The term "strained ankle" is actually a misnomer for a sprained ankle. Strains occur when muscle tissue or tendons begin to tear, causing pain in that muscle. A sprain occurs when a ligament is damaged or begins to tear, causing pain. Ligaments are tissues that connect the bones in a joint, so a strained ankle is actually a sprained ankle since the damage in the ankle joint is to a ligament, not a muscle or tendon. The term "strained ankle" is not commonly used in medical terminology.
A pain that feels like a strained ankle might be a sprained ankle. This occurs when the ligaments in the joint are stretched or twisted beyond their means, leading to tearing of the tiny fibers that make up the ligament. A sprain will result in swelling and tenderness, as well as a loss of mobility, and a sprained ankle sufferer is likely to be unable to put pressure on the joint for several days or weeks, depending on the severity of the injury. The RICE treatment (rest, ice, compression, and elevation) is used to address a sprained ankle. These practices are aimed at reducing swelling, thereby reducing pain and increasing blood flow to the injury.
A muscle strain can sometimes be confused for a strained ankle. Muscles become strained when they are stretched or twisted beyond their means, leading to tearing of the tiny fibers that make up the muscle. These injuries can also be treated using the RICE treatment, and the pain can radiate into the ankle, making a sufferer believe he or she has endured a strained ankle. If a muscle strains so severely that the muscle tissue tears completely from itself or from the tendons that attach it to bone, the injury is then known as a muscle rupture. Ruptures can be extremely painful and difficult to recover from; surgery may be necessary to repair the ruptured muscle.
Sprained ankles often occur among athletes. A good way to combat the likelihood of a sprained ankle is to wear highly supportive footwear. Some athletes go so far as to use athletic tape to tape the ankle joint; this will limit mobility to a point, but it will offer additional support that will prevent the ankle from moving in unnatural motions.