How do bones develop and grow overtime?

When you are born, you're bones are made out of cartilage. This is so they harden over time and grow. (A babies soft spot is cartilage in the skull) The stretch and harden over time, becoming calcium deposits. Using osteoblasts and osteoclasts, the full grown bone "adapts" to the outer affects by curving and bending minutely to overcome a greater challenge (bone vaccine)

Source: taking anatomy and physiology on bones for a semester.