GB2107170A - Orthopaedic footwear - Google Patents

Abstract

A removable shoe insert for enabling an abnormal foot to fit a shoe of a given size consists of a semi-rigid insole 11 shaped to fit the shoe and space-filling members such as in the toe-region 12 bonded to the insole. The space-filling members where required are preferably made of a resilient polyurethane foam if located in the toe or plantar region or of a rigid polyurethane-foam if located at the heel, and may conveniently be made by forming an insole of the appropriate size, placing the insole together with a lining bag for the shoe and either a cast of the foot or the covered foot itself within the shoe, and introducing into the shoe an appropriate quantity of polymeric material so that it can cure in situ to form a space-filling member of the correct shape. <IMAGE>

Description

SPECIFICATION Improvements in or relating to orthopaedic footwear This invention relates to orthopaedic footwear, and more particularly to means for adapting footwear to abnormal feet.

Prior art techniques of providing footwear for abnormal feet include the manufacture of surgical boots or shoes which are custom made to fit individual feet accurately. Surgical footwear of this kind is extremely expensive, and there is a need for a cheaper alternative. It is also known to provide surgical footwear by using a standard form of shoe by filling the internal space between shoe and foot with a resilient material, as described for example in United Kingdom Application No. 2,021,927A.

Moreover, sporting footwear such as ski boots have been provided for normal feet by modifying a standard rigid metai outer shell with internal inserts to fit individual feet, as described for example in PCT Application No. WO 79/00886.

These prior art techniques have the characteristic that they adapt only one type of footwear design to the respective foot. There is a need for a footwear modifier which is transferable between different footwear designs of the same size, in order that a user may transfer the modifier to a different shoe. Moreover, in the case of flexible footwear, it has been found that polyurethane foam space-fillers confer undesirable flexure characteristics on the shoe. For example, a foamed insert for a foot lacking toes tends to produce excessive shoe flexion. This leads to excessive creasing of sole and upper, early split formation and permanent upward deflection of the toe of the shoe.

It is an object of the present invention to provide a shoe insert for adapting a shoe to an abnormal foot, the insert having improved transferability and the shoe-insert combination having improved flexure characteristics compared with the prior art.

The present invention provides a removable shoe insert for adapting a shoe of a given size to fit a given abnormal foot, the insert comprising an insole shaped to fit the shoe and at least one space filling member attached to the insole, the member being moulded and arranged to fill the space between the foot and the shoe. The space filling member is preferably formed from a foamed polymeric material.

It has been found that a shoe insert in accordance with the invention is capable of adapting different shoes to a given deformed foot, and the insert-modified shoe has improved flexure characteristics during the user gait cycle.

Moreover, a removable shoe insert of the invention may easily be adapted to take account of growth or change in shape of the foot to provide continued comfort. The insert may also be inspected for wear and repaired as necessary.

Since the insert is formed on an insole of a standard size, it may easily be transferred to other shoes of different designs if necessary.

In the case of an abnormal foot having a raised heel, the corresponding space-filling member is preferably moulded from a rigid grade polyurethane foam and is located on the heel portion of the insole.

For an abnormally short foot, or a foot having a raised plantar region, the space-filling member is preferably moulded from a resilient grade polyurethane foam and is located on the toe and/or plantar region of the insole.

The insole is preferably made from thermally formable polymeric material such as high molecular weight polyethylene.

The space-filling member may have a footcontact surface region covered with a fabric material bonded to the member.

In a further aspect, the invention provides a method of making a removable insert for adapting a given shoe to a given abnormal foot including the steps of: (a) forming a stiffening insole and a removable lining bag for the shoe, (b) providing a cover for, or a cast of, the foot, (c) placing the cast or covered foot on the insole within the lining bag inside the shoe, and (d) introducing at least one polymeric material into the lining bag and forming a space-filling member attached to the insole, the member filling the space between the lining bag and the covered foot or cast of the foot.

