An ankle sprain is a very common injury. According to the American Academy of Orthopedic Surgeons, approximately 25,000 people sprain their ankles every day. The ankle joint is comprised of three bones, the tibia, fibula and talus. These three bones are connected by ligaments, and a sprain is an injury to a ligament by either stretching or tearing. There are three types of ankle sprains: inversion sprain, eversion sprain and syndesmosis sprain. Each type is caused by a different mechanism of injury.
Inversion Ankle Sprain
An inversion ankle sprain occurs when the foot is rolled inward and pointed down; this causes the ligaments on the outside of the ankle to be stretched or torn. Inversion of the ankle can occur when stepping in a hole, or on top of another person's foot. The most commonly injured ligament in this scenario is the anterior talofibular ligament. This connects the fibula and the talus. Pain is located primarily on the outside of the ankle toward the front.
Eversion Ankle Sprain
An eversion ankle sprain is caused by the foot being rolled outward, stretching beyond the limits of the ligaments on the inside of the ankle. This type of ankle sprain can occur when jumping, running or being on uneven terrain. The ligament that is most commonly injured in this type of sprain is the deltoid ligament. This ligament attaches the tibia to the talus and calcaneus bones.
Syndesmosis Sprain
A syndesmosis sprain is more commonly known as a "high ankle sprain." This type of sprain is caused by the foot being forced into an outward rotation. This injury occurs most commonly in football, basketball and soccer players. These athletes are frequently planting their foot and changing direction, which can create this outward rotation. The injury occurs to the connective tissue between the two lower leg bones, the tibia and the fibula. This connective tissue is called the syndesmosis.
