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.
Activities such as bending the knee, kicking or running can worsen the pain. The calf muscle, or gastrocnemius, aids in propelling you forward while walking or running. A strain at the upper end of the gastrocnemius causes pain in the back of the knee that worsens with knee bending or rising to your tiptoes. The popliteus muscle helps stabilize the knee joint during movement. Injury to this muscle can be challenging to diagnose.