An epiphyseal plate, more commonly known as a growth plate, is a anatomical structure present at the ends of the long bones of children and adolescents. These plates contain rapidly dividing cells that allow bones to become longer until the end of puberty. A growth plate will thin over the course of adolescence, becoming an inactive epiphyseal line by the time an individual reaches adulthood. Structurally fragile, the fracturing of a growth plate from physical trauma can cause stunted growth.
Growth plates, though part of a child's skeletal system, have a biological function that is different from that of the bones surrounding them. They are active construction sites where cells rapidly divide through mitosis. These new cells become part of the body's long bones. Growth plates play a large role during puberty, most noticeably when an adolescent goes through a growth spurt. By age 18 in females and 21 in males, a growth plate will have become an epiphyseal line.
Genetic disorders affect the function of growth plates. The most common is achondroplasia, a genetic condition responsible for more than half of dwarfism cases worldwide. One in 25,000 people are born with the condition. Achondroplasia causes growth plates to work incorrectly, leading to severely reduced height and stature. Despite these limitations, those living with achondroplasia lead otherwise normal lives.
Growth plates are made from soft cartilage, so fracture through physical trauma is a real possibility for adolescents involved in physical activities such as sports. For example, the break or fracture of a growth plate can lead to stunted growth in the affected limb. Surgery, physical therapy and close observation are essential to ensure that affected bones continue to develop normally. In cases where the growth plate is damaged beyond repair, follow-up surgeries might be necessary to allow easier mobility in adult life.
Outside of their biological function, growth plates are unique in that they provide valuable information to scientists such as forensic anthropologists. Considering how growth plates shrink through adolescence, measuring their size through X-rays allows scientists to determine the relative age of an adolescent when no documentation is present. This information can lead to the positive identification of the victim of a crime. The same scientific technique is used to measure the age of people whose bones are discovered at archeological sites. If archeologists can determine the age distribution of an ancient society, that information gives them a deeper insight into how that society functioned.