Some causes of a swollen right leg are a sprained ankle, an anterior cruciate ligament injury, a broken leg, thrombophlebitis and lymphedema. Leg swelling is often caused by fluid retention in leg tissues. Problems with the kidneys, lymphatic system or circulatory system can also cause leg swelling, notes Mayo Clinic.
Swelling in the leg is very common after a serious injury. People who experience leg swelling should limit movement, elevate the leg to improve blood flow and contact a doctor. Thrombophlebitis is a condition in which a blood clot in the leg can cause swelling. Lymphedema is the build up of lymphatic fluid in the tissues due to problems with the lymph vessels or removal of lymph nodes, states WebMD.