A sprain is an injury to a ligament. Ligaments are strong tissues around joints which attach bones together. They give support to joints. A ligament can be injured, usually by being stretched during a sudden pull. The ligaments at the side of the ankle are the ones most commonly sprained.
A damaged ligament causes inflammation, swelling, and bleeding (bruising) around the affected joint. Movement of the ankle joint is painful when you have a sprained ankle.
The severity of a sprain is graded into:
• Grade I - mild stretching of the ligament without joint instability.
• Grade II - partial rupture (tear) of the ligament but without causing joint instability (or with mild instability of the joint).
• Grade III - complete rupture (tear) of the ligament with instability of the joint. Sometimes this is simply called a severe ankle sprain.