WO1990005504A1

WO1990005504A1 - A full foot posted orthotic

Info

Publication number: WO1990005504A1
Application number: PCT/AU1989/000510
Authority: WO
Inventors: Peter Anno Wynd
Original assignee: Peter Anno Wynd
Priority date: 1988-11-24
Filing date: 1989-11-24
Publication date: 1990-05-31
Also published as: CA2003881A1

Abstract

Method of manufacture of orthotic including making plaster cast of foot (sub-talar joint neutral, forefoot pronated), modifying cast to required shape, inserting cast in moulding means where (a) planar surface of cast corresponds to varus or valgus deformity of foot, (b) means is cast in model of shoe with inflatable lining, (c) inlet tube included in lining; plastics mixture poured into mould, plastics may be leather or like, may be injection cast in inflatable lining; plastics mixture cured, cast and mould separated, orthotic cut to size. Fully posted orthotic also disclosed.

Description

A FULL FOOT POSTED ORTHOTIC

The present Invention relates to orthotics and In particular, to orthotics which accommodate and/or support not only the rear and mldfoot but also the forefoot in their functional planes during gait.

BACKGROUND ART

Orthotics are used to bio-mechanically control the individual's feet during gait.

Orthotics adjust the osseous alignment and allow the foot to adapt to and function on the ground with i ncreased effi ci ency.

The foot functions most efficiently If it can supinate and pronate around its Sub Talar joint's neutral position. (Sub Talar Joint's neutral is where the joint is neither supinated nor pronated).

The "normal" foot is slightly supinated (pointing Inwardly) as it swings through the air during gait and on heel strike moves through the STJ neutral position to a pronated position (pointing outwardly) within a second.

The foot returns to its STO neutral position just before heel lift; the forefoot increases its weight bearing and begins to lock against the rearfoot to form a rigid lever.

Once the heel lifts, the muscles lever the body over this locked leverage mechanism (propulsion) to repeat the process on the other foot.

Variations in osseous relationships may place any part (i.e.

calcaneus, metatarsal heads) of the foot which contacts the weight bearing surface, in a plane other than the weight bearing surface, during the STJ neutral position.

These "functional planes" may be measured by placing the foot in its STJ neutral position and comparing the forefoot to the rearfoot position, or the whole foot to the leg.

A forefoot which is everted to the weight-bearing surface while the STJ is neutral will lock against the rearfoot earlier in the gait cycle; while the inverted forefoot at STJ neutral will retard the locking

mechanism's timing or cancel its formation completely.

Variation to this theme may occur if one or more metatarsal heads function in different "Functional planes" to each other.

Inefficiency in the locking mechanism during propulsion results in abnormal motion, subluκation or dislocation of the foot's joint complexes. State of the Art othotics are mainly of two basic designs:

1. A hard shell which terminates posteriorly to the metatarsal heads and, therefore does not support them in their "functional plane" after "heel lift".

2. A soft flexible orthotic which again does not support the metatarsal heads in their "functional plane" after "heel lift"

The proposed orthotic will not only control the rear, mid and forefoot before "heel lift" but also after "heel lift" by accommodating or supporting them in their "Functional" planes.

Formation of the locking mechanism can thus be controlled to provide appropriate functional efficiency of the foot during gait.

OBJECT OF THE INVENTION

It is an object of the present invention to provide an orthotic which controls the rear, mid and forefoot before heel lift but also after heel lift by accommodating and supporting them in their functional planes.

It Is also an object of the present invention to provide a method of manufacturing an orthotic which has the abovementioned advantages.

DISCLOSURE OF THE INVENTION

According to one aspect of the present invention there is discloseda method of manufacture of an orthotic, comprising the steps of making a positive plaster cast of a foot while the sub-talar joint is in neutral and with the forefoot fully pronated about both the mid tarsal joint

longitudinal and oblique axes, modifying said plaster cast according to a required shape, inserting said plaster cast in a moulding means whereby the plane of its planar surface corresponds to the varus or valgus deformity of the foot, wherein a plastics mixture is poured into said mould and allowed to cure according to the properties of the plastics mixture.

