A baby is born with zones of cartilage in its bones that allow growth of the bones. These areas, called growth plates , allow the bones to grow longer as the child grows. By the time the child reaches an age of about 18 to 25 years, all of the cartilage in the growth plate has been replaced by bone. This stops the bone from growing any longer. Even though bones stop growing in length in early adulthood, they can continue to increase in thickness throughout life. This thickening occurs in response to strain from increased muscle activity and from weight-lifting exercises.
Sam was always tall for his age. When he was born he was 21.5 inches long. By the time he was 1 he was 33 inches long. All the way through school he was always the tallest kid in his school. by high school he was was in high school he was 6ft 4 inches tall and finally stopped growing. He was self conscious about his height when he was a kid but know that he was 30 and an adult he embraces it as part of who he is.
When does Sam have the least growth plates?