There are four main types of casts designed for broken bones and fractures: Plaster Cast Plaster casts are made up of two parts: bandage on the bottom and a hard covering made out of plaster on the top. These types of casts are primarily used for broken legs or arms and can stay on for about 6-12 weeks. During your recovery time, the hard protection layer of plaster will keep your broken bone safe and immobilized. Synthetic Cast Synthetic casts made of fiberglass are a more breathable, light cast designed for fractures and bone breaks. Your doctor will first slide a stockinette over your injury and then cast your break with this special moldable plastic. Splint Splints are adjustable supports that are used to protect more minor injuries. They can be taken on and off so that you can ice your injury, reduce swelling around the injured area, and potentially take more X-rays as your injury begins to heal. Your doctor will provide you with very specific splint instructions that will be unique to your injury for the most optimal outcome.