Pain in the ankle joint for no reason can be caused by trauma, infectious and non-infectious inflammation, metabolic bone disease, and osteoarthritic tumors. 1. Trauma: If the patient accidentally knocked down or fell on the ankle, resulting in ankle sprain or ankle fracture, it may show localized pain, swelling and dysfunction of the ankle. 2. Infectious and non-infectious inflammation: common infectious inflammation, such as septic arthritis, acute osteomyelitis, mostly due to bloodstream infection, manifested as redness, swelling, heat and pain in the ankle area, accompanied by systemic symptoms of infection and poisoning. 3. Metabolic bone disease: such as gout, mainly due to abnormal purine metabolism in the body, there will be localized pain, redness and swelling of the ankle as well as gout stones. 4. Bone and joint tumor: common benign tumors, such as osteochondroma and osteoblastoma, the patient in addition to the symptoms of local pain, there will be local bony bumps. In addition to the above factors, there may be other reasons, it is recommended to go to the hospital as soon as possible for examination, after the doctor clarifies the cause of the disease, give targeted treatment.