what causes swollen ankles?

Well, it could be a number of things.
The question is, are you swollen in one ankle or both ankles? Also is there any pain or discomfort associated with swelling? Another vital question is how far does the swelling go? How quickly did it come along?
These are all questions that help a Podiatrist diagnose the cause of your ankle swelling.
NOTE: Before I go further if you have any concerns and would like to speak to a podiatrist feel free to click here
If you have only one swollen ankle, it is likely caused by a fracture or sprain from an injury. Some of the most common causes of ankle injuries are:
  • Medial Ligament injury
  • Lateral Ligament injury
  • Talar Dome Fracture
  • Anteroinferior tibiofibular ligament injury (Ankle Syndesmosis)
  • Medial Malleolus stress fracture
  • Flexor hallucis longus tendinopathy
  • Potts fracture
  • Sinus Tarsi Syndrome
If both your ankles are swollen it can be a symptom of a multitude of medical conditions, including pregnancy, infection, heart problems, and more. It could also be caused by a side effect of medications you’re taking, such as those for high blood pressure, diabetes, and arthritis.
If you fall into any of the above categories, your swollen ankles are a bi-product caused by issues that are above your waist and maybe a long-term side effect of your condition.
If you don’t have an underlying medical condition that might cause swelling or oedema in your ankles, the following could be the cause.

Standing or sitting down for long periods of time

To explain why this can happen I need to run through blood flow.
Your heart works hard to pump blood around your body. With the help of gravity, the blood easily flows to your lower body.
The last stop is your feet.
Getting the blood down when you’re standing or sitting is no problem.
Helping the blood flow back up to your heart is where your body needs to work against gravity.
The blood has to flow back up the leg but can’t do so without the help of your muscles.
The most helpful muscles in your legs to take on this job are your Gastrocnemius muscles also called your calf muscles.
This is called venous return.
Your calf muscles work together with your muscles in your lower body to help the blood flow back up to your heart. 
When your muscles are relaxed and don’t contract, the blood isn’t pushed upwards against gravity.
When you stand or sit, the muscles tense up and the blood flow is impeded.
This can cause the blood to pool in your lower body.
Causing Swelling or oedema in your ankles.

If this scenario sounds like you try the following tips to reduce the swelling.

1. The simplest trick is to go for a walk. This helps the fluids pulling in your ankles to mechanically shift up using your calf muscles as you take each step.
2. Calf raises are a good way to contract those calves if you’re unable to walk.
3. If you’re in a chair – raise your feet up and straighten your legs and point your toes forward and back to contract your calf muscles while you’re seated.
4. If you’re able to lay down – elevate your feet to a level higher than your chest and let gravity do the work for you.

Ankle Sprain

If you’re experiencing ankle pain or stiffness and If you can recall falling or tripping or an object hitting your ankle.
Then it’s probably a safe bet that the swelling in your ankles is due to recent trauma.
An ankle sprain is a common injury and can occur if one of the ligaments that support your ankle becomes stretched or torn.
 The most common ligament injury is the medial ligament.