The current invention concerns a plaster bandage and/or orthosis, specifically a plaster bandage and/or orthosis manufactured in a polymeric foam.

State of the art

CA 1 ,167,341 describes a plaster bandage manufactured in situ through the reaction and foaming up of a polyurethane prepolymer composition applied to a bandage, immediately before the application of the plaster bandage to the to be immobilized limb.

The disadvantage of such a plaster bandage is that for in situ manufacturing, the polyurethane prepolymer composition has to be applied and subsequently foamed by, for instance, the application of water. Such a labor-intensive application demands a relatively large level of accuracy from the nursing staff and requires continuous cleaning of the working surface on which the plaster bandage is constructed.

US 8,100,843 describes a preformed plaster bandage made from a polymeric shape memory foam. This plaster bandage is manufactured in an initial form with a diameter smaller than the diameter of the limb to be immobilized. Subsequently, the plaster bandage is heated to a temperature higher than the glass transition temperature of the polymeric shape memory foam, after which the plaster bandage is reshaped into a temporary form with a diameter larger that the diameter of the limb to be immobilized. The plaster bandage is cooled in this temporary shape to under the glass transition temperature of the polymeric shape memory foam and is thereby fixed in this temporary shape.

The plaster bandage is applied to the limb to be immobilized in this temporary shape and subsequently heated until above the aforementioned glass transition temperature, causing the polymeric shape memory foam to return to said intial form and to tighten around the limb to be immobilized. Finally, the plaster bandage is cooled again until below the glass transition temperature of the polymeric shape memory foam and the polymeric shape memory foam is fixed to a correct fitting, offering the required support for the limb to be immobilized.

A disadvantage of a plaster bandage according to US 8,100,843 is that the method for application is relatively complex and time consuming, due to the repeated heating and cooling procedure.

The current invention aims to offer a solution to the aforementioned disadvantages.

Summary of the invention

The current invention concerns a plaster bandage and/or orthosis manufactured in a polymeric foam, whereby the polymeric foam has a Tg of minimum 60°C and an elongation at break of at least 25 % at a temperature Ta = Tg-20°C.

The current invention also concerns a plaster bandage and/or orthosis manufactured in a polymeric foam, whereby the polymeric foam has a Tg of minimum 60°C and an elongation at of at least 25% at a temperature Ta = Tg-10°C.

Ideally, the polymeric foam has an E-modulus < 1000 kPa at a temperature Ta.

Also preferred the polymeric foam has a density of between 50 and 250 kg/m3, more preferably of between of 70 and 130 kg/m3.

In accordance with a preferred application method the polymeric foam is a so- called shape memory foam, in particular a polyisocyanate based or polyurethane foam.

The polymeric foam is ideally thermoset foam. The current invention also refers to a method of application of the aforementioned plaster bandage and/or the aforementioned orthosis to the human or animal limb to be immobilized, whereby the method of application comprises the steps of:

a) providing of a plaster bandage and/or orthosis made from polymeric foam; b) heating of the polymeric foam to a minimum temperature Ta = Tg-20°C; c) applying of a plaster bandage and/or orthosis around a limb to be immobilized at a minimum temperature Ta;

d) cooling of the polymeric foam to a temperature lower than Ta.

Detailed description of the preferred application method Definitions

The glass transition temperature (Tg) of a polymer marks the transition of a polymer from a hard, relatively brittle state (glassy state) to a softer rubbery state in which the polymer demonstrates a certain level of elasticity. Tangibly, this transition should be considered as a temperature zone, whereby for clarity the stated Tg values are defined by the loss modulus of the polymer according to the Dynamic Mechanical Analysis (DMA) (ASTM D7028-07e1 - standard test method for DMA Tg)).

Shape memory foam is defined as a polymeric foam with shape memory, whereby elasticity shows a sharp decline at Tg (glass transition temperature). At a temperature T > Tg it has a tendency to return to its primary form (micro- Brownian movement).

Thermoset is a term indicating the binding of individual chains in the polymeric foam by covalent bonds (cross-links).

Elongation at break is the parameter indicating the extent to which the polymeric foam can be stretched before a break occurs. This is determined according to ISO 1798. The E-modulus is a parameter, which indicates the relationship between the stress and the strain of the material. This parameter is used to characterize the stiffness of a material. As mentioned above, this parameter is dependent on temperature. The E-modulus is determined according to ISO 1798.

A plaster bandage according to the present invention primarily consists of a predefined three-dimensional form, formed of a polymeric foam, preferably a polyisocyanate based or polyurethane polymeric shape memory foam, whereby the polymeric foam according to the invention is characterized by a Tg of minimum 60°C and an elongation at break of at least 25% at a temperature Ta which equals Tg-20°C or equals Tg-10°C. The tensile strength of the polymeric foam at a temperature Ta is preferably < 150 kPa.

