A lateral ligament ankle sprain occurs when the ligaments on the outside of the ankle are stretched beyond their limits, causing pain and swelling. Most sprained lateral ligaments are minor and improve with simple treatment. But severe cases can weaken the ankle, leading to repeated sprains and chronic ankle pain. So how do you diagnose a tear of the ankle ligaments, and what should you do? 

What are the lateral ligaments?

Ligaments are strong fibrous structures connecting bones. Three ligaments connect the top and bottom of the ankle joint on the outside. Spraining the ankle damages one or more of these lateral ligaments — an injury also known as a lateral ankle ligament sprain.

A lateral ligament ankle sprain occurs when the ankle rolls inwards or twists — typically while walking or running on uneven surfaces, playing sports involving a change of direction, or after an unexpected fall.

The more times you sprain your ankle, the more likely you are to sprain it again.

Symptoms of a lateral ligament ankle sprain

A sprained lateral ligament causes pain on the outside of the ankle. Other symptoms include:

  • A pop or crack at the time of injury
  • Swelling, forming immediately or overnight
  • Bruising
  • Stiffness from inflammation, worse in the morning and easing with activity
  • Instability of the ankle joint, which can occur with complete tearing of the ligaments
  • Tenderness over the ligaments

Your doctor diagnoses a lateral ligament sprain by carefully examining the ankle and foot. It’s essential to exclude a fracture or cartilage injury. An X-ray, ultrasound, or MRI is often needed to confirm a ligament tear and rule out other injuries.

Treatment of a sprained lateral ligament

thlete with a lateral ligament ankle sprain on the outside of the ankle

Almost all torn ligaments in the ankle are treated without surgery. Even complete lateral ligament tears improve with bracing and physiotherapy. Tearing your ligaments doesn’t mean you need an operation.

We suggest a three-phase process to get you back to sport:

  • Phase 1 — rest from sport, compression, and regular icing to limit swelling. A short course of ibuprofen can help, and a small cast boot may provide extra support.
  • Phase 2 — range of motion exercises, stretching, and calf strengthening. Balance exercises are essential to prevent recurrence.
  • Phase 3 — complex exercises, a gradual return to running, and change-of-direction work. Your therapist will introduce agility drills to test the ankle.

When an ankle sprain isn’t getting better

About 10% of lateral ligament sprains don’t improve with simple treatment. In these cases, see your doctor and consider imaging to confirm the diagnosis. An ultrasound or MRI can diagnose other problems, such as a peroneal tendon tear or ankle cartilage damage.

Other injuries that can accompany a sprain include:

  • Fractures of the small bones around the ankle, such as the anterior process of the calcaneus, the base of the fifth metatarsal, or an os trigonum
  • Cartilage damage in the ankle joint

Is an injection an option?

Occasionally an injection helps rehabilitation progress. A common cause of ongoing ankle pain after a rolled ankle is persistent inflammation in the ankle joint or ankle arthrofibrosis, and a cortisone injection directed at this inflammation can reduce pain and allow more effective rehab. We perform injections under ultrasound to improve accuracy and avoid nearby nerves and blood vessels.

We’d usually consider this only if you haven’t improved with rehabilitation over three to six months. For full details — including who it suits, the evidence, and costs — see our dedicated guide to a cortisone shot for a sprained ankle.

Occasionally, surgery is needed to remove inflamed tissue or reconstruct the ligaments. We reserve surgery for cases that fail rehabilitation.

Frequently asked questions about lateral ligament ankle sprains

Why do I keep twisting my ankle?

Repeated ankle twists cause more damage to the outside ligaments, which makes further sprains more likely. This is why seeing a therapist after a sprain matters — balance and strength work genuinely reduce the risk of it happening again.

Why won’t my ankle heal after a sprain?

Not all sprained ankles involve ligament damage alone. Rolling your ankle can also damage tendons or cartilage. If you’re not improving, see an experienced doctor who can identify why the problem is persisting.

Can a torn ligament in the ankle heal without surgery?

Yes. Even with tears of all the ligaments outside the ankle, full function can be regained without surgery. We suggest a short period of rest in a walking boot followed by progressive physiotherapy.

Is a deltoid ligament sprain treated differently?

Yes. The deltoid ligament on the inside of the ankle is much larger and stronger than the lateral ligaments, so a tear is a more severe injury requiring extended rehabilitation. For complete deltoid tears, we recommend surgical repair.

How long does a lateral ligament ankle sprain take to heal?

A minor sprain often settles within a few weeks, while more significant tears take longer and need a full three-phase rehabilitation programme before returning to sport. Balance work is the part most often skipped — and the part that most reduces the risk of recurrence.

Final word from Sport Doctor London about lateral ligament ankle sprains

Not all ankle injuries are benign and settle with physiotherapy alone. If your ankle isn’t improving, see an experienced sports doctor to diagnose and manage it properly — particularly to exclude the fractures, tendon tears, and cartilage injuries that hide behind a “simple” sprain.

If you have a persistent ankle problem, Dr Masci can assess you in London, including ultrasound in clinic. Contact the team here or call +44 (0) 203 488 0350.

Related conditions: