Bulging bags on the inner side of the feet may be caused by cysts, rheumatoid arthritis, gout, osteophytes or tumors. 1. Cysts: due to frequent walking on the lower limbs and excessive exertion related to the emergence of excessive local pressure, so that the synovial fluid in the joints and synovial membrane to the weak point of the bulging cysts. 2. Rheumatoid arthritis: rheumatoid arthritis will stimulate the synovial membrane hyperplasia, cause joint deformation, appear to cause ankle bulge. 3. Gout: Gout can cause gout stones, which can also lead to the appearance of localized painful lumps. 4. Osteomalacia: due to bone irritation. This will lead to narrowing of the joint space and localized hyperplasia, which will lead to hard lumps on the inner side of the ankle. 5. Tumor: the bulge on the inner side of the foot, there may be neoplastic changes, such as can be caused by subcutaneous lipoma or soft tissue tumors protruding outward. Patients should go to the hospital in time to determine the cause of the condition under the doctor’s diagnosis, and take appropriate treatment according to different situations for treatment.