Sprained ankle

What is a sprained ankle, and how common is it?

A sprained ankle is an injury to the ligaments (the tough bands of tissue that hold your ankle bones together)¹. Most involve the outer side of the ankle, which is why doctors call it a lateral ankle sprain. It usually happens when your foot rolls or twists inwards, often with the foot pointing down².

It's the most common muscle and joint injury in people who are physically active, and it's common in everyone else too³. Sprains are graded I to III, from mild stretching to a complete tear with the joint becoming unstable⁴. Treat a rolled ankle as a real injury, even when the pain eases quickly.

What causes it, and who gets it?

Most sprains start with a sudden twist: changing direction quickly, twisting on a planted foot, an impact during sport, walking on uneven ground, or missing a step on stairs, which is common in high heels⁵. Sport is a common setting, especially indoor and court sports⁶.

Sprains are recorded more often in females than in males, and more often in children and teenagers than in adults⁶. That's about how often they happen, not why.

If you've sprained an ankle before, tell your clinician. Repeated sprains can lead to chronic ankle instability (an ankle that keeps giving way)⁷.

What does it feel like, and how is it diagnosed?

A sprain usually brings pain, swelling and tenderness on the outer side of the ankle, often with bruising, and sometimes trouble walking⁸⁹. Swelling can take months to settle, and the ankle may feel unstable⁸.

A podiatrist or doctor will ask how it happened and examine the ankle, adding imaging only when it's needed³. A test of how loose the ligament is tends to be most accurate 4–5 days after the injury¹⁰.

The main thing to rule out is a broken bone. For adults, the Ottawa ankle rules (a short set of checks) help decide whether an X-ray is needed. They're good at ruling out a break, but often flag people who don't have one, so a positive result alone shouldn't decide it¹¹¹². If the injury wasn't a simple inward roll, have a GP or podiatrist check for other injuries rather than assuming it's a sprain¹³.

What helps first?

Most sprains do best with functional treatment: a brace or tape for support, plus gentle exercise started early, rather than a long time in a cast¹⁰¹⁴. A proper brace or tape works better than a simple elastic bandage¹⁰. Early exercise, including balance work, helps reduce repeat sprains and is linked with quicker recovery¹⁰¹⁴. A podiatrist or physiotherapist can fit a brace or tape and set up an exercise plan with you.

A cast for 4 weeks or more gives poorer results¹⁰¹⁴. For a severe sprain, a short spell (under 10 days) in a cast or rigid support can ease pain and swelling before functional treatment starts¹⁰¹⁴. Complication rates and getting back to daily activities don't seem to differ much between the two approaches¹⁵.

What helps if that isn't enough?

If your ankle feels unstable at the first check, or hasn't improved after 2 weeks of treatment, see a doctor⁹. Pain or instability that lingers after initial treatment may need referral to an orthopaedic service (a team that treats bone and joint problems), and shouldn't be put down to slow healing alone².

Braces can help prevent repeat sprains¹⁰, so it's worth asking about one for sport. A physiotherapist or podiatrist can also plan a rehabilitation program that works on both strength and balance.

How long does it take to get better, and how can I stop it coming back?

Recovery isn't always complete: many people still have symptoms six months later⁷. Pain and swelling settling doesn't mean the ankle has fully recovered. It can stay unstable, which raises the risk of spraining it again². Not having proper rehabilitation after the first sprain can contribute to chronic ankle instability¹⁷. Going back to demanding activity too soon may raise the risk of repeat sprains and long-term ankle problems, so build up in stages².

To lower the chance of another sprain, start guided exercises early, work on balance and strength, and keep going after the pain has settled¹⁰¹⁴. Take extra care on uneven ground, on stairs and when changing direction quickly.