Glossary
Fibula
Quick answer
The fibula is the thin bone on the outer side of the lower leg. It carries little body weight, but its upper end, the fibular head, anchors the lateral collateral ligament and the biceps tendon, notes Dr. Pablo Gelber, who sees knee patients at Aman Hospital in Doha.
What it is
The fibula runs alongside the tibia from just below the knee to the ankle. It does not form part of the knee joint itself. Its knobbly top, the fibular head, sits just below and behind the outer side of the knee, where you can feel it under the skin.
Several important structures attach there: the lateral collateral ligament, the biceps femoris tendon (one of the hamstrings) and parts of the posterolateral corner. The common peroneal nerve, which lifts the foot and supplies feeling to the top of the foot, wraps around the neck of the fibula just below the head.
Why it matters for patients
A blow to the inside of the knee, or a violent twist, can pull these structures off the fibular head, sometimes with a small flake of bone. That points to a lateral collateral ligament or posterolateral corner injury, which often needs prompt specialist assessment. Because the peroneal nerve lies so close, a doctor checks for numbness on the top of the foot or weakness lifting the foot or toes after such injuries. Pain on the outer knee can also come from the joint between the fibula and tibia, though this is less common.
Frequently asked questions
Is a fibular head fracture serious?
The break itself is usually minor, but it can signal a significant ligament injury or nerve stretch. It needs a careful knee examination rather than being treated as a simple bruise.
Why does my foot feel numb after an outer knee injury?
The peroneal nerve runs around the fibula near the knee and can be bruised or stretched. Numbness or a weak, dropping foot after injury needs prompt medical review.
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