Growth plates are specialized areas of developing cartilage found near the ends of long bones, important for skeletal development in young individuals. They are responsible for bone lengthening as a child grows. Their presence indicates active bone growth, a process distinct from adult bone structure.
Understanding Growth Plates in the Elbow
The elbow joint is formed by three bones: the humerus (upper arm bone), and the radius and ulna (forearm bones). In children, growth plates, also known as epiphyseal plates or physes, are located at the ends of these long bones within the elbow joint. These cartilaginous plates produce new bone, allowing bones to grow in length. The cartilage cells within the growth plate rapidly divide and then are gradually replaced by bone tissue, a process that adds length to the bone shaft.
Growth plates are primary sites for longitudinal bone growth. They are composed of cartilage with distinct zones where cells proliferate and are replaced by bone. This process is regulated by various factors, including hormones, ensuring proper bone development. Their continued activity allows children to increase in height and attain adult bone size.
Elbow Growth Plate Injuries
Growth plates are areas of relative weakness in a child’s skeletal system. Because they are made of cartilage, less rigid than hardened bone or surrounding ligaments and tendons, growth plates are more susceptible to injury. An injury that might result in a sprain for an adult could lead to a fracture of a growth plate in a child. These injuries commonly occur in active children and adolescents, particularly those participating in sports that involve repetitive elbow motions, such as baseball, tennis, or golf.
Common causes of elbow growth plate injuries include:
Falls
Direct trauma
Hyperextension of the elbow joint
Repetitive stress from overuse
“Little Leaguer’s elbow” is a well-known condition resulting from overuse and inflammation of the growth plate on the inside of the elbow in young baseball players. Symptoms often include:
Pain
Swelling
Tenderness
Limited range of motion or a visible deformity
Diagnosis typically involves a physical examination and X-rays, although growth plates can be difficult to see clearly on X-rays because they are cartilaginous. Sometimes, comparison X-rays of the uninjured limb or advanced imaging like MRI or CT scans may be needed for a precise diagnosis. Treatment is necessary to avoid potential long-term complications, such as altered bone growth or limb length discrepancies.
Growth Plate Closure and Adult Bones
As a person matures, growth plates undergo “closure” or “fusion.” During this process, the cartilage within the growth plate is gradually replaced by solid bone, completing longitudinal bone growth. Once a growth plate has fully closed, it becomes an epiphyseal line, a faint line visible on X-rays, and the bone can no longer lengthen.
The timing of growth plate closure varies among individuals and different bones, but generally occurs during late adolescence. For girls, elbow growth plates typically close between the ages of 13 and 16, while for boys, this usually happens between 15 and 17 years old. This closure is influenced by hormonal changes during puberty. Consequently, adult bone injuries differ from those in children, as adults sustain fractures to the hardened bone itself rather than to the growth plate. Adults also tend to have slower healing times for fractures compared to children, whose bones are more flexible and have active growth processes.