A cast is an immobilizing bandage used as an alternative to regular plaster bandages. It is also referred to as a cast bandage or plastic plaster.
What is a cast?
A cast is an immobilizing bandage that is used as an alternative to the normal bandages made of plaster. It is also called a cast bandage or a plastic cast. Unlike the “normal” dressing, a cast is made of plastic rather than plaster. Casts, like plaster casts, are also used to treat bone fractures. In some cases, plaster casts are also combined with cast bandages.
Shapes, types and styles
A cast bandage usually consists of a stretchable carrier fabric. This backing fabric is made of fiberglass or polyester. For stability, the stretchable carrier fabric is coated with a plastic resin. When immersed in water, this plastic resin is activated and hardens. Curing varies depending on the water temperature and the immersion time. The colder the water, the less time is left for modeling. In another variant, the cast can also be applied dry. For this, the stretchable base material is wrapped around the affected limb. The plastic resin coating is then activated by misting with water. Normally, casts are cured within half an hour. A fully cured cast is also fully loadable. In conservative fracture treatment, a conventional cast is usually first applied to the patient. These conventional casts allow longitudinal splitting immediately after curing. This allows the affected limb to swell further. This would not be possible with the circular cast bandage. Only when the limb has swollen down again can a cast be applied. For this reason, they are sometimes referred to as secondary bandages.
Structure and mode of operation
The cast bandage is applied to the affected extremity. It is then used for mechanical fixation of the bone fracture. Generally, cast dressings are used primarily for uncomplicated and stable fractures. Before applying the cast, the fracture must first be repositioned to its anatomically correct position. This process is also known as reduction. The bandage is then used to stabilize and immobilize the affected limb. With the help of the cast, the body should be given the opportunity for tissue healing and rehabilitation. The bandage restricts movements that would not be conducive to healing. This is the only way to allow new bone formation. Cast and plaster casts are often used on children. Typical fractures treated with casts include fractures of the forearm, radius, scaphoid of the hand, lower leg fractures in children, uncomplicated lateral malleolus fractures, and metatarsal and tarsal fractures. For fractures that are treated surgically, casts are usually used for temporary immobilization before surgery. They may also be used postoperatively.
Medical and health benefits
Casts offer several advantages over casts. For example, they have a significantly lower weight than plaster bandages. In particular, bandages that patients must wear for a very long time can be burdensome and delay healing because of their heavy weight. Despite their low weight, casts have greater strength. They also harden more quickly than plaster casts. This means that full weight-bearing capacity can be achieved very early on. Plaster casts are sensitive to water. Casts are not sensitive to water. There is also a special padding and underlay material that allows showering or bathing with the cast bandage. Cast bandages are available in many colors and even with motif printing. This promotes acceptance, especially among children. But cast bandages do not only have advantages. They are significantly more expensive than plaster bandages. The higher costs are usually too high for bandages that have to be renewed frequently. Casts are also expensive for dressings that are worn for only a few days. Cast bandages are also not very permeable to water vapor or air. Patients therefore sweat more under these bandages. The rough surface of the bandages also poses the risk of damaging clothing. Disposal of the cast bandages is also more problematic. In addition, it is suspected that the cast bandages may contain allergenic substances.In terms of medical effectiveness, there are no real differences between the two types of casts. Thus, the complications of cast bandages are also the same as those of plaster casts. If the padding is inadequate, pressure ulcers can occur. If the casts are applied too tightly or if the affected limb subsequently swells, complete or partial disturbance of blood flow may occur. If this circulatory disturbance is not recognized, a Volkmann contracture could be the result. In a Volkmann contracture, the muscles of the forearm are shortened due to a lack of blood flow. Nerves can also be damaged by the lack of blood flow. Typical of Volkmann contracture is a so-called claw hand. The pressure of the upper edge of a lower leg cast on the head of the fibula can also cause pressure damage to nerves. Peroneal paralysis is typical in this case. Prolonged immobilization can also lead to muscle atrophy. Deep vein thrombosis is also a known risk of therapies involving prolonged immobilization. A feared consequence of deep vein thrombosis is life-threatening pulmonary embolism.
