A cast holds a broken bone (fracture) in place and prevents the area around it from moving as it heals. Casts also help prevent or decrease muscle contractions and help keep the injured area immobile, especially after surgery, which can also help decrease pain.
The hard, outer layer of a cast is made of either plaster or fiberglass. Cotton and other synthetic materials are used to line the inside of the cast to make it soft and provide padding around bony areas, such as the ankle, wrist, or elbow. This also pads nerves and blood vessels.
Special waterproof cast liners may be used under a fiberglass cast so the cast can get wet without falling apart. These waterproof liners can only be used after the injured area has stopped swelling, usually a week or two after the initial injury. Waterproof casts can’t be used after surgery or when pins are used because of the risk of infection.
Your child can take a bath, shower, and even swim in a pool with a waterproof cast. However, they should not sit in a hot tub, go to the beach, or swim in the ocean or a pond while wearing their waterproof cast.
Waterproof casts must get completely submerged in water daily to keep the lining of the cast in good condition. They should be removed by an experienced clinician or technician who understands the specific demands of waterproof casts.

For some injuries, the first cast may be split in order to allow room for swelling. The sides of the bivalve cast will be taped with cloth medical tape. The cast is secured from the inside at the top and bottom, so if the tape starts to peel, the cast should not fall apart. You can buy more tape at a local pharmacy in case the tape does start to peel off. If everything looks good at a follow-up appointment, your child’s doctor may apply a new layer of casting material to close the bivalve cast and prevent it from becoming too loose as swelling comes down.










Casts are a common treatment for fractures. Casts are used to immobilize injured bones, promote healing, and reduce pain and swelling while the bone heals. They are sometimes put on an arm or leg after surgery to protect the bone and ensure it remains in proper alignment.
Getting a cast put on is not painful. You and your child will be brought into the cast room by one of our cast technicians. The cast application will vary depending upon what type of cast your child will be receiving. Your cast technician will go over the specific details with you.
Your child will feel warmth as the fiberglass gets hard. It will not burn but should feel warm like a bath. This reaction will last about 10 minutes. It will take less than five to 10 minutes for the cast to completely set.
This is a good thing to ask about during your appointment. A waterproof cast might or might not be the right option for your child. If your child is eligible for a waterproof cast, they will need to wait at least one to two weeks before switching to a waterproof cast. This is because the tissues around a broken bone often swell at first. Many insurance companies do not cover the cost for a waterproof cast. If not, you may purchase a special waterproof sleeve to protect your child’s plaster or fiberglass cast.
Waterproof casts are ideal for baths, showers, and swimming pools. Your child should not wear their waterproof cast in the ocean, a hot tub, at the beach, or in a pond. Sand and debris can get inside the cast and irritate the skin.
Waterproof casts must get completely submerged in water daily to keep the lining of the cast in good condition. When the time comes, make sure an experienced clinician or technician removes your child’s waterproof cast.
If your child has a broken leg and has been instructed not to bear weight on their cast, there are many kinds of assistive devices to help them get around:
Cast removal can be a scary thing for children. The cast technician will use an oscillating saw to remove the cast. An oscillating saw does not spin, it rapidly vibrates back and forth. The cast saw makes a lot noise. Some children are afraid of this at first, but start to laugh when they feel the vibration of the saw cutting through the cast material.
It is very important to tell your cast technician if your child has picked out some of the padding or placed anything inside the cast.
Once your child has been fitted with a cast there are important guidelines to follow. Our cast technicians will go over these instructions with you and your child.
Older children with body casts may need to use a bedpan or urinal in order to go to the bathroom. The following tips will help keep the body cast clean and dry and prevent skin irritation:
If your child’s cast has gotten wet, please contact us immediately at 617-355-6021.
Unless your child has a waterproof cast, a wet cast can lead to complications and needs immediate attention.
A nurse will decide if your child needs to be seen that day, or the next. If your child’s fiberglass or plaster cast has gotten wet, your child may need to be seen that day.
If your child’s cast gets wet after normal business hours, please contact the orthopedic physician on call through the page operator at 617-355-6000. Your child may need to be seen in the emergency department to have their cast changed.
Contact your child's doctor or health care provider if your child develops one or more of the following symptoms