A fractured fibula is a break in the smaller of the two bones in your lower leg. The fibula runs along the outer side of your leg from just below the knee down to the ankle. Unlike the tibia, the larger bone next to it, the fibula isn’t a major weight-bearing bone. Its primary job is providing structure to your leg and serving as an anchor point for muscles, tendons, and ligaments. That said, a break in the fibula can still significantly affect your ability to walk and move your ankle, and some fractures require surgery to heal properly.
Where the Fibula Sits and Why It Matters
The fibula sits on the lateral (outer) side of your lower leg, running parallel to the much thicker tibia. At its lower end, it forms the bony bump on the outside of your ankle, called the lateral malleolus. At its upper end, the fibular head sits just below and to the outside of the knee joint. Because the fibula connects to important structures at both the knee and ankle, a break anywhere along its length can affect joint stability, even though the bone itself carries very little of your body weight.
The location of the fracture along the fibula largely determines how serious the injury is. A break near the ankle often involves the ligaments that hold the ankle joint together, which can make the entire joint unstable. A break higher up, near the knee, can threaten the nerve that wraps around the fibular head, potentially causing numbness or weakness in the foot.
How Fibula Fractures Happen
Most fibula fractures result from a twisting or rolling motion at the ankle, the kind of awkward step off a curb or landing from a jump that forces the foot into an unnatural position. Direct blows to the outer leg, car accidents, and falls from height are also common causes. Sports that involve quick direction changes, like basketball, soccer, and trail running, carry higher risk.
One particularly deceptive pattern is called a Maisonneuve fracture. In this injury, a twisting force at the ankle tears the ligaments holding the lower tibia and fibula together, then travels up through the membrane connecting the two bones and fractures the fibula near the knee. The ankle looks like a bad sprain, but the actual bone break is much higher up the leg. This is why doctors sometimes X-ray the full lower leg after what seems like a simple ankle injury.
Types of Fibula Fractures
Doctors classify fibula fractures near the ankle using a system based on where the break sits relative to the syndesmosis, the tough ligament complex that binds the lower tibia and fibula together at the ankle.
- Type A (below the syndesmosis): The break is below the ankle joint line. These fractures are generally stable because the ligaments holding the ankle together remain intact.
- Type B (at the syndesmosis): The break runs through the level of the syndesmosis. These may or may not involve ligament damage, so stability varies.
- Type C (above the syndesmosis): The break is above the ankle ligaments, which almost always means the syndesmosis itself is torn. These fractures tend to make the ankle joint unstable and more often require surgery.
Fractures can also occur at the fibular head near the knee (proximal fractures) or along the middle of the bone (shaft fractures), though ankle-level breaks are the most common.
Symptoms to Expect
The hallmark signs of a fibula fracture are pain on the outer side of the lower leg or ankle, swelling, and bruising. The pain is often dull at rest but becomes sharp when you try to stand or walk. Swelling can spread across the ankle and into the foot, sometimes making it hard to tell a fracture from a severe sprain just by looking.
You may notice a significant loss of ankle mobility. Bending the foot up, down, or side to side can feel restricted and painful. Some people can still hobble on the injured leg, which is one reason fractures sometimes get mistaken for sprains and go undiagnosed for days.
Emergency doctors use a set of clinical guidelines called the Ottawa Ankle Rules to decide whether an X-ray is needed. You’ll typically get imaging if you have bone tenderness along the back edge of the fibula or at the tip of the outer ankle bone, or if you can’t take four steps in the emergency room. These rules help avoid unnecessary X-rays while catching fractures that need treatment.
When Surgery Is Needed
Not all fibula fractures require an operation. Stable fractures where the bone fragments haven’t shifted out of position, typically less than 2 millimeters of displacement, can often heal in a walking boot or cast. You’ll have follow-up X-rays over the coming weeks to confirm the bone stays aligned as it heals.
Surgery becomes necessary when the fracture is unstable, meaning the bone fragments have shifted enough to disrupt the alignment of the ankle joint. Open fractures (where bone breaks through the skin) and fractures with nerve or blood vessel damage also require surgical repair. The operation typically involves a plate and screws to hold the bone in its correct position while it heals. For fractures that tear the syndesmosis, the surgeon may also place a screw or a flexible device between the tibia and fibula to restore that connection.
Recovery Timeline
Most fibula fractures heal completely in six to eight weeks, though returning to full activity takes longer. The timeline depends heavily on whether you had surgery and how complex the injury was.
For the first six weeks, whether you had surgery or not, the focus is on protecting the healing bone. You’ll likely wear a boot and may be told to keep weight off the leg entirely or to limit how much weight you put through it. During this phase, gentle ankle movements like pumping the foot up and down, making circles, and sliding the heel back and forth help prevent stiffness. Strengthening work during this early window focuses on the hip, core, and thigh muscles to prevent the rest of your leg from weakening while the ankle is immobilized.
Between weeks seven and twelve, most people begin transitioning out of the boot. This is when resistance band exercises for the ankle start, along with standing calf stretches and a gradual progression of calf raises. You might begin with only 25% of your body weight through the injured leg during heel raises and slowly build toward equal weight on both legs.
From weeks thirteen through sixteen, exercises become more demanding: single-leg squats, lunges, step-ups, and lateral movements. The goal is rebuilding the strength and control needed for everyday activities and, eventually, sports.
By weeks seventeen through twenty, people recovering from surgical repairs typically progress to jumping and hopping drills, starting on two legs and advancing to one. Clearance to return to sports or high-impact activities usually comes after you can demonstrate solid single-leg strength and pain-free movement through the full range of your ankle.
Nerve Damage and Other Complications
Fractures near the top of the fibula carry a specific risk: injury to the common peroneal nerve, which wraps around the fibular head just below the knee. If this nerve is damaged, you may notice weakness or an inability to lift the front of your foot (a condition called foot drop), numbness on the top of the foot or shin, or a tingling, pins-and-needles sensation in the lower leg. Most mild nerve injuries from fractures improve over time, but severe cases can require additional treatment.
Other potential complications include delayed healing or nonunion, where the bone fails to knit back together on schedule. Smokers, people with diabetes, and those with poor nutrition face higher rates of delayed healing. Stiffness and chronic swelling in the ankle are common if rehabilitation is skipped or cut short, which is why sticking with a structured physical therapy program matters even after the bone itself has healed.