Anatomy of a Child’s Bones
A child’s long bones do not grow from the center outward. Instead, growth occurs in the growth plates—areas of developing cartilage located near the ends of long bones.
The growth plate regulates growth and helps determine the length and shape of the mature bone. Only when a child is fully grown do the growth plates harden (ossify) into solid bone. In fact, because muscles and bones develop at different rates of speed, a child’s bones may actually be weaker than the ligaments that connect them. This makes the growth plates more vulnerable to fracture. What is often a bruise or sprain in an adult can be a potentially serious growth plate injury in a growing child.
Description
A child’s bones heal faster than an adult’s so it is extremely important for your child’s injured bone to receive proper treatment immediately, before it can begin to heal. Ideally, this means being examined by an orthopaedic specialist within 5 to 7 days of the injury, especially if manipulation to align the bone is required. Without prompt evaluation, treatment and follow-up care by an orthopaedic surgeon experienced in orthopaedic trauma, the long-term consequences of a growth plate injury may include limbs that are crooked or of unequal length. Fortunately, advances in care have made serious problems such as these quite rare.
Symptoms of a Growth Plate Fracture
Any child who experiences an injury that results in visible deformity, persistent or severe pain, or an inability to move or put pressure on a limb should be examined by a physician immediately. The area around the end of the broken bone (near the joint) will be swollen, warm, very tender, and may appear crooked when compared to the uninjured side.
Causes and Risk
All growing children are at risk for a growth plate injury, with a reported peak in adolescents. A growth plate fracture can be caused by a single traumatic event, such as a fall or automobile accident, or it can be the result of chronic stress and overuse. Studies have shown that these fractures occur twice as often in boys; one third are due to competitive sports such as football, basketball or gymnastics; and approximately 20 percent occur as a result of activities such as biking, sledding, skiing or skateboarding.
Diagnosing Growth Plate Fractures
In addition to a physical examination, your child’s orthopaedic specialist will probably use X-rays to determine if a growth plate fracture occurred. Other diagnostic tests, such as magnetic resonance imaging (MRI), computed tomography (CT), or ultrasound may also be requested.
Growth plate fractures are classified according to the degree of damage to the growth plate itself. The Salter-Harris classification of growth plate fractures, as described here, is one of the most widely used.
- Type I fracture—Breaks through the bone at the growth plate, separating the bone end from the bone shaft and completely disrupting the growth plate.
- Type II fracture—Breaks through part of the bone at the growth plate and cracks through the bone shaft.
- Type III fracture—Crosses through a portion of the growth plate and breaks off a piece of the bone end. More common in older children because the center of the growth plate has begun to harden; instead of continuing across the bone, the fracture angles down and breaks the bone end.
- Type IV fracture—Breaks through the bone shaft, the growth plate, and the end of the bone.
- Type V fracture—Rare; occurs due to a crushing injury to the growth plate from a compression force.
Treatment of Growth Plate Fractures
Treatment depends on the fracture type. Other factors that may affect bone growth and fracture healing include age and health of the patient, associated injuries, and the amount of displacement of the broken ends of the bone (occurring through the growth plates).
- Type I fracture—May disrupt bone growth. Often treated with cast immobilization, however, if surgery is required, internal fixation (pins) may be used to hold bone together and ensure proper alignment.
- Type II fracture—The most common growth plate fracture. Most are treated with cast immobilization. Generally heals well, although surgery may be required.
- Type III fracture—Treated with surgery and internal fixation to ensure proper alignment of both the growth plate and the joint surface.
- Type IV fracture—Commonly stops bone growth. Treatment includes surgery and internal fixation.
- Type V fracture—Almost always accompanied by a growth disturbance. Can often be treated with cast immobilization, however surgery is sometimes required.
Long-Term Outcomes
Growth plate fractures must be watched carefully to ensure the most successful long-term results. In some patients, a bony bridge will form across the fracture line, preventing the bone from growing longer or causing the bone to curve. Orthopaedic surgeons have developed techniques to remove this bony bar and insert fat, cartilage, or other materials to prevent it from reforming.
In other cases, the fracture actually stimulates growth in the injured bone, causing it become even longer than the healthy bone. Surgical techniques can help achieve a more even length.
Depending on the fracture, it is important to have regular follow-up visits with your physician for one year. Complicated fractures (types III, IV and V) as well as fractures to the thighbone (femur) and shinbone (tibia) may require follow-up until the child reaches skeletal maturity.