As soon as one of your bones break, your body springs into action to fix the injury. The time it takes for a bone to heal depends on a lot of things, such as the person's age and location of the break.

Within a couple hours, a blood clot forms around the break. Inside the blood clot, special cells called phagocytes begin cleaning bone fragments and killing any germs which might have gotten in around the break. Phagocytes are part of the immune system. The word phagocyte means 'cells that eat' in Greek, so these cells are named after the way they surround and destroy unwanted bacteria and material.

Next, a soft callus made mostly of collagen is created around the fracture by another special group of cells called chondroblasts. This stage can last anywhere from 4 days to 3 weeks.

A hard callus forms next as osteoblast cells create new bone, adding minerals to make it hard. This stage typically begins 2 weeks after the break, and ends somewhere between the 6th and 12th week.

Lastly, the bone is remodeled. Special cells called osteoclasts break down extra bone around the fracture until it's completely healed and returned to its original shape. Bone remodeling is a very slow process which can take anywhere from 3 to 9 years to complete!