Describe the changes that a broken bone undergoes as it is healing.

When a bone breaks your body immediately begins working to heal it. Within the first hours of a fracture a blood clot forms around the break and special cells call phagocytes begin cleaning germs from the bone fragments. Then, a soft callus composed of collagen is created around the break. Next, a hard callus forms as osteoblast cells work to create new bone to aid in the reconstruction process. After all is said and done the bone is remodeled by cells called osteoclasts. The bone will be completely rebuilt in 3-9 years.