This is part of a DFTB minor injuries series. Today’s post is about ankle injuries.
When should I x-ray an ankle?
The Ottawa ankle rules are a decision tool for x-ray in patients with an ankle injury.
If there is pain in either malleolar region, and one of the following then an x-ray is indicated:
- Inability to bear weight (walk four steps) immediately after the injury and when examined.
- Bone tenderness along the distal 6 cm of the posterior edge of the fibula or tip of the lateral malleolus.
- Bone tenderness along the distal 6 cm of the posterior edge of the tibia or tip of the medial malleolus.
The Ottawa ankle rules are very sensitive – so if your patient does not meet the criteria for x-ray, it is very unlikely that your patient has a fracture.
There is no evidence for CT or MRI in acute ankle sprain.
Can we use the Ottawa ankle rules in children?
The rules were originally validated in adults, but the analysis since shows that they can be used in children too. The introduction of the Ottawa ankle rules in one hospital in the UK reduced the number of x-rays ordered by 7% and showed no increase in the number of missed fractures.
It should be noted that these rules are meant to be applied to those patients who have the ability to walk prior to their injury, and can localise pain with verbal communication. For every 1000 patients that exhibit negative Ottawa ankle rules, 14 will actually have fractures.
Understanding ankle x-rays and managing fractures
I’ve written this up in a separate post – ankle x-ray interpretation.
What is a sprain?
A sprain is where you stretch or tear a ligament by applying abnormal force. Sprains usually occur in ankles, knees, wrists or thumbs.
Symptoms are usually pain, swelling, bruising, tenderness, difficulty using the joint functionally and even mechanical instability if severe.
Sprains can be classified according to severity:
- Grade I – mild stretching of the ligament complex without joint instability.
- Grade II – partial rupture of the ligament complex without joint instability.
- Grade III – complete rupture of the ligament complex with instability of the joint.
How do we assess ankle stability?
There are two tests to assess this – the anterior drawer test and the talar tilt test.
Anterior drawer test: hold the leg with one hand and use the other hand on the back of the foot to gently pull it forward. If there is excessive forward movement of the foot then the test is positive.
Talar tilt test: hold the leg with one hand and use the other hand to hold the foot and gently invert it. If there is excessive tilting then the test is positive.
They are much more clearly explained in these videos:
How do we best manage a sprain?
Simple management includes analgesia, and PRICE (protect, rest, ice, compression, elevation).
- Protect from re-injury – this can include using a supportive shoe
- Rest the ankle for up to 72 hours
- Wrap some ice in a towel and hold it against the ankle for 15 mins every few hours for the first 72 hours
- Use a simple tubigrip or elasticated bandage (it helps with the swelling and offers support) but take it off at night
- Elevate the ankle on a pillow until the swelling settles
Do I immobilise it or encourage them to walk?
The patient should avoid heat, massage or running for the first 72 hours after the injury.
If the sprain is severe, then immobilising it for a short time can help their symptoms, but they need to be encouraged to begin mobilising after a day or two to avoid stiffness. If the sprain is mild then advise the patient not to immobilise the ankle. They should encourage gentle movement as soon as they can tolerate it.
What is the recovery time?
The usual recovery period, if the sprain is uncomplicated, is for the patient to be able to walk in 1-2 weeks, run in 6-8 weeks and return to their regular sporting activity in 8-12 weeks.
If in 7 days they still have difficulty walking or worsening symptoms, they should get a review.
