The invention will primarily be described in relation to inserts for footwear, particularly performance footwear such as dancing, ballet and athletic shoes, however it also extends to orthotic devices which are fitted directly to the foot or indirectly with the use of some form of containment such as hosiery, bandages, strapping or layered materials. These broader aspects of the invention should therefore be borne in mind and the following description of preferred embodiments should not be deemed to be any way limiting on the scope of the invention.

When it comes to providing functional assistance and comfort to the foot, dancers have always been at a disadvantage. This is due mainly to the restrictive accommodation of dancing footwear as exemplified by ballet slippers. Any insole with support or support padding limits the range of foot function (flat foot position to en pointe) and also causes the slipper to bulge out, especially at the inner side of the foot. These types of insoles are not functionally or aesthetically acceptable.

Dancers and other athletes who perform high impact and repetitive activities with their feet often develop soft tissue and bone pathology in the foot and leg. This situation is compounded when supportive and cushioned footwear cannot be worn during these activities. Dancers who wear ballet slippers are

particularly at risk and suffer a number of painful conditions ranging from aches, cramps and tendonitis to stress fractures or complete fracture of the bones in the feet. Gymnasts, boxers and sprinters have similar problems.

A"high arched"foot is of paramount importance for a ballet dancer. When the foot is maximally arched, the bones of the foot are locked together and the foot is rigid. This rigidity provides the stability necessary to maintain an"en pointe" (or tiptoe) dancing position.

This position also necessitates strengthening and maintaining the strength of the muscles both in the leg and the foot. Dancers are not permitted to dance"en pointe"until the foot and the leg muscles are strong enough to ensure stability, control and safe dancing in this position. The"arched"foot look is also considered aesthetically pleasing and all dancers strive to enhance the"look"of the foot.

In many sporting endeavours, and certainly in classical dance, the foot has little protection from the performing surface, or the repetitive nature of the activity being undertaken in training and performance.

In"normal"foot function, the bones of the foot will move slightly from a locked position to an unlocked position depending on the function of the muscles. These changes allow the"shock"forces from the ground to be dissipated via the soft, tissues within the foot when the foot is unlocked, and for control and stability to be achieved when the foot is locked. When the muscles which control these movements are weak or used inappropriately the foot cannot sustain good function. Poor foot structure also results in poor foot function.

This invention was inspired out of the necessity to treat dancers and other athletes who had developed serious injuries due to the combination of

unprotected repetitive activity and poor"sustained"foot function-often due to muscle fatigue.

OBJECT OF THE INVENTION It is therefore an object of the invention to provide an orthotic device which will enhance the arch profile and performance of the foot, particularly in restrictive performance footwear.

It is a further object of the invention to provide protection to the foot from abnormal impact forces.

SUMMARY OF THE INVENTION According to the broadest aspect of the present invention there is provided an orthotic device which comprises a substantially rigid moulded sheet of resiliently deformable plastics material which provides continuous contact with the arch of the foot whether the foot is flat or pointed, after it has initially been moulded to substantially conform with the shape of the arch of the foot.

DETAILED DESCRIPTION OF THE INVENTION The orthotic device is formed from a plastics material which is moulded by heat, microwaves or other appropriate means to produce a high arch profile. The plastics material is chosen from the range of plastics having a shape"memory"property which permits it to be flattened out under applied pressure and then to return to its original memorized configuration once the applied pressure has been removed. The sheet plastics material should also be such as to provide a firm yet flexible contact with the arch of the foot. The sheet will suitably range in thickness from less than one millimetre to a few millimetres, preferably approximately one millimetre, and may comprise several sheets laminated together.

The ability of the resiliently flexible orthotic device to be moulded enables it to be shaped or reshaped to the arch contours of the particular foot it is to be used with by a simple process such as direct heating using a hair dryer or the like. or by placing it in a microwave oven. When the device is heated or microwaved, it softens sufficiently to enable shaping.

