Bone has an amazing capacity to heal itself. After a bone breaks, the process of building new bone begins. Blood rushes to the wounded area, forming a fracture hematoma, or mass of blood that protects the injury. New, immature bone cells begin to form around the injury. In a process that can take between 6 weeks and 6 months, the immature bone cells mature and develop into solid bone, and the broken bones eventually knit back together.
At one time, we used to automatically put the injured limb in a cast to prevent overstressing the fracture while it heals. However, we have since learned that complete immobilization can seriously weaken the leg muscles; therefore, we now try to stress-relieve the wounded area with crutches and a functional cast made of fiberglass that allows for some movement. By doing this, we can prevent weight from being put on the broken bone, but the knee can still have some range of motion, which will prevent the muscles from atrophying.
Displaced fractures are surgical emergencies that can be treated by either closed reduction or open reduction, depending on the type of injury.