GB2068237A - Splints or casts made from reinforced resin - Google Patents

Abstract

A flexible container 1 contains a settable resin 9 and reinforcement 3, 4 and 5 for the resin and means 6, 7 and 8 for enabling the resin in the container to be set. A device providing a splint or cast which comprises such a flexible container may be used in human or veterinary medicine. <IMAGE>

Description

SPECIFICATION Improvements in or relating to splints or casts The present invention relates to veterinary or human splints or casts for general and emergency use and, in particular, relates to glass reinforced plastics material (GRP) splints or casts.

Splints or casts for broken bones are traditionally made from plaster of paris, often using a bandage impregnated with plaster of paris slurry. The bandage is repeatedly wrapped round the broken limb to build up a sufficiently thick layer. It has often been found, however, that a plaster of paris splint is not sufficiently strong to provide sufficient protection and, if the splint or cast is made thick enough to provide sufficient strength, it can be very heavy and clumsy, so preventing effective use of the injured limb. The general inconvenience of this procedure is so great that, for example, if a horse were to fracture a foreleg, it would be usual to destroy the animal.

In an attempt to overcome the disadvantages of plaster of paris splints, attention has been directed to the use of glass reinforced plastics material (GRP), especially glass reinforced polyester resin, for surgical splints or casts. The conventional use of this material, however, is not without its disadvantages and safety hazards. The use of GRP in the treatment of human limb fractures may not be acceptable in such environments as hospitals.

The following disadvantages have been encountered in the use of conventional GRP splints.

First of all, the resin generally used exudes an unpleasant smell.

Secondly, the application of the resin can be messy unpleasant and dangerous. It is usual to use brushes and rollers in the application, which must afterwards be cleaned with such highly inflammable solvents as acetone.

Furthermore, if a glass fibre mat is used to reinforce the resin and this is cut to the desired shape, the release of highly irritating glass particles is not easy to avoid.

Thirdly, in addition to the safety hazards of the use of the solvent such as acetone, there is also a safety hazard from the catalysts which are used to set the resin. The catalysts are generally strong oxidising agents whose contact with skin can cause serious damage and, should they contact eyes, may cause blindness if not washed out within seconds.

Fourthly, the reaction of resin with catalysts is generally exothermic and, consequently, the GRP can become hot whilst setting. A spillage of hot resin onto the patient or animal being treated is difficult to avoid, can be painful and may even cause further injury.

Fifthly, if use is made of a conventional GRP splint to an animal in the field, it may be difficult to avoid ingress of dirt and damp which will reduce the strength of the GRP and may even prevent the resin setting. It is important for any emergency use that the GRP splint should set as quickly as possible.

If the setting time is speeded up by increasing the amount of catalyst or accelerator present, then the time during which the resin can be worked into a glass fibre reinforcing mat is also reduced and application consequently becomes more difficult.

Sixthly, the application of a conventional GRP splint is an expensive technique which requires some surgical or veterinary skill and practice.

According to a first aspect of the present invention, there is provided a flexible container containing a settable resin and reinforcement for the resin and means for enabling the resin in the container to be set when desired. Conveniently, the means for enabling the resin to be set comprises a catalyst for the resin, which catalyst is within the flexible container and is kept separate from the settable resin until it is desired to set the resin.

Thus, according to a second aspect of the present invention, there is provided a flexible container containing a settable resin, a catalyst therefor and reinforcement for the resin, the catalyst being kept separate from the settable resin until it is desired to set the resin.

If the resin is settable on exposure to light or other radiation, the enabling means may comprise at least a portion of the flexible container, which portion is transparent to the light or the other radiation. If the resin is settable on exposure to heat; the enabling means may comprise at least a portion of the flexible container, which portion is heat conductive.

According to a third aspect of the present invention, there is provided a device suitable for use in providing a splint or cast, which device comprises a flexible container containing a settable resin and reinforcement for the resin and means for enabling the resin in the container to be set when desired.

Although a device in accordance with the present invention may readily be used as a splint or cast, other uses are envisaged. Such a device may be used as a repair pack for various articles and may even be used in situations in which it is not normally possible to use GRP; thus, a device in accordance with the invention may be used as an underwater repair pack for boats or other structures.

According to a fourth aspect of the present invention, there is provided a splint or cast, which splint or cast comprises a flexible container containing a settable resin, a catalyst therefor and reinforcement for the resin, the catalyst being kept separate from the settable resin until it is desired to set the resin. It will be appreciated that such a splint may be suitable for veterinary use or, indeed, may be used in the treatment of fractures of human limbs.

