Fractures, or broken bones, are one of the most common medical problems. It is estimated that 6.8 million fractures occur in the United States each year alone, with approximately 900,000 of them requiring hospitalization. To treat a fracture so that the patient regains full use of an injured arm or leg the bone ends must first be brought back into alignment; then, the fracture must be held together until the bone ends grow back together. Closed or simple fractures, in which the bone ends do not penetrate the skin, have always been relatively easy to treat. Open or compound fractures were usually fatal prior to the advent of antiseptics in the 1860s because infection would set in. The earliest method of holding a reduced fracture in place was to use splints--rigid strips laid parallel to each other alongside the bone. Ancient Egyptians used wood splints made of bark wrapped in...