Ankle pain and swelling: causes and when to worry

Common causes

After an injury

• Ankle sprain. Stretching or tearing of the ligaments, usually on the outer side, causes pain, swelling, bruising and tenderness. Sprains are graded from mild to a complete tear.^[2]
• Fracture. A broken ankle or foot bone can look like a sprain. Severe pain, swelling, bruising, inability to bear weight, or visible deformity suggest a fracture.^[6]
• Achilles tendon rupture. A sudden pop or stab at the back of the ankle with weakness in pushing off.^[7]

Ongoing or recurring problems

• Chronic ankle instability, with repeated giving way and swelling after activity, most often after a sprain that never fully recovered.^[8]
• Arthritis, with pain, stiffness and swelling that build gradually, often after an earlier injury.^[9,10]
• Inside-the-joint problems such as impingement, a cartilage injury (see osteochondral lesions of the talus), or a tendon injury (see peroneal tendon injuries), which can cause pain that persists after a sprain.^[1]
• Tendon problems, such as pain behind the heel from the Achilles tendon, or pain and swelling on the inner ankle from the posterior tibial tendon.^[11,12]

After a twisting injury: do I need an X-ray?

A clinical checklist, the Ottawa ankle and midfoot rules, helps decide whether X-rays are needed after an ankle or foot injury. A systematic review of 66 studies found that the ankle rules were very sensitive (99.4%) for detecting a fracture, which means that a person who has none of the findings is very unlikely to have one, but they were not very specific (35.3%), so an X-ray after a positive finding will often show no fracture.^[3] The findings include bone tenderness at specific spots and an inability to take four steps. If you can’t bear weight or you have bone tenderness, get evaluated.

Ligament damage is often best judged a few days after the injury, when swelling has settled a little: an earlier guideline found that delayed physical examination four to five days after the injury was the most reliable way to assess the severity of the ligament damage.^[4]

What helps in the first days

For most sprains, early treatment consists of protecting the ankle, reducing swelling, and starting to move it as soon as comfort allows.^[2,13] Rest, ice, compression and elevation are commonly used, and a brace, wrap or boot can support the ankle. A review of treatments found strong evidence for early mobilization and for anti-inflammatory medicines for pain and swelling, with moderate evidence for exercise and manual therapy, and exercise-based rehabilitation reduces the chance of another sprain.^[13,14] Ask a clinician whether you may safely use anti-inflammatory medicines. Incomplete rehabilitation is the most common cause of chronic ankle instability after a sprain, which is why a rehabilitation program matters even when the pain has settled.^[2]

When to have it evaluated

• an ankle that keeps giving way or turning
• pain or swelling that lasts more than several weeks after an injury
• stiffness or catching in the joint
• pain that is getting worse rather than better

For more, see chronic ankle instability, ankle arthritis and ankle and foot fractures.

When to seek care