A bulge in the ankle after a broken foot may be related to ankle ligament injury, ankle fracture, tendon sheath cysts, etc. 1. Ankle ligament injury: due to improper activities caused by the ligament tissue around the ankle joint stretching and tearing, local bleeding, manifested as pain, joint swelling, etc., bulging bag is caused by hematoma. 2. Ankle fracture: mostly due to external violence or indirect violence, ankle pain, swelling, tenderness and other symptoms, subcutaneous bruising, ecchymosis, may consciously ankle bulge a bag. 3. Tendon sheath cyst: it is a kind of cystic mass near the joint, and its etiology is related to long-term inflammatory stimulation, trauma, strain and other factors, and it can appear in the hand, ankle and other parts. Tendon sheath cysts are often hemispherical, and patients may present with a bulging ankle. There are many reasons that lead to a bulging ankle after a broken foot, it is recommended to go to the hospital in time, to clarify the cause of the disease.