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A knee strain is an acute injury in which tendons and ligaments become stretched or torn. Most strains occur because of direct blows to the knee, extreme bending or twisting of joints, or overuse through repetitive activity. The most common symptoms include pain, swelling, loss of mobility, and a lack of strength. Depending on the severity of a knee strain, an individual may be able to ease symptoms and recover with rest and simple home remedies. A serious strain usually requires immediate medical attention, surgery, and several weeks of physical therapy.
Knee tendons and ligaments connect muscles to leg bones, provide stability, and allow the knee joint to move and bend. The anterior cruciate ligament (ACL) is an especially large, important ligament that is commonly strained in sports and other physical activities. The ACL and nearby tendons can be injured when the knee strikes the ground, or when a sudden twist extends the joint beyond its normal range of motion. Strains can also result from repetitive activity, such as lifting heavy objects or frequently sprinting and stopping.
A knee strain usually results in intense, immediate pain and swelling. An individual may find that it is impossible to bend the knee or put weight on the leg without assistance for many days. Damaged tissue becomes inflamed and stiff, and is usually very tender to the touch. A person may also notice a cracking or popping noise when moving the knee, which is a sign of internal swelling and pressure on the joint.
A mild strain, one in which the leg still has some mobility and the pain is not overwhelming, may heal in as little as two weeks. Healing time can be shortened by resting the leg as much as possible and icing the joint regularly. Over-the-counter anti-inflammatory drugs can help to reduce swelling, and a knee brace can be used to provide stability and cushioning. Once a knee begins feeling better, light stretching exercises can help to promote strength and flexibility. Doctors often recommend that people can take short walks and perform lunges to rehabilitate damaged knee tissue.
More severe, debilitating strains should be evaluated by licensed physicians. A doctor can examine the knee, take x-rays to check for tears and damaged cartilage, and decide on the best treatment. Some injuries require invasive surgery to mend torn tendons and ligaments. Recovery after knee surgery can take up to six months and typically includes regular sessions with a physical therapist. By working with a therapist and following doctors' orders, an individual with a bad knee strain is usually able to return to everyday activities and sports.