Like other pains in the body, pain in the back of the knee can be caused by several conditions or issues. A Baker's cyst is a common cause, as is the presence of arthritis in the knee, or even muscle strains and ligament sprains. A direct impact or trauma to the back of the knee can also cause pain, and this is especially common among athletes or people participating in athletic activities. Some injuries will heal on their own with proper rest, though others may require more intensive rehabilitation to alleviate pain.
A Baker's cyst occurs when swelling from another injury leads to the formation of a cyst. Cysts are usually formed by excess fluid, which can build into a tough nodule that pushes out against the back of the knee, causing pain. The knee may swell, and it may become tender to the touch. The best way to treat a Baker's cyst is for the person to allow the leg to rest for a significant period of time and apply ice to the area. Heat may help as well. If the pain does not go away after a few days to a week, the sufferer should contact a medical professional to see if there are any other treatments available, such as a prescription anti-inflammatory medication.
Arthritis is one of the more common causes of pain in the back of the knee, especially among middle aged and elderly people. When the cartilage in the bones of the knee starts to wear out, it allows those bones to rub against each other, forming bone spurs that can press against surrounding nerves. Arthritis can be a very painful condition, and there are no cures for it, though steps can be taken to alleviate the pain and slow the degeneration of the knee joint. This usually involves taking pain medications and anti-inflammatory pills, as well as losing weight, gently exercising the joint to maintain its flexibility, and trying to avoid putting too much pressure on the knee.
Muscle strains and ligament sprains can cause pain in any part of the knee. Strains and sprains occur when muscles and ligaments, respectively, are stretched beyond their normal range, leading to tearing in the tiny fibers that make up the tissue. These injuries also generally heal on their own with plenty of rest and icing, though in more severe instances, surgery may be necessary to repair the damage.