Ankle pain is often due to an ankle sprain. A sprain is an injury to the ligaments, which connect bones to one another. In most cases of ankle sprain, the ankle is twisted inward, causing small tears in the ligaments. This makes the ankle unstable. The tearing leads to swelling and bruising, making it difficult to bear weight on the joint.
Once an ankle is sprained, the injury may take a few weeks to many months to fully heal. Often, the injured ankle remains a little weaker and less stable than the uninjured one. A proper recovery program can prevent this problem.
Other structures in the ankle that can be damaged and cause pain are tendons (which join muscles to bone), cartilage (which cushions joints), and blood vessels. Adjacent areas can cause pain to be felt in (referred to) the ankle — these include the foot, lower leg, knee, and even hip.