Cast Care Instructions Introduction

  • The function of a fiberglass or plaster cast is to immobilize and protect a broken or fractured bone or joint. It holds in place the broken bone keeping it in proper alignment to prevent movement during the rehabilitation process.
  • Orthopedic medical casts may also be used to help rest a bone or joint to relieve pain that is caused by moving it (this is often the case with a severe sprain, but no broken bones).
  • Casts and splints come in many different forms, the type of cast you would have really depends upon the reason for immobilization or the fracture type.
  • There are two general type of material a cast can be made out of, plaster or fiberglass. There have also been casts make of polyester tape as well. Fiberglass casting tape is the most used at present.

How a Cast is Applied

The size and shape of a cast you will received is really dependent upon which body part the fracture or sprain occurs. That part of the body is what needs to be protected by the cast. Each doctor will decide based upon experience and current medical practice which cast is best for the type of fracture you have.

  • Cast application
    • Prior to application of the casting material (plaster or fiberglass), a "stockinette" is placed on the skin and extends from the beginning to the end of where the orthopedic cast is to be (at the hand and near the elbow for a short arm wrist cast). This stockinette protects the skin from the casting material and also helps to keep your skin dry.
    • Once the stockinette is applied, soft cotton or synthetic polyester padding is rolled over top of the stockinette. This cotton layer provides protection to both the skin and greats a cushioning between the fiberglass helping to aid in healing.
    • Next, the plaster or fiberglass cast material is dipped into water. Excess water is shaken off and the cast material is rolled around the injured limb and allowed to dry.
    • The cast will start to solidify in about 3-5 mins minutes after it is put on, but it takes much longer to be fully dry and hard.
    • Be especially careful with the cast for the first 1-2 days because it can easily crack or break while it is drying and hardening. It can take up to 24-48 hours for the cast to completely harden.
  • Plaster casts
    • A plaster cast is made from rolls or pieces of dry muslin that have starch or dextrose and calcium sulfate added.
    • When the plaster gets wet, a chemical reaction happens (between the water and the calcium sulfate) 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
    • Fiberglass casts are also applied starting from a roll of fiberglass tape 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. Some fiberglass casts may even be colored.

Ice and Elevation

  • A doctor may want the person to use ice to help decrease the swelling of the injured body part. (Check with a physician before using ice.)
  • To keep the cast from becoming wet, put ice inside a sealed plastic bag and place a towel between the cast and the bag of ice.
  • Apply ice to the injury for 15 minutes each hour (while awake) for the first 24-48 hours.
  • Try to keep the cast and injured body part elevated above the level of the heart, especially for the first 48 hours after the injury occurs.
  • Elevation will help to decrease the swelling and pain at the site of the injury.
  • Propping the cast up on several pillows may be necessary to help elevate the injured area, especially while asleep.

Taking Care of Your Cast

  • Always keep the cast clean and dry.
  • If the cast becomes very loose as the swelling goes down, call the doctor for an appointment, especially if the cast is rubbing against the skin.
  • Cover the cast with a plastic bag or wrap the cast to bathe (and check the bag for holes before using the bag a second time). Some drug stores or medical suppliers have cast covers—plastic bags with Velcro straps to seal out water for protection during bathing. Avoid showers; use the bathtub and hang the covered cast or injured body part outside of the tub while you bathe. Do not lower the cast down into the water.
  • If a fiberglass cast gets damp, dry it (make sure it dries completely). Because a fiberglass cast allows air through it, a hairdryer on the cool setting should do the trick (do not try to dry it using a hairdryer without a cool setting—you could burn yourself). If you have any trouble getting the cast dry, call a doctor to find out if the cast needs to be replaced.
  • If the cast gets wet enough that the skin gets wet under the cast, contact the doctor. If the skin is wet for a long period of time, it may break down, and infection may occur.
  • Sweating enough under the cast to make it damp may cause mold or mildew to develop. Call the doctor if mold or mildew or any other odor comes from the cast.
  • Do not lean on or push on the cast because it may break.
  • Do not put anything inside the cast. Do not try to scratch the skin under the cast with any sharp objects; it may break the skin under the cast. Do not put any powders or lotions inside the cast.
  • Do not trim the cast or break off any rough edges because this may weaken or break the cast. If a fiberglass cast has a rough edge, use a metal file to smooth it. If rough places irritate the skin, call the doctor for an adjustment.
  • An arm sling may be needed for support if the cast is on the hand, wrist, arm, or elbow. It is helpful to wrap a towel or cloth around the strap that goes behind the neck to protect the skin on the neck from becoming sore and irritated.
  • If the cast is on the foot or leg, do not walk on or put any weight on the injured leg, unless the doctor allows it.
  • If the doctor allows walking on the cast, be sure to wear the cast boot (if given one by the doctor). The boot is to keep the cast from wearing out on the bottom and has a tread to keep people in casts from falling.
  • Crutches may be needed to walk if a cast is on the foot, ankle, or leg. Make sure the crutches have been adjusted properly before leaving the hospital or the doctor's office.

