Orthopedic surgeon Robinson describes three types of bones that break: ribs or skull, with which the underlying organs must be protected; facial bones, which require accurate, fine correction; and large, long bones, which must be held in place promptly and securely. Dr. Robinson shows x-rays of broken femurs and a diagram of how bone heals, explaining that the deformity must be corrected first and then held in place until a bridge of new bone is formed. A patient demonstrates the range of motion in his formerly fractured elbow that was held together with a metal plate and screws. Other x-rays display the intramedulary, a diamond-shaped stainless steel nail used to hold a femur fracture in place and allow weight bearing. A model of the hip joint and femur with surrounding muscles proves that without such a supportive rod, the muscles would override the bones and cause deformity or shorten the length of the leg. Dr. Southwick introduces former patient William Brown and explains how a metal rod was inserted.