Pain behind the knee can be caused by a Baker's cyst, which is typically mild, as stated by the Mayo Clinic, or deep vein thrombosis (DVT), which can lead to more serious blood clot issues, as described by WebMD. In order to properly diagnose pain behind the knee, professional medical attention is necessary, especially since the pain can be a symptom of something more serious.
A Baker's cyst can lead to a tight, uncomfortable feeling behind the knee, according to the Mayo Clinic. This is due to fluid buildup within the cyst, and the amount of pain or discomfort can be exacerbated with increased activity or certain leg movements. Typically, Baker's cysts are caused by arthritis, cartilage tears or other joint issues.
Symptoms of deep vein thrombosis include warmth, redness and swelling at the site of the blockage, as stated by WebMD. The pain can also be experienced in the calf or thigh. Pulmonary embolism, which involves a blocked artery in the lung, can be a sign of deep vein thrombosis. Symptoms to watch for include shortness of breath, chest pain that increases with deep breaths, coughing up blood, an increased heart rate and fainting. However, diagnosing deep vein thrombosis can be difficult, since the symptoms can also be a sign of other health issues.