Growth plates, also known as epiphyseal plates, are areas of cartilage near the ends of long bones in children and adolescents. They are responsible for the longitudinal growth of bones, allowing individuals to increase in height. Their eventual closure signals the end of linear growth and the achievement of adult stature.
The Process of Growth Plate Closure
Growth plate closure involves endochondral ossification. Within the growth plate, cartilage cells (chondrocytes) divide and enlarge. These older chondrocytes then degenerate and calcify, forming a scaffold.
Subsequently, osteoblasts (bone-forming cells) and osteoclasts (bone-resorbing cells) invade this calcified cartilage. Osteoblasts deposit new bone tissue, while osteoclasts remodel the area. This continuous replacement of cartilage with bone leads to the complete fusion of the epiphysis (bone end) and diaphysis (bone shaft), closing the growth plate.
The General Order of Closure
Growth plates throughout the body do not all close at the same time, following a general sequence. Growth plates in the hands and feet close earlier than those in the longer bones of the limbs. The calcaneus (heel bone) is among the first to fuse, followed by the distal tibia and then the proximal tibia in the lower leg.
The process moves from the extremities towards the torso. The distal femur (thigh bone) closes after the lower leg bones. The distal radius, in the forearm near the wrist, is one of the later growth plates to fuse among the limb bones. While most growth from long bones concludes around the end of puberty, some growth plates, such as those in the spine, may remain open into the late teens or early twenties.
The timing of growth plate closure differs between sexes. Females experience earlier growth plate closure compared to males. The majority of growth plates in females close between 13 and 15 years of age, whereas in males, this occurs between 15 and 17 years. This difference accounts for the earlier cessation of growth observed in females.
Factors Affecting Closure Timing
Several influences can affect the timing of growth plate closure. Genetic factors play a role, determining an individual’s skeletal maturation timeline. Family history provides an indication of growth patterns.
Hormonal levels also control growth plate activity. Growth hormone and sex hormones, particularly estrogen in both sexes, regulate the endochondral ossification process and influence when growth plates fuse. Adequate nutrition, including sufficient calcium and vitamin D, supports healthy bone development and can affect the timing of growth. Certain medical conditions, such as hormonal imbalances or chronic illnesses, can accelerate or delay growth plate closure. For example, precocious puberty can lead to earlier closure, resulting in shorter adult stature.