The term "strained ligament" is actually an inaccurate term. Ligaments cannot be strained; only muscles and tendons can be strained. A ligament can, however, be sprained, so instead of calling the injury a strained ligament, it should be called a sprained ligament. The similarity between the two words often leads to confusion, and it is common to hear people refer to a ligament injury as a strained ligament. A sprained ligament occurs when the fibrous tissues that connect bones in a joint are overstressed, overstretched, or twisted unnaturally, resulting small tears in the ligament fibers.
While the term "strained ligament" is inaccurate, a strain and a sprain are very similar. Both injuries involve tearing of tissue, and both injuries require sufficient rest, icing, and rehabilitation to completely recover from the injury. The only real difference is the type of tissue being damaged: a strain refers only to muscles and tendons, and a sprain refers only to ligaments. When a ligament is strained, one will feel a sudden or sharp pain in a particular joint, followed by tenderness or aches. Minor ligament sprains may not prevent one from participating in physical activities, but more moderate or severe sprains will require sufficient time to heal. Sprained ligaments generally take longer to heal than muscle strains.
Much of the confusion — calling the injury a strained ligament rather than a sprained one — is also perpetuated because the injuries often feel similar and the treatments are similar. The injuries can also be incurred in the same manner. Twisting unnaturally, bearing an unexpected burden or a burden that is more weight than the muscles or ligaments can handle, or direct trauma can cause either a muscle strain or a ligament sprain. Both injuries may be accompanied by swelling or bruising, tenderness, aches, and loss of mobility, and both can be helped by icing and rest. The most severe sprains and strains often require surgery as well, as the ligaments or muscles become completely ruptured and must be reconnected.
A sprained ligament should be treated using the RICE method: rest, ice, compression, and elevation. Rest allows the ligaments to heal on their own, and it reduces the risk of re-injury. Ice keeps swelling down and dulls the pain. Compression also keeps swelling down, and elevation promotes blood flow and prevents bruising and swelling. A sprained ligament can take anywhere from a few days to several weeks to heal.