The fibula is the thin bone that runs along the outer side of your lower leg, from just below the knee down to the outer ankle bone, where it forms part of the ankle joint.
What your fibula does and how it gets injured
Your fibula runs parallel to the tibia, the main weight-bearing bone of the lower leg, but it carries relatively little of your body weight directly. Its primary roles are stabilizing the ankle joint and providing attachment points for muscles that control foot and ankle movement. The lower end of the fibula forms the outer bump of your ankle — the lateral malleolus — which is the most commonly fractured bone in ankle injuries. In an ankle sprain, the ligaments attaching to the fibula are the structures most often stretched or torn. A fibula stress fracture can also develop gradually from repetitive impact, producing pain along the outer lower leg that's easy to mistake for a muscle problem or shin splints.
Why fibula injuries are underestimated
What feels like a minor ankle twist can involve significant ligament damage at the fibula, and stress fractures in the bone can be present for weeks before the pain becomes severe enough to prompt evaluation. Both tend to heal better — and more completely — when addressed with targeted rehabilitation rather than rest alone.
Why "walking it off" doesn't always work
The ankle's stability depends on both the bony structure of the fibula and the integrity of the surrounding ligaments. When those ligaments are stretched, even slightly, the joint becomes less stable and compensation patterns develop quickly — often leading to recurring sprains or chronic ankle instability if the underlying weakness isn't addressed. Physical therapy targets exactly that.
How Sword Health can help
Whether you're recovering from an ankle sprain, a fibula fracture, or recurrent ankle instability, a physical therapist can guide your rehabilitation and help you rebuild strength and confidence in the joint. Sword connects you with that care from home, at whatever stage of recovery you're in.
About the author
Carolina Moreira
Medical Director of Clinical Development at Sword Health
