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 is one of the most common causes of knee pain at the back of the knee, and is due to inflammation of the popliteal bursa which sits behind the knee joint. Causes: It is usually caused by fluid associated with arthritis or a cartilage tear leaking into the bursa and causing it to swell, but it can occur after any damage to the knee.