Glossary
Avulsion fracture
Quick answer
An avulsion fracture happens when a ligament or tendon pulls off the small piece of bone it is attached to, instead of the ligament itself tearing. Around the knee it is common in teenagers and after twisting injuries, explains Doha knee surgeon Dr. Pablo Gelber, who treats these injuries at Aman Hospital.
What it means
Avulsion means pulling away. In a sudden, forceful stretch, the weakest point gives way. In young people with growing bones, that is often the bone at the attachment rather than the ligament.
Examples around the knee include the tibial spine avulsion, where the ACL pulls off its bony attachment, common in children; the Segond fracture on the outer tibia; PCL avulsions at the back; and avulsion of the fibular head with the LCL.
Why it matters
An avulsion can be good news in one sense: bone heals to bone more reliably than torn ligament heals to itself. If the fragment is put back in place and fixed, the ligament can work normally again.
The risk is missing it. A small fragment can be hard to see on X-ray, and a displaced piece that is left can block movement or leave the knee loose.
How it is treated
X-ray and often CT or MRI show the size and displacement of the fragment. Undisplaced avulsions may be treated in a brace or cast. Displaced ones, especially tibial spine and PCL avulsions, are often fixed with screws or sutures, frequently through arthroscopic keyhole surgery.
Frequently asked questions
Is an avulsion fracture worse than a ligament tear?
Not necessarily. When the fragment is reduced and fixed, healing is often reliable because bone heals well. The outcome depends on displacement and timely treatment.
How long does an avulsion fracture take to heal?
Bone usually heals in around six to eight weeks, with further rehabilitation afterwards to restore strength and movement.
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