Casting material

Details Casting material Casting material

2002-01-22

2004-08-24

Lucchesi, Nicholas D. (Department: 3624)

Surgery: splint, brace, or bandage

Orthopedic bandage

Splint or brace

C602S006000

Reexamination Certificate

active

06780162

ABSTRACT:

This application is a national stage application, according to Chapter I of the Patent Cooperation Treaty. This application claims the priority date of Jan. 10, 2000 for Great Britain Patent Application No. 0000331.9.
BACKGROUND OF THE INVENTION
This invention relates to the field of orthopaedic medicine and more specifically to an improved medical bandage formed of a moisture curable resin and a flexible permeable substrate, a method of manufacture of such a medical bandaging product, and a bandaging system comprising such a bandage within a moisture impervious package with means for resealing the package against entry of moisture.
Medical bandages for use in the treatment of injuries, such as broken bones requiring immobilisation of a body part, are generally formed from a strip of fabric or scrim material impregnated with a substance that hardens into a rigid structure after the strip has been wrapped around the body member. The hardening substance traditionally used in carrying out this procedure is Plaster of Paris.
Conventional practice has been to fabricate or splint upon an injured limb by initially applying to the limb a protective covering of a cotton fabric or the like and then overwrapping the covering and limb with a woven cloth impregnated with Plaster of Paris which has been wetted by dipping in water immediately prior to application. This is still in widespread use but possesses several significant disadvantages. For example, the above described application procedure is messy and time consuming. Several components are required and considerable skill is necessary.
In order to alleviate the above-recited disadvantages of the application procedure for Plaster of Paris casts and splints, unitary splinting materials have been devised and are disclosed in, for example, U.S. Pat. Nos. 3,900,024, 3,923,049 and 4,235,228.
All of these patents describe a padding material with a plurality of layers of Plaster of Paris impregnated cloth.
Such unitary splinting materials are not as messy and can be applied more quickly but still suffer from a number of disadvantages inherent in Plaster of Paris materials.
All Plaster of Paris splints have a relatively low strength to weight ratio, which results in a finished splint that is very heavy and bulky.
Plaster of Paris splints are slow to harden, requiring 24 to 72 hours to reach maximum strength. Since Plaster of Paris breaks down in water, bathing and showering are difficult.
Even if wetting due to these causes can be avoided, perspiration over an extended period can break down the Plaster of Paris and create a significant problem with odour and itching.
A significant advance in the art of casting and splinting is disclosed in U.S. Pat. Nos. 4,411,262 and 4,502,479.
The casting materials disclosed in these patents comprise a flexible fabric impregnated with a moisture curing resin enclosed in a moisture free, moisture impervious package.
Compared to Plaster of Paris, these products are extremely lightweight, have a very high strength to weight ratio and can be made relatively porous, permitting a flow of air through the casting material.
Prior art moisture curing systems included a package within which is contained a plurality of layers of fabric, such as fibreglass, impregnated with a moisture curing resin.
No provision is made for re-closing the package, so that the entire material must be very quickly used after removal from the package since such moisture curing resins will cure in a relatively short period due merely to contact with atmospheric moisture.
This technology has permitted the development of lightweight, easy to apply splints, as exemplified in U.S. Pat. Nos. 4,770,299, 4,869,049, 4,899,738, 5,003,970 and 5,415,622. Such splints now dominate the market for medical splints.
However, known fabrics have the disadvantage that, if the fabric, e.g. fibreglass, is cut this may leave cut fibres and yarns projecting from the splinting material.
As manufactured, this fabric is relatively soft and flexible, and has relatively good conformability. Moreover, the substrate is fully enclosed with the surrounding padding material.
After curing, however, the cut fibres and yarns become hard and needle-like. These projections can project through the thickness of the padding material into contact with the skin of the patient causing skin-sticks, cuts, irritation and itching.
Moreover, the splinting manufacturing process utilising flat fabric is relatively labour intensive since the fabric must be overlaid with other layers of fabric, usually 4 to 8, to produce the substrate. In order to properly form the substrate, the overlaid layers must be carefully aligned so that the width and thickness are even.
In instances where the multiple overlaid layers are stitched together, even more labour is required. Such multi-layered fabrics tend to be bulky and may require a high proportion of resin, further adding to the weight of the finished product. Several layers can mean the product is difficult to handle, whereby each additional layer may reduce flexibility.
Most fabrics used for the substrates of casting and splinting materials are knitted fabrics, as these are inexpensive and readily available. However, knitted fabrics have the disadvantage that there may be limited width-ways conformability
Knitted products may also suffer from the disadvantage of having limited torsional stiffness and directionally specific properties, which can be important for the treatment of specific injuries.
Linear fabrics of knitted orthopaedic products often require a relatively large amount of hardening agent, typically 40% by weight of the total weight.
From the above discussion, it can be seen that both the conventional Plaster of Paris casting method and the more recent moisture curable resin casting method possess both advantages and disadvantages.
On the one hand, Plaster of Paris casts are bulky, heavy and difficult to apply whereas moisture curable resin casts are lightweight, durable and relatively easy to apply.
Plaster of Paris can be very easily stored and used as needed since it has a relatively long shelf life so long as it is not completely wetted.
On the other hand, the moisture curable resins are very sensitive to the presence of even minute amounts of moisture, which requires that either the material be packaged in a wide variety of different shapes and sizes or unused portions be discarded, generating a substantial amount of waste and increasing the effective cost of the product.
BRIEF SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to provide a bandaging product that has a substrate that is uniform in dimension without the requirement for additional fabrication steps after formation of the substrate.
It is an object of the invention to provide a bandaging product that has a braided or tubular substrate that does not require additional layers for strength.
It is an object of the invention to provide a bandaging product that utilises a tubular braided fabric structure as a bandaging substrate.
It is also an object of the invention to provide a bandaging product that combines the advantages of both Plaster of Paris and moisture curable resin systems while avoiding their respective disadvantages.
Thus, according to a first aspect of the present invention there is provided a medical bandaging product having a moisture curable hardening agent and a flexible liquid-permeable substrate wherein the flexible liquid permeable substrate is a braided and/or tubular fabric.
In one embodiment, the substrate will carry the hardening agent in and/or on its structure, ready for easy curing and application.
Surprisingly it has been found that the use of a braided and/or tubular fabric for the flexible permeable substrate of a bandaging product gave a product that prior to curing or hardening is easy to handle with good conformability but which after curing gives a rigid strong orthopaedic product.
This gives an orthopaedic product, such as a casting or splinting product that is stronger and wears better against abrasions, than the

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