Preferably, the reinforcement comprises a fibreglass mat, but may comprise any other appropriate material such as Kevlar (Registered Trade Mark) or any other suitable natural or synthetic woven or non-woven material.

The flexible container can, of course, take up the shape of the limb or any other object to which it is applied and will enable the materials therein and the unpleasant smell to be contained.

In a preferred embodiment, the catalyst is contained in one or more small containers or bags within the flexible container; the small containers or bags are suitably flexible also and are desirably such that they are strong enough to remain intact during normal handling but are readily broken or ruptured when it is required to set the resin; lightweight polyethylene bags may appropriately be used.

In another preferred embodiment, the catalyst is used in paste form as an impregnation in the reinforcement, preferably fibreglass, which is placed at one end portion of the flexible container. The resin is placed in the other end portion of the container and separated from the catalyst by a removable clip, made for example of extruded polyvinylchloride, positioned across the container. When it is desired to set the resin, the clip is removed and the resin worked down into the reinforcement containing the catalyst. Of course, the flexible container itself should be strong enough to stand up to the forces imposed during the mixing of the catalyst with the resin and should be chemically inert to the chemicals it contains. Suitable materials for the flexible container will depend on the resin and catalyst used but may include polyethylene, nylon and polytetrafluoroethylene.Advantageously, the flexible container is translucent or transparent for a purpose to be described hereinafter. The flexible container may be a heavyweight polyethylene bag closed by a heat seal, a high frequency weld or any other suitable means of closure.

The reinforcing material may comprise fibreglass, which may be in the form of a woven mat or in chopped strands. As another possibility, or even in addition, the reinforcement may comprise Courlene (Registered Trade Mark), polypropylene, nylon, Terylene (Registered Trade Mark)or any other suitable material which may be in the form of woven rovings, cloths or chopped strand mats.

The resin is preferably pre-accelerated polyester resin, but could also be, for example, a suitable epoxide or a furane. The resin may be set or cured by the action of a suitable catalyst, accelerator or hardener or by application of heat or light. The way in which the resin is set will, of course, depend on the resin itself. When fibreglass is used as the reinforcement, a resin to glass ratio of 1.1 : 1 may be found to be a suitable combination. A resin incorporating a chemical colour change means is especially preferred: such a resin changes colour during curing or setting so that the colour of the set resin is noticably different from the colour of the uncured resin.

It is at least for this reason that a translucent or transparent flexible container is preferred.

There may also be provided heat insulating means for preventing heat escaping from at least part of the flexible container. The heat insulating means preferably comprises a backing pad of felt, foam or other suitable material which may be provided on one side of the flexible container to protect the casualty from heat generated during the curing or setting reaction. Furthermore, the insulating means may act as a cushion between the casualty and the splint or cast.

For a better understanding of the present invention, and to enable the same to be put into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 shows a schematic plan view of an embodiment of the invention; Figure 2 shows a schematic sectional view taken along the line Il-Il shown in Fig. 1; Figure 3 shows a schematic plan view of another embodiment of the invention; and Figure 4 shows a schematic cross-section of the embodiment of Fig. 3, in use.

There is shown in the drawings a flexible container 1 made of a heavyweight polyethylene bag which is substantially flat. The bag can be regarded as a flattened tube having two opposed ends 1 a and 1 b which were initially open but, in the finished article as illustrated, are shown closed by respective closure means such as heat seals 2. It will be appreciated that the closure means may be any other convenient form of closure such as high frequency welds.

Within the flexible container 1, there is a sandwich of reinforcement material comprising three layers 3, 4 and 5. The lowermost layer and the uppermost layer comprise glass fibre chopped strand mats 3 and 5 whose mass per unit area is 600 g/m2. In between the glass fibre chopped strand mats 3 and 5 is a single layer of woven glass rovings 4 also having a mass per unit area of 600 g/m2.

Suitably distributed between the various layers 3, 4 and 5 of the reinforcement mate- rial are three catalyst bags 6, 7 and 8. One the catalyst bags 6 is situated between the lowermost layer 3 and the middle layer 4, whereas the remaining two catalyst bags 7 and 8 are situated between the middle layer 4 and the uppermost layer 5. Each catalyst bag is a lightweight polyethylene bag containing a suitable amount of catalyst which is to be used to catalyse the curing or setting of resin 9, which takes up the remainder of the volume in the flexible container 1. A suitable resin is S.R.L. 3504A polyester resin, the curing or setting of which may be catalysed by M.E.K.P. 50% catalyst.

