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.
Some of the fluid from the knee joint can drain to the back of the knee causing a swelling, called a baker's cyst. These are usually painful, unless they burst when the fluid can enter the calf muscles and cause swelling and burning there. The other source of swelling behind the knee can be a clot. Get seen.