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::Orthopedic cast

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File:Fibreglass leg cast.JPG
Full-length leg cast with fibreglass top layer being used to immobilise a fractured leg. The cast shoe is used to aid weight bearing with the aid of crutches.

An orthopedic cast, body cast, plaster cast, or surgical cast, is a shell, frequently made from plaster, encasing a limb (or, in some cases, large portions of the body) to stabilize and hold anatomical structures, most often a broken bone (or bones), in place until healing is confirmed. It is similar in function to a splint.

Plaster bandages consist of a cotton bandage that has been combined with plaster of paris, which hardens after it has been made wet. Plaster of Paris is calcined gypsum (roasted gypsum), ground to a fine powder by milling. When water is added, the more soluble form of calcium sulfate returns to the relatively insoluble form, and heat is produced.

2 (CaSO4·½ H2O) + 3 H2O → 2 (CaSO4.2H2O) + Heat<ref name="equation">{{#invoke:citation/CS1|citation

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The setting of unmodified plaster starts about 10 minutes after mixing and is complete in about 45 minutes; however, the cast is not fully dry for 72 hours.<ref name="Schmidt">{{#invoke:Citation/CS1|citation |CitationClass=journal }}</ref>

Nowadays bandages of synthetic materials are often used, often knitted fiberglass bandages impregnated with polyurethane, sometimes bandages of thermoplastic. These are lighter and dry much faster than plaster bandages. However, plaster can be more easily moulded to make a snug and therefore more comfortable fit. In addition, plaster is much smoother and does not snag clothing or abrade the skin.<ref name=adkins>{{#invoke:Citation/CS1|citation |CitationClass=journal }}</ref>

An orange short arm cast with a fiberglass top layer being cut and removed with a specialized cast saw.

Orthopedic cast sections
Intro  History  Limitations of plaster casts  Cast types  Cast-cutting  See also  References  External links  

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