According to another aspect of the present invention there is disclosed an orthotic manufactured using the abovementioned method.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic superior view of a foot illustrating the skeletal arrangement,

Fig. 2 is a medial view of the skeletal arrangement of Fig. 1,

Fig. 3 is a rear view of a pair of feet illustrating the supinated and pronated positions of the feet during gait. Fig. 4 is a rear view and front view of different functional examples of feet whilst the sub-talar joint is in the neutral position,

Fig. 5 is a schematic diagram of a forefoot on a post to be

considered in the workings of the present invention,

Fig. 6 is a schematic side view of an orthotic using prior art technology,

Fig. 7 1s a schematic side view of an orthotic using different prior art technology,

Fig. 8 is a schematic side view of an orthotic of one embodiment of the present invention,

Fig. 9 is a schematic side view of an orthotic of another embodiment, Fig. 10 is a rear view of an orthotic of another embodiment,

Fig. 11 is a rear view of an orthotic of a further embodiment,

Fig. 12 is a schematic side view of an orthotic of a further

embodiment,

Fig. 13 is a schematic side view of a foot modei and a casting lining used to manufacture an orthotic of the preferred embodiment,

Fig. 14 is a perspective view of a casting mould with casted foot model, modified foot model and casted orthotic,

Fig. 15 is an inverse plan view of an orthotic cast using methods of the preferred embodiments, and

Fig. 16 is a lateral view of the orthotic of Fig. 15 showing varus forefoot support.

BEST MODE OF CARRYING OUT THE INVENTION

The drawings, Figs. 1 to 7 help illustrate the prior art. Figs. 1 and 2 illustrate the components of a foot while Fig. 3 illustrates a foot in a supinated and pronated condition. The foot 1 is basically separated into three parts, namely the rear foot 16, the midfoot 17 and forefoot 18. The rear foot 16 includes the calcaneus 7 and talus 8 which are joined by the sub-talar joint 10. The midfoot 17 includes the mid-tarsal joint 11 and the forefoot 18 includes the metatarsal shaft 9, the metatarsal heads 3 and the hallux 12. As seen in Fig. 1, the foot has a medial column 5 and a lateral column 6.

Fig. 4 illustrates examples of the functional planes whilst the sub-tarlar joint 10 is in the neutral position. Fig. 4(a) illustrates an inverted (varus) functional plane on the forefoot 18 whilst Fig. 4(b) shows an inverted (varus) functional plane of the rearfoot 16. Fig. 4(c) shows an inverted functional plane of the medial column whilst Fig. 4(d) shows an everted (valgus) functional plane of the rearfoot 16.

Illustrated in Figs. 5 and 6 is a schematic diagram of a foot using an orthotic. In Fig. 5, 5 metatarso phalangeal joints 3 resting on a post 4 is illustrated. The post 4 is any bulk material that "in this case" wil allow the forefoot to function in a plane determined by its varus

deformity. The view is a front view showing the medial side 5 and a laterlal side 6.

The orthotic 15 which is illustrated in Fig. 6 is shown with a foot resting thereon. The various parts of the foot are illustrated showing the rear foot 16, the mid foot 17 and part of the forefoot 18 being supported by the orthotic 15 in midstance.

This orthotic 15 is designed to post a varus deformity of the forefoot 18.

It 1s seen that the calcaneus 7, the mid foot 17 and the metatarsal shaft 9 are supported by the orthotic 15 while the first metatarsal phalangeal joint 3 and the great toe, or tallux 12, are suspended.

When on heel lift, the calcaneus 7 leaves the ground, the body weight is transferred forward along the metatarsal shaft 9, and forces the metatarsal phalangeal heads 3 to descent to contact a stable surface (e.g. the surface of the inner soleK

Fig. 6 illustrates a known orthotic 15 whereby a hard shell

terminates posteriori ly to metatarsal heads 3 and, therefore does not support them in their "functional plane" after "heel lift". Illustrated in Fig. 7 is a soft flexible orthotic 14 of the prior art which again does not support the metatarsal heads 3 in their "functional plane" after "heel lift".

The orthotic 13 the present invention illustrated in Fig. 8 not only controls the rear foot 16, the midfoot 17 and the forefoot 18 before "heel lift", but also after "rheel lift" by accommodating or supporting them in their functional planes. The formation of the locking mechanism of the gait can thus be controlled to provide appropriate functional efficiency of the foot during gait.

The orthotics 13 are manufactured of any material able to provide appropriate support and allow the foot to move as required. For example. thermosets or thermoplastics, with or without micro-balloons or any other synthetic and/or natural fillers.

Illustrated in Fig. 9 is another embodiment of the orthotic 21 of the present invention illustrated with a synthetic filler 22 with two sections of corks/rubber compound 23 with a leather shell 24 surrounding the orthotic.

In another embodiment illustrated in Figs. 12 an orthotic 25 has layers and/or sections 26 of materials and/or fibres of properties appropriate to the treated areas are attached or hinged to each other and/or attached or contained by an outer cover 27. The various parts 29 of an orthotic 28 illustrated in Figs. 10 and 11 can have their density reduced by using either a softer material in parts of the orthotic 28 or removing the support as illustrated in Fig. 11.

