An ankle sprain: a case-based approach

The case: a rolled ankle

A 22-year-old dashes for a bus, steps awkwardly off a kerb, and feels the ankle roll inward with a sharp pain on the outer side. It swells quickly, bruises over the next day, and hurts to walk on, though hobbling a few steps is just about possible. This is the classic picture of an inversion sprain, where the ankle twists inward and stretches or tears the ligaments on the outer side. Most such injuries are sprains rather than breaks. Even so, a fracture can produce very similar swelling and pain, so the first job is to work out whether the bones might be broken and an X-ray is needed, rather than assuming it is only a sprain.

The Ottawa ankle rules in plain terms

To avoid unnecessary X-rays while catching fractures, clinicians use a simple, well-tested checklist called the Ottawa ankle rules. In plain terms, they ask two things. First, can you bear weight, meaning could you take about four steps both immediately after the injury and when being examined, even with a limp? Second, is there tenderness pressing on specific bony points around the ankle and foot? If you cannot walk those few steps, or there is tenderness over those key bony spots, an X-ray is recommended to look for a break. If you can walk and those points are not tender, a fracture is very unlikely and an X-ray can usually be avoided. These rules guide, but do not replace, a clinician's judgement.

When an X-ray is needed

An X-ray is a quick, painless scan that shows the bones and reveals most fractures. Following the Ottawa ankle rules, it is recommended when someone cannot bear weight as described, or has tenderness over the specific bony landmarks the rules identify. This matters because a broken ankle may need a plaster cast, a special boot, or occasionally surgery, whereas a sprain is managed with support and time. Not every twisted ankle needs imaging; the value of the rules is that they safely spare many people an X-ray while still picking up the injuries that need one. A clinician at a minor injuries unit, urgent treatment centre or emergency department can apply the checklist and arrange an X-ray if it is warranted.

Self-care for a sprain

Most ankle sprains recover well with simple measures over days to a few weeks. In the first couple of days, the familiar approach is to rest and protect the ankle, apply a cold pack wrapped in a cloth for short spells to ease swelling, gently support or bandage it, and keep the foot raised when resting. Over-the-counter pain relief, taken as directed, helps you stay comfortable and moving. Rather than complete rest for long periods, gently returning to gentle movement and weight-bearing as pain allows helps recovery and prevents stiffness. Avoid heat, alcohol and vigorous massage in the very early stage, as these can worsen swelling. If the ankle is not improving after a week or two, or keeps giving way, ask a clinician or physiotherapist for advice.

Red flags that need urgent care

Some signs mean you should not wait. Phone 999 or attend an emergency department if the ankle or foot looks clearly deformed or out of shape, if a bone is showing through the skin, or if the foot becomes pale, blue, cold or numb, or you cannot move the toes, as this can signal harm to bones, blood vessels or nerves. Severe, uncontrolled pain, rapidly worsening swelling, or a wound over the injury also need urgent care. For a painful ankle that you cannot walk on, or that is not settling, a minor injuries unit, urgent treatment centre or NHS 111 can advise and check whether an X-ray is needed. When unsure after a twist or fall, it is safer to have it assessed.