The growth plates, or epiphyseal plates, are structures made of cartilage found near the ends of long bones in children and adolescents. These plates are solely responsible for adding length to the bones, a process that determines a person’s final height.
The Structure and Function of Epiphyseal Plates
The epiphyseal plate is a thin, specialized layer of hyaline cartilage located between the epiphysis (the end of the bone) and the metaphysis (the shaft of the bone). This cartilage acts as the engine for longitudinal growth in the body’s long bones, such as those in the arms and legs. The process of bone lengthening that occurs here is called endochondral ossification, a mechanism where cartilage is systematically created and then replaced by bone.
Within the plate, cells called chondrocytes continually divide and multiply in the proliferative zone, stacking themselves into columns. As these cells mature, they enlarge in the hypertrophic zone and eventually die, leaving behind a calcified matrix. Blood vessels and bone-forming cells, known as osteoblasts, then invade this matrix, replacing the calcified cartilage with solid bone tissue.
This continuous cycle of cartilage creation and bone replacement is how the bone grows longer during childhood and adolescence. The plate itself maintains a relatively constant width until the body signals that skeletal maturity has been reached. The completion of this growth process typically occurs in the late teens to early twenties, marking the end of a person’s height gain.
The Permanence of Growth Plate Fusion
Once the period of skeletal growth concludes, the growth plate permanently closes, a process known as epiphyseal fusion or closure. This closure is a biologically final event because the cartilage cells responsible for creating new bone material are completely replaced by solid bone. The entire epiphyseal plate turns into a thin, bony line called the epiphyseal line, and the bone is considered fully mature.
The process of fusion is heavily regulated by hormones, particularly the sex steroids estrogen and testosterone, which surge during puberty. Although both hormones are involved, estrogen is understood to play the primary role in triggering the final closure of the plates in both males and females. Estrogen accelerates the programmed aging, or senescence, of the growth plate chondrocytes, leading to their eventual exhaustion and replacement by bone.
Since the delicate structure of multiplying cartilage cells no longer exists after fusion, there is no tissue left to “reopen” or reactivate. No known dietary supplement, pharmacological treatment, or natural method can reverse this transformation of cartilage into solid bone.
Surgical Options for Limb Lengthening
While the natural growth plates cannot be reopened, medical science offers a procedure to increase bone length after skeletal maturity, known as distraction osteogenesis. Instead, a surgeon performs a controlled, low-energy cut through the solid bone, an action called a corticotomy, to separate the bone into two segments.
A specialized external or internal fixation device is then attached to the bone segments. After a short waiting period, the device is used to slowly and gradually pull the two bone segments apart, typically at a rate of about one millimeter per day. This slow separation stimulates the body’s natural healing response to fill the gap with new bone tissue, a process called callotasis.
Distraction osteogenesis is an invasive and demanding procedure that requires a long recovery period. Patients must wear the distraction hardware for months, followed by a consolidation phase where the new bone hardens. The procedure carries risks, including nerve injury, joint stiffness, and infection at the pin sites, and is generally reserved for correcting significant limb-length discrepancies or congenital deformities.