The polymeric foam has preferably a density of between 50 and 250 kg/m3, or ideally a density of between 70 and 130 kg/m3.

The polymeric foam is preferably a thermoset foam.

In its initial state the three-dimensional form of the plaster bandage defines a cavity with an internal diameter smaller than the external diameter of the limb to be immobilized limb (for instance a forearm). By heating the plaster bandage to a temperature equal to or above Ta, the plaster bandage can be shaped, or more specific be stretched as well in the longitudinal direction as in the direction of the diameter, whereby the plaster bandage can be applied smoothly and without pain for the patient around the limb to be immobilized.

By manufacturing the plaster bandage in a polymeric foam with an E-modulus of maximum 1000 kPa, preferably maximum 700 kPa at a temperature of Ta, the plaster bandage can be shaped manually. The average person can exert a force of circa 2N.

This means that a polymeric foam with a Tg = 60°C and an E-modulus of maximum 1000 kPa, preferably maximum 700 kPa, at Ta, can be sufficiently stretched by an average person to enlarge the internal diameter to such an extent that it can be applied with ease to the limb to be immobilized. Besides increasing the internal diameter of the plaster bandage, the polymeric foam of this invention also allows a person to stretch the plaster bandage in a longitudinal direction, allowing it to be slided over the relevant limb and limiting the wall thickness and the weight of the plaster bandage to a minimum.

Damage to the plaster bandage by stretching is prevented by the relatively high elongation at of the polymeric foam at temperature Ta.

The aforementioned characteristics of the polymeric foam consequently allow an application of the plaster bandage at a temperature of Ta, without the need to freeze it in its stretched state by cooling to a temperature below Ta, prior to application. This facilitates a quick and easy application of the plaster bandage.

At room temperature the E-modulus of polymeric foam is preferably minimum 5000 kPa, preferably minimum 7000 kPa, whereby the plaster bandage offers sufficient support and immobilization to the limb to be immobilized limb and thereby preventing accidental deformation of the plaster bandage.

The plaster bandage or the orthosis of this invention can be easily manufactured by pouring a reactive mixture into a negative mold, whereafter the mixture is allowed to harden in its initial shape to form the polymeric shape memory foam. This initial shape is also the shape to which the plaster bandage will return after reshaping at a temperature above Tg.

After manufacture, the plaster bandage or orthosis can be applied to a limb to be immobilized according to the following method: (a) heating the plaster bandage or orthosis and in particular the polymeric shape memory foam to a temperature Ta or to a temperature above Ta ; (b) reshaping (widening or stretching) of the polymeric shape memory foam; (c) applying the plaster bandage or orthosis over the limb to be immobilized (whether or not at the same time as step (b)); (d) cooling the polymeric foam to a temperature lower than Ta.

Upon cooling, the polymeric shape memory foam will return to its initial shape and as such will tightly fit around the limb to be immobilized. If necessary, the plaster bandage can be further reshaped manually after application and prior to cooling, for instance, to achieve an even better fit and provide more comfort around the limb.

An added advantage of the plaster bandage or the orthosis of this invention is the possibility to reheat the bandage, after cooling below temperature Ta, to a temperature above temperature Ta, whereby the plaster bandage or the orthosis can be reshaped manually. This may be required to achieve a new better fit for the immobilization of the limb, for instance after a reduction of the initial swollen state wherein the limb was first immobilized.

The removal of the plaster bandage or the orthosis can also be easily and quickly achieved by heating the plaster bandage or the orthosis to a temperature equal to or higher than Ta.

In an alternative embodiment the plaster bandage or the orthosis contains a padding layer applied to the inside (cavity) of the plaster bandage or the orthosis. In this case the paddinglayer provides a contact layer between the plaster bandage or the orthosis and the skin of the limb to be immobilized. This padding layer can also be applied to the limb to be immobilized prior to the application of the plaster bandage or orthosis. The padding layer can contain any material, e.g. natural fibers, synthetic fibers, synthetic foams, (PE, PVC, PU...), rubber, woven or non-woven synthetic fabric, 3D textile, etc. These materials may contain anti-microbial additives, or phase change materials, odor adsorbing additives, active wound care substances, water absorbing particles, heat reflecting pigments. The padding layer can consist of one or more layers, the layers made of any of the materials above mentioned or a combination thereof. The padding layer may function as a comfort layer to relieve pressure points, or as a heat barrier between the plaster and the limb during the heating step which is required for application of the plaster (or similarly for reshaping or removal of the plaster). It can be preformed according to the form of the limb, either or not with a thumb protector. For easy application around, it is preferably made of a stretchable material.

The current invention is by no means limited to the manifestation of the plaster bandage or orthosis described above, nor to the described method for application of such plaster bandage or such orthosis and can be achieved through a variety of methods without falling outside the scope of this invention.