A sprain (from the French espraindre - to wring) is an injury which occurs to ligaments caused by a sudden overstretching (for the muscle injury, see strain). The ligament is usually only stretched, but if it's completely torn, a longer period of immobilization and surgical repair may be necessary. Degrees Although some signs and symptoms can be used to assess the severity of a sprain, the most definitive method is with the use of Magnetic Resonance Imaging (MRI). Sprains are graded in four de… (More on Sprain)