Ankle sprains are one of the most common orthopedic injuries. A sprain is defined as a tearing of a ligament. A ligament is a dense piece of tissue that holds two bones together at a joint. The majority of ankle sprains are “inversion” sprains, when the foot turns inward. This type of sprain usually injures two ligaments on the outside of the ankle, the anterior talofibular ligament and the calcaneofibular ligament. Occasionally, a ligament over the front of the ankle complex, called the anterior tibial fibular ligament, is injured as well. The ligaments on the inside of the ankle can be injured as well, although this less frequently.

Flexibility is defined as the ability of a joint to move through its normal range of motion during function. Perhaps the best means of defining flexibility is with an example. For many people the hamstring muscles in the back of the thigh lack normal flexibility. For these folks a stretching sensation is felt in the back of the thigh when they attempt to bend forward and touch their toes while keeping their knees straight. Normal flexibility would allow them to touch the floor without a stretching sensation in their hamstring muscles. A standard for normal flexibility has been established for each large joint in the body.