The metaphysis is an area of the bone which grows during childhood. When children are born, the metaphysis is comprised primarily of cartilage, which allows the bone some room to grow over time. As people grow up, the cartilage grows and slowly ossifies into solid bone. Depending on the bone and the person, all of the long bones have usually finished growing completely by age 25, and many of the bones stop growing long before this point.
The end of the bone, the rounded area which articulates with other bones, is known as the epiphysis. Between this area and the metaphysis lies the epiphyseal plate, an area of the bone which expands as the bone grows. Sometimes the epiphyseal plate is considered part of the metaphysis. Below the metaphysis is the diaphysis or shaft of the bone, which makes up the main section of the bone.
In childhood, this part of the bone has a very rich blood supply which is designed to promote healthy growth. The fact that the bones are still growing explains why children heal more quickly from fractures, because their bones are better able to recover. However, the increased blood supply also comes with a problematic aspect: Children can develop a number of medical problems in their bones such as cancers and infections which are made worse by the rich blood supply in the metaphysis.
One problem which children can experience is osteomyelitis, a bone infection. Osteomyelitis spreads more quickly when there is an ample blood supply to carry the infection. Children can also develop bone cysts and cancers like osteoblastoma, enchondroma, and fibrosarcoma in their rapidly growing bones. Treatment for these conditions can be complicated by the rapid growth of the bone. Disorders of bone growth can also occur and lead to problems such as disparities in limb length.
Physical anthropologists have conducted a number of studies examining the growth of bone over time and have arrived at some highly accurate estimates of when growth begins to slow and stop. These estimates can be used to accurately date long bones even when the rest of a body is not available, because someone can examine the bone, note the development of the metaphysis and epiphysis, and determine how old the person was. This information is used in the investigation of modern crime as well as in the field of anthropology, where understanding of bone development has allowed people to estimate the approximate age at death of ancient human populations.