A suitable size for the flexible container is approximately 14 cm X 32 cm, the shorter sides being the ends la and 1 b of the flexible container 1 which were intially opened but are now closed by means of the heat seals 2.

Each layer 3, 4 or 5 of reinforcement material is conveniently cut to approximately 13 x 30 cm so that, with the mass per unit area for each layer being 600 g/m2, the total mass of the three layers is of the order of 100 g. Each catalyst bag 6, 7 or 8 measures approximately 2 cm X 5 cm and contains approximately 5 cm3 of catalyst. 225 g of resin 9 is suitably added to the open ended flexible container 1 before it is sealed.

In Fig. 2 there can be seen an outside felt pad 10 in place adjacent to one surface of the flexible container 1. In use, this pad 10 acts as heat insulating means between the casualty and the flexible container 1, which may become warm during the setting of the resin 9.

Referring now to Figs. 3 and 4, there is shown a flexible container 11, made of a heavyweight plastics material, which is substantially flat. The container can be regarded as a flattened tube. A heat seal 12 at one end and a heat seal 13 at the other define an enclosed volume which contains resin 14 at one end and reinforcing material 15 impregnated with catalyst at the other. At least the volume containing the material 15 is divided by a further heat seal 16 and a clip 17, generally made of polyvinyl chloride, which retains the resin away from the catalyst, until the cast is to be used. In use, as shown in Fig. 4, the heat seal 16 will divide cast 18 into two portions about a limb 19, so that the cast 18 can be removed by pivoting about the heat seal 16.

Although, in an alternative embodiment, the resin may be placed with the reinforcing material and the catalyst in the separate portion at an end of the container, we have found better consistency and easier use by spreading a paste catalyst evenly through the reinforcement, and putting the resin in the end portion.

Material now preferred for the flexible container is Nylon 11; polyethylene is possible but is permeable to some of the resins and solvents that may be used, and not as strong.

Glass reinforcement is two layers of 300/150 Stitchmat cut to 200 mm X 400 mm (approximately 8" to 16") with a total weight of 150 g. ("Stitchmat" is a Trade Mark). Resin is a non-accelerated polyester resin from Resinous Chemicals, reference A/ POLIC-UP002. Resin/glass ratio preferred is 1.1 to 1 (i.e. 165 g). Accelerator is an amine-N,N Dimethly -P-Toluidene 99%.

Preferred addition of 0.25% to 2% according to conditions of use and setting time desired.

Catalyst is 10 g. of benzoyl peroxide in paste form, spread between the two layers of glass fibre. Preferred system is to place one layer of glass with woven side up, spread catalyst paste and then apply a second layer of glass with woven side up, to form a sandwich with the catalyst in the middle, and a layer of woven glass in contact with a layer of chopped strand mat.

A foam or felt pad is placed on one surface of the flexible container. This pad acts as a heat insulating means between the casualty and the flexible container which may become warm during the setting of the resin. Material preferred is 6 mm thick Vito-lene EVA foam.

The foam also makes the cast more comfortable for the casualty ("Vito-lene EVA" is a Trade Mark).

Other sizes of cast are in use with one or more layers of reinforcing material according to the size of limb or other part to be protected and the strength required.

It will be appreciated that resin and catalyst may be selected to provide the desired rate of setting.

A narrow flexible container may be used to form a "gutter" splint surrounding three sides of a fractured limb. It may be found that a single such GRP splint is strong enough and the splint can, of course, easily be removed for examination and treatment and then replaced. It is even possible, when more protection or greater strength is required, to lay a second splint over the open side left by the first splint to provide a second gutter splint.

The second splint can be applied immediately after the first and the two will not normally stick together.

A further refinement is to divide the main body of the flexible container longitudinally for example by heat sealing, and insert two or more strips of reinforcing material. This ensures that the cast can easily be removed without any possibility of having to resort to cutting, since the heat seal acts as a "hinge".

See Figs. 3 and 4. It also means that the splint or cast can readily be removed and replaced for medication, since it only needs bandaging to hold it in place to give full support.

The outer flexible container is conveniently supplied packaged in a polythene bag which also contains a standard cotton bandage for holding the splint or cast in position, so that no tools or other equipment are needed when used under emergency conditions in the field.

