Egypt's second faith is Coptic Christianity. Copts are heirs of an ancient Christian rite. Coptic Christianity was the predominant religion in Egypt until the 10th century when a lot of Christians diverted to Islam. Christianity itself was brought in Egypt by St. Mark in the middle of the first century AD.
Other possible causes of swelling behind the knee include abscesses (infections); tumors of the skin, soft tissue, or bones; bleeding; deep venous thrombosis (blood clot in the deep veins of the legs); or deformity of the joint after a fracture of any of the bones of your knee joint.
Deep Vein Thrombosis (DVT) can cause leg pressure, swelling. Deep vein thrombosis (DVT) is a condition in which a blood clot forms in one of the deep-seated veins in your body. Certain genetic conditions increase your risk for DVT, as do medical conditions (such as obesity or pregnancy) and certain medications.