How Do My Bones Grow?
When you were a baby, you had very soft bones made up more of cartilage than bone. The cartilage was slowly replaced by harder and stronger bone, filled with network of calcium laid down by cells.
You have layers of these cells in the shape of plates at the ends of the bones. These are called “growth plates,” and they close up when you reach full adult height.
As you grow, living bone tissue makes your bones grow larger along with the rest of your body. Then, when you are about 18 or 20 years old, your bones stop getting bigger.
Inside the bones, however, there is still a lot of growing taking place. As the old bone cells wear out, they are replaced by new bone cells. Because your bones are alive, your body is able to mend any that break.