Pain behind the knee possibly indicates a Baker's cyst, which is the accumulation of synovial fluid at the back of the knee, or deep vein thrombosis, which involves the formation of a blood clot in the leg, according to Healthgrades. An injury or inflammatory condition may also cause pain behind the knee.
Pain behind the knee refers to a sore or uncomfortable sensation behind the knee joint, explains Healthgrades. The pain may also involve stiffness, a burning feeling or unusual warmth. Some people suffer excruciating pain that restricts movement.
Synovial fluid decreases friction between the cartilages of the knee joints by providing lubrication, notes Healthgrades. In people with a Baker's cyst or deep vein thrombosis, typical symptoms include pain and bruises or swelling at the back of the knee or calf. Other possible causes of pain behind the knee include an overuse injury, rheumatoid arthritis, osteoarthritis, or a torn hamstring muscle, ligament or cartilage.
Deep vein thrombosis is a potentially fatal condition, as the blood clot in the leg can burst and lead to a stroke, heart attack or pulmonary embolism in the lung, according to Healthgrades. It is essential to contact a doctor immediately if a person suffers pain behind the knee and accompanying symptoms such as bruises or swelling behind the knee or calf, warmth or redness at the back of a single knee, or breathing trouble.