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.
This muscle group acts to extend the leg while straightening the knee. A pulled or strained quadriceps muscle causes pain in the front of the thigh. A severe pull or muscle tear causes an abrupt, sudden, acute pain that occurs during activity (often while sprinting). It may be accompanied by swelling or bruises on the thigh.