Ankle Sprains and Instability

What is an ankle sprain?

An ankle sprain means a partial or complete tear of the ligaments of the ankle. The most common ankle sprain occurs on the lateral (outside) part of the ankle. This is an extremely common injury which affects many people during a wide variety of activities. Ankle sprains most commonly occur in isolation, but can also occur in the setting of an ankle fracture (i.e. a broken ankle).

It is also possible to sprain the ligament on the medial (inside) part of the ankle, called the deltoid ligament, but this is a much rarer injury.

What are the symptoms an ankle sprain?

Patients report pain after having twisted or 'gone over' on their ankle. This usually occurs due to an inversion injury, which means the foot rolls underneath the ankle or leg. It commonly occurs during sports or walking on uneven ground. The main complaint is of pain on the outside of the ankle, along with various degrees of swelling and bruising (i.e. bleeding under the skin). Depending on the severity of the sprain, a person may or may not be able to put weight on the foot. 

What are the risk factors for an ankle sprain?

The major risk factor for spraining an ankle is participating in sports like basketball or football, where it's easy to twist the ankle or step on another player’s foot.
Some people are predisposed to ankle sprains. In people with heels which are slightly turned inwards (hindfoot varus), these injuries are more common. This is because the inward posture of the heel makes it easier to turn on the ankle.
One of the biggest risk factors for spraining an ankle is if you’ve sprained it in the past. Severe sprains can result in an unstable ankle, which of course makes it easier to sprain again. Those who have weak muscles, especially weak peroneal muscles (which run along the outside of the ankle), may also be more predisposed. 


There are multiple ligaments in the ankle. Ligaments in general are those structures that connect bone-to-bone. Tendons, on the other hand, connect muscle-to-bone and allow those muscles to exert their force. In the case of a lateral ankle sprain, there are several commonly sprained ligaments. The two most important are the following:

  1. The ATFL or anterior talofibular ligament, which connects the talus to the fibula on the outside of the ankle.
  2. The CFL or calcaneofibular ligament, which connects the fibula to the calcaneus below.  

Finally, there is a third ligament which is not as commonly torn. It runs at the outside back of the ankle and is called the PTFL or posterior talofibular ligament.

Common (lateral) ankle sprains must be differentiated from a high ankle sprain, which is completely different and located higher up the leg.

How is an ankle sprain diagnosed?

Ankle sprains can be diagnosed fairly easily given that they are common injuries. The location of pain on the outside of the ankle with tenderness and swelling in a patient who has sustained an inversion injury is very suggestive. In these patients, plain X-rays also suggest that the bone has not been broken and instead the ankle ligaments have been torn or sprained.

It is very important, however, not to simply regard any inversion injury as an ankle sprain, because other injuries can occur as well. For example, the cartilage inside the ankle joint can be damaged, leading to ongoing pain and potential for progression to arthritis. The peroneal tendons can be torn. There can also be fractures in other bones around the ankle including the fifth metatarsal and the anterior process of the calcaneus. In severe cases, and in those that do not get better in the expected time frame, an MRI may be warranted to rule out other injuries.

What are the treatment options?

Surgery is not required in the vast majority of ankle sprains. Even in severe sprains, the lateral ligaments will heal without surgery. The grade of the sprain dictates the treatment required. Perhaps more important though is the patient’s ability to bear weight. Those that can bear weight even after the injury are likely to return very quickly to play. Those who cannot walk may need to be immobilised, and can expect a longer rehabilitation.

In general, treatment in the first 48 to 72 hours should follow the RICE principles: resting the ankle, icing on and off for 20 minutes every two hours, compressing with tubigrip or similar, and elevating the foot and ankle above the level of the heart (“toes above the nose”). Those patients who cannot bear weight often feel more comfortable in a removable walking boot until they can put weight through their ankle again.

Physiotherapy is a mainstay of treatment. Early range of movement is important to prevent contractures and stiffness, and patients should learn to strengthen the muscles around the ankle, particularly the peroneals. An ankle brace can be used in an athlete until a physio believes that the ankle is strong enough to return to play without it. Surgery is rarely indicated but may be needed in a patient who has cartilage damage, tendon ruptures, fractures or other related injuries. Ligaments are only repaired or reconstructed in cases of chronic instability in which the ligaments are no longer properly stabilising the ankle.

How long does it take to recover?

Recovery depends on the severity of the injury. For minor sprains, a return to activities or sports is often within several days. For very severe sprains, it may take many weeks. It should be noted that high ankle sprains take considerably longer to heal.

Outcomes for ankle sprains are generally quite good. Most patients heal from an ankle sprain and are able to get back to their normal lives, sports and activities. Some people, however, who sustain a severe sprain and do not properly rehab their ankle may go on to have chronic ankle instability. Chronic instability is characterised by repeated ankle sprains. Such repeated episodes can be dangerous because they can lead to ankle joint damage. These patients should be identified and considered for repair.

Frequently Asked Questions

What is a high ankle sprain and is that different from a regular ankle sprain?

A high ankle sprain refers to tearing of the ligaments that connect the tibia to the fibula. This connection is called the syndesmosis. These are different and much less common than standard lateral ankle sprains, but must not be missed since they are a more serious injury and often require surgical intervention.

Do ankle sprains ever need to be repaired acutely?

Ankle sprains rarely, if ever, needed to be treated with surgery. The vast majority simply need to be treated with rest, ice, compression and elevation followed by physical therapy and temporary bracing. Surgery may be recommended in cases with other injuries.

I have sprained my ankle many times. Should I be concerned?

Yes. The more you sprain an ankle, the greater the chance that problems will develop. For example, ongoing instability of the ankle can lead to cartilage damage inside the ankle joint. You should see your doctor if this is occurring.