Normally, fractured bones or joints are immobilised during the healing process by applying a cast of plaster of Paris or a polymer material. This has the disadvantage that the fracture is completely immobilised for the time that the cast is applied, leading to muscle wasting and a long rehabilitation time. Also, because the cast sets permanently, the fractured bones cannot be adjusted once the cast has been applied and nor can any wound or dressing readily be inspected. A plaster of Paris cast is also applied wet, which may lead to sterility problems. Finally, such casts are generally heavy.

It is an object of the present invention to provide a splinting device that mitigates at least some of the aforementioned disadvantages.

According to the present invention there is provided a splinting device comprising a flexible envelope, a filling of a thermoplastic material that has a solid-liquid phase change temperature in the range 30C to 70C and means for heating the filling to the phase change temperature. Advantageously, the phase change temperature lies in the range 40C to 60C and is preferably approximately SOC.

Advantageously, at temperatures above the phase change temperature, the thermoplastic material is thixotropic.

Advantageously, the envelope comprises a plastics bag.

Advantageously, the heating means includes an electrical heating device.

Advantageously, the electrical heating device is contained within the envelope. The electrical heating device may comprise an electrical element or, alternatively, it may include a plurality of electrodes, for passing an electrical current through the thermoplastic material to cause ohmic heating thereof.

The invention provides the following advantages:

-the device is lightweight; -it is applied dry, giving improved sterility; -it is very easy to apply and remove; -the thermoplastics material has a fast solidification time; -because the material can change phase repeatedly, the fracture can be adjusted after solidification; -rehabilitation time is reduced; -the device can be removed to permit dressing and wound inspection; -the material is radioleucent, permitting X-ray, CT and MRI scanning; -the device is re-usable; and -treatment using the device is entirely non-invasive.

Use of the device also reduces the period of joint restriction, allows for alignment changes in long healing periods and provides for early mobilisation.

An embodiment of the invention will now be described, by way of example, with reference to the accompany drawings, in which: Figure 1 is a plan view of the splinting device laid flat; Figure 2 is a perspective view of the splinting device set in a U-shaped form.

Figure 3 is a section on line 111-111; and An example of a splinting device is shown in Figures 1 and 2. The splinting device 1 includes an envelope 2 in the form of a closed plastics bag having two substantially square sides 3 that are sealed to one another around their four edges 4. The envelope 2 contains a filling 5 of thermoplastics material that changes phase from a solid to a liquid at a temperature in the range 30C to 70C, advantageously 40C to 60C and preferably approximately SOC. This thermoplastics material 5 may, for example, be

the product sold under the trade mark THERMAPHASE Grade FSF-52, manufactured by Orcus Inc. This material has a phase change temperature of 52C, above which the material is in the form of a thixotropic liquid.

The envelope 2 also contains an electrical heating element 6, shown in Figure 1 in broken lines, for heating the thermoplastics filling 5 to the phase change temperature.

This element 6 is connected to a pair of electric terminals 7 provided on the outer surface of the envelope 2 Current may be supplied through the terminals 7 to the heating element 6 from a suitable AC or DC power source.

Alternatively, the thermoplastics filling 5 may be heated by passing a current directly through the thermoplastics material (providing that the material is electrically conductive). A pair of electrodes may be provided within the envelope, through which a potential difference may be applied across the thermoplastics medium. These electrodes may, for example, be formed on the inside faces of the sides 3.

Alternatively, a non-electrical heating means may be provided: for example, the device may contain chemicals for generating heat by means of an exothermic chemical reaction. An external heating source may also be used.

In use, a current is supplied through the heating element 6 to heat the thermoplastics filling 5 to the phase change temperature. At this temperature, the thermoplastics filling changes state to a thixotropic liquid that can be moulded to any desired shape.

Traction is applied to align the fractured bones correctly and the heated splinting device is then applied to the site of the fracture and moulded into shape. For example, in the case of a broken forearm, the splinting device 1 may be wrapped around the arm in a U-shaped form, as shown in Figure 3. The current is then switched off, allowing the thermoplastics filling to cool and re-solidify, after which traction can be released. The splinting device 1 acts in the same way as a plaster of Paris cast to retain the fractured bones in correct alignment and to protect them during the healing process.

One major advantage of the device is that the thermoplastics material can be softened whenever necessary to correct the alignment of the bones, to check any wound or

dressing, and to allow manipulation of the joints and exercise of the muscles. Muscle wastage can thus be reduced and rehabilitation time can be shortened considerably.

The splinting device is very lightweight and more comfortable than a traditional plaster of Paris cast. It is applied dry, ensuring sterility. The materials are also radioleucent permitting the use of X-rays, CT or MRI scanning. The splinting device is also completely re-usable.

Various modifications of the invention are possible. For example, the splinting device may take various different forms and shapes for use at different fracture sites, for example on the upper limbs, lower limbs and wrist joints. They may also be manufactured in different sizes for use on adults or children. The device may also be printed with an attractive design or, for children, cartoon characters.