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.
Muscles of thigh end near the top of the knee joint, hence any strain to the muscles in front or back of thighs can cause swelling above the knee. Children and young adults with foot abnormalities like flat feet, knock knees or those with weak muscles can have swelling above the knee with overuse of knee joint.