Avulsion Fracture

Avulsion fractures happen when a bone fragment separates from the rest of the bone. In children, they are most common in sports like soccer, football, gymnastics, and other sports that involve sudden changes in direction, leaping, and kicking. Avulsion fractures are most common around the hip or pelvis but can also occur in the ankle, foot, finger, elbow, or knee.

Avulsion fractures occur most frequently in female athletes between the of ages 13 and 14 and in male athletes between the ages of 15 and 17.

To understand avulsion fractures, it helps to understand the interactions between tendons, muscles, and bones. Tendons connect muscles to bones. When a soccer player kicks a ball, for instance, their muscles provide the power while their tendons transfer this power to their bones, moving the leg so that it sends the ball down the field.

Avulsion fractures happen when a set of muscles puts more pressure on the bone than the bone can withstand. As youth sports have become more competitive, many young athletes are developing extremely strong muscles. When a muscle is stronger than the bone it’s attached to, it becomes more likely that the force of the tendon can cause a small piece of bone to break away from the rest of the bone.

In addition to the rapid development of muscle strength during adolescence, the rapid rate of growth during childhood and adolescence can lead to tighter muscles and tendons in young athletes, which can result in increased tension on the location where the tendon attaches to the bone.

In growing athletes, avulsion fractures typically occur around soft areas of cartilage called apophyses — areas of the skeleton where the bone is rapidly developing and not yet fully ossified (hardened). Once a child reaches mature height, these areas become as strong as the rest of the bone, but until then, the apophyses are prone to injury.

Some avulsion fractures are acute injuries that occur during the sudden, explosive motions or changes in direction common in soccer, tennis, gymnastics, and football.

In other cases, avulsion fractures are overuse injuries that develop over time through repetitive stress on the bone, such as in running.

• A popping or cracking sound (acute injury)
• Bruising or swelling around the injury
• Pain that spreads to surrounding areas of the body
• Pain when moving the affected limb
• Limping or trouble walking
   

Your child’s doctor will examine the injured area and ask about the sports your child plays and when they started feeling pain.

The doctor may order an X-ray to look for signs of bone damage. They may also perform a sports ultrasound, which allows them to see the muscles, tendons, and bone as your child moves their limb.

In some cases, magnetic resonance imaging (MRI) can help diagnose or confirm an avulsion fracture.

Most avulsion fractures do not require surgery. But your child will need to take time off from sports to allow their injured bone to heal. It’s possible your child will need to use crutches or wear a brace or a cast.

Full recovery from an avulsion fracture can take anywhere from a couple of weeks to several months, depending on the severity and location of the injury.

The Boston Children’s Hospital Orthopedics and Sports Medicine Center provides comprehensive assessment, treatment, and follow-up care to children, adolescents, and young adults with avulsion fractures. We understand the importance of sport in young athletes’ lives and provide the best care possible to help our patients return to their sports safely, without risking further injury.