Detailed instructions for use of a cast similar to that shown in Figs. 3 and 4 1. Remove outer polythene packing, being careful not to cut or pierce the inner plastics material bag. If there is any liquid resin showing in the outer pack, or the inner bag is cut accidentally, it is best to reject the splint and use another. If no others are available, fold the bag to close the leak as well as possible and clean up any spillages.

You now have a long plastics material bag with a clip across, dividing it into two compartments. Keep folded at the clip. Grip the folded pack with one hand and slide the 'C'shaped part of the clip off with the other hand.

2. Unfold the bag and hold with the small section containing the resin at the top until the resin drains down into the glassfibre. Then lay on any flat surface with the foam facing downwards and work the resin backwards and forwards over the glassfibre for at least 1 minute until it appears a uniform colour all over. The discarded clip may be used to help spread the resin initially, but it is important to knead the bag thoroughly by pushing down all over with the fingers to ensure that the resin is pushed well into the glass, which is already impregnated with catalyst. The action should, therefore, be alternate spreading and kneading.

3. Apply to limb or other area requiring support. The foam backing must be towards the patient to provide a soft bed for the splint and protection from the heat of reaction which will otherwise cause discomfort. In the 5 to 10 minutes while the resin is curing, the temperature will rise. As supplied, the foam extends slightly beyond the pack in every direction to ensure that this protection is provided.

The splint or cast obtained is very strong and can normally provide sufficient support for a limb when applied as a "gutter" splint with one open side. It is important that it should not be more than half way round the limb or it will be difficult to remove and probably require cutting.

If the width of the splint available exceeds half the circumference of the limb, simply fold the edge of the container back on itself.

Similarly, the top and bottom of the splint can be folded back away from the limb. This will leave a curved foam surface, fully supported when the resin sets, which is very comfortable for the patient and greatly reduces the likelihood of ulceration.

When the surgeon requires maximum strength of a complete shield round the limb concerned, it is recommended that a second "gutter" splint should be applied from the opposite side. They will not stick to each other and there will, therefore, be no major problem in removal.

4. Hold in position using for instance elastic, crepe, or cotton bandages or adhesive bandage. The splint will begin to set within 3 or 4 minutes and it is essential that it is bandaged in position within this period. It will then set to the exact shape of the limb, providing firm but comfortable support, and should achieve sufficient strength to support the limb within 10 minutes. These times may be exceeded slightly under very cold conditions in the field. The splint is otherwise unaffected by water or outside weather conditions and is, therefore, very suitable for emergency treatment for which it was originally designed.

5. Because none of the materials used are affected by water, the splint can be removed for clinical treatment of injuries to the limb, washed if necessary, and bandaged back in position.

Removal When applied as a "gutter' '-splint as recommended, removal is straightforward. Just remove the bandages and lift off.

It is apparent that the application of a splint in accordance with the present invention to a fractured limb is an operation which does not necessarily call for great veterinary or surgical skill. Thus, such splints may be of use to farmers for first aid.

Claims (12)

1. A flexible container containing a settable resin and reinforcement for the resin and means for enabling the resin in the container to be set when desired.

2. A flexible container containing a settable resin, a catalyst therefor and reinforcement for the resin, the catalyst being kept separate from the settable resin until it is desired to set the resin.

3. A flexible container according to Claim 1 or 2, wherein the resin is settable on exposure to light or other radiation and the enabling means comprises at least a portion of the flexible container, which portion is transparent to the light or other radiation.

4. A flexible container according to Claim 1 or 2, wherein the resin is settable on exposure to heat and the enabling means comprises at least a portion of the flexible container, which portion is heat conductive.

5. A device suitable for use in providing a splint or cast, which comprises a flexible container in accordance with any one of Claims 1 to 4.

6. A device according to Claim 5, wherein the reinforcement comprises a fibreglass mat.

7. A device according to Claim 5 or 6, wherein the catalyst is used in paste form as an impregnation of the reinforcement.

8. A device according to any one of claims 5 to 7, wherein the catalyst is impregnated in the reinforcement and there is provided a division in the container so as to form two compartments containing reinforcement.

9. A device according to claim 8, wherein the resin is kept separate from the catalyst until required to be mixed therewith by a clip encompassing the container.

10. A device according to claim 8 or 9, wherein the division is formed by a heat seal between opposing surfaces of the container, which is made of plastics material.

11. A device substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

12. Any novel feature or combination of features disclosed herein.