A cast holds a broken bone in place as it heals. Casts also help to prevent or decrease muscle contractions, and are effective at providing immobilization, especially after surgery. Casts immobilize the joint above and the joint below the area that is to be kept straight and without motion. For example, a child with a forearm fracture will have a long arm cast to immobilize the wrist and elbow joints.
Casts are made of fiberglass that comes in a variety of colors or plaster of paris. Cotton and other synthetic materials are used to line the inside of the cast to make it soft and to provide padding around bony areas, such as the wrist or elbow. Special waterproof cast liners may be used under a fiberglass cast, allowing the child to get the cast wet. Consult your child's doctor for special cast care instructions for this type of cast.
Fiberglass--comes in a variety of colors, patterns, and designs. Cotton and other synthetic materials are used to line the inside of the cast to make it soft and to provide padding around bony areas, such as the wrist or elbow. Special waterproof cast liners may be used under a fiberglass cast, allowing the child to get the cast wet. Consult your child's doctor for special cast care instructions for this type of cast.
A plaster of paris cast is made from rolls or pieces of dry muslin that have starch or dextrose and calcium sulphate added.
When the plaster gets wet, a chemical reaction happens (between the water and the calcium sulphate) that produces heat and eventually causes the plaster to set, or get hard, when it dries. A person can usually feel the cast getting warm on the skin from this chemical reaction as it sets. The temperature of the water used to wet the plaster affects the rate at which the cast sets. When colder water is used, it takes longer for the plaster to set, and a smaller amount of heat is produced from the chemical reaction.
Plaster casts are usually smooth and white.
Fiberglass casts are also applied starting from a roll that gets wet. After the roll gets wet, it is rolled on to form the cast. Fiberglass casts also get warm and harden as they dry. Fiberglass casts are rough on the outside and look like a weave when they dry.