Which of the following instructions is most important for a patient who has just had an arm cast applied?

Casts and splints are orthopedic devices that are used to protect and support broken or injured bones and joints. They help to immobilize the injured limb to keep the bone in place until it fully heals.

Casts differ from splints because they provide more support and protection for a limb that is injured or broken. They are made from materials like plaster or fiberglass that can be easily molded to the shape of the injured arm or leg.

Splints, also known as half-casts, provide less support than casts, but are faster and easier to use. They also can be tightened or loosened easily if the swelling in the arm or leg increases or decreases.

Ready-made or off-the-shelf splints are available in many different sizes and shapes. In some cases, custom-designed splints must be used. Velcro straps make it easier for the patient or healthcare provider to put the splint on or take it off.

When are casts and splints used?

Casts and splints are used when a bone is broken. They can also be used following orthopedic surgery. Sometimes splints are used immediately following an injury due to swelling of the affected area. After the swelling goes down, then a full cast might be applied to the injured limb.

A cast might have to be replaced during the healing process if the injured area becomes less swollen and the cast gets looser. In that case, the cast might be replaced with a splint to provide more freedom of movement.

What types of casts and splints are available?

Casts are partly made from fiberglass or plaster, which form the hard layer that protects the injured limb and keeps it immobilized.

Fiberglass has several advantages compared to plaster. It weighs less, so the cast made from it will be lighter. More durable and porous, fiberglass allows air to flow in and out. Fiberglass is the better choice in case the limb must be X-rayed during the healing process. It is also available in a variety of colors.

Plaster costs less than fiberglass and is more malleable (is more easily shaped) than fiberglass in certain cases.

How is plaster and fiberglass casting done?

Before the casting material is applied, a stockinette is placed around the area that will be covered by the cast. Afterwards a layer of padding made of cotton or another soft material (Webril®) is rolled on to further protect the skin. The padding also provides elastic pressure to help healing.

Plaster comes in strips or rolls that are moistened and rolled on over the padding. Plaster materials are made from dry muslin that is treated with starch or dextrose and calcium sulfate.

After the process of applying the casting material is completed, the material will start to dry in about 10 to 15 minutes. The temperature of the skin might rise as the plaster is drying because of a chemical reaction that occurs. When plaster is used, it can take from 1 to 2 days for the cast to harden completely. The patient must be careful during this period because the plaster might break or crack while it is hardening. The cast will appear smooth and white after it hardens.

Like plaster, fiberglass materials come in rolls. Strips are moistened and applied to form the cast. The cast will appear rough after it has dried.

How do you relieve pain and swelling after the cast or splint is applied?

• Keep the injured arm or leg elevated for 1 to 3 days after the cast or splint is applied. The injured limb should be in a position higher than your heart to allow fluids to drain.
• Apply ice to the cast or splint at the site of the injury. The ice should be placed in an ice pack or a plastic bag to avoid direct contact with the cast or splint.

What are some tips for taking care of the cast?

• Avoid placing pressure or weight on the cast. If you have a leg injury and have a walking cast, make sure that the cast has hardened completely before you attempt to walk on it.
• Keep the cast clean and dry. A hair dryer with a cool setting may be used to dry a fiberglass cast if it becomes damp. Call your doctor if the cast does not dry or if the skin under the cast becomes wet.
• Cover or wrap the cast with a plastic bag before you take a shower or bath. Cast covers made from plastic with Velcro straps or rubber gaskets are sold at some medical supply stores or drug stores.
• Do not place any objects inside the cast. Avoid using lotions or powders on skin underneath the cast.
• Don’t attempt to scratch itchy skin under the cast with a sharp object. This might result in an infection if the skin is cut or broken.
• Call the doctor if you notice a strange or unpleasant smell coming from the cast. Perspiration or moisture under the cast can cause mold or mildew to grow. The skin can break down and become infected if it remains wet for a long time.
• Do not trim, file or break off rough areas around the edge of a plaster cast. A metal file may be used to smooth the rough edges of a fiberglass cast.
• Do not try to remove the cast yourself.

How are casts and splints removed?

Your doctor will remove the cast with a special cast saw when the bone has healed sufficiently. The cast saw has a flat, rounded metal blade that vibrates. It can cut through the cast without injuring the skin underneath. The doctor will cut the cast in several places, usually along both sides of the cast. The cast is then spread and opened and a special tool is used to lift it off. Scissors are used to cut through the protective padding and stockinette layers which then are removed.

What are some complications associated with casts and splints?

Complications can range from minor to severe and may vary according to the length of time that the cast is worn.

Pressure sores: A sore may develop on the skin under the cast. This can happen because the cast was too tight or did not fit correctly, causing excess pressure on one area.

Compartment syndrome: This is a major complication caused by a tight or rigid cast that constricts a swollen limb. When the pressure inside the cast builds up, it can cause damage to the muscles, nerves or blood vessels in the area covered by the cast. The damage may be permanent if it is not discovered and treated promptly. Call your doctor or visit the emergency room immediately if you notice any of the following symptoms.

• Numbness or tingling in the affected limb.
• Cold or pale skin or skin with a bluish tinge.
• Burning or stinging.
• Increased pain or swelling.