The medial ankle swelling can be caused by the following reasons: 1, tendon sheath cyst or ankle cyst. When gout involves the ankle joint, there can be swelling on one side of the ankle joint, accompanied by redness of the skin and formation of gout stones, then the blood uric acid should be checked and the X-ray and CT of the ankle joint should be examined for early diagnosis and treatment; 3, ankle joint infection, when the ankle joint is infected with bacteria or tuberculosis, there can be local swelling, accompanied by an increase in skin temperature and systemic symptoms, such as fever. When there is a tumor in the local soft tissue of the ankle joint, there can be pain, swelling and pressure pain in the inner side of the ankle joint, and the swelling can be palpated, then the MRI of the ankle joint should be examined for diagnosis.