External immobilization of the extremities is the oldest form of fracture treatment. References to plaster use and various immobilization techniques are scattered throughout historical records. The use of plaster of Paris, also referred to as plaster, in fracture management dates back to the eighteenth century Turkish Empire. Plaster bandages became commercially available in 1931. Despite the development of plastic (i.e., fiberglass) casting products, the plaster bandage persists as the most economical and versatile material for immobilization techniques.1
Immobilization of an injured extremity begins at the scene of the accident. According to Advanced Trauma Life Support guidelines, the injured extremity must be aligned and immobilized after the appropriate management of any life-threatening problems.2 Prehospital immobilization of fractures is invaluable for pain control, prevention of soft tissue injury, prevention of any new or further injury to neurovascular structures, and management of edema. External immobilization with splinting or casting is often the definitive management of injured extremities in the Emergency Department. Knowledge and expertise in this therapeutic procedure are essential for any Emergency Physician.
Splints are commonly used for the immobilization of upper and lower extremity injuries. A splint is a hard bandage that is not circumferential and prevents movement of the fracture site. Splinting may be the definitive management of certain injuries. Splints have the distinct advantage of being quick and easy to apply, and they are designed to accommodate postinjury swelling. The major disadvantages of splints are that they provide slightly less rigid immobilization than casting and require an Orthopedic Physician visit within a few days to be replaced with a cast.
Casts, which are generally circumferential, are better suited for the definitive treatment of fractures and ligamentous injuries. Casts provide superb immobilization and allow for the maintenance of a reduced fracture. The rigidity of a cast limits the amount of swelling and soft tissue edema in the first 24 to 48 hours after the injury and is therefore associated with an increased risk of developing a compartment syndrome. Casts should be used with caution in the management of acute fractures. They are often split (bivalved) to allow swelling and prevent the development of a compartment syndrome before the patient is discharged from the Emergency Department.
ANATOMY AND PATHOPHYSIOLOGY
Casts and splints rely on the principle of a three-point mold to maintain fracture reduction (Figure 113-1). When applying a cast or splint, the application of directed force to the underlying bones should be uppermost in one’s mind. To obtain a three-point mold, place one point of contact over the convex side of the fracture site. The other two points of force are aimed in an opposite direction, proximal and distal to the fracture, and from the concave side. This is the classic teaching of Sir John Charnley who noted that “a curved plaster is necessary in order to make a straight ...