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.
The hamstring muscle fibers gradually become tendon fibers near the knee to attach to bone. One can appreciate the thick tendon bands when feeling behind the knee joint. The hamstring muscle is balanced by the quadriceps muscles on the front of the thigh that cause the knee to extend. Together the hamstrings and the quadriceps help control power and stability of the knee joint, allowing activities like walking, running, jumping, and squatting.