MATERIALS

Plaster of Paris bandage

Plaster of Paris bandage is available in a ready-made form or is prepared locally.

To prepare plaster of Paris bandage, use dry cotton gauze (muslin) bandage, 500 cm long and 15 cm wide. Unroll a portion of the bandage on a dry table with a smooth top and apply plaster powder (anhydrous calcium sulfate or gypsum) evenly to the surface (Figure 17.21).

Figure 17.21

Gently but firmly rub the powder into the mesh of the cotton and carefully roll up the powdered portion. Begin the same process with the next section until the entire roll has been powdered. The plaster bandage can be used immediately or stored in a dry place for future use.

Fibreglass

Fibreglass cast and splint material is available from suppliers in ready-made rolls. It is lighter than plaster and resistant to water, but is more difficult to remove and is more expensive.

CAST APPLICATION

1	Clean the skin and apply dressings to any wounds. If available, apply stockinet to the extremity, avoiding wrinkles. Next, apply a uniform thickness of cotton padding over the stockinet and put extra padding over any bony prominence such as the patella, the elbow or the ankle (Figure 17.22).
Figure 17.22
2	Soak the plaster roll in a pail containing water at room temperature. Do not use warm water as the heat given off by the plaster as it sets may burn the patient. Leave the plaster in the water until it is completely soaked and the air bubbles cease to rise.
3	Gently pick up the ends of the bandage with both hands and lightly squeeze it, pushing the ends together without twisting or wringing (Figure 17.23).
Figure 17.23
4	While applying the plaster, hold the relevant part of the body steady in the correct position. Movement will cause ridges to form on the inside of the plaster. Work rapidly and without interruption, rubbing each layer firmly with the palm so that the plaster forms a homogenous mass rather than discrete layers.
5	Apply the plaster by unrolling the bandage as it rests on the limb. Do not lift it up from the patient or apply tension to the roll. Overlap the previous layer of plaster by about half the width of the roll (Figure 17.24).
Figure 17.24
6	Mould the plaster evenly around the bony prominences and contours. Leave 3 cm of padding at the upper and lower margins of the cast to protect the skin from irritation by the edge of the cast. This can be folded back over the edge and incorporated in the last layer of plaster to provide a smooth edge (Figure 17.25).
Figure 17.25
7	Mould the cast until the plaster sets and becomes firm. Complete drying takes 24 hours so advise the patient to take care not to dent the cast or apply weight to it during this time.
8	The technique for application of a fibreglass cast is similar, but the fibreglass is slightly elastic and will contour to the body more easily. It sets firmly in about 30 minutes and will not be affected by water after that time.

SPLINT APPLICATION

1	Measure the length of material needed to secure the limb. Place 3–5 layers of the measured padding on a flat surface and unroll 5–10 layers of plaster on to the padding (Figure 17.26).
Figure 17.26
2	Grasp the plaster layer at each end, dip into the water and gently squeeze together without twisting. Place the wet plaster on the padding and smooth with the palm into a homogeneous layer.
3	Place the splint on the extremity, with the padding side toward the patient, mould it to the limb contours and secure with an elastic bandage or gauze wrap (Figure 17.27).
Figure 17.27
4	An alternative method is to split a circular cast lengthwise, remove the anterior half and secure it similarly with an elastic bandage.

Patient instructions

Give oral and written instructions to the patient and/or to accompanying relatives or other attendants. Give the instructions in non-technical language that the patient can understand, as in the example below.

REMOVING A CAST

Remove the cast with an oscillating electric cast saw, if available, or with plaster shears (Figure 17.28).

Figure 17.28
1	Make two cuts along opposing surfaces of the cast, avoiding areas where the bone is prominent. Begin cutting at an edge, then loosen the cast with a plaster spreader (Figure 17.29).
Figure 17.29
2	Complete the division of the plaster and the padding with plaster scissors, being careful not to injure the underlying skin (Figure 17.30).
Figure 17.30
3	Under difficult conditions, or if the patient is a child, soften the plaster by soaking it in water, or water with vinegar added, for 10–15 minutes and then remove it like a bandage.

Complications

Most problems are caused by improper initial application of the cast.

Pressure sores
Pressure sores result from skin necrosis caused by localized pressure from the inner aspect of the cast. They occur over prominent bony areas, from ridges formed in the plaster during improper application and from foreign bodies placed under the cast. Common sites are:

Areas under pressure begin as painful spots but, if ignored, the underlying skin becomes anaesthetic as an open wound develops. Drainage on the cast follows, often with a foul smelling odour. Treat pressure sores as follows.

1	Put on a new cast or cut a window in the plaster at the suspected site (Figure 17.31). If there is ulceration, clean the wound and treat with dressing changes.
Figure 17.31
2	Fill the hole in the cast with padding and replace the plaster window. Hold the plaster in place with a firm bandage (Figure 17.32).
Figure 17.32

Skin blistering

The skin under the plaster becomes dry and scaly because the discarded epithelium is not washed off. Rarely, the skin is susceptible to plaster or fibreglass allergy and dermatitis develops. In hot weather, staphylococcal infection of the hair follicles and sweat glands can lead to a severe painful and purulent dermatitis.

Antihistamines, systemic antibiotics and elevation of the limb should relieve the symptoms within 48 hours. In severe cases, or if there is no improvement, use another method to treat the fracture.

Typical casts and splints
• Figure 17.33: Short arm thumb spica cast
• Figure 17.34: Long arm cast
• Figure 17.35: Short leg patella tendon bearing cast
• Figure 17.36: Cylinder cast
• Figure 17.37: Hip spica cast
• Figure 17.38: Minerva jacket
• Figure 17.39: Sugartong splint
• Figure 17.40: 3-way ankle splint

Figure 17.33

Figure 17.34

Figure 17.35

Figure 17.36

Figure 17.37

Figure 17.38

Figure 17.39

Figure 17.40