We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.
Health

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

What Causes an Avulsion Fracture?

By Shelby Miller
Updated: May 17, 2024
Views: 19,416
Share

An avulsion fracture is a type of bone injury in which a small piece of bone known as a fragment breaks away from the rest of the bone. A consequence of a fall or other impact injury or of an abrupt pulling of tissue away from the bone, an avulsion fracture tends to damage the small protrusions of bone to which ligaments or tendons attach. Typically seen in athletes who jump or land explosively, one example of this type of injury is an avulsion of the tibial tuberosity, the small swelling on the tibia bone felt just below the kneecap. A sudden and violent extension or straightening of the knee joint can cause the patellar ligament, which connects the patella or kneecap to the tibial tuberosity, to pull so hard away from the bone that it breaks the tuberosity right off.

Most commonly occurring in the lower body, an avulsion fracture is seen in areas like the pelvis, knee, and ankle where the major muscles of locomotion attach. The ischial tuberosity in the hip, for instance, a bony prominence in the lower pelvis on the ischium bone, is a potential site of an avulsion fracture. This is because the large muscles of the hamstring group on the back of the thigh attach here via strong tendons.

As the hamstrings can be very tight, a sudden overstretching of the muscles can overpower the body’s stretch reflex, a neurological constraint that is placed on muscles to prevent stretching to the point of tearing. This reflex causes them to spring back before they become overstretched. In the case of very sudden and explosive movements, however, especially in the untrained individual, the stretch reflex can become overwhelmed.

The resulting force can create such a strong pull on the muscles’ attaching tendons that the tuberosity or protrusion to which they attach breaks off from the rest of the bone. An avulsion fracture caused by a powerful muscle contraction such as this is more likely in children, however, than in adults. In adults, the tendon typically absorbs the force and it is the tendon that tears, not the bone. A child’s still-developing bones may not be able to withstand the pull on the protrusion by the tendon, and an avulsion fracture is the result.

Avulsion fractures may also be caused by bone pulling away from bone via their connecting ligaments. At the ankle joint, for instance, the bones of the shin and talus bone in the ankle are joined by several powerful ligaments. A forceful overstretching of these ligaments as experienced during an ankle sprain may break off a small piece of bone at the place where the ligaments attach. Typically, this type of injury is treated the same as a muscle tear or ligament sprain — with rest, ice, and compression like any soft tissue injury — and therefore surgery is not required unless the bone is pulled a considerable distance away from the injury site.

Share
WiseGeek is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.

Editors' Picks

Discussion Comments
Share
https://www.wisegeek.net/what-causes-an-avulsion-fracture.htm
Copy this link
WiseGeek, in your inbox

Our latest articles, guides, and more, delivered daily.

WiseGeek, in your inbox

Our latest articles, guides, and more, delivered daily.