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.
Swelling of the knee can be caused by injuries to the joint as well as many different medical conditions. Depending upon the cause, knee swelling may be painful or may not produce any other symptoms. In some cases, you may notice tenderness, warmth, difficulties with moving your knee joint, muscle weakness, or bleeding or bruising. Injuries to your knee, including sprains (damage to the stabilizing ligaments of the joint), can lead to diffuse swelling of the knee area.