Casts

What is a cast?

A cast firmly holds a part of your body in place. Healthcare providers use casts to stabilize and protect your body after an injury.

Healthcare providers refer to wearing a cast as a form of immobilization — it prevents that part of your body from moving. Unlike splints, you can’t take a cast off or adjust it while you’re wearing it.

Which injuries require wearing a cast?

Casts are most commonly used to hold a part of your body in place while you’re healing after a bone fracture (a broken bone). You might need a cast after other injuries or some types of orthopaedic surgery, too, but that’s much less common.

Your provider will custom-fit a cast to the part of your body that has a broken bone, including your:

• Arm or elbow.
• Wrist and hand.
• Leg or knee.
• Ankle.
• Foot.

Types of casts

There are two types of casts — fiberglass and plaster. Fiberglass casts are more common. Fiberglass is lighter and more durable than plaster. It’s also porous (not airtight) so air can get through it, which can make wearing a cast more comfortable. You might be able to choose a specific color if you need a fiberglass cast.

Plaster is easier to work with and form to your body’s shape, but most providers use fiberglass these days. You might need a plaster cast if you experience a displaced fracture (your broken bone is pushed out of its usual place). Plaster can sometimes be better than fiberglass because it’s easier to mold around your bone, but it’s still less common.

What happens before a cast is applied?

Before a healthcare provider puts a cast on your body around the broken bone, they’ll examine your injuries. They’ll also set (realign) your bone to make sure it heals back together correctly. Depending on which type of fracture you experience, you might need a closed reduction or surgery to set your bone.

During a closed reduction, your provider will physically push and pull your body on the outside to line up your broken bones on the inside. They’ll give you a type of anesthesia to make sure you don’t feel pain during the closed reduction.

The most severe fractures need surgery. The most common type of bone fracture surgery is internal fixation. Your surgeon will insert pieces of metal into your bone to hold it in place while it heals. They’ll give you general anesthesia so you sleep through the surgery.

Your provider will put a cast on once they’ve set your bone and it’s safe to immobilize it.

How is a cast applied?

A healthcare provider will apply a cast to your body in layers:

• They’ll put a layer of soft, stretchy fabric called a stockinette on your body around the broken bone.
• Next, they’ll roll cotton or another soft padding over the stockinette. The padding and stockinette put light, constant pressure on the area to help it heal and prevent swelling.
• Fiberglass and plaster both come in rolls of strips. Your provider will moisten the strips and lay them around your body.
• They’ll keep layering fiberglass or plaster strips around the fracture until they’ve completed the cast.

How long does it take to get a cast?

It can take anywhere from 15 minutes to around an hour to apply a cast. How long it takes depends on which type of cast you need and where on your body you need it. Smaller casts (like on your wrist) take less time, and bigger casts (like on your legs) take longer to apply.

How long does it take for a cast to dry?

It depends on which type of cast you’re getting. Fiberglass casts start drying right away and might only take a few hours. Plaster casts usually take a day or two to completely harden.

Be careful with your cast while it’s still drying. It won’t have its full strength or protection until it’s hardened all the way. Fiberglass will look and feel rough when it’s dry. Plaster will look smooth and white when it’s hardened.

Your provider will give you specific instructions for taking care of your cast while it’s drying.

What happens after a cast has dried?

For the first few days after you get a cast, you should:

• Elevate the cast as often as you can. You can prop the cast up on couch cushions or pillows for extra support.
• Ice the cast to prevent swelling. Make sure the ice or ice packs don’t drip or sweat on the cast. Put ice in a sealed bag and wrap it in towels to prevent moisture from getting in or on your cast.
• Move your fingers or toes if you have a cast on your arm or leg. Your provider will tell you how often to move to prevent stiffness.

What are the benefits of having a cast?

Casts are usually the best way to protect a bone while it heals after a fracture. They’re extremely safe and effective. Once your bone has healed, it’s quick and easy to remove a cast.

Follow your provider’s instructions about which activities you can do, and what you should avoid while you have a cast.

What are the risks of wearing a cast?

Casts have very few risks. The most serious complications can include:

• Skin.
• Pressure sores.
• Compartment syndrome.
• Deep vein thrombosis (DVT).
• Infections.

How long do you have to wear a cast?

It depends on which type of fracture you have and where the broken bone is. Most people need to wear a cast for six to eight weeks. It might take more or less time depending on how quickly your bone heals.

How can I take care of a cast?

The best way to prevent complications while you’re wearing a cast is to take good care of it:

• Don’t put too much weight or pressure on the cast. If the cast is on your leg or foot, make sure it has hardened completely before walking on it. Your provider will tell you when it’s safe to use that leg and will show you how to move or walk safely. If you need them, they’ll show you how to use crutches.
• Avoid getting the cast wet or damp. Your provider will show you how to cover the cast in plastic wrap or special plastic guards while you’re bathing. Don’t submerge the cast in water. Avoid splashing the cast with water as much as possible.
• Don’t stick anything into your cast. Your skin might itch, but never stick anything like a coat hanger or back scratcher into your cast. Don’t use skin care products, lotions or baby powder on, in or near your cast. Talk to your provider if you’re experiencing severe itching.
• Don’t get the cast dirty. Avoid dirt, dust and sand while you’re wearing the cast. Anything that gets in it can irritate your skin.
• Never try to remove the cast yourself. Don’t take the cast off yourself, and don’t try to peel or break pieces off it. Talk to your provider if the cast seems like it’s peeling, cracking or coming loose on its own.

How is a cast removed?

Your provider will remove the cast with a special saw. A cast saw has a blade that cuts through the cast, but it’s not sharp enough to hurt your skin underneath.

Your provider will cut the cast in several places, usually along both sides. Then, they’ll spread and open the cast and lift it off. They’ll use scissors to cut through the protective padding and stockinette layers.

Never try to remove the cast at home. Only a trained healthcare provider can safely remove a cast.

What should I do if my cast hurts?

Contact your provider right away if your cast hurts, especially if the pain is getting worse. Talk to your provider if you notice any of the following changes:

• Skin discoloration around the cast (above or below it).
• Severe itching.
• A bad odor.
• The cast is cracking, breaking or feels soft anywhere.