One method of constructing an orthotic of the preferred embodiment includes the steps of placing a special slipper over each foot of the patient, moistened plaster being located within the supper. The feet are then positioned correctly and this position is checked visually and by feeling with the fingers. The plaster supper is allowed to harden and removed from the foot. It can be cut so that it can be removed if

necessary. A cast foot model 30 (Fig. 13) is then prepared using the plaster moulds. The cast foot model 30 is then compared with the properly aligned feet of the patient and modified if necessary and possible. The foot model 12 has a tube 33 passing through it.

A pair of shoes into which the orthotic is to be placed are inserted and protected in a plastic shoe bag in a workstation device. The pair of shoes contain a casting lining 31 having an inlet tube 32 (Fig. 13). The shoelaces of the shoes are bound in normal wearing positions. Plaster is moistened and poured around the outside of the plastic shoe bag in the workstation device and the plaster is let to harden. The inlet tube 32 of the pair of casting linings 31 are attached to the tube outlet 34 of the foot models, and Inserted Into the shoes. The foot models 30 are connected to the workstation and aligned to the right position. The next step is to cast and finish the orthotic by mixing the components and casting and injecting them through the tube into the casting lining. The tube 33 is closed until the components are sufficiently cured. The shoes and

mouldings are detached and the orthotic within the casting lining is removed. The inlet tube 32 is then removed from the orthotic and the orthotic is ready to be inserted into a shoe for the patient. In this way, the orthotic is so casted in the shoe of the patient so that it is already the correct size and alignment.

In another method of constructing an orthotic, (using components as illustrated in Fig. 14) plaster moulds of the feet and cast foot models 30 are prepared as previously described. The foot models 30 are then inserted into the casting moulds 36. The foot models 30 are modified to fit the dimensions of the closed casting moulds 36 when the casting moulds 36 are closed, the casting materials are cast with modified foot models 37 therein. Once the casting materials are cured, the casts is removed and the orthotic 38 is then finished by cutting the edges and checking. The orthotic 38 can be covered with a suitable material if required. The orthotic is able to be cast injected through a tube or aperture similar to the above described method.

In another method of constructing the orthotic of a preferred embodiment includes casting foot models 30 as described previously. The foot models 30 are modified by smoothing the soles. These modified foot models 37 are aligned in the workstation and presoaked leather is placed underneath the entire soles of the modified foot model 37. Other materials are able to be

inserted between the layers. The foot models are pressed onto the folded leather and the leather is allowed to dry. When the leather is dry, the pressure is relieved and the moulded leather blanks are removed. These leather blanks are cut to size and their edges are bonded if necessary. These orthotics are then the shape which is required.

The orthotic 38 illustrated in Figs. 15 and 16 is shown to have a flange (shaded). The orthotic 38 in Fig. 16 shows varus forefoot support (shaded). Variations of support will occur depending on varus or valgus deformities of the rearfoot, entire forefoot, medial or lateral columns.

It is noted that different size moulds are used to cast different size orthotics.

The foregoing describes only some embodiments of the present

invention, and modifications obvious to those skilled in the art can be made thereto without departing from the scope of the present invention.

Claims

1. A method of manufacture of an orthotic, said method comprising the steps of making a positive plaster cast of a foot while the sub-talar joint is in neutral and with the forefoot fully pronated about both the mid tarsal joint longitudinal and oblique axes, modifying said plaster cast according to a required shape, inserting said plaster cast in a moulding means whereby the plane of its planar surface corresponds to the varus or valgus deformity of the foot, wherein a plastics mixture is poured into said mould and allowed to cure according to the properties of the plastics mixture.

2. Method according to claim 1, wherein said modified plaster cast of foot are modified in order that the orthotic is cast in the desired shape to fit in a shoe.

3. Method according to claim 1 wherein said orthotic is cast by

injection through a tube or aperture.

4. A method of manufacture of an orthotic, said method comprising the steps of making a positive plaster cast of a foot while the sub-talar joint is 1n neutral and with the foot fully pronated about both the mid tarsal joint longitudinal and oblique axes, placing the positive plaster cast of the foot in a cast model of a shoe having an inflatable casting lining located therein, casting an orthotic in said casting lining via injection means, allowing said cast orthotic to cure, removing the plaster casts and finishing with an orthotic of correct size and alignment.

5. Method according to claim 4 wherein said injection means includes an inlet tube in said casting lining.

6. A method of manufacture of an orthotic, said method comprising the steps of making a positive plaster cast of a foot while the sub-talar joint is in neutral and with the forefoot fully pronated about both the mid tarsal joint longitudinal and oblique axes, modifying the positive plaster cast and placing in a casting mould, inserting moist leather or like substance in said casting mould and allowing to dry while said modified positive plaster cast is pressed against said leather, removing said casting mould and cutting said orthotic to size.

7. Method of manufacture according to claim 6 wherein other filling materials are used within the shell of the leather or like substance.

8. An orthotic manufactured according to any one of the claims 1-7 wherein said orthotic is full posted.