The insole is preferably made by moulding thermally formable, rigid-grade polymeric material, such as high molecular weight polyethylene, to a last of the shoe. The cover is preferably provided by fitting the foot with a sock of fabric material which is bondable to the polymeric material of the space-filling member.

Conveniently, the polymeric material is a polyethylene foam and the fabric material has a surface layer of polyurethane film arranged to be outermost of the sock and bondable to the spacefilling member. The lining bag may conveniently be made from polymer film heat-shrunk onto a last of the shoe.

In the case of a short foot, the space-filling member is of resilient polymeric material such as a flexible polyurethane foam. In the case of a foot requiring heel support, the space-filling member is of comparatively rigid polymeric material such as rigid-grade polyurethane foam. Where the foot is both short and in need of heel support, the method includes the additional step of introducing a second polymeric material into the lining bag to form a foamed polymeric heel support attached to the insole, the first and second polymeric materials forming respectively flexible and rigid foams.

To provide an insert for an abnormal foot much smaller than the size of shoe, it may be necessary for the insole to extend to the upper surface of the shoe interior in order to provide a sufficient support for a substantial space-filling member.

Such a modified insole, which may extend to cover the entire interior surface of the shoe, or even higher, may conveniently be made by thermally forming a polymeric material on the shoe last.

In order that the invention might be more fully understood, embodiments and examples thereof will now be described, by way of example only, with reference to the accompanying drawings, of which: Figure 1 shows a shoe insert of the invention appropriate for a short foot, Figure 2 shows a shoe and a removable insert therefor of the invention for a foot having length and plantar deficiencies, Figure 3 shows a removable insert of the invention for a foot having a length and plantar deficiencies and requiring a heel support, Figure 4 is a sectional view of a shoe containing a cast of a foot prior to forming an insert of the invention, and Figure 5 is a sectional view of an insert suitable for a foot substantially smaller than the shoe to be worn.

Referring to figure 1, there is shown a shoe insert 10 comprising a semi-rigid shaped insole 11 of high molecular weight polyethylene bonded to a toe-region space-filling member 12 of flexible or resilient polyurethane foam. The member 12 has a foot-contact surface region of finely-knitted nylon (polyamide) material 1 3 bonded to it. The insole 11 is bonded to a foot-contact surface region 1 7 of thin sheet polyurethane foam (Poron RTM).

In figure 2, an insert similar to that of figure 1 is shown, and previously described parts have like references with the prefix 10 replaced by 20. The insert 20 has an insole 21 and toe-region spacefilling member 22, and additionally has a plantar support region 24 formed as an extension of the member 22. The member 22 and plantar support 24 are of flexible polyurethane foam and are covered by material 23 in the foot-contact region.

The insert is shaped appropriately for a shoe 25.

In figure 3, parts equivalent to those described in figure 2 have the prefix 30 replacing the prefix 20. In this drawing there is shown an insert 30 equivalent to that shown in figure 2 with the addition of a heel support 36 of rigid-grade polyurethane foam attached to the insole 21. The insert 30 has a foot-contact surface region 37 covered by a thin sheet of prefabricated polyurethane foam (Poron RTM).

Referring now also to figure 4, there is shown a sectional view of a shoe 40 containing a cast 41 of an abnormal foot. The cast 41 and shoe 40 have internal spaces 42, 43 and 44 at the toe, plantar and heel regions respectively.

The inserts described in figures 1 and 2 are made as follows. The insole is made by heatshaping high molecular weight polyethylene (i.e.

Ortholen, trade name) in sheet form 4 mm to 6 mm thick. The insole is shaped on a last appropriate to the shoe to be modified by the insert. A polyethylene shoe liner bag is then made from 280-300 gauge polyethylene film, the film being cut to size and the cut portions heat-sealed together. The bag is then heat-shrunk over the shoe last to form a shoe liner of the correct shoe shape, and subsequently removed from the last.

