 to 300 to the surface on which the foot rests. When a foot is encased in a plaster cast, therefore, the lower surface of the cast in the region of the arch of the foot normally slopes to a corresponding degree. In order for a walking heel applied under the arch of a foot to be both stable and comfortable in use, it has therefore been necessary either to provide a heel having an asymmetric section, or to build up the cast in the region of the arch to produce a level bearing surface.The former solution is proposed in the U.S. specification No. 3307536, but the usual clinical practice is to build up the surface of the cast. This entails additional weight and drying time for a cast formed from plaster of paris, or considerable additional expense when more modern fracture bracing materials are used.

The present invention provides a sole which can be applied directly to the asymmetric undersurface of a lower leg cast, while still providing a stable and comfortable support on which to walk.

According to the present invention there is provided a leg cast sole comprising an elongate web for attachment to the lower surface of a leg cast, and a ground contacting member depending from said web, the ground contacting member including a pair of ground contacting projections spaced one on each side of the longitudinal axis of the sole, the material of the sole being sufficiently flexible to yield under the weight of the user bearing asymmetrically on the sole, so that each projection contacts the ground in use.

Preferably, the ground contacting member is in the form of a rib extending transversely of the sole, and having a generally "W-shaped" transverse section.

Preferably, the sole is adapted to extend the length of the lower surface of the cast in use.

Indeed, the sole may be adapted to extend partly around the heel of the cast, in order to provide a buffer to reduce the shocks of heel strike in use.

This protection may be enhanced by providing a plurality of ground contacting members, such as a plurality of the transversely extending ribs mentioned above. The forward-most ground contacting member is preferably positioned immediately adjacent the forward end of the sole, in order to provide protection for the toes. A support provided just under the toes allows greater inclination of the cast relative to the ground before the toe comes into contact with the ground, than does a similar support placed further back on the sole.

The sole is preferably formed from a foamed plastics material, such as foamed polyurethane.

The material of the sole should be flexible, but not too compressible otherwise the sole will not provide a stable support.

It is particularly preferred that the sole be formed from foamed polyurethane having a density of from 0.3 to 0.7 g/ml, and a Shore A hardness of from 40 to 70.

The sole may be attached to a cast by any suitable means, and preferably by means of a bandage of the same material as that from which the cast is made.

If the sole is provided with a plurality of transversely extending ribs, bandages may conveniently be positioned between such ribs.

Where the sole is provided with a heel tab extending around the heel of the cast, the heel tab is preferably provided with a transversely grooved lower surface in order to provide a purchase for the bandage which is used to retain the heel tab in position.

A A sole according to the present invention is now described, by way of example, with reference to the accompanying drawings, in which:~ Fig. 1 is a side elevation of a sole according to the invention, Fig. 2 is a view from underneath the sole of Fig. 1, Fig. 3 is a section on line AA of Fig. 2, Figs. 4A and 4B are schematic representations of the sole flexing under an asymmetric load, and Fig. 5 is a side elevation of the sole fixed to a cast, with the fixing means omitted for clarity.

Referring to the drawings, a sole for a cast comprises a web portion 1 having a concave upper surface 3 in order to facilitate attachment to the under-surface of a foot cast 4. The web decreases in width from the toe end 5 to the heel end 7. On the under-surface of the web 1, and formed integrally therewith are five ground contacting members 9. Each ground contacting member 9 is in the form of a transversely extending rib having a generally "W-shaped" transverse section, as can most clearly be seen from Fig. 3. This means that each ground contacting member 9 presents a pair of projections 1 1, 12 spaced one on each side of the longitudinal axis of the sole.

At the heel end of the sole there is provided a heel tab 13, having a number of transversely extending grooves 1 5 on its lower surface.

The five ground contacting members 9 are of different heights, the largest being the centre one, so that in use the major support comes under the arch of the foot.

As has been mentioned above, the sole of the present invention is able to provide a stable and comfortable support for the foot, even in the region of the arch of the foot where the lower surface of the cast is asymmetrical. The mechanism by which this is achieved is shown diagrammatically in Figs. 4A and 4B. A foot 1 5 has a lower surface 17 which is asymmetrical in the region of the arch of the foot. Since the sole conforms closely to the lower surface 1 7, it will be seen that in the region of the arch, the sole is slightly displaced relative to the centre line of the foot. Therefore, when the user places weight on the sole, with the foot in the normal position, one projection 11 strikes the ground before the other projection 12. This causes the sole to flex laterally in the region of the arch so that the projection 1 1 is forced outward. The projection 12 therefore also comes into contact with the ground, providing a stable support.

It will be appreciated that because the sole can conform to the asymmetrical under-surface of the foot, the same sole can be used either for the left or for the right foot. Furthermore, because the web is flexible, the same size of sole can be used for different sized feet, and even for children's feet.

The smaller the foot on which the sole is used, the greater the extent to which the heel portion 7 is wrapped around the heel of the cast as shown in Fig. 5.

Claims

1. A leg cast sole comprising an elongate web for attachment to the lower surface of a leg cast, and a ground contacting member depending from said web, the ground contacting member including a pair of ground contacting projections spaced one on each side of the longitudinal axis of the sole, the material of the sole being sufficiently flexible to yield under the weigh. of the user bearing asymmetrically on the sole, so that each projection contacts the ground in use.

2. A leg cast sole according to claim 1, wherein the ground contacting member is in the form of a rib extending transversely of the sole, and having a generally "W-shaped" transverse section.

3. A leg cast sole according to claim 1 or claim 2, comprising a plurality of such ground contacting members.

4. A leg cast sole according to any preceding claim, wherein the web is adapted to extend the length of the lower surface of a cast in use.

5. A leg cast sole according to any preceding claim, wherein the web is adapted to extend around the heel of a cast in use.

6. A leg cast sole according to any preceding claim, having a ground contacting member immediately adjacent the forward end of the sole.

7. A leg cast sole according to any preceding claim, being formed from a foamed plastics material.

8. A leg cast sole according to claim 7, wherein said foamed plastics material is foamed polyurethane.

9. A leg cast according to claim 8, wherein said foamed polyurethane has a density of from 0.3 to 0.7 g/ml, and a Shore A hardness of from 40 to 70.

10. A leg cast sole substantially as hereinbefore described with reference to the accompanying drawings.