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.
What can pain behind the knee be a symptom of? Swelling from knee injuries and ailments produces lump-like appearances on both sides of the knee. For example, the bursa, a sac of fluid that protects and cushions the joints, can become irritated and enlarged, explains WebMD.