The abnormal foot to be fitted to the shoe is clothed in thin fabric such as stockinette, and the material is bundled to give extra thickness in areas such as beyond the toes and over tender prominences of the foot where freedom is required. The extra thickness of material is held in place with thin adhesive tape.

The foot is then further covered with a sock of knitted nylon fabric surface with polyurethane film (Ambla P072, trade name). This material acts both as a barrier to protect the foot during polymerisation of the foam and as a durable cover to the foam. The sock is cut and heat-sealed with en electric hot knife to tailor, from the material, a custom-shaped sock for the patient's foot. It is worn with the polyurethane film outermost. It is further tailored as necessary to achieve a good fit without wrinkling. The cut seams are then reinforced with a 1 cm wide of Opsite (trade name) polyurethane film.

The areas on the sock to which it is desired to bond the foam are selected. The remaining areas of the sock are then painted with a release agent, perchlorethylenum. The insole is then placed within the shoe liner bag inside the shoe ready for polyurethane foam insertion. A suitable flexible or resilient polyurethane foam system has been found to be that manufactured under the tradename Pedilen W150 by Otto Bock. It is a two component system which is commercially available, and is of sufficiently low viscosity for ease of mixing.

A suitable quantity of the two components of the polyurethane foam system are measured (a minimum quantity for effective mixing is 25 ml of each), and mixed with an electric mixer for 10 seconds. Sufficient foam must be produced to fill the space left between-foot and shoe.

The mixed foam components are quickly poured into the polythene bag in the shoe and the patient's foot (clothed in two layers of material) is inserted. The patient is asked to bear weight on the foot in a neutral position, the heel is held well back into the heel of the shoe and the shoe is held tight by laces or by hand for two minutes. After two minutes the foam will have adopted its final shape and the patient can sit for a further three minutes as it is held still for completion of polymerisation. This produces a space-filling member (12,22-23 in figures 1 and 2) which compensates for a foot having length and/or plantar deficiencies.

The foot and insert are removed leaving the Ambla sock attached in places to the foam by virtue of the polyurethane-surface of the sock. The foam itself bonds strongly to the insole. The unattached sock portions are trimmed away leaving free edges to be cemented around the edges of the foam. The foam is machined and finished where necessary. Small irregularities caused by wrinkling of the outer polythene bag can be machined off. This makes the fit of the insert slightly looser in the shoe, making it easier to remove and replace. The insert can be used 24 hours later.

As an alternative to the above procedure, a positive mould or cast of the abnormal foot may be employed as illustrated in figure 4, rather than the foot itself. It is preferable to employ a cast when the attitude of the foot requires passive correction which cannot be achieved easily when the foot is in the same shoe. It is also preferable in cases when the patient's foot is difficult to insert rapidly into a shoe, such as for example a flail foot.

The insole which is required for this technique may be made up to the positive mould or cast of the foot with plantar surface mouldings if required, instead of by forming as set out above on a last.

The insole may also be checked against the mould itself. The insole when completed is placed inside a polythene bag in the shoe as in the case of a patient's foot set out above.

The positive cast is rectified as necessary and covered with a latex rubber sock stretched tightly to avoid any wrinkling. It is checked for positioning in the shoe as illustrated in figure 4. Polyurethane foam is mixed as previously described and poured into the shoe around the foot cast. The cast and insert are removed after 5 minutes. Because of the smooth, foam-releasing surface of the cast and the skin which forms on the foam, a lining material on the foot-contact regions of the foam is not necessary. Finally, excess foam is trimmed away and the insert finished as necessary.