As it hardens, it memorises the shape into which it has been formed.

Although there are a large number of known plastics materials which exhibit the above properties and which would be suitable for forming the flexible orthotic device according to the invention, the preferred plastics material is the product sold under the trade name Quikformm by Acor Orthopaedic, Inc. of the U. S. A. This product has a moulding temperature of around 200°F.

The function of the resiliently flexible orthotic device is threefold, viz: (1) to stimulate the arch and the superficial muscles under the foot, (2) to remind the wearer to"pull up the arch"using the muscles of the leg and foot, and (3) to engender confidence in the wearer by providing a sensation of support under the arch of the foot.

The orthotic device can be made to fit the template of the performance footwear it is to be used with and suitably includes a portion which enables it to be secured to the heel portion of the footwear. For instance, the orthotic device can be secured with a two

way thin adhesive wafer or a thicker velcro@ dot to enable transfer between footwear. In addition, the orthotic device could be strapped directly to the foot or retained within a suitable stocking.

In another aspect of the invention, there is provided a multi-layered orthotic device. This device comprises the mouldable sheet of plastics material referred to hereinbefore, sandwiched between a shock absorbent layer and a covering layer. The covering layer is intended to lie adjacent the foot of the wearer and the shock absorbent layer is intended to face the sole of the wearer's shoe.

The shock absorbent layer and the covering layer may also comprise multi layers of the same or different material to increase shock absorbency if required or to provide additional stimulus or comfort to the arch.

The shock absorbent or base, layer can be manufactured from any conventional shoe insert material commonly used for this purpose. Typical examples of these materials are foamed plastics and rubber materials such as polyurethanes and polyisoprenes. Particularly preferred are the Poron Medical Cellular Urethanes.

These are engineered, high density, microcellular urethane foam materials designed for use in orthotic and prosthetic applications. PoronX medical materials are mechanically foamed, resulting in excellent thickness tolerance and lot to lot consistency. They will not thin out or take a compression set, and will retain 95% of their original thickness for the life of the product.

These materials are excellent shock absorbers. Each of the cells in the material acts like a tiny spring or energy absorber. Coupled with the compression set properties, these materials will not lose their ability

to absorb shock over time.

The preferred Poron layer used is a split material with a roughened surface, which is laminated to the rest of the other layers, and a smooth surface. The smooth surface contacts the insole of the footwear, which allows the orthotic device to coil and recoil with minimal friction.

Poron materials are easily cut and fabricated and can be adhered or laminated to a wide range of other materials. Gram for gram, this material is a superior shock absorber and this lightweight quality makes it suitable for use in the invention.

The covering, or top, layer of the orthotic device is selected from a range of materials having one or more of the following properties: -protects the skin of the plantar surface of the foot, -resists moisture retention, -has suitable formability to be able to withstand the coil and recoil movement of the orthotic device, -withstands repetitive use, -increases comfort under the arch of the foot, -is hypoallergenic, -increases the stimulus under the arch.

The preferred covering is leather. Other covers specifically designed for sweaty feet, skin disorders and increased tactile stimulus may also be used.

The three layers of the orthotic device are preferably adhered together with a commercial adhesive which is commonly used in the footwear industry. A particularly preferred adhesive is sold under the trade name Duall zu The last size and shape of the footwear will determine the dimensional parameters of the multi-layered orthotic device. Body weight and the intended activity will determine the thickness of the shock absorbent layer and the covering layer.

The shock absorbent layer is suitably cut to the dimensions of the full last of the footwear.

The inner sheet of plastics material is limited in width to the width of the last and limited in length to the length of the inner longitudinal arch. (This dimension is calculated on the length of the last). This layer is therefore significantly shorter at both ends than the shock absorbent layer and the covering layer.

The outer covering layer is cut either to the actual dimensions of the last (as with the shock absorbent layer) or 1 mm larger to enable extra shock absorbency to be added at any time if required.

