Orthopedic casts typically consist of three layers. The outer layer, or the “shell”, is typically constructed of a quick drying bandage that hardens and becomes rigid upon drying. The shell layer provides the necessary rigidity and is typically made of either plaster, for its high formability, or fiberglass, for its faster drying time and lighter construction. The middle layer typically consists of padding to separate the rigid shell from the skin and provide comfort. The inner layer is typically a cotton gauze that interfaces directly with the skin and is also for comfort.
Most casts are removed using an electrically powered, oscillating saw. The blade of the saw is typically configured as a circular blade with fine teeth, where the blade oscillates about the center of the saw. Examples of such saws include the Stryker® 940 cast cutter, American Orthopaedic™ BSN 0295-200 cast cutter, and De Soutter CleanCast™ oscillating cast saw.
Several aspects of such a conventional design result in less than optimal performance. The saw can not make continuous cuts, but is applied successively in a line. Due to the circular geometry of the blade, the depth of the cut varies. As a result, portions of the cut away from the center of the blade application are often not fully separated and must be re-cut with the saw. Additionally, due to the high velocity of the blade, a saw is typically used to cut only through the shell layer, where scissors or other implements are used to cut through the padding and gauze. The high frequency oscillations produce uncomfortable noise levels and considerable dust when cutting. Moreover, the use of an oscillating saw for cast removal creates a potential for iatrogenic injury and patient discomfort. Burns and abrasions can occur from the heat created by frictional forces and direct blade contact.