An avulsion fracture occurs when a muscle or tendon is pulled so hard at the spot where it attaches to the bone that it tears a small piece of bone away. Avulsion fractures can occur on any part of the body, but they are most common in the ankles, hips, and elbows.
Anyone can suffer an avulsion fracture of the ankle, but athletes and children are more prone to them than the rest of us.
When the ankle is twisted in a way that causes an ankle injury, there are two things that can happen—either a tendon or ligament tears, or it pulls on the spot where it attaches to the bone with enough force to pull off a piece of that bone; this is an avulsion fracture of the ankle.
Symptoms of an Avulsion Fracture of the Ankle
The symptoms of an ankle avulsion fracture are similar to the symptoms of a sprained ankle, and indeed avulsion fractures are sometimes misdiagnosed as sprains. The only way to determine whether you have suffered an ankle sprain or an avulsion fracture of the ankle is to have an x-ray or MRI taken.
If you suffer this type of injury, you will feel severe pain immediately, and swelling will occur very quickly. Bruising may occur immediately, or bruises may not appear until later.
What Causes Ankle Avulsion Fractures?
Athletic activities—particularly certain sports, i.e., basketball, soccer, and football—are a frequent cause of avulsion fractures of the ankle.
One reason athletes can be at greater risk is that that ankle avulsion fractures can sometimes be caused by muscle contractions pulling a tendon or ligament away from the bone.
Most people have neurological limitations that prevent the muscle from exerting sufficient force to cause such an injury, but in order to achieve better performance, athletes can and do train themselves to overcome this limitation.
Treatment for an Avulsion Fracture of the Ankle
Surprisingly, if the injury is not too severe, treatment for ankle avulsion fractures is not necessarily invasive, and is often similar to treatment for a sprain—RICE treatment.
That is, Rest, Ice (for the swelling and inflammation), Compression (which can be achieved with bandages), and Elevation of the affected ankle.
In addition to ice, NSAIDs (non-steroidal anti-inflammatory drugs) can also be helpful for reducing swelling. A less severe injury that does not require aggressive treatment is one in which the fragments of bone pulled away are too small to be concerned about, or in which the bone fragment has not been pulled too far away from the rest of the bone.
If the bone fragment has been pulled more than a few centimeters out of position, however, surgery and/or casting may be necessary.
Ankle Avulsion Fractures in Children
As noted above, children are more prone to avulsion fractures than adults, because children’s bones are weaker than the bones of adults and more likely to break before the tendons or ligaments attached to them break.
Furthermore, there is a part of a child’s bone called the growth plate that is weaker because it is still growing. Therefore, different treatment is sometimes called for when this type of injury happens to a child. If an avulsion fracture occurs to the growth plate, surgery is more likely to be necessary.
If you are having trouble understanding why this is the case, imagine gluing a rubber band to your desk; if you pull hard enough on the rubber band, it will break—as a tendon might.
If you glue that same rubber band to a piece of paper, however, the paper will rip long before the band breaks. This is an imperfect analogy, but it should work well enough for you to get the idea.
Correct treatment for ankle avulsion fractures in children is very important; if the fracture is not treated properly it can affect the growth of the bones, creating long-term problems. At minimum, treatment is likely to involve a cast, and possibly surgery.