How a Cast Is Removed

  • Do not try to remove the cast.
  • When it is time to remove the cast, the doctor will take it off with a cast saw and a special tool.
    • A cast saw is a specialized saw made just for taking off casts. It has a flat and rounded metal blade that has teeth and vibrates back and forth at a high rate of speed.
    • The cast saw is made to vibrate and cut through the cast but not to cut the skin underneath.
    • After several cuts are made in the cast (usually along either side), it is then spread and opened with a special tool to lift the cast off.
    • The underlying layers of cast padding and stockinette are then cut off with scissors.


  • After a cast is removed, depending on how long the cast has been on, the underlying body part may look different than the other uninjured side.
    • The skin may be pale or a different shade.
    • The pattern and length of hair growth may also be different.
    • The injured part may even look smaller or thinner than the other side because some of the muscles have weakened and have not been used since the cast was put on.
    • If the cast was over a joint, the joint is likely to be stiff. It will take some time and patience before the joint regains its full range of motion.


Many potential complications are related not only to wearing a cast but also to the healing of the underlying fracture.

Immediate complications

  • Compartment syndrome
    • Compartment syndrome is a very serious complication that can happen because of a tight cast or a rigid cast that restricts severe swelling.
    • Compartment syndrome happens when pressure builds within a closed space that cannot be released. This elevated pressure can cause damage to the structures inside that closed space or compartment—in this case, the muscles, nerves, blood vessels, and other tissues under the cast.
    • This syndrome can cause permanent and irreversible damage if it is not discovered and corrected in time.
    • Signs of compartment syndrome
      • Severe pain
      • Numbness or tingling
      • Cold, pale, or blue-colored skin
      • Difficulty moving the joint or fingers and toes below the affected area.
    • If any of these symptoms occur, call the doctor right away. The cast may need to be loosened or replaced.
  • A pressure sore or cast sore can develop on the skin under the cast from excessive pressure by a cast that is too tight or poorly fitted.

Delayed complications

  • Healing problems
    • Malunion: The fracture may heal incorrectly and leave a deformity in the bone at the site of the break. (Union is the term used to describe the healing of a fracture.)
    • Nonunion: The edges of the broken bone may not come together and heal properly.
    • Delayed union: The fracture may take longer to heal than is usual or expected for a particular type of fracture.
  • Children are at risk for a growth disturbance if their fracture goes through a growth plate. The bone may not grow evenly, causing a deformity, or it may not grow any further, causing one limb to be shorter than the other.
  • Arthritis may eventually result from fractures that involve a joint. This happens because joint surfaces are covered by cartilage, which does not heal as easily or as well as bone. Cartilage may also be permanently damaged at the time of the original injury.

When to Call Your Doctor

  • Check the cast and the skin around the edges of the cast everyday. Look for any damage to the cast, or any red or sore areas on the skin.
  • Call the doctor immediately if any of the following happen:
    • The cast gets wet, damaged, or breaks.
    • Skin or nails on the fingers or toes below the cast become discolored, such as blue or gray.
    • Skin, fingers, or toes below the cast are numb, tingling, or cold.
    • The swelling is more than before the cast was put on.
    • Bleeding, drainage, or bad smells come from the cast.
    • Severe or new pain occurs.



Broken Arm


Broken Arm Overview


A broken or fractured arm means that one or more of the bones of the arm have been cracked. This is a common injury occurring in both children and adults. In adults, fractures of the arm account for nearly half of all broken bones. In children, fractures of the forearm are second only to broken collarbones.

  • Basic anatomy: The arm consists of 3 major bones. The humerus runs from the shoulder to the elbow. This is called the upper arm, or, simply, the arm. At the elbow, the humerus connects with 2 bones: the radius and the ulna. These bones go from the elbow to the wrist and are regarded as the forearm.
  • Important terms related to a broken arm

o Alignment: The relationship of how the broken portions of the bone come together. This is an indication of how badly a bone is broken.

o Angulation: The angle formed by the broken pieces of bone. Another measure of the seriousness of the break.

o Closed fracture: A broken bone without an open skin wound

o Comminuted fracture: A bone that is broken in multiple pieces

o Dislocation: A bone that has come out of a joint

o Displaced fracture: A broken bone with the parts of the bone not aligned

o Fracture: A crack in the bone. This is another word for a broken bone.