It has been found that it may be preferable to employ polyurethane foams of differing resiliency on different regions of the insole. As has been said the toe and plantar regions of the insole should be covered by a resilient or flexible grade of foam as shown in figure 3. Where a heel support is required however, the insole heel region should be of rigid-grade polyurethane foam as shown in figure 3 in order adequately to support a patient's weight. The method of the invention then requires that these two different foams be inserted sequentially into the shoe and bonded to the insole. To achieve this, a positive mould or cast is employed in the method previously described. The resilient foam-forming mixture is first inserted, and when this has set the insole is removed. The resilient foam is then trimmed away from the heel region of the insole on which it is not required.The insole with resilient foam on toe and/or plantar region is then replaced in the shoe liner bag together with the cast, and the combination is replaced within the shoe. Care is taken to ensure correct relative repositioning of cast, insert, bag and shoe. The rigid-grade polyurethane foamforming mixture is then inserted, and the mixture sets to fill the space under the heel of the cast. The insert is then removed and excess foam trimmed away as necessary. This provides an insert of the kind shown in figure 3 which is: (i) load-bearing in the heel region, (ii) comfortable in the toe and plantar regions, (iii) removable for use with different shoes, (iv) sufficiently stiff to confer acceptable flexure characteristics on a shoe, and (v) capable of being modified to compensate for foot growth of wear.

Referring to figure 5, a modified insole 51 is adapted to take the form of the entire interior surface of the shoe; this may be achieved by thermally forming high molecular weight polyethylene on a last of the shoe. The modified insole 51 contains a space-filling member 52 of polyurethane foam, the surface 53 of which adjacent to the cast or foot 54 is shaped by placing the cast or covered foot into the modified insole and a suitable quantity of foam mixed foam components poured into the space surrounding the foot as described above. It may be necessary to ensure that while the foam is curing the patient keeps his foot at a suitable location within the insole. This will not in general be on the lower interior surface of the insole and for that reason the use of a cast is sometimes preferable.

Claims (14)

1. A removable shoe insert for adapting a shoe of a given size to fit a given abnormal foot, the insert comprising an insole shaped to fit the shoe and at least one space-filling member attached to the insole, the member being moulded and arranged to fit the space between the foot and the shoe.

2. A removable shoe insert according to Claim 1 having a space-filling member made of a foamed polymeric material.

3. A removable shoe insert according to either preceding claim having a space-filling member made of a rigid polyurethane foam and located on the heel portion of the insole.

4. A removable shoe insert according to any preceding claim having a space-filling member made of a resilient polyurethane foam and located on the toe or plantar region of the insole.

5. A removable shoe insert according to any preceding claim in which the insole is made from a thermally formable polymeric material.

6. A removable shoe insert according to any preceding claim in which the insert is made from a high molecular weight polyethylene.

7. A removable shoe insert according to any preceding claim having a fabric material bonded to the foot-contact surface region of the space-filling member.

8. A method of making a removable insert for adapting a shoe of a given size to a given abnormal foot which includes the steps of: (a) forming a stiffening insole and a removable lining bag for the shoe, (b) providing a cover for, or a cast of, the foot, (c) placing the cast or covered foot on the insole within the lining bag inside the shoe, and (d) introducing at least one polymeric material into the lining bag and forming a space-filling member attached to the insole, the member filling the space between the lining bag and the covered foot or cast of the foot.

9. A method according to Claim 8 in which the insole is made by moulding a thermally formable, rigid polymeric material to a last of the shoe.

10: A method according to either Claim 8 or Claim 9 in which the cover is provided by fitting the foot with a sock of fabric material which is bondable to the polymeric material of the spacefilling member.

11. A method according to Claim 10 in which the said polymeric material is a polyethylene foam and the fabric material has a surface layer of polyurethane film arranged to be outermost of the sock and bondable to the space-filling member.

12. A method according to any of Claims 8 to 11 in which the lining bag is made from polymer film heat-shrunk onto a last of the shoe.

13. A method according to any of Claims 8 to 12 including the additional step of introducing a second material into the lining bag to form a foamed polymeric heel support attached to the insole, the first and second materials forming respectively resilient and rigid foams.

14. A removable shoe insert substantially as hereinbefore described, with reference to either Figures 1 and 2, Figure 3 or Figure 5.

1 5. A method of making a removable shoe insert substantially as hereinbefore described.