The flexible characteristic (coil and recoil) of the orthotic device according to the present invention is unique and sets it apart from other insole devices.

Other insole devices are designed to supply shock absorbency, to carry a medicament (eg. Charcoal odour eaters within the insole), to restrict foot function or to support the bones of the foot. The present orthotic device provides constant contact with the arch, stimulating the skin, nerve endings and the superficial muscles under the foot.

The flexibly resilient orthotic device is not an arch support as it is designed to allow the foot to be flexible and the characteristics of the device do not provide any extrinsic support to the foot whatsoever.

The orthotic device will be available as an "off the shelf"purchase, and will be packaged according to the size of the performance footwear. It will preferably be distributed in flat form, with clear instructions and simple diagrams explaining the moulding process.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a side cross-sectional view of an orthotic device in an extended configuration, Figure 2 is a top plan view of the orthotic device show in Figure 1; Figure 3 is a partial top perspective of the orthotic device shown in Figures 1 and 2, in an arched configuration; Figure 4 is a cross-sectional view of the orthotic device shown in the previous Figures in situ, with in a ballet shoe, and Figure 5 is a cross-sectional view of the orthotic device and ballet shoe shown in figure 4 in an "en pointe"configuration.

DESCRIPTION OF PREFERRED EMBODIMENT A preferred embodiment of the invention will now be described with reference to the accompanying drawings, in all of which like reference numerals refer to like parts.

Figures 1 and 2 show a multi-layered flexible

orthotic device in a form in which it would be purchased or in a form it would assume under a flat foot in performance footwear.

The orthotic device comprises a shock absorbent layer 10, a mouldable sheet of plastics material 11 and a covering layer 12.

The shock absorbent layer 10 consists of a 1 mm layer of Poron@, as referred to hereinbefore; the mouldable sheet of plastics material 11 consists of a 1 mm thick insert fabricated from QuickformTM positioned in the arch region only of the orthotic device ; and the covering layer 12 consists of a 1 mm thick layer of leather. All layers are adhered together with the adhesive Duall 88, also previously referred to.

As noted, Figures 1 and 2 illustrate the form the orthotic device takes when it is purchased.

Accordingly, in order to transform it into a useable product with a memorized arch configuration as shown in Figure 3, the orthotic device must be subjected to radiant heat or microwave radiation of a sufficient intensity to enable the sheet of plastics material to become mouldable, without adversely affecting the integrity of the covering and the shock absorbent layers.

One preferred method to achieve this utilizes a hair dryer on high heat. The hair dryer is held approximately 20 cm away from the orthotic device and hot air is directed at the outer surface of the shock absorbent layer 10. Heat is not applied to the covering layer 12.

The nozzle of the hair dryer is moved up and down to direct an even flow of hot air to the mouldable sheet of plastics material 11. The plastics material typically softens after a few minutes of such treatment. The orthotic device is then bent in half so that the undersides face each other, and is rolled to and fro

between the hands several times. It is placed topside facing upwards on a flat surface and the central portion is bent into an exaggerated arch by pushing the toe end and the heel end towards each other until they are approximately 2cms apart. This shape is maintained until the orthotic device cools. When completely cool, the orthotic device is placed in the footwear. If required, securement can be achieved using a velcro fixing or the like under the heel.

As weightbearing occurs on the arch, the flexible resilient orthotic device will slide forward and flatten as shown in Figure 4 then recoil when the heel is lifted or weight is transferred to the lateral border of the foot as shown in Figure 5. The orthotic device will ensure contact with the arch at all times.

Should the orthotic device lose its arch shape over a period of time due to excessive and continued use, it can simply be reheated as above to reestablish the required arch shape.

Whilst the above has been given by way of illustrative example of the invention, many modifications and variations may be made thereto by persons skilled in the art without departing from the broad scope and ambit of the invention as herein set forth.