o Fracture-dislocation: A broken bone that has also come out of a joint

o Greenstick fracture: An incomplete fracture seen in children where only one side of the bone is broken

o Malunion: Healing of the bone in an unsatisfactory position

o Nonunion: Failure of the pieces of bone to heal back together

o Occult fracture: A broken bone that does not appear initially on the x-rays

o Open fracture (compound fracture): A fracture that has a laceration in the skin overlying the break or a fracture that has a piece of bone sticking through the skin

o Pathologic fracture: A broken bone that is due to a weakness of the bone itself from some other disease


Broken Arm Symptoms

Most broken arms have these symptoms:

  • A large amount of pain and increased pain when moving the arm
  • Swelling
  • Maybe an obvious deformity compared to the other arm
  • Possible open wound either from the bone puncturing the skin or from the skin being cut during the injury
  • Decreased sensation or inability to move the limb, which may indicate nerve damage


When to Seek Medical Care

Call your doctor after an accident if these signs are present:

  • Significant pain that is not relieved by ice and home pain medications such asacetaminophen (Tylenol) or ibuprofen (Motrin)
  • A large amount of swelling or mild deformity of the arm compared to the opposite arm
  • Significant pain with use or limited use of the affected arm
  • Pain in one specific part of the arm when it is pressed

Your doctor may advise you to go directly to a hospital's emergency department. Under the following conditions, go directly to the hospital for emergency care:

  • Visible bone sticking out through the skin
  • Heavy bleeding from an open wound
  • Complete lack of movement or sensation of part of the arm
  • Obvious deformity that looks drastically different from the usual appearance
  • Loss of consciousness
  • Many other injuries


Exams and Tests

The initial evaluation by any physician, in the office or in the emergency department, begins with a thorough history and physical exam. By finding out the details of the accident, the doctor is able to determine what damage was done based on the mechanism of the trauma.

After taking a history, the physician will do a complete physical exam with special focus on the painful areas. The doctor is looking for signs of a fracture (such as swelling or deformity) and checking for possible nerve or blood vessel damage.

X-rays are typically the test used to assess for broken bones. At least 2 views of the arm are taken. Initially, most broken bones will have an apparent fracture or other abnormality on the x-ray. Some fractures are not always visible on the first set of x-rays. In those instances, a CT scan or MRI may be done immediately for further evaluation, or follow-up x-rays may be obtained at a later date.


Broken Arm Treatment


Self-Care at Home

  • The most important aspect offirst aid is to stabilize the arm. Do this by using a towel as a sling. Place it under the arm and then around the neck. An alternate approach to keep the arm from moving is to position a rolled and taped newspaper along the swollen area and to tape it in place.
  • Apply ice to the injured area. This can help to decrease pain and swelling. Place ice in a bag and leave it on the arm for 20-30 minutes at a time. It may be helpful to place a towel around the ice bag or in between the bag and the skin to protect the skin from getting too cold. Never put ice directly on the skin.


Medical Treatment

The most important aspect of treating fractures is to determine which ones can be treated with outpatient care and which require admission to the hospital.

In most instances, the broken arm will be able to be treated in the emergency department.

  • Most fractures will need to have a splint or partial cast applied to stabilize the broken bones. Some breaks especially in the upper arm and shoulder may only need to be immobilized in a sling.
  • In addition to splinting the broken arm, the physician will prescribe medicines for pain control and ice to decrease swelling.
  • Typically, wounds that warrant admission to the hospital are these:

o Bones that have gone through the skin or have lacerations over the broken area

o Fractures that are associated with nerve damage

o Fractures that are associated with blood vessel damage

o Complicated fractures that have multiple breaks, involve the joints, or are unable to be stabilized in the emergency department or doctor’s office


Next Steps



Most broken arms will not require admission to the hospital. For all other fractures, the treating doctor will suggest you follow up with an orthopedic doctor (bone specialist). At that time, the orthopedist will determine what further care (continued splinting, casting, or surgery) is necessary based on the type of fracture.

Additional follow-up instructions for fractures include the following:

  • Wear any support device (splint, sling, or brace, for example) until the doctor sees you for follow-up.
  • Keep your splint orcast clean and dry.
  • Apply ice to the injured area for 20-30 minutes 4-5 times a day.
  • Keep your arm elevated above the heart as much as possible to decrease swelling. Use pillows to prop your arm while in bed or sitting in a chair.
  • Take pain medicine as prescribed. Do not drink or drive if you are taking narcotic pain medication.
  • Call your doctor for increased pain, loss of sensation, or if your fingers or hand turn cold or blue.