Growth plates, or epiphyseal plates, are areas of specialized cartilage found at the ends of long bones in children and adolescents. These structures play a significant role in the development and lengthening of bones. Growth plates are susceptible to injury and can be “broken,” formally called a growth plate fracture. Understanding these injuries is important because they can impact a child’s bone growth.
Understanding Growth Plates
Growth plates consist of hyaline cartilage, a flexible and rubbery tissue. They are located in the metaphysis, a wide section of the bone between the shaft and the rounded end, at each end of long bones such as the femur or humerus. These plates contain chondrocytes, specialized cartilage cells that continuously divide.
New cartilage forms on the epiphyseal side of the plate, while on the diaphyseal side (closer to the bone shaft), this cartilage is replaced by new bone tissue in a process called endochondral ossification. This process allows bones to grow longer. As children and adolescents mature, around ages 13-15 for girls and 15-17 for boys, these growth plates gradually harden and fuse into solid bone, at which point longitudinal bone growth ceases.
How Growth Plates Are Injured
Growth plates are vulnerable because they are softer and weaker than the surrounding solid bone, ligaments, and tendons. An injury that might result in a sprain for an adult can cause a growth plate fracture in a child. Approximately 15% to 30% of all fractures in children and adolescents involve growth plates.
These injuries commonly result from direct trauma, such as falls, twisting motions, or direct blows to a limb. High-impact activities and competitive sports like football, basketball, gymnastics, skiing, skateboarding, and biking are frequent causes. Repetitive stress, often seen in sports training like gymnastics or baseball pitching, can also lead to growth plate injuries due to overuse. Boys experience these fractures more often than girls, partly because their growth plates mature and close later.
Identifying a Growth Plate Injury
Signs and symptoms of a growth plate injury include pain and tenderness, especially when pressure is applied directly over the growth plate. Swelling, warmth, or redness around the end of the bone, near a joint, are also common indicators.
A child might experience difficulty moving the affected limb or be unable to bear weight or put pressure on it. In some instances, a visible deformity, such as a crooked appearance of the limb, may be present. Due to the similarity of these symptoms to sprains or other fractures, professional medical evaluation is important. Diagnostic methods involve X-rays, which can reveal fractures or changes in the cartilaginous growth plate. If X-rays are inconclusive or more detail is needed, magnetic resonance imaging (MRI) or computed tomography (CT) scans may be used to visualize soft tissues or small fractures.
Repairing Growth Plate Injuries and What to Expect
Treatment for growth plate injuries depends on the fracture’s severity and location. Mild fractures that are stable and not significantly displaced can be managed with immobilization. This involves applying a cast or splint to the injured limb for several weeks, allowing the bone to heal naturally without movement. During this period, activities are limited, and weight-bearing on the affected limb is avoided.
More complex or displaced fractures, where bone fragments are out of alignment, require a procedure called reduction to reposition the bones correctly. A closed reduction involves a doctor manually realigning the bones, under pain medication or sedation, without making an incision. If the fracture is severe or unstable, surgical intervention, such as open reduction and internal fixation, may be necessary. This involves making an incision to reposition the bone fragments and then securing them with implants like screws, wires, or metal plates. A cast is applied even after surgery to ensure proper healing.
Recovery time for a growth plate fracture varies, ranging from several weeks to a few months, influenced by the child’s age, fracture type, and location. Younger children heal faster. After the cast is removed, physical therapy may be recommended to restore strength, flexibility, and range of motion to the injured area.
A key consideration for growth plate injuries is the potential for growth disturbances, such as limb length discrepancies or angular deformities if the injury affects the growth process. For example, a severe injury to the growth plate around the knee can potentially lead to a shorter, longer, or crooked leg. Regular follow-up appointments, often involving X-rays of both limbs for comparison, are important for at least a year, and sometimes until skeletal maturity, to monitor bone growth and detect any complications early.