The presence of an epiphyseal plate indicates that an individual is still in the process of growing. The epiphyseal plate, also known as the growth plate, is a layer of cartilage found at the ends of long bones in children and adolescents. This cartilage is where new bone is produced, allowing the bones to lengthen as a person grows.
As children reach their late teens or early twenties, the epiphyseal plates gradually ossify, turning into bone and eventually closing. Once this occurs, no further growth in length of the bones can take place. Therefore, seeing an epiphyseal plate in an X-ray or a medical imaging study is a sign that the person has not yet reached their full adult height.