A growth plate fracture in a child or adolescent is an injury to the physis or epiphyseal plate, a layer of specialized cartilage located near the ends of long bones. Its function is to create new bone tissue, which is the sole mechanism responsible for the lengthening of bones as a child grows. Understanding how these structures work and the potential impact of an injury is important for ensuring the best possible outcome for a child’s development.
Anatomy and Function of Growth Plates
Growth plates are temporary structures found in the long bones of the body, such as the femur, tibia, and radius, typically with one at each end of the bone. These plates are situated between the epiphysis, the end of the bone, and the metaphysis, the wider portion of the bone shaft. The growth plate itself is composed of cartilage cells, called chondrocytes, which actively divide and multiply in a process that drives bone elongation.
New cartilage cells are produced on the side closest to the epiphysis, while older cells facing the metaphysis are replaced by solid bone tissue. Because this region is made of softer cartilage rather than calcified bone, the growth plate is structurally the weakest point in the developing skeleton. This vulnerability means that a force which might cause a sprain in an adult often results in a fracture through the growth plate in a child.
Salter-Harris Classification of Injuries
When a fracture occurs through the growth plate, physicians use the Salter-Harris classification system to describe the injury, which directly influences treatment and prognosis. This system categorizes the injury into five main types based on the specific path the fracture takes through the bone’s anatomy. The risk of long-term growth disturbance increases with the higher-numbered types.
Type I fractures involve a horizontal separation that runs entirely through the growth plate, without breaking the bone itself. Because the fracture bypasses the cells responsible for bone production, this type generally carries a good prognosis with a low risk of growth arrest. Type II is the most common growth plate fracture, where the break runs through the plate and then extends upward into the metaphysis, leaving the epiphysis intact. This injury is relatively stable and has a favorable outcome following proper treatment.
Type III fractures are less common and involve a break that runs through the growth plate but then turns and exits through the epiphysis and into the joint surface. Since this fracture disrupts the joint and involves the reproductive layer of the growth plate, it carries a higher risk of growth issues and requires surgical correction. A Type IV fracture is more severe, traveling through all three components: the metaphysis, the growth plate, and the epiphysis. This injury significantly disrupts both the growth mechanism and the joint alignment, leading to a worse outcome and a high likelihood of surgery.
The rarest and most serious is the Type V fracture, which is a compression or crushing injury to the growth plate. This crushing force obliterates the cartilage cells, making it difficult to diagnose initially and resulting in the highest risk for complete growth arrest.
Immediate Management and Treatment
Upon suspicion of a growth plate fracture, a medical professional will conduct a physical examination and order imaging tests, most commonly X-rays, to visualize the injury. In some cases, mild growth plate fractures may not be clearly visible on a standard X-ray, requiring diagnosis based on the mechanism of injury and physical symptoms. Prompt diagnosis and treatment are important because a child’s bones heal quickly, and proper alignment must be achieved before the healing process sets in.
Treatment depends heavily on the Salter-Harris type and the degree of displacement, which is how far the fractured bone fragments have shifted out of place. For non-displaced fractures, and often for Type I and Type II injuries, non-surgical treatment is sufficient. This involves a closed reduction, where the doctor gently manipulates the bone fragments back into the correct anatomical position without making an incision, followed by immobilization with a cast or splint. The cast protects the bone and holds it stable while the growth plate heals, a process that takes four to six weeks.
More complex or displaced fractures, particularly Salter-Harris Types III, IV, and V, often require surgical intervention. This involves an open reduction and internal fixation (ORIF), where the surgeon makes an incision to directly visualize and realign the bone fragments. Metal hardware, such as pins, screws, or wires, is then used to hold the pieces securely in place, ensuring the growth plate and joint surfaces are perfectly aligned. This anatomical restoration is necessary for minimizing the risk of future growth problems and preserving joint function.
Addressing Long-Term Growth Consequences
The primary concern following a growth plate fracture is the potential for long-term complications. The most significant complication is growth arrest, the premature cessation of growth in the affected bone. This occurs when the injury damages the active cartilage cells, causing a bony bridge, or physeal bar, to form across the growth plate, halting the bone’s ability to lengthen.
Growth arrest can lead to two main deformities, especially in younger children who have significant growth remaining. The first is a limb length discrepancy, where the injured bone stops growing, resulting in a shorter limb compared to the uninjured side. The second is an angular deformity, which happens if only a portion of the growth plate is damaged, causing the healthy part to continue growing and making the limb grow crookedly. Fractures near the knee, such as the proximal tibia and distal femur, are associated with a higher risk of growth problems.
Because these complications can develop months or even years after the initial injury, long-term monitoring is necessary. Children who sustain a growth plate fracture, especially higher-risk types, require regular follow-up appointments and X-rays until they reach skeletal maturity. If a physeal bar is small, a surgeon may be able to remove it to allow the remaining growth plate to resume function. If significant limb length discrepancy or angular deformity occurs, secondary surgical treatments, such as limb lengthening procedures or osteotomies to reshape the bone, can be performed to correct the issue.