Orthopedic casting

Orthopedic cast
A short leg cast with a fibreglass top layer being used to treat a fractured foot.
Synonyms	Body casts, plaster cast, surgical cast
[]

An orthopedic cast, or simply cast, is a shell, frequently made from plaster or fiberglass, 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.

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.

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.

Due to the nature of the dressing in that the limb is unreachable during treatment; the skin under the plaster becomes dry and scaly because the discarded outer skin cells are not washed or brushed off. Also, plaster of Paris casts can result in cutaneous complications including macerations, ulcerations, infections, rashes, itching, burns, and allergic contact dermatitis, which may also be due to the presence of formaldehyde within the plaster bandages. In hot weather, staphylococcal infection of the hair follicles and sweat glands can lead to severe and painful dermatitis.