An ankle sprain is an injury to the tough bands of tissue (ligaments) that surround and connect the bones of the leg to the foot. The injury typically happens when you accidentally twist or turn your ankle in an awkward way. This can stretch or tear the ligaments that hold your ankle bones and joints together.Allligaments have a specific range of motion and boundaries that allow them to keep the joints stabilized. When ligaments surrounding the ankle are pushed past these boundaries, it causes a sprain. Sprained ankles most commonly involve injuries to the ligaments on the outside of the ankle.